Hacking Roomba - Tod E.Kurt Part 8 ppt

193 Chapter 10 — Using Roomba as an Input DeviceFigure 10-2 shows how you might hold Roomba and draw with it, while Figure 10-3 shows a drawing made with RoombaSketch.. Granted, as Figur

The implementation is straightforward; the main hurdle is conceptual as you’re using Roombadriving data without commanding the robot to move.

Instead of simply drawing lines as pixels onto the screen, an array of Lineobjects is created.Each Lineholds an array of points that define the line Each time draw()is called (deter-mined by framerate), the current line is added if the Spot button is being held down Eachpress and release of the Spot button creates a new Lineobject and thus a new line to be drawn

Listing 10-1: RoombaSketchLine[] lines = new Line[numlines];

int l = 0;

int strokeW = 5;

void draw() {computeRoombaLocation(); // same as beforeparseRoombaSensors();

System.exit(0);

}if( roombacomm.cleanButton() ) {

rx = width/2; ry = height/2;

rangle = 0;

strokeW = 5;

}if( roombacomm.bumpLeft() ) {strokeW ; if( strokeW<1 ) strokeW=1;

}if( roombacomm.bumpRight() ) {strokeW++; if( strokeW>100 ) strokeW=100;

}if( roombacomm.spotButton() ) {if( drawing ) {

if( rx != rxo && ry != ryo )lines[l].addPoint((int)rx,(int)ry,strokeW);

}else {drawing = true;

l++; l %= numlines;

lines[l] = new Line();

193 Chapter 10 — Using Roomba as an Input Device

Figure 10-2 shows how you might hold Roomba and draw with it, while Figure 10-3 shows a

drawing made with RoombaSketch The ability to change the pen stroke width while drawing

enables a much more fluid line than is possible with a normal mouse You can create very

organic drawings Granted, as Figure 10-2 shows, using Roomba as a mouse requires a bit

more physical movement than with a normal mouse, but with some people complaining that

computer users don’t get enough exercise, you can now point to the Roomba and say, “That’s

my mouse.”

F IGURE 10-2: Using Roomba as a mouse

F IGURE 10-3: A drawing made with RoombaSketch

Using Roomba as a Theremin

The theremin is a strange and unique musical instrument It’s played without even touching it;placing your hands in front of it in particular ways adjusts its pitch and loudness The BeachBoys song “Good Vibrations,” old Star Trek episodes, and countless horror movies have usedthe theremin to good effect, so you have undoubtedly heard it It produces a clear pure sinewave tone that glides between notes and sounds vaguely human-like

Invented in 1919 by Leon Theremin, the theremin was the result of research into electrostaticproximity sensors Figure 10-4 shows the inventor playing his instrument The theremin con-sists of two antennae, one for controlling pitch and one for controlling volume The pitch antenna

is usually vertical and on the right-hand side of the player The circuitry inside the thereminmeasures the varying capacitance between the player’s body and the antennae and adjusts theloudness and pitch accordingly If you’ve ever used your body to get better reception on your

TV, you’ve experienced how the theremin works

Making a Theremin Out of Roomba

The two Roomba dirt sensors are apparently capacitive-based and thus a likely candidate to use

as a theremin input Unfortunately, they do not seem to be tuned to picking up human-sizedvariations But the other downward-facing sensors offer an alternative for the pitch control By

195 Chapter 10 — Using Roomba as an Input Device

tilting Roomba left and right you can get a few bits of resolution by combining the cliff sensors

with the wheeldrop sensors Figure 10-5 shows how Roomba can be used to detect variations

in tilt The scale of the tilt is a bit exaggerated in the diagram to demonstrate the effect Since

the theremin glides from one pitch to the next, having relative pitch adjustments via tilting

actually works pretty well

F IGURE 10-4: Leon Theremin

and his musical instrument

F IGURE 10-5: Tilting Roomba for pitch control

No sensors triggered Pitch change = 0

Left cliff sensor triggered Pitch change = +1

Left cliff & front left cliff sensors triggered Pitch change = +2

Left cliff & front left cliff & left wheeldrop triggered Pitch change = +3

Listing 10-2 shows the core of a Processing sketch called RoombaTheremin As before, the

draw()method calls parseRoombaSensors()and draws a growing vertical line showingpitch change Figure 10-6 shows what the sketch looks like after running for a while and per-forming with it Figure 10-7 shows the typical way you hold and use the robot when playing itwith RoombaTheremin

