(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot

(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot(Đồ án tốt nghiệp) Design and manufacture of cable driven serial robot

HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

FACULTY FOR HIGH QUALITY TRAINING

GRADUATION PROJECT DESIGN AND MANUFACTURE OF CABLE-DRIVEN

Academic Year: 2017-2021

Ho Chi Minh City, June 2021

First and foremost, we would like to express our gratitude to our family, who have nurtured and provided us with the opportunity to study and grow into the people we are today, as well as to all of you Especially the students from class 17146CL1 who assisted the team with the project implementation.We would like to express our heartfelt gratitude

to Mr Vu Quang Huy for guiding and sharing many valuable experiences with us

throughout the project's implementation

We'd also like to express our gratitude to the teachers at Ho Chi Minh City University of Technology and Education, particularly those who eagerly assisted and imparted

knowledge during the group's learning process The knowledge we gained during the study

is not only the foundation for the project implementation process, but it is also a valuable asset for us if we decide to start a business in the future

Thank you so much once again

Name of Student Tưởng Thọ Đạt Lào Nguyên Phong Trương Thị Nhi

We now live in a culture where robots are utilized to accomplish both simple and sophisticated activities, assisting humans in performing repetitive, dangerous, and demanding duties or maybe extremely challenging

There are many types of industrial robots created in areas such as manufacturing, military surveillance, weapons, medicine and healthcare, transportation, and safer and more efficient research

The primary goal of this project is to investigate how to build, simulate, and operate a robot arm model that can move freely in a plane (Planar robot arm) using a ring control method using Servo and Step motors From there, the initiative wants to contribute to the open loop technique of robotics research work in college and university laboratories

Cable robots are structurally similar to parallel-actuated robots, but with the fundamental difference that cables can only pull the end-effector, but not push it These input constraints make feedback control of cable robots a lot more challenging than standard robots In this project, we present a computationally efficient control design procedure for a cable robot with two cables, which is kinematically determined as long as all cables are in tension The control strategy is based on dynamic aspects of a statically feasible workspace This computational framework is recursively used to find a set of reachable domains, using which, we are able to expand the region of feasibility by connecting adjacent domains through common points The salient feature of the technique

is that it is computationally efficient, or online implementable, for the control of a cable robot with positive input constraints However, due to the complexity of the dynamics of the general motion of a cable robot No cable interference is considered in this project Finally, the effectiveness of the proposed method is illustrated by numerical simulations and laboratory experiments on a two-degree-of-freedom cable robot

With what has been stated, together with the enthusiastic working spirit and the ultimate help of the instructor, the group has completed the thesis " DESIGN AND MANUFACTURE OF CABLE-DRIVEN SERIAL ROBOT."

Giờ đây, chúng ta đang sống trong một nền văn hóa nơi người máy được sử dụng để thực hiện cả các hoạt động đơn giản và tinh vi, hỗ trợ con người thực hiện các nhiệm vụ lặp đi lặp lại, nguy hiểm và đòi hỏi cao hoặc có thể cực kỳ thách thức

Có rất nhiều loại robot công nghiệp được tạo ra trong các lĩnh vực như sản xuất, giám sát quân sự, vũ khí, y học và chăm sóc sức khỏe, giao thông vận tải, nghiên cứu an toàn và hiệu quả hơn

Mục tiêu chính của dự án này là nghiên cứu cách xây dựng, mô phỏng và vận hành một

mô hình cánh tay robot có thể di chuyển tự do trong mặt phẳng (cánh tay robot Planar) bằng phương pháp điều khiển vòng sử dụng động cơ Servo và Step Từ đó, sáng kiến mong muốn đóng góp vào kỹ thuật vòng mở trong công việc nghiên cứu chế tạo robot trong các phòng thí nghiệm cao đẳng và đại học

Robot cáp có cấu trúc tương tự như robot hoạt động song song, nhưng có sự khác biệt

cơ bản là dây cáp chỉ có thể kéo thiết bị tác động cuối chứ không thể đẩy nó Những ràng buộc đầu vào này làm cho việc kiểm soát phản hồi của rô bốt cáp khó khăn hơn nhiều so với rô bốt tiêu chuẩn Trong dự án này, chúng tôi trình bày quy trình thiết kế điều khiển hiệu quả về mặt tính toán cho rô bốt cáp có hai dây cáp, được xác định động học miễn là tất cả các dây cáp đều ở trạng thái căng Chiến lược kiểm soát dựa trên các khía cạnh động của một không gian làm việc khả thi về mặt tĩnh Khung tính toán này được sử dụng đệ quy để tìm một tập hợp các miền có thể truy cập, bằng cách sử dụng chúng, chúng tôi có thể mở rộng vùng khả thi bằng cách kết nối các miền liền kề thông qua các điểm chung Đặc điểm nổi bật của kỹ thuật này là nó hiệu quả về mặt tính toán, hoặc có thể triển khai trực tuyến, để điều khiển một robot cáp với các ràng buộc đầu vào tích cực Tuy nhiên, do

sự phức tạp của động lực học của chuyển động chung của robot cáp Không có nhiễu cáp được xem xét trong dự án này Cuối cùng, hiệu quả của phương pháp đề xuất được minh họa bằng các mô phỏng số và các thí nghiệm trong phòng thí nghiệm trên rô bốt cáp hai bậc tự do

