«HYBRID MOBILE ROBOT SYSTEM: INTERCHANGING LOCOMOTION AND MANIPULATION by PINHAS BEN–TZVI A thesis submitted in conformity with the requirements for ...»
HYBRID MOBILE ROBOT SYSTEM:
INTERCHANGING LOCOMOTION AND
A thesis submitted in conformity with the requirements
for the degree of Doctor of Philosophy
Graduate Department of Mechanical and Industrial Engineering
University of Toronto
© Copyright by Pinhas Ben-Tzvi, 2008
HYBRID MOBILE ROBOT SYSTEM:
INTERCHANGING LOCOMOTION AND MANIPULATIONDoctor of Philosophy Pinhas Ben-Tzvi Department of Mechanical and Industrial Engineering University of Toronto, 2008 ABSTRACT This thesis presents a novel design paradigm of mobile robots: the Hybrid Mobile Robot system. It consists of a combination of parallel and serially connected links resulting in a hybrid mechanism that includes a mobile robot platform for locomotion and a manipulator arm for manipulation, both interchangeable functionally.
All state-of-the-art mobile robots have a separate manipulator arm module attached on top of the mobile platform. The platform provides mobility and the arm provides manipulation. Unlike them, the new design has the ability to interchangeably provide locomotion and manipulation capability, both simultaneously. This was accomplished by integrating the locomotion platform and the manipulator arm as one entity rather than two separate and attached modules. The manipulator arm can be used as part of the locomotion platform and vice versa. This paradigm significantly enhances functionality.
The new mechanical design was analyzed with a virtual prototype that was developed with MSC Adams Software. Simulations were used to study the robot’s enhanced mobility through animations of challenging tasks. Moreover, the simulations were used to select nominal robot parameters that would maximize the arm’s payload ii capacity, and provide for locomotion over unstructured terrains and obstacles, such as stairs, ditches and ramps.
The hybrid mobile robot also includes a new control architecture based on embedded on-board wireless communication network between the robot’s links and modules such as the actuators and sensors. This results in a modular control architecture since no cable connections are used between the actuators and sensors in each of the robot links. This approach increases the functionality of the mobile robot also by providing continuous rotation of each link constituting the robot.
The hybrid mobile robot’s novel locomotion and manipulation capabilities were successfully experimented using a complete physical prototype. The experiments provided test resultsthat support the hypothesis on the qualitative and quantitative performance of the mobile robot in terms of its superior mobility, manipulation, dexterity, and ability to perform very challenging tasks. The robot was tested on an obstacle course consisting of various test rigs including man–made and natural obstructions that represent the natural environments the robot is expected to operate on.
This thesis is the result of four years of work whereby I have been accompanied and supported by many people. It is a pleasant aspect that I have now the opportunity to express my gratitude to all of them.
I would first like to thank my supervisors, Professor Andrew A. Goldenberg and Professor Jean W. Zu. I owe them a great deal of gratitude for showing me their enthusiasm and integral view on research and their mission for providing only the highest quality work and not less. Besides being exceptional supervisors, they were remarkably supportive and understanding not only with the regular academic activities, but also with their dedicated support during life hardships. I am very thankful that I have come to get to know them in my life. At the same note, I would like to extend a special gratitude to Mrs. Elizabeth Catalano for her dedicated help and support. Her remarkable professional aptitude and friendly approach greatly contributed.
In the lab, I was surrounded by knowledgeable and friendly people who helped me daily. Many thanks to my colleagues Dr. John Yeow, Dr. William Melek, Dr.
Peyman Najmabadi, Dr. Cyrus Raoufi, Dr. Danny Ratner, Sadath Malik, Masatetsu Wake, Shingo Ito, Dr. Helei Wu, Dr. Hong Zhao, Yi Li, and Hong Xia from the Robotics and Automation Laboratory at the University of Toronto; and to Alireza Hariri, Peyman Honarmandi, Parag Dhar, Andrew Sloboda and Hansong Xiao from the Vibration and Computational Dynamics Laboratory at the University of Toronto.
I am grateful to Engineering Services Inc. (ESI) for providing me with a highly professional and nurturing environment, where I was successfully able to integrate the Hybrid Mobile Robot (HMR) prototype and also for providing their resources and
for his contributions and help with implementing the control hardware architecture for the HMR. Specifically, for providing the detail design of the electrical boards, the OCU and electrical wiring. I would also like to thank Matt Gryniewski, Rob Stehlik, Dr. Liang Ma and Dr. Jun Lin from ESI for their help.