Listing 10-2: RoombaThereminint pitch = 70;

int dur = 6;

int pshift = 0;

void draw() {parseRoombaSensors();

line( x,y, x,y+2);

}void parseRoombaSensors() {if( roombacomm.cliffLeft() ) pshift++;

if( roombacomm.cliffFrontLeft() ) pshift++;

if( roombacomm.cliffRight() ) pshift ;if( roombacomm.cliffFrontRight() ) pshift ;if( roombacomm.wheelDropLeft() ) pshift++;

if( roombacomm.wheelDropRight() ) pshift ;if( roombacomm.wheelDropLeft() &&

197 Chapter 10 — Using Roomba as an Input Device

F IGURE 10-6: RoombaTheremin tracking tilt changes to modify pitch

F IGURE 10-7: The three main positions when performing with RoombaTheremin

Better Sound with the Ess Library

The necessary time delays between each note sent to Roomba makes for a less-than-convincing

theremin simulation Instead of a smooth tone characteristic of a theremin, the best that can be

done on Roomba is a repetitive beep-beep-beep that is limited by the time it takes the robot to

execute the SONGand PLAYcommands

An optional library for Processing called Ess makes it really easy to load, play, and manipulate

sounds on your computer It is built on JavaSound (the standard Java sound API), but is much

easier to use than JavaSound normally is For example, the following snippet is a completeProcessing sketch that loads an MP3 file, pitch shifts it up five semitones, and plays it.

Ess is available at www.tree-axis.com/Ess/and, like any Processing library, is installed byunzipping its downloaded zip file into the librariesfolder of the main Processing applica-tion After restarting Processing, Ess is visible when you use the Sketch ➪ Import Library menucommand

Touchless Sensing

Another way of triggering pitch changes that is perhaps more theremin-like is to flip Roombaover and use the cliff sensors as hand proximity sensors Figure 10-8 shows how this works Byholding your hand over one or more of the cliff sensors, you un-detect a cliff The cliff sensors

are barrier sensors just like the wall sensor, but its logical sense is flipped and it’s called a cliff

sensor instead of a floor sensor It’s more logical (and marketable) to say cliff sensor instead of

floor sensor

But flipped over and used as a theremin, these cliff sensors work well detecting hands, as long

as your hand has its fingers together and is mostly parallel to the surface of Roomba Listing 10-3shows a variation of the previous code, called RoombaThereminToo It includes the Ess librarymethod of making sound and has a modified version of parseRoombaSensors()to deal

with the fact that it should change pitch when not detecting a cliff The other features of that

method are that by pressing both wheels down, it mutes the audio Pressing the bump sensorstarts the audio back up again

You’ve probably noticed that parseRoombaSensors()doesn’t actually change the pitch Itsets the pshiftvariable but doesn’t act on it That’s because changing the pitch of a soundwhile it’s playing causes an audible glitch By waiting for the sound to finish playing throughand changing its pitch before it loops again, the pitch transitions are smooth In Ess, if themethod channelLoop()is declared in your sketch, it will be called when a sound is finishedplaying By adding that method and a check to see if pshiftis actually set, the pitch (actu-ally the ratehere since it’s a faster computation and yields the same result) can be changedseamlessly

199 Chapter 10 — Using Roomba as an Input Device

F IGURE 10-8: Alternate playing method, used in RoombaThereminToo

Listing 10-3: RoombaThereminToo, Using Ess and Hand-Waving

if( !roombacomm.cliffLeft() ) pshift++;

if( !roombacomm.cliffFrontLeft() ) pshift++;

if( !roombacomm.cliffRight() ) pshift ;

if( !roombacomm.cliffFrontRight() ) pshift ;

if( !roombacomm.wheelDropLeft() ) pshift++;

if( !roombacomm.wheelDropRight() ) pshift ;

if( !roombacomm.wheelDropLeft() &&

Turning Roomba into an Alarm Clock

Roomba is now so familiar that it’s almost like a pet Why not have it sleep at your feet like afaithful dog? Except unlike a dog, with Roomba you can set the exact time when it will wakeyou up And you can even make it turn on the radio for you

Listing 10-4 shows the basics of the Processing sketch RoombAlarmClock, an alarm clockimplemented on Roomba It has the following features:

䡲 Alarm: Beep and make noise at a particular wakeup time.

䡲 Snooze button: Must hit both the left and light bump sensors.

䡲 Turn off alarm: Pick up Roomba and press the Power button.

䡲 Turn on or off radio on iTunes: Press the Clean button to play or pause.