Với những gì đã nêu, cùng với tinh thần làm việc hăng say và được sự giúp đỡ tận tình của thầy hướng dẫn, nhóm đã hoàn thành khóa luận “THIẾT KẾ VÀ THI CÔNG ROBOT NỐI TIẾP ĐIỀU KHIỂN BẰNG CÁP”

NHIỆM VỤ ĐỒ ÁN TỐT NGHIỆP I PHIẾU NHẬN XÉT ĐỒ ÁN TỐT NGHIỆP II PHIẾU NHẬN XÉT ĐỒ ÁN TỐT NGHIỆP V ACKNOWLEDGEMENTS VIII ABSTRACT IX TÓM TẮT X TABLE OF CONTENT XI LIST OF ACRONYMS USED IN THIS REPORT XIII LIST OF TABLES XIV APPENDIX XV

CHAPTER 1: INTRODUCTION 1

1.1 Overview and issues: 1

1.2 Limit the scope of the study 2

1.3 Research Methods 2

1.4 Contents presented in chapters 3

CHAPTER 2: THEORETICAL BASIS 4

2.1 Definition of robot 4

2.2 Types of industrial robots and their application 5

2.3 Classification of robots 7

2.4 Forward kinematics [2] 9

2.5 Inverse Kinematics [2] 10

2.6 Plan the trajectory of the robot [2] [3] 11

2.7 Jacobi and Velocity Dynamics [2] 13

2.8 Robot dynamics [2] 14

2.9 Robot controller [2] 16

2.10 Sensor equipped on the robot [2] 19

2.11 Communication I2C bus [4] 22

CHAPTER 3: DESIGN AND CONSTRUCTION OF HARDWARE FOR CABLE DRIVEN ROBOT 25

3.1 Mechanical design 25

3.2 Flexural strength test [5] 25

3.3 Joint Torques Calculations 32

3.4 Sort and choose the right cable type [6] 35

3.5 Electrical design 37

4.1 Block diagram of the system 60

4.2 The forward and reverse kinetics of the robot 62

4.3 Workspace and trajectory plan for robots [3] 65

4.4 Jacobi and velocity dynamics [2] 75

4.5 Calculating the dynamics of the cable robot [2] 75

4.6 Design a simulation program on Matlab-Simulink with Simscape 79

4.7 Computed-Torque Control simulation with differential function [11] 81

4.8 Design realistic model control program via Matlab Simulink 93

CHAPTER 5: PROJECT RESULTS 96

5.1 Simulation results 96

5.2 Actual results 98

CHAPTER 6: CONCLUSIONS AND DEVELOPMENT ORIENTATIONS 99

6.1 Criteria for experimentation 99

6.2 Conclusion 99

6.3 Acquired Knowledge: 99

6.4 Limitations of the topic: 100

6.5 Direction of Development 100

REFERENCES 101

MAIN CODE APPENDIX 102

Computer(ized) Numerical(ly) Control(led) Inter-Integrated Circuit

Serial Data Line Serial Clock Line Acknowledge Not Acknowledge Circuit Breaker

Table 2 1: D-H parameter sheet 9

Table 3 1: Table technical specification of Cable [7] 36

Table 3 2: Specifications of Servo driver Mitsubishi MR-J2S-20A 42

Table 3 3: Specifications of Servo Motor HC-KFS23 43

Table 3 4: General specifications of Encoder Omron E6B2 – CWZ6C 44

Table 3 5: Specifications of Arduino UNO R3 45

Table 3 6: Specifications of Arduino MEGA 2560 46

Table 3 7: Specifications of CB 2P 16A Panasonic BBD2162CNV 47

Table 3 8: Specifications of Pulse Input 220VAC Out 24V 5A 120W 48

Table 3 9: Specifications of Reusable 8 x 300 mm Plastic Drawstring 49

Table 3 10: Specifications of Terminal Block Switchboard 12 Pole 25A 600V 50

Table 3 11: Specifications of Terminal Block Switchboard 6 Pole 25A 600V 50

Table 3 12: Specifications of Plastic Troughs for Electrical Wiring 51

Table 3 13: Specifications of Emergency Stop -LAY37-11ZS 52

Table 3 14: Specifications of Spiral Wire Wrap Cable 53

Table 3 15: Specifications of Hold Button With LED 220V-LA38-11DNZS 54

Table 3 16: Specifications of Signal Lights 10mm 55

Table 3 17: Specifications of LM2596 56

Table 3 18: Specifications of Round Cosse Head 57

Table 3 19: Specifications of Module Opto 58

Table 3 20: Specifications of Cosse Head Y 58

Table 3 21: Specifications of Electrical cabinets 600x400x180mm 59

Table 4 1: Parameter table DH of robot 63

Table 4 2: Table of robot parameters 76

Figure 2 1: Robot (Internet) 4

Figure 2 2: Articulated Robot Arm (Internet) 5

Figure 2 3: Articulated Robot Arm 2 (Internet) 6

Figure 2 4: Polar or Spherical Robot Arm (Internet) 7

Figure 2 5: Polar or Spherical Robot Arm 2 (Internet) 7

Figure 2 6: Modeling joints and links robot [2] 9

Figure 2 7: Block diagram of the Robot Control System 16

Figure 2 8: Open-loop control system (a) Closed-loop control system (b) 17

Figure 2 9: The robot's arms and legged dynamics [2] 17

Figure 2 10: Hardware structure of a typical robot control system 18

Figure 2 11: Basic joint control system block diagram of a typical robot 18

Figure 2 12: The working principle of the LVDT [2] 21

Figure 2 13: The incremental encoder disc a single ring [2] 22

Figure 2 14: The Absolute encoder disk by Gray codes and 8-bit binary codes [2] 22

