Servo magazine 11 2007

Tạp chí Servo

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ENTER WITH CAUTION!

08 Robytes by Jeff Eckert

Stimulating Robot Tidbits

10 GeerHeadby David Geer

2007 FIRST Robotics Competition Winners

14 Ask Mr Roboto by Pete Miles

Your Problems Solved Here

by Bryce and Evan Woolley

Welcome to the (WowWee) Family

68 Different Bits

by Heather Dewey-Hagborg

Neural Networks for the PIC Microcontroller

Part 3 — Hebbian Learning

76 Appetizer by Bryan Bergeron

The Black Widow Contest Winner

78 Then and Nowby Tom Carroll

PAGE 62

Breathe new life into an old robot.

Features & Projects

SERVO Magazine (ISSN 1546-0592/CDN Pub Agree

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Jeff Eckert Tom Carroll Gordon McComb David Geer Pete Miles R Steven Rainwater Michael Simpson Kevin Berry Fred Eady Brett Duesing Brian Cieslak Mark Miller Robert Doerr James Baker Chad New Bryce & Evan Woolley Heather Dewey-Hagborg

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We are not responsible for mistakes, misprints,

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advertising placed in SERVO Please send all

In the commercial robotics world,

all eyes are on the recent iRobot

vs Robot FX patent infringement

lawsuits, in which iRobot is seeking to

prevent Robot FX from selling any

more Negotiator robots While there

are a number of facets to the case

destined for the tabloids, one

undisputed part of the story is that

the suit comes on the heels of a

competition between Robot FX and

iRobot for a $280M contract with the

US military Robot FX won the

contract Whether iRobot — maker of

the popular Packbot — gets another

crack at the contract, the suit is

important in that it marks an

important milestone in the growth of

the military robot industry

To follow my reasoning, consider

the Gartner Hype Cycle, a popular

model of technology-based products,

first proposed by the Gartner Group

(www.gartner.com) in 1995 (see

Figure 1) According to the model,

the first phase of a Hype Cycle is

the “technology trigger,” marked by

a significant breakthrough, public

demonstration, product launch, andrelated events that generate press andindustry interest

The next phase — the “Peak ofInflated Expectations” — is marked byover-enthusiasm and unrealisticexpectations In reality, there may besome successful applications of thetechnology, but there are morefailures than winners The onlyenterprises making money at thisstage are conference organizersand magazine publishers Followingthis over-hype and user/investorfrustration from unmet expectations,technology-based products enter the

“trough of disillusionment.” Becausethe press usually abandons the topicand the technology, this is the end formany products

Products that survive the trough

of disillusionment – which may lastmonths, years, or decades – are keptalive by companies that understandthe technology’s applicability, risks,and benefits The “slope ofenlightenment” marks the time whenthere is practical, commercially-viable

application of thetechnology – that is,some companies enjoycash flow

Finally, the productand underlying technologyreach the “plateau ofproductivity,” which ismarked by the appearance

of stable, accepted,second, and thirdgeneration products

Because it’s oftendifficult to directly track the few companiesthat are commerciallysuccessful during the

Trough of Disillusionment

Slope of Enlightenment

Plateau of Productivity GARTNER HYPE CYCLE FIGURE 1

“slope of enlightenment,” external events — such as lawsuits

— serve as useful indicators I’d like to propose this is the

lawsuit point (shown in red in Figure 1) between the ‘trough

of disillusionment” and “slope of enlightenment.”

Historically, companies producing products aren’t

bothered as long as they’re in an academic lab or smoldering

in a company barely making a profit on the technology

However, as soon as the technology — and market — are

mature enough to generate significant, sustainable revenue,

then holders of patents (and their attorneys) take notice The

motivation for a suit may be strictly monetary Some patent

holders develop and hold on to a patent with no intent of

developing a product Instead, they hope that a technology

will become viable before the term of their patent ends A

suit may be motivated by competition from a rival in the

marketplace In some cases, a suit is simply to establish the

right of a company to compete in a given market

The iRobot–Robot FX suit suggests that the military

robotics industry has survived the trough of disillusionment

and is well on its way to the slope of enlightenment There

have been lawsuits in medical robotics, a sign that the

robotics industry is making progress in this area, as well

How long before we see major lawsuits for home robots

or assistive robots is unclear However, when we do see

lawsuits, it’ll be a sign that the field is maturing Hopefully, the

robotics companies involved in these suits will be financially fit

enough to not only survive but thrive in the new economic

environment SV

Dear SERVO:

Regarding the 09.2007 issue beginning on page 67, “TwinTweaks — Robot vs.Wild” the problem stated was that theautomotive steering vehicle had trouble making tight turns.The Wooleys solved part of the problem quite accurately withthe Ackermann steering geometry, but you still have a solidrear axle (wheels, axle, and drive gears acting as a single unit).Thus, driving both rear wheels with relatively equal forcewhen you try to turn, the front end gets pushed and you wind

up going in a wider radius than the front wheels are set for Inthe process of turning, the rear wheels want to slip becausethe outside wheel is traversing a larger arc than the insidewheel If you’re going in a straight line, like drag racers do, asolid rear end is great But if you want to make some turns,then you need a differential And they almost had it — looking

at the photo on the bottom of page 69 titled ‘Vex Differential.’You need to cut the axle in two (a loose sleeve joining the twoends will allow independent motion and still keep the axlesrelatively concentric) and put a bevel gear on each axle end sothat they mesh with the third bevel gear that’s attached to thedifferential carrier This will allow continuous power to beapplied to both rear wheels, irregardless of each wheel’sspeed.You guys are doing great — hang in there.You’ll neverknow what you can do until you push your limits

— Phillip Potter

continued on page 75

Autonomous Refueling

Demonstrated

The Defense Advanced Research

Projects Agency (DARPA, www.

darpa.gov) has added to its bag

of aeronautical tricks with the

Autonomous Airborne Refueling

Demonstration (AARD) program,

through which it has demonstrated

the first-ever robotic system to refuel

airplanes in flight

In a recent series of tests, the

AARD was fitted to a NASA-owned

F/A-18 Hornet fighter and operated

out of California’s Edwards Air Force

Base Using inertial, GPS, and video

measurements — along with some

special guidance and control

techniques — the AARD managed to

poke a refueling probe into a 32-inch

basket while traveling 250 mph

at 18,000 ft above the Tehachapi

Mountains Some tests were

conduct-ed in straight-and-level flight, under

a range of turbulence conditions that

involved as much as five feet of

side-to-side movement of the drogue

(the small windsock at the end of the

refueling hose)

In its most successful

configura-tion, the AARD hit the target in 18

out of 18 attempts It also managed

to make the connection when the

707-300 tanker and F/A-18 were

executing a turn, which is not usually

attempted with a human pilot In

the tests, the fighter was operating

autonomously; the pilots shown inthe photo were on board “for safetypurposes.”

UAV for Farmers

Most of the glory in the UAVarena goes to exotic military and security aircraft, but a fleet of miniature planes may soon create abuzz over the fields and forests of theheartland, providing surveillance forfarming, environmental monitoring,and forestry

MicroPilot, Inc (www.micro

pilot.com), based in Stony Mountain,

Manitoba, offers a range of UAVs,autopilots, and software products,including the MP-Vision airplane

Earlier this year, MicroPilot’s Crop

Cam division (www.cropcam.com)

introduced a version that has beenconfigured specifically for agriculturaloperations

The CropCam AUV is a guided craft that covers a preprogrammed flight pattern over aquarter section (160 acres) andtakes digital photos along the way

GPS-With an overall length of four feetand a wingspan of eight feet, thesix-pound plane can climb to 2,200feet and complete a survey in about

20 minutes Guidance is provided by

a Trimble GPS unit, and you canchoose among three Pentax cameramodels to get up to eight megapixelresolution for stills and 640 x 480, 30fps, in video mode

Power is provided by a 0.15 cu inengine that draws from a six-oz tank,but it appears that you can also getone that is driven by an Axi brushlessmotor and lithium polymer batteries.Rumor has it that it will run you about $7,000

Bionic Hand Now Available

The Touch Bionics’ (www.touch

bionics.com) i-LIMB Hand, formally

introduced in July at the 12th WorldCongress of the InternationalSociety for Prosthetics andOrthoticsin Vancouver, Canada,looks like a great innovation forpatients who are missing ahand through accidents, acts

of war, or birth defects.Designed to look and operatelike the real thing, it is said to

be the world’s first

commercial-ly available prosthetic devicewith five individually powereddigits

The device operates on anintuitive control system thatuses a traditional myoelectricsignal input to open and closeits fingers Myoelectric controls

The AARD system performs

“better than a skilled pilot.”

Photo courtesy of DARPA.

Image taken by a CropCam AUV.

Photo courtesy of Cropcam, Inc.

The i-LIMB Hand looks and acts like the real deal.

Photo courtesy of Touch Bionics.

by Jeff Eckert

use electrical signals generated by

muscles in the remaining portion

of a patient’s limb, with the signal

being picked up by skin-mounted

electrodes Not shown in the photo is

the available “cosmesis” covering,

which makes it appear more lifelike in

use The device is already being fitted

to patients in many clinics in the US

and Europe

Build Your Own ROV

It’s not pretty, but at least it’s

pretty cheap Designed for ages 12

and up, the ROV-in-a-Box kit from

!nventivity (www.nventivity.com)

sells for $249.95 and includes all of

the required parts (frame, motors,

light, camera, tether, controller,

and battery), plus an instruction

manual It also comes with

propellers, switches, connectors,

“buoyancy devices” (presumably the

chunks of plastic foam shown in the

photo), and pretty much everything

else All you have to provide is PVC

cement, tools, and a video monitor

According to the vendor,

independent left and right props give

it good controllability and zero-radius

turning, and the light is bright

enough to allow night missions

See the company’s website for a six

minute video

Interactive Boybot

He looks quite a bit like theJapanese comic book characterAstro Boy, but the new Zeno bot

from Hanson Robotics (www.hanson

robotics.com) is actually named

after the inventor’s son Zeno’smain claim to fame is how well heimitates human facial expressions,but he also walks, talks, and canlearn to recognize individual humanbeings (using a camera locatedbehind one of his eyes) and addressthem by name

Like other Hanson creations (recallthe familiar talking Einstein bot), Zeno

is based on AI capabilities that helphim learn and interact with his environment, a complex range (62, to

be precise) of facial and neck expressions, his somewhat weirdFrubber™ polymer skin, and the ability

to develop a unique personality.According to Hanson, Zeno and hispals can be used in education, psychiatry, military training, and character development for animation.Some people find him adorable,and others have described him as

“creepy,” so you’ll have to judge foryourself Zeno is still a prototype, butthe plan is to have a commercial version on the market in two years for

R o b y t e s

The ROV-in-a-Box kit comes

more or less complete.