The alarm and snooze times are determined by using Java Dateand DateFormatobjects.Alter the initial time for the alarm to go off (wakeupTime) and the length of the snooze(snoozeSecs) and run the sketch to start the alarm When the alarm goes off, the method

playAlarm()is called, which plays a tune and vibrates Roomba back-and-forth Pressingboth bumpers snoozes the alarm, while picking up Roomba and pressing the Power buttonturns off the alarm until the next day

The radio is turned on and off with the runRadioCmd()method This method uses

Runtime.exec()to execute a system command The particular command shown uses

osascript, the Mac OS X command-line tool for running Applescript statements TheApplescript statement tell app “iTunes” to playpausewill tell iTunes to play if it’spaused or pause if it’s playing So before using RoombAlarmClock, set iTunes to the playlist

or Internet radio station you’d like to wake up with Then, when it’s running, at any time pressthe Clean button to turn on the radio

For other operating systems, change the radioCmdvariable to any command-line commandthat you fancy You could even add additional commands that are triggered for the other but-tons or sensors Perhaps the Max button runs a command that talks to an X-10 controller toturn on the lights If you encapsulate these various commands into a shell script (or batch file

on Windows), you can change it all you want without re-exporting the sketch in Processing

In Chapter 13 you’ll learn how to make Roomba fully autonomous When fully stand-alone,having it be an alarm clock would be even more interesting For example, it could run awayfrom you as you try to turn off the alarm

If you use RoombAlarmClock to wake you up, don’t put Roomba on your nightstand table Itmay very well fall off Roomba is quite sturdy, but why take the chance? Place Roomba on thefloor

201 Chapter 10 — Using Roomba as an Input Device

You probably want to use the simpler serial tether rather than the Bluetooth adapter for the

alarm clock Some computers may power down their Bluetooth interface if it’s idle Regular serial

ports don’t have that problem

Listing 10-4: RoombAlarmClock

String wakeupTime = “6/20/06 07:48 am”;

Date wakeupDate = null;

boolean alarm = false;

int snoozeSecs = 60 * 9; // nine minutes

String radioCmd[] = {“osascript”, “-e”,

“tell app \”iTunes\” to playpause”};

try { wakeupDate = df.parse(wakeupTime); }

catch( Exception e ) { println(“error:”+e); }

Date now = new Date();

if( now.compareTo( wakeupDate ) > 0 )

roombacomm.createSong(5,song);

roombacomm.playSong(5); // play rude song

for( int i=0; i<5; i++ ) { // and shudder a little

Listing 10-4 Continued

Process p = Runtime.getRuntime().exec(radioCmd);

p.waitFor();

} catch(Exception e) { println(“exception:”+e); }}

void parseRoombaSensors() {if( alarm ) {

if( roombacomm.bumpLeft() &&

roombacomm.bumpRight() ) { // snoozewakeupDate.setTime(wakeupDate.getTime()+snoozeSecs*1000);

println(“snooze until “+wakeupDate);

alarm = false;

}else if( roombacomm.wheelDropLeft() &&

roombacomm.wheelDropRight() &&

roombacomm.wheelDropCenter() &&

roombacomm.powerButton() ) {println(“alarm off! (until tomorrow)”);

wakeupDate.setTime(wakeupDate.getTime() +(60*60*24)*1000);

alarm = false;

}}if( roombacomm.cleanButton() )runRadioCmd();

}

Summary

Even though the Roomba’s sensors are primitive, they can be put to some interesting uses.These uses need not be vacuum-related or even robotics-related The cliff sensors are one ofthe best examples of this, becoming non-contact proximity sensors for hands or other movableobjects when Roomba is turned upside down While upside down, the wheeldrop sensors becomebuttons to trigger actions You could even turn the wheels when upside down and register themovement as a variable function

By combining the sensors into more complex aggregations, you can create a novel way to ure something Roomba normally cannot measure Combining cliff and wheeldrop sensors gives

meas-a sense of tilt, but you cmeas-an immeas-agine other combinmeas-ations meas-as well Perhmeas-aps meas-a combinmeas-ation of tons and driving motor over-current sensor could make a weight sensor and turn Roomba into

but-a scbut-ale Or using the distbut-ance but-and but-angle sensors but-and but-a little cbut-alibrbut-ation could yield but-a Roombbut-ayardstick Try making Roomba a DJ input device and “scratch” audio files with it by rotating itback and forth like a record The number of possible sensor combinations is huge and many ofthem produce useful results Even those that produce non-optimal results are fun and instructive