Figure 2 15: Start and Stop Conditions [4] 23

Figure 2 16: Data Acknowledgement [4] 23

Figure 2 17: I2C Read/Write [4] 24

Figure 2 18: I2C Register Read/Write [4] 24

Figure 3 1: Movement type 1 25

Figure 3 2: Link 1 SOLIDWORKS 25

Figure 3 3: Link 2 SOLIDWORDS 26

Figure 3 4: Link 2 26

Figure 3 5: Diagram of forces link 2 27

Figure 3 6: Section [5] 27

Figure 3 7: Section of 1/2 link 2 [5] 28

Figure 3 8: Circular cross section link 2 [5] 29

Figure 3 9: Link1 30

Figure 3 11: Section of 1/2 link 1 [5] 31

Figure 3 12: Force calculation of joints 32

Figure 3 13: Stainless steel 3mm cable 7x7 [7] 36

Figure 3 14: Overview about Controller cabinet 37

Figure 3 15: Paradigm base before paint 38

Figure 3 16: Paradigm base before paint 2 38

Figure 3 17: Paradigm base before paint 3 39

Figure 3 18: Paradigm robot arm 39

Figure 3 19: Paradigm after paint 40

Figure 3 20: Paradigm robot arm assembly 40

Figure 3 21: Paradigm Finish 41

Figure 3 22: Servo driver Mitsubishi MR-J2S-20A [9] 42

Figure 3 23: HC-KFS23 [10] 43

Figure 3 24: Encoder Omron E6B2 - CWZ6C 2000 xung 44

Figure 3 25: Arduino UNO R3 [8] 45

Figure 3 26: Arduino MEGA 2560 [8] 46

Figure 3 27: MCB 2P 16A Panasonic BBD2162CNV [8] 47

Figure 3 28: Pulse Input 220VAC Out 24V 5A 120W [8] 48

Figure 3 29: Reusable 8 x 300 mm Plastic Drawstring [8] 49

Figure 3 30: TB2512 Terminal Block Switchboard 12 Pole 25A 600V [8] 49

Figure 3 31: TB2506 Terminal Block Switchboard 6 Pole 25A 600V [8] 50

Figure 3 32: Plastic Troughs for Electrical Wiring [8] 51

Figure 3 33: Emergency Stop -LAY37-11ZS [8] 52

Figure 3 34: Spiral Wire Wrap Cable [8] 53

Figure 3 35: Hold Button With LED 220V-LA38-11DNZS [8] 54

Figure 3 36: Signal Lights 10mm [8] 55

Figure 3 37: LM2596 [8] 56

Figure 3 39: Module Opto [8] 58

Figure 3 40: Cosse Head Y [8] 58

Figure 3 41: Electrical cabinets 600x400x180mm [8] 59

Figure 4 1: System block diagram 60

Figure 4 2: Overview about electrical structure 60

Figure 4 3: Diagram of the workings 61

Figure 4 4: Robot model 62

Figure 4 5: Diagram of robot model with coordinate axis system attached 63

Figure 4 6: The working space of the Robot Oxy 65

Figure 4 7: Orbits from A (0;500) to B (200;500) 67

Figure 4 8: Orbits from A (0;500) to B (0;600) 68

Figure 4 9: Speed of end impact point 68

Figure 4 10: Acceleration of end impact point 69

Figure 4 11: The robot's trajectory is triangle 70

Figure 4 12: Speed of end impact point 71

Figure 4 13: Acceleration of end impact point 71

Figure 4 14: The robot's trajectory is circular 73

Figure 4 15: Speed of end impact point 74

Figure 4 16: Acceleration of end impact point 74

Figure 4 17: Algorithm Diagram 79

Figure 4 18: Simulate robot with simscape 80

Figure 4 19: Conver Solidworks to Matlab 80

Figure 4 20: Linear system 83

Figure 4 21: PD computed torque structure 83

Figure 4 22: When Kp=0; Kd=0 84

Figure 4 23: When Kp=50; Kd=0 84

Figure 4 24: When Kd=60 Kd=17 85

Figure 4 26: Simulink block 86

Figure 4 27: From A (300;600) to B (0;600) 87

Figure 4 28: Joint angles and feedback (rad) 87

Figure 4 29: Torque Input (N.m) 88

Figure 4 30: Tracking error (Rad) 88

Figure 4 31: Circle with center I (50;600) R=50 89

Figure 4 32: Joint angles and feedback (rad) 89

Figure 4 33: Torque Input (N.m) 90

Figure 4 34: Tracking Error (N.m) 90

Figure 4 35: Triangle with A (400;400), B (0;500), C (200;600) 91

Figure 4 36: Joint angles and feedback (rad) 91

Figure 4 37: Torque Input (N.m) 92

Figure 4 38: Tracking Error (N.m) 92

Figure 4 39: The Simulink Support Package for Arduino (Internet) 93

Figure 4 40: Some blocks in the Simulink Support Package for Arduino 93

Figure 4 41: The components of an open-loop controller 93

Figure 4 42: The following controller structure 94

Figure 4 43: MATLAB to Simscape Multibody (Internet) 94

Figure 4 44: MATLAB & Simulink 95

Figure 4 45: GUI interface for interacting with the robot 95

Figure 5 1: The robot runs in a triangular trajectory 96

Figure 5 2: The robot runs in a circular trajectory 96

Figure 5 3: The robot runs in a straight line trajectory 97

Figure 5 4: Change the height of the first translation joint 97

Figure 5 5: Change the rotation angle of the 2nd joint 98

Figure 5 6: The actual model of the project 98

CHAPTER 1: INTRODUCTION 1.1 Overview and issues:

Currently, the strong deployment of Industry 4.0 within the world is happening, which is that the perfect combination between the physical and digital hyper-connection system using the web, Internet of things (IoT) AI (AI) The result of technology 4.0 is that the robot Sophia has been granted citizenship of Saudi Specifically, Sophia can simulate quite 62 facial expressions that only humans can have, by using a particularly sensitive camera within the eye, coordinating analysis

of computer algorithms supported Mind-Cloud software additionally, companies within the world have moved from 36% digitalized to 75% digitalized by 2020 Meanwhile, Vietnam remains slow with building infrastructure, which suggests industry 2.0 - mechanization [1]

Currently, Vietnam's conglomerate enterprises are not prepared to participate in the fourth industrial revolution; there are no leading companies producing high-value export products to bring foreign currency into the country Using and importing 4.0 products primarily made in developed countries Moreover, the transmission of the robot is also a problem when the current actuators still have many defects such as belt transmission or direct drive that make the robot operate incorrectly So to know the character of mechanical structures, the way to create a robot model, the way to program and control a robot arm that you simply make yourself, and beyond that, master the engineering technique

In this project, we look at a two-stage cable robot, i.e., a cable robot with two moving platforms connected in series The sea condition introduces disturbance into the system This disturbance is considered while modeling the dynamics of the two-stage cable robot A robust controller is designed which can assure robust tracking

of the desired end-effector trajectory in the presence of the disturbance Simulation results presented show the effectiveness of the controller

With these outstanding advantages, this thesis will present the method of designing, manufacturing, and controlling the model "DESIGN AND MANUFACTURE OF CABLE-DRIVEN SERIAL ROBOT"

1.2 Limit the scope of the study

To master the technique of robotics can be applied to the laboratory of colleges, universities as well as in industrial production The theme has the following goals:

- Design a robot arm model on SolidWorks software

- Workspace planning for robots

- Converting SolidWorks to Simscape multibody

- Programming the inverse kinematics, trajectory and evaluate the simulation results

- Implement hardware-based models designed in SolidWorks

- Designing the robot's electrical parts

- Design instructional interface on Matlab to easily control the real model

- Apply the forward and inverse kinematics, orbit planning to the real model

1.3 Research Methods

After consulting the industrial robot arm types and the transmission methods for the robot arm based on actual requirements, initial goals, together with the enthusiastic advice and help of the instructor, the team has shaped for me the direction and method of implementing the project

The process of implementing the project is as follows:

- Use SolidWorks to design robot arm model Consult with instructor and then optimize the model to achieve the initial goal based on the available materials

- Use Simscape Mutilbody to convert model from SolidWorks to Matlab-Simulink

- Calculate the forward and reverse kinematics and study robot orbital planning

- Use Matlab-Simulink to program and simulate the robot's trajectory

- Fabrication and assembly of robotic-arm model

- Draw electrical diagrams and connect electrical parts to the system

- Study and control the position, speed and direction of the engine

- Controlling robot works in trajectory, collecting data and evaluating results

- Write a program for the control buttons

- Complete the entire system Conclude and draw gaps and directions for future development

1.4 Contents presented in chapters

The rest of the project is as follows:

Chapter 2 Theoretical basis:

Chapter 2: Presentation of industrial robots, classification of robots by structure and control method, robot control theory, an overview of drive methods, from which to choose the basis of tissue design and control algorithm in the following chapters

Chapter 3 Hardware design:

Chapter 3: Presents a designed model based on the drive methods in Chapter 2 and optimizes the model from the original design to meet the requirements set out Selection of mechanical and electrical parts equipment for the model as well as the hardware construction process

Chapter 4 Algorithm and control method in the robot:

Chapter 4: Presents the methods of forward and inverse kinetics, workspace with orbital planning for robots, programming Matlab-Simulinks, controller design on Simscape multibody as well as on robotic-arm model and conduct data collection for evaluation

Chapter 5 Project results:

Chapter 5: Presents the simulation results of the system, the results of hardware and the results of the operation on the real model

Chapter 6 Conclusion and development direction for the project

Chapter 6: Presents conclusions about the implemented project and possible development directions of the project

CHAPTER 2: THEORETICAL BASIS

Chapter 2 will present definitions, properties, and applications of industrial

robots, how to classify robots according to their structure and control methods, and then select a suitable robot structure for requirements Overview of PID controllers, Denavit-Hartenberg rules, and orbital planning theory to build

algorithms for the model

2.1 Definition of robot

Robots, "Robotics" are machines that can perform jobs automatically by the control of a computer or programmed electronic circuits A robot is an artificial mechanical agent, usually a mechanical electronic system An industrial robot is a programmable machine mechanism capable of working automatically without human assistance A robot is the product of the robotics field, where programmable machines are built that can assist humans or mimic human actions Robots were originally built to handle monotonous tasks (like building cars on an assembly line), but have since expanded well beyond their initial uses to perform tasks like fighting fires, cleaning homes and assisting with incredibly intricate surgeries Each robot has a differing level of autonomy, ranging from human-controlled bots that carry out tasks that a human has full control over to fully-autonomous bots that perform tasks without any external influences In addition, the machines can cooperate with each other A robot arm is a device that works in the same way as a human arm, with several joints that can move along an axis or rotate in certain directions In fact, some robotic arms are constructed and programmed to work with the correct way of following the human arm's movements Benefits of using industrial robot arm in production: Industrial robot arm, can move much faster than a human arm An industrial robotic arm increases productivity and accuracy Properly functioning robotic arms greatly reduce production errors caused by workers and greatly reduce labor costs

Figure 2 1: Robot (Internet)

2.2 Types of industrial robots and their application

2.2.1 Articulated Robot Arm

Definition: An Articulated Robot Arm is a robot with rotary joints Articulated

robots can range from simple two-jointed structures to systems with 10 or more interacting joints and materials They are powered by a variety of means, including electric motors

Characteristics: With the relative association between the movement capacity of

the joints and the number of degrees of freedom Articulated Robot Arm works very skillfully, but the positioning accuracy depends on the position of the working unit

in the work area The working area of this robot is almost like a sphere

Application: For example: bomb-handling robots have hand-like attachments,

which closely simulate the movements of a human hand This can be used to open doors, handle or move sensitive ammunition Articulated robotic arms are also commonly used in assembly lines, die casting, gas welding, and even paint spraying The illustrations for Articulated Robot Arm are shown in Figure 2 2 and Figure 2 3

Figure 2 2: Articulated Robot Arm (Internet)

Figure 2 3: Articulated Robot Arm 2 (Internet)

2.2.2 Polar or Spherical Robot Arm

Definition: Polar or Spherical Robot Arm This type of robot is configured to form

a polar coordinate system using a combination of two rotating joints and a linear joint, they connected to a single base with a helix This results in a workspace and a range of spherical motion

Characteristics: The rigidity of the Polar or Spherical Robot Arm is lower than

the Cylindrical Robot Arm and the Cartesian Robot Arm The positioning accuracy

of the Polar or Spherical Robot Arm also depends on reach

Application: In addition to gas welding and arc welding, polar robots are also

used in environmental monitoring, planetary and underwater exploration, and also

in hospitals such as rehabilitation machines and physiotherapy

The illustrations for Polar or Spherical Robot Arm are shown in Figure 2 10 and Figure 2 11

Figure 2 4: Polar or Spherical Robot Arm (Internet)

Figure 2 5: Polar or Spherical Robot Arm 2 (Internet)

2.3 Classification of robots

To position and orient the working part arbitrarily in 3-dimensional space, the robot needs 6 degrees of freedom, of which 3 degrees of freedom for positioning, 3 degrees of freedom for orientation [2]

2.3.1 Classification of robots according to their structure

Take two primitive forms of motion as the standard:

- Linear motion in the direction of X, Y, Z in three-dimensional space normally

creates angled cubes, called Prismatic (P)

-The motion of rotation around the axes X, Y, Z is denoted by (R)

With three degrees of freedom, the robot will operate in the workspace depending

on combination P and R for example:

- PPP workspace will be a rectangular box or cube

- The RPP workspace is a cylindrical block

- The RRP workspace is a sphere

- The RRR workspace is a sphere

2.3.2 Classification of robots according to the control method

There are 2 types of robot control: open-loop and closed-loop

Open-loop control, using a stepper drive (electric motor or hydraulic motor, pneumatic, .) whose distance or angle is proportional to the number of control pulses This is simple but has a low level of accuracy