Photo courtesy of !nventivity LLC.

Zeno — a 17-inch mechanical boy — walks, talks, and interacts

on a personal level.

Photo courtesy of Hanson Robotics.

In 2007, the Worcester Polytechnic

Institute (WPI) supported

Massachusetts Academy of

Mathematics and Sciences at WPI (or

MASS Academy, Team 190) won the

FIRST Robotics World Championship

in the Georgia Dome in Atlanta on

April 14 Team 190 designed and

constructed the winning robot —

Goat-Dactyl — early in the season

Goat-Dactyl is a wheel-locomotive

robot with sensors for autonomous

control and R/C for remote Team 190

designed the robot to accomplish

specific, competition-related tasks as

part of the FIRST 2007 competition

The robot completes the tasks as part

of a game in competition and

collabo-ration with other teams’ robots

This year’s competition game —

called “Rack ‘N’ Roll” — tested the students’ and their robots’ ability to (1)hang inflated colored tubes on pegs,configured in rows and columns, on a10-foot-high center “rack” structure;

(2) program a robotic vision system tonavigate the robot; and (3) “lift” otherrobots more than 12 inches off thefloor, according to Brad Miller, a Team

190 member

The leaders of the competitionformed the aforementioned rack structure out of eight columns withthree pegs each on which robot teamscould place their tubes

“Every other column had a greenlight The teams calibrated theirrobots’ cameras to track the light

Six robots took the field during amatch Officials assigned the robots

to either the blue or red alliancefor competition The teams earnedpoints by hanging their alliance-coloredtubes on one or more of the rackpegs,” says Miller

According to Miller, each hungtube was worth two points unless itwas contiguous (either vertically orhorizontally) with another hangingtube of your alliance color “Thetotal point count in this case wasequal to two raised to the powercorresponding to the length of thematched tube row or column (e.g., onetube = two points, two tubes = fourpoints, three tubes = eight points afull circle of eight tubes = 256points!),” Miller explains

Team 190 made the Goat-Dactylrobot from a kit that every team had toadhere to The kit includes parts for therobot’s pneumatic and electrical systems, as well as a choice of motors.The robot itself consists of four CIM FR801-001 motors, which drivethe robot

The large, broad metallic gripperthat is the primary capability of therobot opens and closes with the aid of

an RS-540 gear motor (Banebots) TwoGlobe 409A587 motors actuate therobot’s ramps

The team machined both the

Contact the author at geercom@alltel.net

by David Geer

2007 FIRST Robotics Competition Winners

The FIRST (For Inspiration and Recognition of Science and Technology)

Robotics Competition pits high school robotics teams against each other

(and themselves!) with a different robot kit and task each season.

Students with Goat-Dactyl competition

robot and control console queuing up

before a match The driver is thinking

about strategy Dan Jones, robot

operator, is in the foreground and

Colin Rody, driver, is in the background.

Goat-Dactyl, mouth wide open, just before completing the lift of alliance partners Dan Jones, operator, operating the controls in the background.

chassis and gripper elevator from

scratch They used 6061 aluminum

C-channel and Lexan materials They

cut the lifting ramps via laser out of

5052 aluminum sheet metal They

used sheet metal in gauges ranging

from 02” to 065” in thickness

Team 190 folded the aluminum

ramps over, dimpled them with holes,

and then riveted everything together

The gripper top is Lexan; the gripper

bottom is fiberglass

The pneumatics included a

Thompson compressor, accumulator

tanks from Clippard, solenoid

valves from SMC and Parker, and

Bimba actuators

The actuator specs included three

1.5” bore by 3” stroke cylinders per

side of the robot, which presented

sufficient force to lift competing

robots off the floor by more than

a foot The robot also featured a

.75” bore by 8” stroke cylinder for

grabbing onto and lifting the large

inflated rings

Both of these maneuvers were

useful for competition scoring

Computer Controlled

Each team is constrained to a

kit that includes two PIC 18F8722

microprocessors One is the slave and

one is the master processor The

master processor controls the motor

and communications and interfaces

with the human operator

The slave contains all the original

programming from the team’s coders

The robot passes some data between

the master processor and the slave to

process the actuators’ values

Team 190 coded the robot’s

program in the C language The

coders used both the Microchip

tools that come with the kit, and the

Eclipse IDE

While teams in the FIRST

competi-tion can stick with Microchip’s tools

that come with the kit, they are free to

use other programming tools

“Our students use Eclipse as the

development environment (IDE) for

work developed by other teams tomake a development environmentthat suited us Eclipse has a hugenumber of collaborators so eventhough it’s free, it is much higherquality than many of the commercialproducts,” says Miller

Team 190 also uses a softwarelibrary named WPILib, which is a development framework that supportsthe standard FIRST devices like speedcontrols, the CMU camera, and gyros,for example

Command and Control

Team 190, as other teams, built acustom control system for interfacingwith the competition-specified operator interface That interface is thecontrols that enable the drivers and therobot to “talk” to each other

The FIRST supplied controller connects with joysticks, switches,potentiometers, and other controlhardware The controller transmits

“control positions” to and from therobot This enables the robot’s driver tomanipulate the robot in competitionwhile designing a unique set of controls for their purposes

Team 190 used two joystick controls for driving, and a separatecontrol box of “arcade buttons” and switches to control the tubemanipulator and robot-lift functions,according to Miller Two operators handle the robots, one controlling the drive and the other controlling themanipulator and peripheral functions.The robot has many sensors,which help automate tasks such as lowering the robot’s lifts and raising the tube manipulator to

Team 190 members Dan Jones, operator, (back) and Paul Ventimiglia, mechanical lead (front) making last minute repairs

on the robot between matches.

Team 190 putting a tube on the rack despite blocking attempts by

a robot from the red alliance.

Team 190 hanging a tube on the middle section of the rack.

During selection for team alliesbefore competition, Team 190 chose teams with compatible designsand tactics

“Through our excellent scoutingand “intelligence” program, we wereable to pick teams that we knewwould make our alliance strong Littledid we realize that they would alsomake us look good, as well,” says BradMiller, a Team 190 member

From among all the possibilities,Team 190 ended up collaborating withteams that all had maroon team shirtcolors similar to their own

“Denying that matching team shirtswas one of our selection criteria, wenonetheless took this as a good sign and have since celebrated thisoccurrence by producing “Don’t MessWith Maroon” championship shirts,”

SELECTING ALLIES

pre-specified heights.

The goals for the robot were to

endow it will the best abilities to win

the game set before all the robots

while staying within competition limits

The major constraints for the robotsinclude weight — 120 lbs and under —total size, the ability to recognize

other robots, compete better thanother robots, and to stay within cost limitations

The Answers

In response to these goals and limitations, Team 190 worked on lowering their bot’s weight whileattaining its overall goals

“Our original robot-lift design wasdouble the acceptable weight Wewent through many different designapproaches, including using aluminumhoneycomb surfaces or making ourown foam-core sheets, before finallysettling on a unique sheet-metal boxstructure which was dimpled forimproved strength This same approachwas used in nearly all aspects of thedesign,” says Miller

The tube gripper lays in front ofthe robot to grab tubes from theground and catapult them high in theair to rack them up for scoring (Thetube gripper is in the front of the robotthat can grab tubes from the groundand lift them to any height on the rackfor scoring.)

“Two of the unique features ofthe gripper are: It can grab tubes

on the fly, without requiring the robot to come to a stop to pick themup; and second, it closes and lifts using a mechanism driven by a single pneumatic actuator Usually two motions like this would requiretwo actuators, but due to some clever design, only one is needed,”Miller explains

The team mounted the tubegripper on an extension mechanism(elevator) to get it to the right heightafter it grabs the tube and sets it tothe proper angle, Miller furtherexplains The gripper is empowered

by a single air cylinder that bothcloses the robot’s claw and raises thetubes up to a 55 degree angle in asingle motion

“In addition,” says Miller, “the top digit of the claw is a four bar articulated linkage that curls aroundthe tube, giving us maximum

Worcester Polytechnic Institute

Goat-Dactyl using its tube gripper to

lift a tube during competition.

The robot’s tube gripper is mounted on

an extension mechanism (an elevator)

that it uses to get it to the right height

after it grabs the tube and sets it to

the proper angle.

Team 190 between finals matches, on the field resetting the robot to play again while being overlooked by head ref, Aidan Browne.

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Q. It is my understanding that

the HSR-8498HB servos that

are used in the Robonova

humanoid robot have position

feedback capabilities, so I bought a

couple of them from Tower Hobbies

I have been trying for several days

now to figure out how to get position

data from these servos

From what I have seen on the

Internet, all I have to do is send the

servo a 50 microsecond pulse, and

it will return a position signal that is

similar to the regular pulse width

to move the servo I am missing

something here Can you help me?

— Pete Senganni

A. The key to doing this is to use

a pullup resistor on the signalline This is required for bi-directional communication since the signal line is an open collector

Figure 1 shows a simple schematic forconnecting an HSR-8498HB servo to

a BASIC Stamp Here, I used a 1K ohmresistor as a pullup resistor on thesignal line Without the resistor, you will not receive a signal back from the servo Figure 2 shows a

sketch of the PWM (Pulse WidthModulation) control signal timing that

is required for this servo to return itscurrent position

To obtain the current position ofthe servo, you need to send a 50 µspulse to the servo then wait for a minimum of 2 ms before measuringthe width of the return pulse The critical element required to measurethe pulse width is to make sure that the servo signal line that is connected

to the microcontroller is changed from

an output signal line to an input signalline immediately prior to measuring

Tap into the sum of all human knowledge and get your questions answered here!

From software algorithms to material selection, Mr Roboto strives to meet you where you are — and what more would you expect from a complex service droid?