Chapter 16

Other Projects

part

in this part

Connecting Roomba

to the Internet

The objects in our homes are becoming smart Not just the obvious

ones like the TV and stereo, but also the more mundane ones like the

stove and vacuum cleaner The “smart home” movement of a decade

ago with its centralized house computer is giving way to the emergent

phe-nomena of all the little parts of our homes becoming smart

If you have a Roomba robotic vacuum cleaner, you’re already aware of this

Roomba has more computing power than large corporations could afford in

the 1960s Imagine what bits of disposable computing will be present in our

everyday devices a few decades from now

A smart object is useful, but as anyone who has used the Internet can attest

to, connecting smart objects with each other leads to entirely new and

higher-level interactions This network effect characteristic is so important,

it’s considered a field of study in and of itself The effect has long been

recognized (no one will go to a stock exchange with only a few traders, and

a phone company with 10 users isn’t nearly as useful as one with 10,000

users), but it took computers and the Internet to bring it into sharp focus

Network effects can apply to any aspect of a group that becomes more

effi-cient or useful when a higher percentage of the group participates

We do not yet live in a world where a large percentage of the objects in our

lives are smart and networked, but we are on the brink Often with network

effects, once a critical mass of participants has been reached, all others in

the group quickly follow suit A recent example of this is e-mail: Before

1990 it seemed like no one had it, and then just a few years later suddenly

everyone did

Right now, only certain household objects are smart, and even fewer are

networked Recent advances in networking allow even the simplest smart

device to communicate with others and to do it cheaply This chapter

dis-cusses two of those types of devices that enable networking via Ethernet

Why Ethernet?

Both RS-232 and Bluetooth turn Roomba into a kind of networked object,

but a subservient one Objects communicating through simple serial

proto-cols like those two require a computer translator to convert between the

TCP/IP protocol used on the Internet and the simpler serial port protocol

 About Ethernet

 Choosing the right embedded Net device

 Building an Ethernet adapter

 Using the SitePlayer Telnet

 Using the Lantronix XPort

 Updating RoombaComm for network use

chapter

in this chapter

The object is beholden to a single computer and cannot function without it Ethernet is thesimplest and most pervasive physical protocol that can handle TCP/IP as a peer, rather thanbeing subservient to a larger computer However, even though it’s the simplest, dealing withEthernet and TCP/IP requires a great deal more processing power than a simple serial port.

䡲 Ethernet breaks all transmission streams into frames, a kind of data packet.

䡲 Ethernet supports multiple devices on the same cable

The packetization of data was an important and crucial step in the creation of the Internet.Before packets, computers were connected with serial cables or phone lines These dedicatedcircuits joined just two computers together If you wanted your computer to talk to anothercomputer, you had to get another serial port or phone line It wasn’t a very scalable design, soEthernet was created to allow multiple computers to use the same wire In order to keep onecomputer from monopolizing the wire, data transmission was divided into frames and sent oneafter the other Between frames other computers could interrupt to transmit their own data.Ethernet is a physical layer protocol and thus is only valid on a local area network (LAN) Tocommunicate between LANs, a higher-level protocol is needed, and the one everyone uses now

is the Internet Protocol (IP) IP provides a common, open language for all networked devicesand is the reason why the Internet works If you then want to recreate a virtual direct connec-tion between two computers on the Internet, you can use the Transmission Control Protocol(TCP), which exists on top of IP the way IP does on top of Ethernet TCP and IP are so com-monly used together that they’re often called TCP/IP TCP/IP doesn’t require Ethernet towork In fact, there are many alternatives to Ethernet The most common alternative available

to consumers is Wi-Fi (also known as 802.11b/g)

To create a device that exists on the Internet like any other, you need to implement TCP/IPand Ethernet (if using Ethernet) These are complex protocols, not something you can quicklywhip up by hand For Ethernet, there are several chips that provide that protocol’s functional-

ity For TCP/IP, there are several tiny stacks (collections of interlocking software) that fit within

modern microcontrollers and talk to these Ethernet chips

In the open-source realm, one of the most popular TCP/IP stacks is uIP available from

www.sics.se/~adam/uip/ This is a great stack that has been ported to many different types of microcontrollers The downside of rolling your own embedded TCP/IP system is that the Ethernet chips are all surface-mounting and hard to solder for a hobbyist

Fortunately, several companies have done the hard work of putting together an Ethernet chip,

a microcontroller, and a TCP/IP stack and making it all function To the user of these devices,