Closed-loop control (Servo-type control), using position feedback signal to increase control precision There are 2 servo controls: point-to-point control and contour control

- With point-to-point control, the working part translates from point to point in a

straight line at a low speed (no work) It only works at the stops This type of control is used on spot welding, conveying, riveting, nailing, etc

- Contour control ensures any working parts move at a controllable speed This

type of control can be encountered on arc welding, spraying robots

2.4 Forward kinematics [2]

Denavit-Hartenberg convention: Suppose in the kinematic sequence of the machine hand there are n joints, the nth joint connects nth links with n + 1

Figure 2 6: Modeling joints and links robot [2]

To model the robot, we are using a D-H to represent, the first thing to do is to mount the reference axis on every rotating joint All joints are represented in the z-axis If the joint is a rotating joint, the z-axis will be oriented in the direction of the displacement producing a right-hand convention If the joint is a translational joint, the z-axis of the joint is along the direction of travel If an is the distance of the common perpendicular line between the axis zn-1 and zn, the direction of the V-axis will be along the direction of segment an The direction of the y-axis is determined according to the right-hand rule Since then there is the D-H parameter sheet

Where: a: is the length of the link

α: is the twist of the link or the deviation angle between the two axes zi-1 and zi

d: is the distance deviation of the plane containing axes xi-1 and xi

θ: is the angle of rotation or the angle between the axes xi-1 and xi

The use of the Denavit-Hartenberg convention yields the link transformation matrix,

[i-1Ti] is shown in formula (2.1) with the parameters determined in table D-H [2]

- Algebraic method

- Geometry method

- Geometry method combined with algebra

2.6 Plan the trajectory of the robot [2] [3]

Plan the trajectory of the robot [6] is to generate reference input signals for the robot controller so that the robot moves in the desired trajectory Point-to-Point trajectories are trajectories that pass through two predetermined points in a specified time, line orbits are trajectories that pass through many points in a predetermined continuous line The project uses Third Degree Polynomials to create the trajectory for the robot

Want the working head to go through two specified points in space, from the beginning and the end of the work head to solve the inverse kinetics problem, determine the beginning and end values for the jointing variables

q0 = q (t0), qf = q (tf) Considering a jointing variable, find an expression for q (t) that satisfies the condition of position (q) and velocity (v) at the beginning and the end Value at time t0:

2.7 Jacobi and Velocity Dynamics [2]

Many job tasks require the robot have to control its trajectory, direction, position, and speed Here, the Robot end effector velocity and its relationship with the velocity of the joints variables are analyzed The Jacobi matrix is one of the important properties of a mechanical manipulator that is also analyzed, explored, and introduced The Jacobi matrix is an essential mathematical tool for analyzing, controlling functions as well as operating robots

The Jacobi matrix is the geometrical representation of the elements in a structure per unit of time Jacobi has a relationship with time when the angle values change over time Therefore, we can find the Jacobi matrix by taking the derivative of a function position with all the variables

The Jacobi matrix can be calculated by taking the derivative of each equation with all the variables And we use such a principle for calculating Jacobi robot

 

1 21

1 1

2

2 2

1 2 3 4 5 6

d dx

d dy

d dz

d x

d y

d z

2.8 Robot dynamics [2]

Robots are interdisciplinary fields including physics, mechanics, both static and dynamics, control theory, robot vision, signal processing, computer programming, and manufacturing Kinetic research also contributes greatly to helping us in the process of controlling robots Hand dynamics are mainly written in the vector form

of Second-Order Differential Equations and can be performed as state variable descriptions

As is well known, if we apply mass to acceleration, we give it a force Likewise,

if we induce a rotation acceleration on the robot's body, it will generate a moment

on its body like this:

F =m a

To create single-link acceleration for robots, we need to have an actuator capable

of generating a sufficiently large force or a large enough moment on the robot's link

to move them with the required speed To be able to calculate the actuator output required, we need to define the kinetic relationship that affects the mechanisms of the robot

2.8.1 The Euler-Lagrange Approach

The radial force of a mass m moving around a point with radius r and the angular velocity ω is calculated as follows:

The Rotational Kinetic Energy of a mass m is:

2

12

Where: ( )r is the mass distribution at radius R per volume In the simple case, with a mass m and q points, the above equation becomes the new equation:

2

So:

2 2

q is a vector of n general axes with a component axis qi

 is the vector of n general forces with the component forcesi

The Lagrange function is the difference of kinetic energy minus potential energy

2.9 Robot controller [2]

2.9.1 Concept of the robot controller

The controller is a device that handles network communication, information between input/output devices, controls the movements and actuators of the robot according to the request It accepts the necessary input signals with a robot and output signals to control the engine or actuator to respond to the operational requirements of the robot and the world around it Controllers come in a variety of types with varying degrees of complexity in design, depending on the functions of the robot as well as the complexity of the tasks the robot has to perform