P9

P12 P11 P13 P15 RES

VDD VIN

1 K Ω +5V

SIGNAL GND 4.8-6.0V +4.8 - 6.0V SERVO POWER

HSR-8498HB SERVO AND CABLE

SERVO

Figure 1 Connecting an HSR-8498HB servo to a BASIC Stamp for positional bi-directional control.

the pulse width Or there will be

no return signal from the servo (that

you can see)

The following BASIC Stamp

sample code is all that is needed to

measure the position feedback from

the HSR-8498HB servo This code

sample assumes that the signal line is

connected to P15 on the BASIC Stamp

The Delay_50us constant of 63 is the

conversion factor for a 50 µs time

delay on a BASIC Stamp 2px This delay

constant will be different for different

Stamps The “tmp*8/10” is a

conversion factor to convert the

PULSIN value back to microseconds

on a BASIC Stamp 2px (again this

conversion factor will be different for

different BASIC Stamps)

Because of the pullup resistor, the

logic state of the Servo_Pin will be

high when it is not driven Since

the PULSOUT command on a Stamp

toggles the current state of the output

pin, it is manually set LOW prior to

servo, so the servo will

positive pulse On a

BASIC Stamp, the

PULSIN command

auto-matically changes the

pin’s state to an input

state, so nothing

spe-cial needs to be done to

measure the incoming

pulse from the servo

This program will

continually read the

position of the servo

and display the results

on a debug window

When the servo horn is

the right), the position will change

on the debug window Notice what Isaid here — when the servo horn ismanually turned Whenever the position is being read, the power to theinternal motor of the servo is turnedoff, which allows the servo horn to beeasily rotated by hand This is actually

a good feature to have when you areposing a humanoid robot for teachingnew body positions The drawback tothis, however, is that the motor losespower for a moment when the position

is being read This may cause someservo jittering in some closed loopposition control applications

The HSR-8498HB servo doesrequire the position command pulse to

be updated every 20 ms, like regularanalog servos If you continually readthe servo’s position once betweeneach position update cycle (i.e., onceevery 20 ms), the servo will jitter, and

have about half the normal outputtorque It is best to read the servotorque once every several positionupdates, such as once every fiveupdate cycles (or once every 100 ms).This will begin to minimize the amount

of servo jitter and torque loss due toreading the servo position

For those that are not familiar withthe HSR-8498HB servos, these servosare specifically designed for roboticapplications They look quite a bit different from standard R/C servos.Figure 3 shows a photo of two ofthem One of the nice features of theseservos is that they can be reconfiguredfor different applications, whichincludes a “bearing” joint at the bottom of the servo case, so that themain servo horn isn’t supporting theentire weight of the robot when theservo is used as a joint

Figure 3 shows one of these servos

Figure 3 HSR-9498HB servo configurations;

traditional servo configuration (left); RoboNova servo-bracket configuration (right).

50µs

500 - 2500 µs 2µs (MINIMUM)

OUTPUT FROM MICROCONTROLLER

TO SERVO

OUTPUT FROM SERVO

No-load Speed @ 4.8V 0.26 sec/60°

No-load Speed @ 6.0V 0.20 sec/60°

Stall Torque (4.8V) 84 oz/in (5.2 kg-cm)

Stall Torque (6.0V) 103 oz/in (7.4 kg-cm)

Idle Current Draw 8 mA

No-load Current Draw,

Running 200 mAStall Current Draw 1200 mA

configured to look like a standard

R/C servo, and the other servo is

configured for a robotic knee joint

Each servo comes with an accessory

package with the different

configura-tion opconfigura-tions Table 1 shows the

specifications for this servo

noticed that wires to theservo are all black, and not thetraditional yellow-red-blackcolored wires in other Hitecservos This can make determining the signal wirefrom the ground wire a bitchallenging The signal wire isactually dark-gray in color, but

it can be difficult to see Thesignal wire is the wire closest

to the two tabs on the side ofthe connector housing (seeFigure 4) The power wire is inthe center, and the groundwire is on the other side of the connector

One of the advancedfeatures of these servos isthat they can also be controlled andprogrammed via RS-232 serial communications In fact, 127 of theseservos can be daisy-chained together

on one signal line In addition, the serial communication protocol canallow changing the proportional and

the servo, servo ID, battery status,position, current draw, and turning theservo on and off

The servos that I used for thisanswer had an older firmware versionwhich doesn’t allow for the serial communication The minimumfirmware revision must be at leastv1.10 There is a little sticker on theinside of the servo’s bottom platewhich identifies the firmware version Ihave sent my servos back to Hitec tohave the firmware version upgraded.Next month, I will continue this topicwith a discussion on how to use serialcommunications to control this servo.For more details about the PWMposition feedback signals and theserial communication protocol, go to

the Hitec Robotics website (www.

hitecrobotics.com) and look under

the download page for the “Pulse ofHMI Protocol” subject There you willfind a file called “HMIprotocol.pdf,”that will keep you busy until next

Figure 4 Closeup view of the connector for

the HSR-8498HB servo — the control signal wire

is dark gray in color located next to the side tabs

>_j[Y Ej^[h8hWdZ.EW

+656*

6SHHGVHF 7RUTXHR]LQ 6WHHO*HDUV

+656*

6SHHGVHF 7RUTXHR]LQ 6WHHO*HDUV

+657*

6SHHGVHF 7RUTXHR]LQ 7LWDQLXP

$//63(&,),&$7,216$792/76

Know of any robot competitions I’ve missed? Is your

local school or robot group planning a contest? Send an

email to steve@ncc.com and tell me about it Be sure to

include the date and location of your contest If you have a

website with contest info, send along the URL as well, so we

can tell everyone else about it

For last-minute updates and changes, you can always

find the most recent version of the Robot Competition FAQ

at Robots.net: http://robots.net/rcfaq.html

— R Steven Rainwater

The former George Air Force Base, Victorville, CA

Autonomous ground robots compete against each other in a simulated urban environment tocomplete a waypoint-following course

www.darpa.mil/grandchallenge

10-11 Canadian National Robot Games

Ontario Science Center, Toronto, Ontario, Canada

Events include novice, advanced, and master mini-Sumo, full-size autonomous and RC Sumo,fire-fighting, line-following, photovore, a walkingrobot race, and a search and rescue contest

http://robotgames.ca

16-17 All Japan MicroMouse Contest

Tsukuba International Conference Center, Tsukuba, Japan

Includes Micromouse, Micromouse Expert level,and Micro Clipper events

www.robomedia.org/directory/jp/game/

mm_japan.html

Museum of Nature and Science, Dallas, TX

The usual assortment of events including Quick Trip, T-Time, wall-following, line-following, and can retrieval An outdoor waypoint-following eventknown as the Long-Haul will also be included this year

com-www.marinetech.org/rov_competition

Museumsquartier, Vienna, Austria

A competition for “cocktail robots” that includesevents such as serving cocktails, mixing cocktails,bartending conversation, and lighting cigarettes

Santiago, Dominican Republic

Autonomous robots compete in line-following andmini-Sumo events

www.aiolosrd.com

Texas Tech University, Lubbock, TX

Students and corporate sponsors build robots fromstandardized kits and compete in a challenge thatchanges each year

www.texasbest.org

Beard-Eaves Memorial Coliseum, Auburn University, Auburn, AL

Regional BEST teams from multiple states compete

in this regional championship

www.southsbest.org

Penn State Abington, Abington, PA

Autonomous robot basketball event in whichrobots must pick up foam balls and shoot or dunkthem into a basket

www.ecsel.psu.edu/~avanzato/robots/con

Send updates, new listings, corrections, complaints, and suggestions to: steve@ncc.com or FAX 972-404-0269

2 MHz Pulse-Width Modulator

Inc., now offers theMCP1631 2.0 MHz, high-

speed pulse width

modula-tor (PWM) The highly

inte-grated device contains a 1

ampere integrated MOSFET

driver, high-speed

compara-tor for over-voltage protection, and both battery-current

and voltage-sense amplifiers in one small package

Protection features, such as under voltage lock out (UVLO)

and over-temperature protection, come standard with the

PWM, which is capable of charging multiple battery

chemistries, including Li-Ion, NiHM, NiCd, and Lead Acid

The MCP1631 PWM provides a means to close the

feedback loop in Switch-Mode Power Supplies (SMPSs)that use microcontrollers for general system intelligenceand control The integration of the PWM’s SMPS input andoutput interface via its voltage comparator, battery-voltage, and current-sense amplifiers — plus its 1A MOSFET driver — enable designers to use this single device

to perform many different functions in their designs Theresult is a smaller design footprint and lower overall cost.Additionally, the MCP1631 is controlled by an easily-programmable microcontroller, meaning that exact chargeprofiles for a variety of battery-charging systems can beaccurately met, while closing the feedback loop with thespeed and precision needed for safe charging and long bat-tery life The PWM’s UVLO and over-temperature protectionfeatures enhance the safety of battery-charger designs.High-voltage versions of the MCP1631 PWM are available (Part # MCP1631HV), which operate from 6V to16V and include a linear regulator (LDO) The standardversions of the device operate from 3V to 5.5V, and do notinclude a LDO Possible applications include handheld

CONTROLLERS & PROCESSORS

· 2 Serial Ports including Bi-Directional USB

· The Wiring Programming Language The Wiring language provides a simplified subset of

C or C++ that hides more advanced concepts like

classes, objects, pointers (while still making them

accessible for advanced users) You get the power

of C or C++ with the ease of a language like Basic.

Programs execute at full C++ speed on the board.

• Dual quadrature encoder support

• Programming cable included with kit

• No additional hardware needed

• Works with BASCOM and AvrDude programming software

Ideal for controlling your small robot With a Microcontroller

and onboard motor controllers, you get all the electronics

that you need (except sensors) on one board.

Kit $37.95 / Assembled $41.95

Programmable Robot Kits

INEX MicroCamp Mega8

· Atmel ATMega8

· Dual DC motor drivers

· 2 Buttons, 2 LEDs

· Serial port

· 5-Analog ports for sensors

· +5V switching power supply

As no soldering is involved and the parts are fully reusable, you can build and rebuild programmable

robots as many times as you like.

$89.95

Also Available:

Electronic Components Servos Motors Hardware Wheels & Tires and More!