I am thankful to the Department of Mechanical and Industrial Engineering at University of Toronto for their support. Special thanks to Prof. Pierre Sullivan, Associate Chair of Graduate Studies, Brenda Fung, Graduate Studies Assistant & Coordinator, and the Department Chair, Prof. Anthony N. Sinclair for their outstanding support and exceptional professional aptitude.
I would like to profoundly thank Annette, my love and best friend, whose presence, companionship and dedicated support helped make the completion of this work possible. And to my adorable daughter Timor, you are always in my heart and mind! I am deeply thankful and lucky to be blessed with a smart, beautiful and understanding daughter.
I am grateful for my parents Jacob and Sara and my brothers Joseph, Israel, and Aaron for their support, understanding, and trust towards my long journey away from home.
TABLE OF CONTENTS
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
CHAPTER 1: INTRODUCTION
1.3 Overview of the Dissertation
CHAPTER 2: BACKGROUND
2.1 Review of Tracked Mobile Robots
2.2 Analysis of Issues and Related Research Problems and Proposed Solutions............. 14 CHAPTER 3: MECHANICAL DESIGN PARADIGM
3.1. Description of the Design Concept
3.1.1 Concept Embodiment
3.1.2 Modes of Operation
3.1.6 Additional Embodiments of the Concept
3.2 Mechanical Design Architecture
3.3 Motor Layout and Driving Mechanisms
3.4 Base link 1 - Tracks
3.5 Built-in Dual-operation Track Tension and Suspension Mechanism
CHAPTER 4: MODELLING AND DYNAMIC SIMULATIONS
4.1 Robotic System Modelling and Postprocessing
4.1.1 Virtual Prototyping and Simulations Using ADAMS Software
4.1.2 Model Structure
4.1.3 Simulations and Postprocessing
4.2 Simulation Results and Discussion
4.2.1 Mobility Characteristics Analysis - Animation Results
4.2.2 Analysis of Track Tension and Suspension Mechanism
4.2.3 Analysis of Motors Torque Requirements
4.2.4 End–Effector Payload Capacity Analysis
viiCHAPTER 5: CONTROL SYSTEM DESIGN PARADIGM
5.1 On-Board Wireless Sensor/Actuator Control Paradigm
5.1.1 On-Board Inter-segmental RF Communication Layout
5.1.2 RF Hardware for the Hybrid Mobile Robot
5.2 Electrical Hardware Architecture
5.2.1 Controllers, Drivers, Sensors and Cameras Layout
5.2.2 Power System and Signal Flow Design and Implementation
5.2.3 Sensor Processor Board
5.3 Robot DOF Coordination and Operator Control Unit (OCU)
CHAPTER 6: EXPERIMENTAL SETUP AND RESULTS
6.1 Research Hypothesis Validation
6.2 Performance Metrics as Design Targets
6.3 Robot Configurations for Manipulation
6.4 Mobility/ Maneuverability Characteristics Testing and Validation
6.5 Traction Configurations
6.6 Traversing Cylindrical Obstacles
6.7 Stair Climbing and Descending
6.7.1 Stair Climbing
6.7.2 Stair Descending
6.7.3 Stair Descending – Other Configurations
6.8 Step Obstacle Climbing
6.8.1 Climbing with Tracks
6.8.2 Climbing with Link 2
6.9 Step Obstacle Descending
6.9.1 Descending with Links 2 and 3
6.9.2 Descending with Base link Tracks
6.10 Ditch Crossing
6.11 Platform Lifting and Carrying Capacity Testing
6.12 Simultaneous Locomotion and Manipulation
6.12.1 Simultaneous Climbing and Manipulation
6.12.2 Simultaneous Descending and Manipulation
6.13 Mobility Configurations for Rubble Pile Climbing
6.14 Robot Configurations for Manipulation
6.14.1 End–Effector Payload Capacity Testing
6.14.2 Adaptive Manipulation
6.15 Robot DOF Speed Runs Testing and Measurement
CHAPTER 7: CONCLUSIONS
7.2 Future Research
APPENDIX A: HYBRID MOBILE ROBOT SPECIFICATIONS
viiiLIST OF FIGURESFig. 2.1: Review of tracked mobile robots.