Figure 2 7: Block diagram of the Robot Control System Control is a function of management that helps to check errors to take corrective actions This is done to minimize deviation from standards and ensure that the stated goals of the organization are achieved in the desired manner In the robot, we can control the linear variable speed, adjust the velocity, the position of the machine arm, or control various variables

A technical control system is always required to ensure at least 2 parts: Controller and Plant (controlled object) These components can form a system with or without

a response as shown in figure 2.15:

Figure 2 8: Open-loop control system (a) Closed-loop control system (b)

2.9.2 Multi-link control structure [2]

The robotic arms or legs consist of hard links or links that are linked through joints The robot arm structure differs from the robot leg structure, the robot arm, the gripper, or the robot end-effector can add degrees of freedom while the robot legged are usually passive or stationary There are two directions for controlling the structure: position and force (moment) The first direction is to control the end position, the second direction is to control the position of the gripper combined with the force to grab the object This is quite important while the object being grasped can break or deform when the impact force exceeds its tolerance and may slip when the forces exerted on the object is not balanced

Figure 2 9: The robot's arms and legged dynamics [2]

Structure of a multi-link robot controller:

Figure 2 10: Hardware structure of a typical robot control system

In this project, we take a high-level master controller and send standard control commands to the slave controllers Each slave controller will control an individual joint normally with PID control, and each joint will respond by a position sensor or rotation angle that can measure the amount directly or indirectly

Figure 2 11: Basic joint control system block diagram of a typical robot

2.9.3 Modeling the robot controller

The general dynamics model for robots is as follows:

M q : V is a matrix n x n, where n is the number of links of the robot Contains

mass and moment of inertia parameters

G q : V is nx1 matrix describing the effect of gravity

From equation (2.24) that the acceleration vector of the joints is calculated as:

Where:  is the torque of the joints, provided by the output of the actuator, and

takes the form of a first-order derivative:

K is the amplification factor

From the modeling of the engine and the power amplifier we obtain:

2.10 Sensor equipped on the robot [2]

To be able to perform the job of replacing humans, robots must be able to sense the changes inside themselves and their surroundings Devices that sense these variable signals are called sensors These are measuring devices, from these measured signals to be fed into a processor or computer to control the robot's operation Basic sensors used in robots are called transducers, which convert physical signals into electrical signals This signal is transmitted to the processor and the controller for the control of the robot on duty

If the sensing ability of the robot increases, the robot will be more flexible, while reducing its dependence on the detailing system, so it will reduce production costs

in these machines

Similarly, if we increase the perceptibility of the robot, increase production efficiency will save production time If a robot is required to perform a new task or modify a task by reprogramming, writing a new program will take a lot of time, but

if the sensor-equipped on the robot, the robot will be easier to work and do not need

to reprogram

A position control algorithm for a sensor-equipped industrial robot is developed based on a transputer network This approach was made by interfacing each transputer directly to its associated drive Every axis is controlled in a closed-loop

by its own transputer Three distance sensors are used to control the orientation of the robot With this sensor system, the distance can be controlled in real-time between uncertain working surface and tool, which is mounted on the end-effector

In robotics, sensors are used to:

- Measurement of robot parameters for the control loops

- Find the location of the object

- Correct parameter error in the robot model and global coordinate system

- Detect and avoid false states

- Detect and avoid obstacles

- Monitor the robot's activities with its surroundings and adjust the robot's operation

to each type of task that the robot must perform

- Monitor environmental changes that may affect the robot's operation

- Check the results of the robot performing the task

2.10.1 Measurement of linear motion

Linear motion transducers are a measure of the movement of structure along a line between 2 points One of their applications is primary sensors that measure links movement, Linear motion transducers transformer which is widely used as the secondary sensor in the system to measure pressure, force, and acceleration or the temperature is converted to linear motion amount by the primary sensor

Linear motion transducers include many types: Straight Slide Potentiometer, rotary potentiometer, differential transformer The Linear variable differential transformer (LVDT) relies on direct displacement similar to a sensing element so very small displacements can be measured The characteristic of the Linear Variable Differential Transformer is high resolution, good stability, making it an ideal measuring device for small displacement

Figure 2 12: The working principle of the LVDT [2]

The LVDT or Linear Variable Differential Transformer consists of one primary winding and 2 secondary windings as shown in figure 2.20 The object

to be measured is attached to the ferromagnetic core that moves inside the tube, creating a change in voltage, and from this change, we will determine the location to be measured

One reason affecting the accuracy of The LVDT is the presence of a harmonic function for the excitation voltage and the parasitic capacitance between the primary windings and the secondary windings which causes the voltage to be zero i.e when the signal output received is the lowest value The above case occurs when the core is centrally positioned evenly spaced from the two secondary windings

2.10.2 Measuring Rotational Motion

The joints of robots are usually controlled by a rotating motion engine For that

reason, people use rotation sensors to measure the speed and position of the engine for easy precise control Popular among them is optical encoder disc The first optical encoder was developed in the late 1940s at the Baldwin Piano Company for use in music tuning equipment Currently, optical encoders are widely used in many fields of automatic control, especially robots and CNC machines Light rays are mounted opposite the photosensitive to perceive light through encoder discs mounted on the rotating shaft, which are intermittent with alternating light and dark The rotating discs can be made of Chromium (Cr), glass, or metal,