More New Products on the way!

medical, consumer, and industrial electronic devices that

require power management and SMPS technology, with a

focus on battery charging Examples include intelligent

power supplies, smart battery chargers, RF remote

devices, handheld scanners, parallel power supplies, and

AC power factor correction

For further information, please contact:

Robot Controller

Board That Does it All

announces the BOTLOGIC Controller

This 4 x 6 inch board controls up to 32

RC servos; 24 of these servo channels

have load sensing circuitry to allow

robots to detect the amount of force

being applied by each servo This servo

feedback will help a robot sense when

a leg has touched the ground, as well

as how much of the robot’s weight is

on each leg When used with a gripper, it will helpdetect when the gripper has touched an object andhow much force the gripper is actually applying to anobject Twenty user inputs are available for connecting

to bumper switches or other sensors, allowing yourrobot to explore its environment Also on-board is a three-axis accelerometer which is perfect for today’s balancingBOTs The built-in SD card interface can be used for load-ing new programs into the robot, as well as storing dataand sound files to use with the built-in audio recordingand playback circuitry User messages or diagnostic datacan be displayed on the 2 x 16 character LCD High current LED drivers can deliver power to up to six externally mounted high brightness LEDs to illuminate theenvironment, show system status, or just look cool Thethree two-amp solenoid drivers can be used to poweraccessories such as motors or fans The daughterboardconnector allows for future expansion or customadd-on features

Control your robot with the optional wireless interface to a PC or through most wireless/wiredPlaystation 2 Gamepad controllers Development toolsare available for both Basic and C

For further information, please contact:

Featured This Month

Participation

22 Being a Safety Jerk

by Kevin Berry

23 Rules for First Time

Participants by Kevin Berry

25 Results — Aug 11 - Sep 11

27 Upcoming — Nov & Dec

tougher job at an event thanbeing the Safety Officer (exceptfor Event Organizer, that is)

Most of the builders are yourfriends, they’ve worked hard toget ready, and are very posses-sive of their designs You — asthe person in charge of keep-ing people from getting hurt

— have a real responsibility

to do the right thing

The first step whenasked to be a SafetyOfficer is to have a discus-sion with the EO Youneed to understand theirtolerance for “gray areas” in

the rules For example, if the rulesays a bot must “spin down” in 30seconds, what do you do with a

“33 second” bot? Do you insistthey meet the 30 seconds, are you allowed to use judgement,

or do you refer this to the EO? Understanding the rules ofengagement is an important step

in avoiding misunderstandings.The next step is to communi-cate with the participants ahead

of time, if possible Let them knowyou are going to be tough onenforcement, so they aren’t surprised during check-in EOsvary widely on safety, so someonecoming from an “easy” event to a

to seasoned pros Like our “Welding Special” and “Heavy Power”

editions, this is intended to be a resource for builders who want to create tougher, nastier bots Which

is really what the sport is all about! — Kevin Berry

Rules for First Time Participants

● by Kevin Berry

Starting in any new sport, club,

or activity brings with it some

uncertainty, hesitancy, or just plain

lack of knowledge Robot combat is

certainly the same way, especially

when coupled with the concept of

instant destruction of your hard-built,

first creation!

Like anything in life, the best

approach is a combination of humble

demeanor and regular, thoughtful

questioning Veteran builders

represent a cross section of society:

from casual participants to intense

competitors; tolerant to impatient;

non-technical to deeply specialized

No matter how tolerant or patient,

nobody wants to reply to a post or

email like this one: “I want to build a

robot and I don’t know how What

do I do?” The first answer to thistype of question is “do the research!”

There are several good books, manyteam and club websites, and locatorsfor nearby competitions that areavailable to first time builders

Next, lay out a design Even ifyou aren’t sure exactly what you aredoing, give it a try Builders are muchmore likely to give advice if it’s in context of a potentially buildable bot,rather than a mythical dreammachine “I laid out this bot usingthe Whyachi gearboxes, but I reallycan’t afford them Anyone got experience with less expensive alternatives like modified HF drillmotors?” This kind of question will

be much better received and — moreimportantly — get a better answer

Builders are busy people and reallydon’t want to spend a lot of time educating people who won’t do their homework

Finally, try to meet some builders

in person Sure, we’d all like to take abot to our first event, but maybe

a better approach is to go as a volunteer, get access to the pits,spend time with participants, andlearn, learn, learn! There has neverbeen an event held that has hadenough willing hands, skilled or not

I know after getting eliminated

in the very first fight of a three day event, my son and I spent the next two sweeping the box and wrangling bots, and had a hugely successful introduction to the sport SV

As in the USA, the sport of robot

combat lives on in the UK,

despite the continued absence of

newly televised events on the scale of

Robot Wars and Battlebots This

sport survives only for the efforts of

those few dedicated event

organiz-ers On both sides of the Atlantic,

these events sustain robotcombat In turn, it is therobot builder and theirmachines that sustain theevent organizers and their

“tough” one might be shocked or

angry if they are denied entry

The final step during actual

safety checks is to make sure to be

calm, level-headed, and non-involved

That means making the rules the bad

guy, not the Safety Officer “I’d like

to overlook that weapon twitch, but

the rules say ‘no movement,’ and it’s

underlined, so you’re going to have

to fix it.” Another tack is personal,but not threatening “If you or someone else gets hurt, I’m going tofeel terrible about it, even if you sayit’s not my fault Let’s work together

In the long run, out of the frenzy andemotion of an event, it’s easy to seethat if the rules are known, buildersshould follow them, and our sportprides itself on a clean safety record

No builders, staff, or spectators hurt.Period SV

A selection of robots from the Xbotz fleet The current update aims to use just two speed controller types across all

of the robots.

UPDATING THE BRITISH FLEET Evolution of a Rob t Army

● by James Baker

events The more combat robots

available to event organizers, the

stronger our sport becomes

My teammates and I (TeamXbotz) keep a robot battle fleet big-

ger than most, but as in the military,

even the biggest fleet needs to be

kept up-to-date and at the sharp

edge to survive

The Xbotz fleet has been fighting regularly for a couple of

years now, and to be honest, are

starting to look very tired The

technology they use is now seven

years old in some cases, so a major

update of all the robots is now beingundertaken This article hopes to give

a little insight into the efforts of oneteam to stay competitive, but alsopractical, as running an active fleetthis big is a huge drain on time andresources, but I personally think it isreally worth it We are still buildingnew machines, as well

For whatever reason, be it arenaconfiguration, available components,

or a wider statement of nationalstereotypes, the past has shown thatthe majority of British robots lackedthe horsepower of their Americancousins, relying instead on good control and agility to bring theirweapons to bear, but leaving themvisibly slower

By far, the most popular drivesolution for robot combat in the UKwas the Bosch 750 watt, 24V motorwith 4QD speed controllers This was

a good solution for us, and it wasrare to see someone successfully use more powerful drive systems

All of the currently active Xbotzheavyweight robots originally used4QD speed controllers

It is a big job to completelyoverhaul a heavyweight fightingrobot, but to update a whole fleet

of heavyweights, featherweights,hobby weights, and artbots within arealistic timescale and budgetrequired a very clear decision-makingprocess We decided that theupgrades must all be reliable; easy touse; offer a packaging, weight, orsize advantage; and be good valuefor the money We also decided that logistically, having all the robots

on common components where possible would be a huge advantage.This is mainly so we can carry fewerspares

First upgrades on the list werechassis, armor, and weapons, butthose subjects are a whole other article, so we can skip those for now.Second on the list were drive sys-tems — namely motors, gearboxes,batteries, and speed controllers Thewheels are fine as they are

All the robots have good, proven drive systems already, sorather than change the motors andgearboxes, it made more sense to us

well-to update the speed controllers andbatteries only

Speed controllers are one area

of your robot you must get right, oryou will always struggle in the arena

We did not want to take advice and

“Wheely Big Cheese” climbs the fence at a school science fair.

Our 60 lb walking artbot “Venom” with electric crushing pincers uses a single Robot Power Scorpion XL and R/C switchers.

The 30 lb robot “Bug” with electric grabber,

uses a Scorpion XL for drive and an

Mtroniks Viper for the grabber.

Our 220 lb robot “Wheely Big Cheese” with

250 lb driver James Baker This robot lost

five lbs just by swapping to a Sidewinder.

The 30 lb robot “Tantrum” uses NiMH batteries and a Scorpion XL for drive, with separate NiCd cells for the weapon motor.

Our other 220 lb robot “Edgehog” has swapped 4QD speed control and Hawker batteries for a Robot Power Sidewinder and NiCd cells, saving over 20 lbs This was used for extra armor.

then regret it later, so we tried

sever-al controllers’ head to head I was so

impressed with one particular speed

controller; I became the European

agent for the company that makes

them The Robot Power Sidewinder

looked really good on paper, and

during testing it exceeded our

require-ments by a long way, so we now

use them in all of our heavyweights

and one of the featherweights

We had a similar experience with

the smaller bots, identifying the

Robot Power Scorpion XL as — by far

— the best controller for all of the

sub-30 lb machines, and the artbots,

except one We used a Robot Power

Scorpion XXL (a modified XL) for this

one robot, as it needed the extra

power the XXL offers

The Robot Power Sidewinder

was the mainstay of the UK

champi-onships this year, stepping in to

keep many robots running when

their regular controllers failed One

key feature to this was that the speed

controller being removed from a

robot was always bigger than

the Robot Power option, so it

always fit The space saved in our

axe-bot Edgehog was unbelievable;

swapping a laptop-sized electronicsbox for something so small gave usroom to make much needed weaponmodifications

Batteries are also an area whereyou cannot afford to get it wrong oryour robot is going to struggle AllXbotz heavyweights ran Hawkersealed lead acid batteries prior to theoverhaul, which always served uswell, but a switch to nickel cadmiumcells was an easy upgrade, allowing

us to lose weight and gain voltage

Two of the smaller bots now usethese also, with the remainder of thefleet running nickel metal hydridecells We considered lithium basedpower, but decided on the NiMHmainly because of the lower cost

Our third area to look at wasradio control All Xbotz robots use

40 MHz Futaba systems, and we

saw no reason to change that Thenew 2.4 GHz technology is veryimpressive, but the 40 MHz equipment has always done the jobfor us, so the money was betterspent elsewhere

The updates to the fleet are progressing well, with the robots done

to date showing improved speed andagility Wheely Big Cheese, for example, is completely transformed.The whole Xbotz army of robots will

be updated before the 2008 seasonstarts, with detailed informationabout each robot, and each event weattend available on our website

(www.xbotz.com) plus an online

shop for European builders, thanks

to www.leafish.co.uk.

See www.robotcombat.com

or www.robotpower.com for

infor-mation about the speed controllers

we use at Team Xbotz SV

Labor Day event at Dragon*con

in Atlanta, GA Results were not

available at press time, but will be

featured in an upcoming issue Go to

www.robotbattles.com for more

information

Championships, presented by

Roaming Robots, were held August

28th-31st at Haven Hafan y MôrHoliday Park, North Wales Go to

www.roamingrobots.co.uk for more

information Results are as follows:

● Heavyweight — 1st: Big Nipper; 2nd:

Terrorhurtz; 3rd: Iron Awe 5

● Annihilator — Tilly Ewe 2.

● Featherweight — Little Flipper 2.

September 1st-2nd atSportspace Hemel Hempstead TeamWind Power took home 1st place

in the Feathers and Heavies, andTeam Big Nipper took home 2nd

in both weight classes Go to

www.robotslive.co.uk for more

information SV

EVENTS

RESULTS — August 11th - September 11th

A Scorpion XL is at the heart (literally)

of our 30 lb artbot “Hellraiser.”