Fig. 3.1: (a) closed configuration; (b) open configuration; (c) exploded view............... 20 Fig. 3.2: Configurations of the mobile platform for mobility purposes
Fig. 3.3: Configuration modes for manipulation
Fig. 3.4: Configurations for enhanced traction
Fig. 3.5: Additional possible embodiments of the design concept
Fig. 3.6: Deployed-links configuration mode of the mobile robot
Fig. 3.7: Stowed-links configuration mode of the mobile robot (top/bottom covers removed).
Fig. 3.8: Open configuration mode and general dimensions (front and top views – all covers removed)
Fig. 3.9: Isometric view of base link track showing internal pulley arrangement.......... 33 Fig. 3.10: Side view of base link track showing general pulley arrangement and track tension/suspension mechanism
Fig. 3.11: A picture of the physical prototype: (a) stowed-links configuration mode; (b) open configuration mode.
Fig. 4.1: Virtual product development diagram.
Fig. 4.2: ADAMS virtual prototype model structure.
Fig. 4.3: Configurations for manipulation
Fig. 4.4: Surmounting circular obstacles
Fig. 4.5: Stair climbing
Fig. 4.6: Stair descending
Fig. 4.7: Step obstacle climbing with tracks.
Fig. 4.8: Step obstacle climbing with links 2 and 3.
Fig. 4.9: Step descending.
Fig. 4.10: Ditch crossing.
Fig. 4.11: Lifting tasks.
Fig. 4.12: Flip-over scenario.
Fig. 4.13: Top ((a) - track tension) and bottom ((b) - suspension) spring array force distribution
Fig.4.14: Link 2 motor torque requirement – step obstacle climbing with tracks (via joint 1).
Fig. 4.15: Link 2 motor torque requirement – Step obstacle climbing with link 2......... 56 Fig. 4.16: Link 3 motor torque requirement – (a) Step obstacle climbing with tracks (via joint 2); (b) Step obstacle climbing with link 3.
Fig. 4.17: Driving pulley motor torque requirement – incline condition
Fig. 4.18: Platform COG vs. load capacity.
Fig. 4.19: Possible configurations for manipulation.
ix Fig. 5.1: Embeddable flat antennas for video and data RF communication................... 66 Fig. 5.2: On-board wireless communication layout and design details (all covers removed).
Fig. 5.3: Hardware architecture: (a) right base link track; (b) left base link track; (c) link 3 – gripper mechanism
Fig. 5.4: XBee OEM RF module
Fig. 5.5: Sensors and cameras layout.
Fig. 5.6: Li-Ion battery packs assembly.
Fig. 5.7: Power/signal distribution board for base link tracks.
Fig. 5.8: Power/signal distribution board for gripper mechanism
Fig. 5.9: Sensor processor board.
Fig. 5.10: Operator control unit (OCU) architecture and robot degrees of freedom....... 83 Fig. 6.1: Configurations for manipulation
Fig. 6.2: Configurations of the hybrid robot for mobility purposes
Fig. 6.3: Configurations for enhanced traction.
Fig. 6.4: Surmounting circular obstacles
Fig. 6.5: Stair climbing
Fig. 6.6: Stair descending
Fig. 6.7: Stair descending – other configurations
Fig. 6.8: Step obstacle climbing with tracks.
Fig. 6.9: Step obstacle climbing with links 2 and 3.
Fig. 6.10: Step descending with links 2 and 3
Fig. 6.11: Step descending with base link tracks – tracks flip on the table
Fig. 6.12: Step descending with base link tracks – tracks rotate on the table............... 101 Fig. 6.13: Ditch crossing.
Fig. 6.14: Lifting capacity testing.
Fig. 6.15: Simultaneous climbing and manipulation
Fig. 6.16: Simultaneous descending and manipulation
Fig. 6.17: Combined mobility configurations for rubble pile climbing (cont’d).......... 108 Fig. 6.18: Configurations for manipulation
Fig. 6.19: Adaptive manipulation configuration steps.
LIST OF TABLESTable 2.1: Table of Comparison.
Table 3.1: Robot Design Specifications.
Table 5.1: Robot Motion Specifications.
Table 6.1: Robot DOF Speed Measurements.