Encoders are classified into two basic types: absolute encoders and incremental encoders The incremental type can measure the rotational velocity

of the disc and thereby calculate the position, while the absolute type can easily measure the angular position with the corresponding velocity

Figure 2 13: The incremental encoder disc a single ring [2]

Figure 2 44: The Absolute encoder disk by Gray codes and 8-bit binary codes [2]

2.11 Communication I2C bus [4]

I2C, also known as Inter-Integrated Circuit, is a synchronous, chip-to-chip protocol for communication in integrated circuits and low-speed peripherals Some

of the common I2C based devices include EEPROM, thermal sensors, and real-time clocks

The I2C bus on the device has an I2C Master that is connected to two bidirectional lines, Serial Data Line (SDA) and Serial Clock Line (SCL) These two lines are connected to a pair of pins on the attached I2C slave device The I2C slave device has a unique 7-bit or 10-bit address that is usually provided by the manufacturer If the address is not unique, refer to the device datasheet to reconfigure the address

The master node generates a clock and initiates communication with the slave device The slave node receives the clock and responds with an acknowledgment to the I2C master

I2C uses the following communication modes:

⚫ Master Transmit: I2C master WRITES data to I2C slave

⚫ Master Receive: I2C master READS data from I2c slave

⚫ Slave Transmit: I2C slave WRITES data to I2C master

⚫ Slave Receive: I2C slave READS data from I2C master

An I2C message consists of a START bit, the data transmitted, and a STOP bit

An SDA going from HIGH to LOW with the SCL still at HIGH indicates a START condition The SDA going from LOW to HIGH with the SCL held at HIGH indicates a STOP condition All other SDA transitions take place with SCL at low

Figure 2 15: Start and Stop Conditions [4]

I2C communication defines the data bytes to be 8-bit long I2C can transmit data of single-byte or multiple bytes During the data transmission, and acknowledge ACK signal follows every byte A clock for ACK is generated by the master, while the receiver (master or slave) generates the ACK by pulling down the SDA and holding it to LOW during the high portion of the acknowledged clock pulse

If the SDA is not pulled LOW during the acknowledge period, it indicates NACK (Not Acknowledge) by the receiver If a slave is not ready to transmit or receive of next data byte, it holds SCL LOW making the master enter a WAIT state Once the slave is ready and releases the SCL, the normal data transfer resumes

Figure 2 16: Data Acknowledgement [4]

The I2C read/write operation takes place as follows:

⚫ The I2C master initiates the communication by sending a START condition followed by a 7-bit slave address and the 8th bit to indicate write (0)/ read (1))

⚫ The master releases the SDA and waits for an ACK from the slave device

⚫ If the slave exists on the bus, it responds with an ACK

⚫ The master continues in either transmit or receive mode (according to the read

or write bit it sent), and the slave continues in its complementary mode (receive

or transmit, respectively)

⚫ The master terminates the data transmission by sending a STOP condition The following image shows a single byte read and write on an I2C slave device

Figure 2 17: I2C Read/Write [4]

The I2C register read/write operation takes place as follows:

⚫ The I2C master initiates the communication by sending a START condition followed by a 7-bit slave address and the 8th bit to indicate write (0)/read (1)

⚫ The master releases the SDA and waits for an ACK from the slave device

⚫ If the slave exists on the bus, it responds with an ACK

⚫ Then, the master writes the registered address of the slave it wants to access

⚫ Once the slave acknowledges the registered address, the master sends the data byte with an ACK after each byte for write/read

⚫ The master terminates the data transmission by sending a STOP condition The following image shows a single byte read and write on a register present in the I2C slave device

Figure 2 18: I2C Register Read/Write [4]

CHAPTER 3: DESIGN AND CONSTRUCTION OF

HARDWARE FOR CABLE DRIVEN ROBOT

Chapter 3 will present about the initial requirements, from which the model will

be designed based on the drive methods presented in the theoretical basis Refer to the advice of instructors, then complete and optimize the model to proceed with construction Next is the presentation of the selected equipment for the model and construction of the mechanical as well as electrical parts

3.1 Mechanical design

Figure 3 1: Movement type 1

3.2 Flexural strength test [5]

Figure 3 2: Link 1 SOLIDWORKS

Figure 3 3: Link 2 SOLIDWORDS

Consider link 2:

We treat them as a dovetail halving to test the flexural strength, assuming joint 1 of the robot does not rotate

Figure 3 4: Link 2

Diagram of forces:(With F1=P; l=350mm)

Figure 3 5: Diagram of forces link 2

With Qy ≠0 and Mx ≠0, we have the case of flat horizontal bending

M

y I

M

y I

Maximum shear stress at rectangular cross section:

Figure 3 7: Section of 1/2 link 2 [5]

167.44( )478.4( ) 4693.104( )