Another 220 lb robot “Carnage” uses a Robot

Power Sidewinder for both drive motors and

another for both weapon motors The Lead

Acid batteries have been replaced with NiCd

packs, saving 10 lbs.

These days, it seems that the

trend within combat robotics is

for people to build two basic types of

robots They are either a super

powerful KE spinner which tries to

destroy everything in its path or

super tough wedge type robots

made to withstand the punishment

from the spinning robots Some

robots will deviate from this trend,

but for the most part, the majority

fall into these categories

In the half dozen years that Ihave been involved with this sport, I

have mainly built sub-light robots,

which are robots that are less than

30 pounds I have always wanted to

build a pneumatic robot capable of

launching another robot into the

roof; however, due to the weight

restrictions on the sub-light classes, I

was never able to build a robot that

could achieve my goal

One day after seeing videos

of various UK pneumatic robots, Idecided it was time to build a full size

60 pound lightweight robot Thisrobot would be something differentthan the norm; a robot that could(hopefully) take the abuse fromthe powerful KE robots and sendthe wedge type robots flying out ofthe arena

In this build report, I will give

a description of how my 60pound ‘launch bot’ “Rocket” became

a reality

The Design

In today’s game, there are manyrobots that wield weapons thatcan destroy an opponent in shortorder, especially in the lightweightclass For this reason, I enlisted thehelp of my friend Bryan Ruddy tohelp me CAD and design this robot After much talking, we agreed

on a list of things that had

to be achieved for this robot to

be successful

We both agreed that therobot should be centered on theflipping system, be highly maneu-verable, have an armor systemwhich could stand up to thetough KE robots, and — mostimportantly — be able to shoot anopponent to the roof! After a fewweeks of CADing, this iswhat we came up with(Photo 1)

Drive

The drive on Rocketuses four BaneBot 42 mm

16:1 (www.banebots.

com) gear motors

upgraded with the 775

sized motor This drive packagemounted to 3” wheels gives a greatbalance of speed and pushingpower Also, the placement of themotors and shape of the base plate were designed for optimalmaneuvering and to eliminate scrubbing of the wheels Whenmounted correctly, I have found theBaneBot units to be very durable andwork extremely well

Armor

Other than the pneumatic system, the armor arrangement is myfavorite part of this robot It wasdesigned to take and repel theattacks from other robots, as well asfacilitate self-righting by letting thearm contact the ground at all times.All of the sides are sloped in order toreduce the amount of surface areathat other robots might be able toget a hit on The armor is very low to the ground making it difficultfor vertical spinning robots to gripand damage

Also, the armor is mounted tothe base plate on a system of customrubberized shock mounts whichallow the armor shell to move andsomewhat flex when hit Made from1/8” titanium, the shell is extremelydurable and has also been designed

to allow various attachments to beadded, depending on the opposingrobot; all of which have yet to

(www.airtronics.net) which they

Building a Lightweight Launch Bot

TECHNICAL KN WLEDGE

● by Chad New

PHOTO 1 After many weeks of design, the final CAD emerged.

PHOTO 2 Parts cut and systems installed, the frame is now ready for wiring and final assembly.

modified for me by adding a

button which can be pressed

when I want the flipping arm

to be activated This button

allows me to focus on driving

the robot while giving the

flip-ping control to a team mate

The battery is a 5,000

mAh 14.8V Li-Poly made by

Thunder Power (www.thun

derpowerrc.com) This pack

was able to free up a lot of

weight, allowing a better distribution

for other items The speed control is

Robot Power Sidewinder; which may

be overkill; however, it gets the job

done well The guys down at

BaneBots built and designed me a

custom voltage booster/timed switch

to operate the valve for the cylinder

The valve requires very high voltage

and only needs to be open for a

fraction of a second; this device takes

care of that task

Flipper

The flipping system uses a

custom-made pneumatic cylinder

pressures greater than 800

PSI Activation of this cylinder is

controlled by a large solenoid valve

Feeding this system is two 20 oz

paintball tanks, also with an inlinebuffer tank to allow for gas expan-sion This arrangement gives Rocketover 20 shots at getting its opponentout of the arena With the massiveamount of force that this system produces, the arms were made from.6” titanium with a 5” S7 steel push-ing plate Overall, I believe this to beone of the best and toughest flippingsystems in the lightweight class

3rd This event is for Fairy, Ant, and

Beetle weight combat robots It will

be held at the Cuyahoga Valley

Career Center (CVCC) (south east of

Cleveland) For complete details

including rules, safety forms, release

forms, maps, and local hotels, see

their website at www.ohiorobot

club.org.

event at the Maidstone LeisureCentre in Kent, England, onNovember 24th, and at the Harvey

Hadden Sports Complex December1st in Nottingham, England Go to

more details

RoboChallenge will present theirThinktank Christmas SpecialDecember 28th-29th in Birmingham,

England Go to www.robochalle

nge.co.uk for more details SV

PHOTO 3 Rocket putting the

LW wedge ‘Homer’ into orbit.

PHOTO 4 The armor mocked up onto the frame ready to be sent for welding.

PHOTO 5 Shined up and with new stickers, Rocket, ready for its first event.

EVENTS

UPCOMING — November and December

I n the March ‘06 issue

of SERVO Magazine, I

introduced you to a

program called AutoFlex — a

tool used for developing

autonomous routines for FRC

(First Robotics Competition)

robot controllers.

The program was created by

members of FRC Team 1675 when

they realized that they were going to

the FIRST (For Inspiration and

Recognition of Science and

Technology) National Championships

in Atlanta, GA without any

autonomous functionality for their

robot Without having access to the

robot until the event, they needed a

way to quickly program the robot

to perform some task during the

autonomous period The solution was

to create a program that would allow

the team’s driver to teach the robot

what it had to do during the

autonomous period by recording the

driver’s commands as he drove

through the autonomous routine

Training took place on the practice

field before the matches started

At the beginning of the match, the

robot would repeat the commands

that it was taught

In 2005 during the Triple play

competition, the robot scored two

tetras during each autonomous

period During the 2006 Aim High

competition, the robot could drive

up to the goal and shoot an entiremagazine of balls through the hole(most of the time)

The original program was a littlecumbersome and complicated to use

While the driver commanded therobot through the routine that was

to be recorded and then played itback during the autonomous mode,

a programmer — with a laptop connected to the robot via a serialcable — chased (or was chased by) therobot as he captured data Thedata then had to be loaded into afile and the whole program wasrecompiled and reloaded into therobot From the sidelines, this was fun

to watch, but those actually involved

in the process were often quitestressed and in peril

Autoflex has been simplified andupdated to version 2.0 to take advantage of the internal EEPROMmemory available in the FRC robot

more laptops and cables, editing data,and reprogramming Programmerstress levels have been greatly reduced!

Imagine This!

During practice, you set yourrobot on the playing field, click abutton on the operator interface andstart driving Then you set your robotback to the starting point, connect adongle to the competition port of theoperator interface and flip the dongleswitch to autonomous and the robotwill replay the practice session you just recorded Don’t like what yousee? Just reset the dongle switch back to the off position and just clickthe program button again to re-record

AUTOFLEX 2.0 New and Improved Autonomous

Programming Tool for FIRST Robots

FIGURE 1 Team 1675’s first robot programmed with Autoflex for the FIRST Triple Play competition would know one tetra from the goal and cap the second during the autonomous period.

by Brian Cieslak

ready to run during the autonomous

period, all in about 15 minutes

Getting Started

A zip file can be downloaded

from the FRC Team 1675 website (see

Web Links sidebar) that includes a

version of the FRC default code with

AutoFlex included I/O mapping for the

default program is as follows:

Joystick 1 - Y axis to PWM_1

Joystick 2 - Y axis to PWM_2

Joystick 1 - X axis to PWM_5

Joystick 2 - X axis to PWM_6

Set your robot to program mode

and download the FRCAutoFlex.hex file

using the IFIdownloader program

available from the IFI website (www.

ifirobotics.com).

Attach a programming dongle to

the competition port of the operator

interface (instructions on how to make

your own are also available from the IFI

website) and set the autonomous

switch to the open position You are

now ready to start programming

your robot for autonomous operation

The FRCAutoFlexCode.hex program

records four inputs: joystick 1 x-axis,

joystick 1 y-axis, joystick 2 x-axis, and

joystick 2 y-axis

Click the trigger on the port 1

joystick to start recording You now

have 15 seconds to drive through your

autonomous routine After 15 seconds,

the robot stops recording commands

even though it lets you keep driving

To replay what you just recorded,

‘close’ the autonomous switch on the

dongle Watch out! Your robot will

start to execute the code you just

recorded The robot will play 15

seconds of commands and then

stop until you open the autonomous

switch again

Once you are satisfied with the

autonomous routine you’ve recorded,

place a jumper on the ‘digital

input 1’ pins This write protects

your autonomous program

from being accidentally erased

if you click the trigger while

Now you are anexpert

For the Beginning FIRST Programmer

If you are justlearning to program

a FIRST robot, asample project that

is fully functional isincluded in the zipfile you can download from the Team

1675 website that can serve as a plate to get you started The program-ming kit that comes with your robotincludes a disk with the MPLAB-IDEprogramming environment and theC18-Complier Version 2.4, as well asthe downloader program You willneed these tools to compile and down-load your program to the robot

tem-Adding Autoflex to Your Existing Code

Adding AutoFlex to your existingcode is simple if all the calls to yourcontrol functions (motor control,manipulator arm, etc.) are made fromthe Default_Routine() function found

in the User_Routines.c file

You must do the following (refer

to the sample code provided):

1) Copy the following files to your project folder, then open MPLAB andadd them to your project:

a) AutoFlex.cb) Autoflex.h

c VEX_eeprom.cd) VEX_eeprom.h2) Open the user_routines_fast.c file Add a call to the function autoflex_playback() to the user_

autonomous_code() function as

shown in Figure 2 Also add the

#include”AutoFlex.h statement at thebeginning of the file

3) Open the user_routines.c file Add acall to the function autoflex_recorder()

to the Process_Data_From_ Master_uP() function as shown in Figure 3.Also add the #include”AutoFlex.h”statement at the beginning of the file.4) Open the main.c file Add a call tothe function rewind_autoflex_playback() to the main()function asshown in Figure 5 Also add the

#include"AutoFlex.h" statement at thebeginning of the file

FIGURE 4 Team 1675’s Aim High robot would drive up to the goal and shoot most of its 10 balls through the hole.

FIGURE 2

5) Configure Autoflex.h to reflect your

robot system Sections that you

may want to consider changing include

the following:

a) Determine how many inputs you

want to capture and which ones

//add defines here to assign

//commands to user controls that

// you want record/

//uncomment to add another input

// Number of inputs we plan to

//record

// Default is set up to save 4 inputs

//You can save up to 6

// inputs You can define two auto

//command lines above

// then change the number of

//inputs on the line below

#define NUM_OF_INPUTS 4ib) You can determine what you want

to use as the ‘Record Button.’ Thedefault is port 1 trigger Button

//define the mechanism that will//act as the record button

//In this example port trigger is a//button on the OI

// that you would press to the//forward position to start recording

#define \AUTO_BUTTON_REV_THRESH \(unsigned char)100 // used by Vex

#define \AUTO_BUTTON_FWD_THRESH \(unsigned char)154 // used by Vex

#define \AUTO_NEUTRAL_PWM_VALUE \(unsigned char)127

#define AUTO_RECORD (p1_sw_trig)//port_1 trigger to start recordingc) You can adjust the length of timeyou want to record commands bychanging the TIME_LIMIT value

Default is 150 tenths of a second(or 15 seconds) The maximum value

of TIME_LIMIT depends on thenumber of inputs you are trying

to save The max number of command values that can be saved

is 1,024 To determine the max timeavailable, use the following formula

(1024/ number_of_inputs) - 1 =max_tenths_of_seconds For exam-ple: (1024/4 inputs)-1 = 255, soTIME_LIMIT could be set to 255tenths_of_seconds (25.5 seconds).// The length of the autonomous routine in tenths of seconds

#define TIME_LIMIT 150d) You can assign which digital portyou want to use for your WRITE_PROTECT jumper If you don’t want

to write protect your autonomouscode or you have used up all your digital ports, re-define WRITE_PROTECT to ‘1.’

// if jumper in place then do not//record (assuming jumper pulls pin//low)

#define WRITE_PROTECT \(rc_dig_in01)

e) Since an FRC robot uses a longer timing interval than VEXrobots during autonomous opera-tion, uncomment the #define FRC 1line to adjust the timing if you areadding Autoflex to a FRC robot

No More Excuses

to Sit Idle!

When I attended FIRST Regionalcompetitions in Milwaukee, WI andCleveland, OH and the FIRST NationalChampionship in Atlanta, I was surprised by how many robots sat idleduring the autonomous segment ofthe match Our team started toutingthe benefits and simplicity of theAutoflex program there and enabledseveral teams to compete during that

15 second period at the beginning ofthe match Even sending the robot out

to a defensive position is better thanjust sitting there

I do want to emphasize, though,that Autoflex is not a substitute for awell thought out autonomous programthat uses sensors and feedback algorithms To be truly autonomous,the robot must be aware of and react

to its environment So programmers,

For Autoflex files

http://team1675.com/

teamdownload.html

For competition port dongle

FIGURE 6 Autoflex was used to program

a large claw-like manipulator during the

autonomous period at the beginning

of the Rack-n-Roll competiton.

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VISIT OUR ONLINE STORE AT

www.allelectronics.com

WALL TRANSFORMERS, ALARMS, FUSES, CABLE TIES, RELAYS, OPTO ELECTRONICS, KNOBS, VIDEO ACCESSORIES, SIRENS, SOLDER ACCESSORIES, MOTORS, DIODES, HEAT SINKS, CAPACITORS, CHOKES, TOOLS, FASTENERS, TERMINAL STRIPS, CRIMP CONNECTORS, L.E.D.S., DISPLAYS, FANS, BREAD- BOARDS, RESISTORS, SOLAR CELLS, BUZZERS, BATTERIES, MAGNETS, CAMERAS, DC-DC CONVERTERS, HEADPHONES, LAMPS, PANEL METERS, SWITCHES, SPEAKERS, PELTIER DEVICES, and much more

A look inside the

mechanics of combat robots

by Brett Duesing, Strategic Research

What gratitude could you

feel for these ruthless gladiators — these brutish, soulless beasts who

breathe fire, wield axes, and ram

each other until one of them lies

dismembered?

Combat robots undoubtedly

satisfy a deep boyish urge to wreck

stuff But a closer look into the

sport of combat robotics reveals

something more The escalating

war of robots produces some

surprising spoils As you enter a

technological future dominated by

satellites, wireless gadgets, and

hybrid cars, you may have these

evil-natured robots to thank.

Life After BattleBots

The sport of combat robotics first

entered the public consciousness

through the BattleBots show on

“As far as thesport goes, some robotbuilders argue whether not being on

TV anymore is good or bad,” says BillyMoon, leader of Team Moon Robotics

“On one hand, the show gave thesport a lot of recognition No matterwhere we go, inevitably people haveseen one of those shows.”

The sport received so much attention that it briefly became a piece

of pop-culture currency The trappings

of BattleBots — the glitzy graphics andoverexcited announcer commentary —also gave the broadcast a veneer

of manufactured hype During theshow’s reign, fighting robots were

parodied on The Simpsons and the

BattleBots aired, much has changedabout bot bouts The events organizedunder the new national RoboticFighting League (RFL) are austereand down-to-business Design andstrategy has taken center stage

“I think overall it’s been good to beout of the spotlight,” says Moon “It’seliminated the people who just wanted

to get on TV It’s let the sport progressthe way it should.”

Moon started building robots forhimself when he was only 10 Now, atthe age of 46, he works at CiscoSystems as a Distinguished Engineer,the highest rank of technical professional Only a couple of dozen multi-disciplined “Ninja-Class” engineers work for the firm, taking onspecial projects that require the mostout-of-the-box solutions During his professional career, Moon has createdmore than 200 new patents, at an

office on “Bring your Kid to Work Day,”

when he will bring in many of his

team’s remote-controlled creations

for a parking lot demonstration

Weekends are spent building and

fighting robots with the rest of Team

Moon, a small coterie of family

members and engineering colleagues

Team Moon began competing

in combat robots six years ago, at

the height of the BattleBots craze Its

early heavyweight robot, Vladinator,

dominated many of the televised

tournaments Now active in the larger

and independent RFL, as well as

the yearly (untelevised) BattleBots

contest, Team Moon operates about

a half dozen robots competitively,

each ranking near the top of their

weight class

Most contests are double

elimina-tion tournaments of three-minute

bouts, where two robots of the same

weight class fight to disable each other

The operator controls include a

“tap-out” button for when the operator

wishes to surrender the match and

save its fighter from further damage

or humiliation Most fights end with

this forfeit button, where one robot

obviously dominates

If the three-minute bell rings,

judges award points to the contenders

based on aggression, strategy, and

damage Typically, it takes two people

per robot to steer the action with

radio controls — one to drive the bot

around the rink, and the other to fire

its weapons

Weapons on super-heavy weight

robots (around 340 lbs) are not kidding

around anymore In a three-minute

match, the offensive maneuvers —

consisting of kinetic thrusts, spinning

blades, or bursts of flame — push out

up to 200,000 joules of energy,

pumping from 2,000 amp, 30 volt

reserves of electric power

“You might think a good armor

would be 1/4 inch thick 4130 or 4340

steel,” says Moon “Most weapons

now will cut through that like butter.”

Since the sport has left the TV

spotlight, more responsive engines and

more sinister hardware have emerged

engineering software, digitally

simulat-ed, and CNC cut

The Devil’s Workshop

“What’s nice about robotics is thatit’s a full system: mechanical, electronic,and artificial intelligence,” Moon says

“You have to know a little bit of everything when you’re building arobot, and that to me is very satisfying.”

For robot builders fascinated with performance, strength, power,mechanical motion, and the gratingsound of metal-on-metal it is appropri-ate that the most advanced addition totheir workshop is, in a sense, a robotitself — a robot that uses mechanicals,electronics, and programming

The biggest addition to the Moonworkroom has been a CNC mill, whichcuts metal pieces automatically fromthe computerized part models Moonpurchased one of the first “personalCNC” machines on the market Thenew mill, put out by Tormach, Inc., isable to precision-cut the thick titaniumarmor, but is smaller and more afford-able than the historically huge factoryequipment The “personal” in the trend

of CNC can be likened to the first sonal computers, where the technolo-

per-gy finally became practical for an vidual in cost, size, and performance.And with the advent of easy-to-useCAM (the software which convertsCAD files into machine cutting paths),CNC technology is becoming closer

indi-in practice to just sendindi-ing a Word document over to a printer Of course,

in this case, the printer is carving outthree-dimensional steel parts

“I’m far from being a machinistmyself,” admits Moon “The Tormach is

an excellent example on how easy CNCmachining is getting If we can use it,then anyone can do it The technologythe way it is now, it’s very affordablecompared to taking your parts to amachine shop every time.” In contrast

to factory-sized CNC mills that bottomout at around $30,000, the PCNC 1100costs under $7,000

“My older boy actually took in aweeks’ course over the summer to dothe CAM programming using a software package called CAMWorks,”

The Team Moon robot fleet.

Team Moon wooden design models.

says Moon “He’s interested enough

that he’s actually making a few parts

on the Tormach machine, which is an

amazing thing to do for a high school

kid My objective for getting him to use

tools has surpassed my expectations.”

Robots Making Robots

Six years ago, a Team Moon robot

began as a cardboardmodel, then a wooden one

The physical prototypeswere tested and tweakedmanually, before the metalparts were finally fabricated

“It took us about a year todesign it and about sixmonths to build it, because

we had to do so much stuff

by hand.”

Now, the shop can pushout the most modernmachines in half the time,thanks to an automateddesign process that is inmany ways more advancedthan that of some commer-cial manufacturers Robotsare now fully designed in SolidWorks, a3D solid modeler For his newest cre-ation — called Eugene — Moon used amechanical simulation software(Cosmos) for various mechanical parts,like stress analysis of the assembly, orrepair exercises, which used volumetricdata to ensure clearances inside themachine for different sizes of tools

The majority of the robot parts arevery complex in construction, having alot of curves and circles that bend inmore than two dimensions “For ourpurposes, we would benefit from having a CNC machine where we couldCAM these difficult shapes, where themachine would do a lot of thethinking, rather than trying to do

it manually The Tormach was areally good choice for usbecause it was specificallydesigned for CNC, whereas a lot

of smaller mills are conversions

of a manual machine There’s alot more you can do from day one with a mill that is set upfor CNC.”

Despite its small size, theone-ton Tormach mill maintains

its cutting power — enough to craft thethick titanium armor — due to the rigidity of its base and table, which aremade of cast iron The mill’s four-axisspindle automatically carves the complicated three-dimensional curves

— ones which would be impossible tocut by hand — in a matter of minutes.The high rate of innovation in thesport of fighting bots can be seen first-hand in the evolution of pieces on themill Given the ability to make a fewiterations, robot parts and assembliesevolve into stronger and more effectivedevices In the past, this was impossi-ble Complex parts needed to beordered at a local machine shop, whichwould take a few days or weeks ofwaiting Now that Team Moon can cuttheir own parts in the garage, they canspeed up the construction process,while enhancing the design At-homeCNC capabilities give the team the ability to refine the robot design as itgoes along

“Even two years ago, there weresome parts we had to send to amachine shop I made a mistake duringdesign about the size of the sprocketfor this standard go-cart wheel,” Moonsays “I’d have this little support piece

on the inside of the sprocket ring togive a little extra support In order toget the piece made at a machine shop,

I really have to order 10 of them

to make it worthwhile, because of theset-up costs

“So I’d order 10, get them back,and the support wasn’t as strong as itcould have been,” Moon recalls “It’sjust not cost-effective to go makeanother one again I’d just have to livewith it, and remember to change itnext time we ordered parts Today, I’djust machine another one TheTormach mill gives us quick turnaround

on rework, which has been invaluable.”

The Spoils of Robotic War

Do the rapid innovations seen inrobot construction have any usesbeyond the arena? Given the robots’warlike disposition, the first thoughtthat springs to mind might be military

or police applications According to

A robot named Goosfraba utilizes a flame-thrower as part of its arsenal A larger- sized combat bot can exert

as much as 200,000 Joules of energy during a single three- minute bout Photo courtesy

of Sam Kronick.

Team Moon’s ax-wielding Eugene

fights the spinning menance called

the Shrederator, designed by Team

LOGICOM The matchup creates

sparks as the two combat robots

contend for the 2006 national

heavy-weight title of the Robot Fighting

League Photo courtesy of Sam Kronick.

armor Some in the military have seen

the sport’s potential as a training tool

for both mechanics and strategic

thinking British Air Force cadets take a

course in building robots and fight

them on the UK bot circuit, the FRA

The biggest impact of combat

robotics may be in the commercial

realm “There are a lot of parts we

have designed and we ask

manufactur-ers to build for us, which actually may

have a lot of use for people,” says

Moon “For example, electric motors

We are very demanding on our motors

We have the highest packed, highest

quality motors money can buy They

have to be super rugged, deliver

con-stant power, and be very lightweight

Five years ago, that was just an odd

request Today, having a high

perform-ance electric motor is a very interesting

thing if you’re a manufacturer of

hybrid cars What would it take to build

a hybrid car? You’d need a lightweight,

high-efficiency electric motor that’s

pretty rugged.”

Because he is an engineer of Ninja

status, Moon is fortunate enough to

work with suppliers who give him

test parts in exchange for feedback

Team Moon often gets prototypes of

early technology that is inaccessible to

normal consumers

“There have been a lot of

manu-facturers that we work with closely,”

Moon says “One of them has taken

motors that were first developed by

combat robots into the wheelchair

business Another vendor was in

satellite communications, and needed

motors to move the parts on satellites

Now it has a whole line of

motors, based on what

they’ve learned from combat

robots.”

Batteries are also a big

factor in hybrid cars Any

electric car designed for

practical use has to contend

with limitations of battery

life, reliable power delivery,

and time it takes to recharge

at a stop at the gas station —

“There are a number of industriesvery dependent on batteries Somebattery makers have given us experimental batteries to test out,”

Moon says “The batteries we need forour robots are just unbelievable Weneed batteries that we can completelydrain in three minutes I need to coolthem down, and then recharge themwithin 25 minutes before they go outagain for another three-minute drain

We need that level of cycling Five yearsago, it was impossible I have batteriesnow that can perform like that.”

“If you can do that with your battery technology, then you can buildpower plants for electric cars; you canbuild laptops and cell phones that cancharge in a couple minutes and thenlast all day If the demand is greatenough, somebody will build it.”

Whatever the future is for tested technology, the more intangible,but perhaps greater, impact of thesport may be on future generations

bot-Robots have brought fathers and sonstogether, teaching the youth not just about competition, but how to

be mechanically self-reliant Ratherthan the passing on the old skills of

traditional tools to the next generation,the advanced science of robot warimparts kids with the relevant high-techskills for later professional or entrepreneurial success: computermodeling, CAM programming, andCNC machining Now that these building technologies have come down

to a personal level of use and ability, the future is wide open SV

afford-Team Moon Robotics is one of theworld’s top competitors in roboticfighting, participating in several eventseach year In the 2006 Robot FightingLeague Championship, the teamplaced five robots in the top three oftheir respective events The Moonfamily lives in Cary, NC

Team Moon Robotics

Will Moon and his friend Patrick Vanderbee sitting on their bot “The Wall.”

Moon and his younger son David bending some titanium David is using the blow torch and Moon is

operating the press.

courtesy of Sam Kronick.

The Firgelli PQ-CIB controller isdesigned exclusively to drive the Firgelli

PQ series of miniature linear actuators

In a previous issue of SERVO, you saw

just how easy it was to build and code

a Firgelli L12 linear actuator driverhardware module from scratch Doingthe same for the PQ12 series of linearactuators is almost effortless, as well

However, if building electronic devicesfrom scratch is not in your mechanical-ly-inclined forte or if you don’t havetime to solder and need a completeand proven linear actuator platform in

a hurry, the PQ-CIB controller is yourbest solution

In the linear motion discussionthat will follow, we’ll take a look atthe PQ-CIB controller hardware andfirmware We’ll also perform a preflightwalk-around on the PQ12 miniaturelinear actuator In the course of ourtalks and walks, we’ll outline somePIC-based firmware and some verybasic PIC hardware to drive the PQ-CIB controller This article is all

The PQ12 Linear Actuator

The PQ12 linear actuator you see inPhoto 1 is formally known as a PQ12f.The “f” in the PQ12’s moniker signifies

“high-force.” The high-force PQ12f cangenerate a force of 15N when the actu-ator is moving at 7 mm/s A peak force

of 18N can be realized when the tor is moving a bit slower at 6 mm/s.The PQ12f is more than twice as power-ful as its faster first cousin the PQ12s.The “s” here means speedy with thePQ12’s linear actuator being able toextend and retract its actuator at 27mm/s That’s over twice the maximumstroke speed of 12 mm/s provided bythe he-man PQ12f And, by the way, theforces and speeds I’ve just outlined aregood for both retraction and extension.The PQ12 linear actuators bothinterface to their control circuitry by way

actua-of a Flex-PCB cable A 1 mm pitchFFC/FPC connector can be used toaccess the PQ12f’s Flex-PCB cable edgecontacts However, you may also choose

to solder lead wires into the solder holes

of the PQ12’s cable There’s no reason

to jeopardize your PQ12 Flex-PCB cable

as you can obtain a Hirose FH21 five-pin

1 mm FFC/FPC connector from Digi-Key.Unless you specialize in wire andprinted circuit board (PCB) interconnects,the acronyms FFC and FPC are a foreignlanguage you don’t speak In a nut shell,FFC stands for Flat Flexible Cable FFCcable consists of thin rectangular copperconductors that are laminated betweentwo layers of polyester insulation A stiff-

PHOTO 1 The PQ12 linear actuator is very compact It measures 36.5 mm at its longest extent, 22 mm at it shortest extent, and is only 22 mm thick The maximum extended stroke is 20 mm.

Instant gratification comes in many forms This month, instant gratification comes in the guise of a simple collection of electronic components designed

to provide multiple control input interfaces to a powered miniature linear actuator For a robomagician like you, instant gratification is a Firgelli PQ-CIB

high-controller hooked up to a Firgelli PQ12 linear actuator.

by FFred EEady

and unmating Due to the way FFC cables

are constructed, they are best suited for

straight one-to-one connections Then,

there is FPC, or Flexible Printed Circuit,

cable The idea behind FPC cable is

identical to the FFC cabling concept except the conductors of FFC

cabling are etched This makes FFC cabling the choice for custom

applications that may also need an odd cabling geometry These

cabling technologies have been around since the 1970s So,

unless you were born just recently, you’ve seen lots of FPC and

FFC cables You just didn’t know what to call them

Unless we only want to completely extend and completely

retract the PQ12f’s actuator, we’ll need to have total control

over how far to allow the actuator to move and complete

control over which way the PQ12f’s actuator will move The

mini-schematic of the PQ12f’s internals shown in Figure 1 tells

us that the PQ12f is logically identical to the L12 linear

actuator we talked about in the previous issue of SERVO That’s

good in the sense that if you read about the L12, your learning

curve will be zero as far as the operation of the PQ12f is

concerned Whether or not you know anything about the

Firgelli L12 linear actuator, it’s rather obvious from Figure 1

that the PQ12f’s internal potentiometer is the key to sensing

the position of thePQ12f’s actuator

The PQ12f’s tor drive motorrequires a powersupply voltage of +5VDC and draws a maximumcurrent of 250 mA Thismakes the PQ12f perfect

actua-as a powerful replacementfor +5 VDC hobby servos inapplications that require thehobby servo to emulate a linear actuator

PQ-CIB Controller Overview

The PQ-CIB controller was designed for Firgelli by the BCITTechnology Centre My PQ-CIB controller is shown in Photo 2

NOTES:

REVERSE POLARITY PROTECTION DIODE

V+

0-10V INPUT 4-20mA INPUT

RC INPUT

RC INPUT H1

INT PGC

EXT

MCLR H2

H1 0-10 VOLTS INPUT PGD

4-20mA INPUT H4

H4

H3 MT1

MOTOR FEEDBACK H2

BATTERY + V+

V+ +5VDC +5VDC

+5VDC

+5VDC

+5VDC

Q5 STD30PF03L

R8 10K

Q1

IRLML2402

R9 10K C4 2.2uF

FH21 1 3 5

Q6 STD30PF03L

R10 249

Q2 IRLML2402

R11 10K

C1

.1uF

IC2 MCP1700T5002E/TT

IN OUT

C3 1uF

Q3 IRLR3714

Q4 IRLR3714

R2 10K

R4

10K

R3 10K

R5 10K

R6 0.27

C6 1.0uF

1 3

R14 1.0M

C2 1.0uF LED1

R12 1K

C5 1.0uF ICSP

1 3 5

BATTERY HEADER

1 3

D3 1N4004

D2 BAS70

R7 10K

CON2

SCREW TERMINALS

1 3 5

IC1

PIC16F676

11 3 4

6 8 10

13 1

2

14

5

RA2/AN2 MCLR/Vpp

RC4 RC3/AN7 RC1/AN5

RA0/AN0 VDD

RA5

VSS

RC5

10K

SCHEMATIC 1 There should not

be anything here a robobuilder like you does not understand.

PHOTO 2 The integrated battery pack

is designed to be detached from the

controller The PQ-CIB controller comes

ready to rock out of the box All you

have to do is add some battery power,

attach a PQ12, and move the slider to

activate the PQ12’s plunger.

FIGURE 1 This is pretty simple stuff for such an accurate and powerful device With the help from a very fast PIC microcontroller, we will have absolutely no problem in keeping up with the position

of the PQ12f’s plunger.

ed at the top of the PQ-CIB controller PCB

stand out I don’t know about you, but to

me they are screaming H-BRIDGE! A look

at Schematic 1 shows us that the PQ-CIB

controller is, in fact, mostly an H-bridge

Everything else is done with firmware that

resides within the Microchip PIC16F676

The PQ-CIB controller firmware accepts

4-20 mA, 0-10 VDC, hobby R/C, and 1 kHz

PWM input signals, which all can be used

to move the PQ12’s actuator

Photo 3 is a reconnaissance view of

the PQ-CIB controller sans battery pack At

the top left edge of Photo 3, you can see

the FH21 FFC/FPC cable socket If you

backtrack to Figure 1, you can easily figure

out how the linear actuator FH21 cable

connector is laid out Pin 1 of the FH21 FFC/FPC is located at

the bottom of the FH21 FFC/FPC cable socket Note that the

FH21 FFC/FPC cable socket pins out all of the odd numbered

signals on the left and the even numbered signals on the right

You can check this against the pin layout shown in Figure 1

The PQ-CIB controller’s PIC16F676 comes

prepro-grammed with the necessary stuff to accept all of the signals

I ran down earlier However, you’re reading this because you

and I are two peas in a pod You’ll want to program the

PQ-CIB controller with your own driver firmware eventually

So, a five-pin PIC programming interface is positioned

directly below the FH21 FFC/FPC cable socket

All of the various inputs — which are rendered mutually

exclusive by the firmware — are handled at the screw

terminals that lie directly below the five-pin PIC programming

interface The PQ-CIB controller firmware is continually

scanning the inputs and locks in on the first valid input type

it encounters Once the PIC16F676’s linear actuator

controller firmware gets a valid input, it reverts to using that

input type exclusively until the PQ-CIB controller is reset

The PQ-CIB Controller Hardware

Schematic 1 tells the tale The PQ-CIB controller is an

H-bridge under the control of a PIC16F676 The simple

layout, a socketed PIC16F676, and use of large 1206 SMT

components make the PQ-CIB controller easy to repair, just in

case you happen to accidentally cause the PQ-CIB controller

to release some magic smoke

The use of firmware to replace hardware is evident in Photo

3 We all know the pitfalls of driving H-bridge configurations

directly You don’t want to turn on the wrong MOSFETs when

driving a motor Normally, some sort of gating logic would be

placed between the PIC H-bridge outputs and the MOSFET gates

to prevent the inadvertent activation of the incorrect pair of

MOSFETs However, the folks at Firgelli and BCIT put together

some firmware to safely drive the PQ12 linear actuators without

the need for the extra PIC-to-MOSFET gate logic

real-world linear actuator project Once thebattery pack is jettisoned, the remainingPQ-CIB controller electronics can be powered from an external power source

To obtain external power, we simply movethe jumper from BATTERY to EXT PWR.You can see this jumper block clearly at thebottom of Photo 3 The demonstrationpotentiometer is also discarded and discon-nected when the battery pack is separatedfrom the PQ-CIB controller electronics.With the demo slider absent, we mustmove the POT/EXT jumper to EXT to utilize the 0-10 VDC input.That’s all we need to say about the PQ-CIB controllerhardware If you’re a robonewbie and H-bridge sounds likesomething from a Latin text book, check out the H-bridge

article that Peter Best did in the July ‘06 issue of SERVO Let’s

take a scenic tour the PQ-CIB Controller firmware

The PQ-CIB Controller Firmware

The PQ-CIB controller firmware’s main program loop pollsthe three inputs (R/C, 4-20 mA, 0-10V/PWM) and determinesthe input type Once the input type is determined, thefirmware then vectors to the input’s service function and loopsthere, processing the input until a reset occurs While servicingthe selected input, the PQ-CIB controller firmware also moni-tors the linear actuator for stalls As you might have alreadydeduced, the PQ-CIB controller firmware uses the PIC16F676’stimers and analog-to-digital (A-to-D) converter heavily Fromthe “flavor” of the source code, I would say the PQ-CIB controller firmware was written using the CCS C compiler.Another good clue that leads me to believe that CCS C

is the compiler of choice lies in the opening declaration code:

at the battery pack edge to allow you to separate the battery pack and the main controller electronics The idea is to allow you to use the PQ-CIB controller as a linear actuator controller out of the box and into your project.

over a range of 180° A pulse width of 1.5 ms will cause

the servo to center its actuator at 90° To rotate the servo

actuator to 0°, a 1.25 ms pulse is transmitted Sending a 1.75

ms pulse will cause the servo to rotate its actuator to the

180° position Thus, a hobby servo system operates in

response to the width of the pulse coming into the servo

The pulse width measurement is defined when the pulse

is logically high and the PQ-CIB controller firmware takes

advantage of that fact The PQ-CIB controller firmware will

begin a pulse width measurement when it detects a low to

high transition on the R/C input When the pulse transitions

from high to low, the value in TIMER0 — which is also called

RTCC in the source code — is read and loaded into the

vari-able RC_In_Voltage The manipulation of TIMER0, or RTCC, is

triggered by the PIC’s interrupt on change mechanism Here’s

the code that makes up the RC input interrupt handler:

Every PIC program requires that the programmer set up

the PIC’s I/O structure The firmware driver for the PQ-CIB

controller is no exception Note that A-to-D definitions and

TIMER0 prescale definitions are included within the defacto

I/O initialization code:

OUTPUT_A(0x00); // clear port A

SET_TRIS_A(0x2B); // A5, A3,A1,A0 = Input

// AN5 4-20ma, AN6 0-10V

//internal clock used with a prescaler of 4

SETUP_COUNTERS( RTCC_INTERNAL, RTCC_DIV_4 );

// enable GLOBAL interrupt

ENABLE_INTERRUPTS(GLOBAL);

// function to determine source type

Prescaling the TIMER0 clock by 4 means that TIMER0 willincrement every four instruction cycles, or once every 4 µs.Once everything I/O is set up and the A-to-D converterand TIMER0 mechanisms are primed, the PQ-CIB controllerfirmware begins its input scanning The first order of the inputscanning business is to turn off the linear actuator motor andhide for a second or so to avoid picking up some noise:

********************************************************* void ScanInputs( void )

{ unsigned long In_Voltage = 0, In_Current = 0;

unsigned long waiting = 0;

MotorOff(); // Motor off and delay to avoid

// false signal on start up delay_us(500000);

delay_us(500000);

*********************************************************

The scanning firmware is contained within an endlessloop The A-to-D converter is called upon repeatedly to readthe 0-10V/PWM and 4-20 mA loop analog inputs If 16 A-to-D converter ticks are collected from an analog input in asample period, there’s voltage on that particular input Here’sthe code snippet form the ScanInputs function that huntsdown incoming voltage or current:

********************************************************* do{

delay_us(500);

waiting=0;

In_Voltage = GetADCResult( InputV );

In_Current = GetADCResult( InputC );

//if there is a voltage or PWM signal detected

if ( In_Voltage > 0x10 ) {

V_PWM_I_SourceAp(InputV);

} //if there is a current signal detected else if (In_Current > 0x10 ) {

The R/C input not only has its own interrupt handler, italso has a special function that is called when voltage isdetected on the R/C input:

*********************************************************

else { do { waiting++;

if(input(PIN_A5)==1) {

RCSourceAp();

} }while (waiting<500);

}

that if the motor feedback voltage is greater than the input

voltage, the actuator will retract On the other hand, if the

motor feedback voltage is less than the input voltage, the

actuator will extend Obviously, if the feedback and input

voltages are within a preset hysteresis window, the motor

will not move

Like the ScanInputs function, the V_PWM_I_SourceAp

function is a never ending do-while loop The linear

actuator’s feedback voltage from its internal potentiometer

wiper is continually read and compared against the voltage

of the selected voltage control input:

*********************************************************

void V_PWM_I_SourceAp( unsigned int Input )

{

unsigned long In_Voltage = 0, FB_Voltage = 0;

unsigned long Previous_FBv = 0;

unsigned int Direction = 0, FB_count=0;

unsigned int OK_to_ext = 0x01, OK_to_ret = 0x01;

In_Voltage = GetADCResult( Input );

FB_Voltage = GetADCResult( FBVolts );

if((abs(In_Voltage - FB_Voltage))

< hysteresis) {

MotorOff();

Direction = Stopped;

}

*********************************************************

Note that a copy of the linear actuator feedback voltage

is stored in a keeper variable every time that the linear

actuator feedback voltage is read The keeper variable is

compared to the next feedback voltage reading to check for

a stalled actuator condition Basically, if the new feedback

voltage is equal to the keeper variable value, the actuator

motor must be stalled Here are the firgelli.h definitions for

MotorOff();

} else if((FB_Voltage > In_Voltage) &&

(OK_to_ret== Yes)) {

OK_to_ext=Yes;

MotorRetract();

delay_us(10);

} else if((In_Voltage > FB_Voltage) &&

(OK_to_ext== Yes)) {

SCREENSHOT 1 Play with the values

of CCPR1L and bits 4:5 of CCP1CON to change the duty cycle Changing the value of PR2 will alter the period of the PWM signal Changing the period also changes the frequency as the frequency is equal to 1/period.

Saelig —www.saelig.com

CleverscopeFirgelli —www.firgelli.com

PQ12; PQ-CIB Controller; L12Custom Computer Services, Inc

www.ccsinfo.com

Sources

the servo to center its actuator at 90° To rotate the servo

actuator to 0°, a 1.25 ms pulse is transmitted Sending a 1.75

ms pulse will cause the servo to rotate its... the PQ12f perfect

actua-as a powerful replacementfor +5 VDC hobby servos inapplications that require thehobby servo to emulate a linear actuator

PQ-CIB Controller Overview... its actuator to the

180° position Thus, a hobby servo system operates in

response to the width of the pulse coming into the servo

The pulse width measurement is defined when