MECHANICAL DESIGN OF A SMALL ALL-TERRAIN ROBOT TOH SZE WEI DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINAGPORE 2002 MECHANICAL DESIGN OF A SMALL ALL-TERRAIN ROBOT TOH SZE WEI (B Eng (Hons.), NUS) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINAGPORE 2002 Mechanical Design of a Small All-Terrain Robot A Page i ABSTRACT The project involved the exploratory development of a small all-terrain robot that has excellent mobility performance in the urban environment The main motivating force behind this project was to have a small man-portable robot to perform urban reconnaissance and surveillance for security purpose, as well as to perform urban search and rescue for civil defence purpose The scope of the project focused mainly on the mechanical design of an articulated track robot, which has a maximum speed of 0.9m/s, and is able to overcome 18cm step, 30cm ditch, 45 slope and climb staircase The most crucial articulated track mechanism is made up of the vehicle drive mechanism and vehicle flipper mechanism During the design of the robot, component packaging, ruggedization and modularity had mostly been taken care of This document gives a full documentation of the mechanical design of the various mechanical modules and the four prototype developments of the robot Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot B Page ii ACKNOWLEDGEMENTS The author wishes to take this opportunity to express sincere appreciation of the guidance, support and assistance given by the following people during the course of the research, which enabled the author to carry out the project successfully: - A/Prof Lim Kah Bin for being a cheerful and motivating supervisor, and for his inspiring guidance and support throughout the project A/Prof Teo Chee Leong for his enlightening advice and informative guidance throughout the project Ms Lim Seok Gek for her moral support and encouragement Dr Tan Jiak Kwang and Dr Goh Cher Hiang, Centre Head and Program Head of DSO National Laboratories respectively, for supporting the author to use the company proprietary work results of an ongoing robotic project for his M Eng dissertation Mr Tan Goon Kwee, DSO National Laboratories for his friendship as well as cooperation and advice in the mechanical design of the vehicle platform He also designed the vehicle electronics module of Prototype Robot and Prototype Robot as well as the vehicle powerpack module of Prototype Robot Mr Lee Kam Choong and Mr Teo Sing Huat, formerly with DSO National Laboratories, for their assistance in the market survey and their advice in the preliminary design of the robot Mr Earvin Liew, Mr Bryan Goh and Mr Tai Siew Hoong, DSO National Laboratories for providing materials for Chapter C, D and E respectively as well their cooperation during the testing and evaluation of the robot Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot Page iii Robotic project team members, DSO National Laboratories: Mr Tan Chee Tat, Mr Nelson Lim, Mr Reuben Lai and Mr Gan Jie Luong for team spirit and assistance for integration with various aspects of the robot Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot C Page iv TABLE OF CONTENTS A ABSTRACT I B ACKNOWLEDGEMENTS II C TABLE OF CONTENTS IV D LIST OF FIGURES VI E LIST OF TABLES IX F LIST OF ABBREVIATION X INTRODUCTION 1.1 OBJECTIVES OF PROJECT 1.2 PROJECT SCOPE LITERATURE SURVEY 2.1 FOUR TYPES OF ROBOTS 2.1.1 Legged Robots 2.1.2 Wheeled Robots 2.1.3 Tracked Robots 2.1.4 Re-Configurable Robots 2.2 COMPARISON FACTORS 2.2.1 Terrain Capabilities 2.2.2 Payloads 2.2.3 Stability 2.2.4 Speed 2.2.5 Complexity 2.3 COMPARISON OF VARIOUS TYPE OF LOCOMOTION 3 7 8 OBSTACLE NEGOTIATING STRATEGIES 10 3.1 PROPOSED ARTICULATED TRACKED ROBOT 3.2 MOTION PLANNING STRATEGIES 3.3 OBSTACLE NEGOTIATING STRATEGIES 10 11 11 SYSTEM DESIGN 13 4.1 SYSTEM CONFIGURATION 4.1.1 Vehicle Platform 4.1.2 Vehicle Electronics 4.1.3 Mission Command Console 4.1.4 Modular Payloads 4.2 VEHICLE PLATFORM 4.2.1 Articulated Tracked Mechanism 4.2.2 Vehicle Drive Mechanism 4.2.3 Vehicle Flipper Mechanism 4.2.4 Coaxial Rotation of Vehicle Drive And Flipper Mechanism 4.2.5 Motor Sizing 4.2.6 Man-Portability Design Consideration 4.2.7 Vehicle Track Profile 4.2.8 Symmetry of Robot 4.2.9 Vehicle Ruggedization 14 14 14 14 15 15 15 16 17 17 18 21 22 24 25 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot VEHICLE PROTOTYPE DEVELOPMENTS 28 5.1 PRELIMINARY PROTOTYPE (PR1) 5.1.1 Vehicle Chassis 5.1.2 Vehicle Electronics Module 5.1.3 Mobility Testing and Evaluation 5.2 SECOND PROTOTYPE (PR2) 5.2.1 Major Design Revisions of PR2 from PR1 5.2.2 Vehicle Chassis 5.2.3 Vehicle Track Module (VTM) 5.2.4 Mobility Testing, Trial and Evaluation 5.3 THIRD PROTOTYPE (PR3) 5.3.1 Design Improvements of PR3 over PR2 5.3.2 Mobility Testing, Trial and Evaluation 5.4 FOURTH PROTOTYPE (PR4) 5.4.1 Design Improvements of PR4A over PR3 5.4.2 Vehicle Chassis 5.4.3 Vehicle Track Module 28 29 33 35 37 37 40 46 50 52 52 57 59 60 60 64 FINAL MECHANICAL DESIGN 68 6.1 VEHICLE CHASSIS (VC) 6.1.1 Flipper Compartment (FC) 6.1.2 Vehicle Electronics Module (VEM) 6.1.3 Physical and Electrical Connections Between the Three Sub-modules 6.2 VEHICLE TRACK MODULE (VTM) 6.3 ASSEMBLY AND DISASSEMBLY OF THE THREE SUB-MODULES WEIGHT AND POWER ANALYSIS 68 71 74 77 78 82 86 7.1 POWER MANAGEMENT 7.1.1 Powerpack Sizing and Distribution 7.2 WEIGHT MANAGEMENT 7.2.1 Design Goal 7.2.2 Platform Weight Page v 86 86 89 89 89 CONCLUSION 91 8.1 RECOMMENDATIONS FOR FUTURE DEVELOPMENT 8.2 REFERENCES 92 93 A OBSTACLE NEGOTIATING STRATEGIES A1 B MOTOR SELECTION A7 B.1 B.2 B.3 B.4 C SELECTION CRITERIA FOR DRIVE AND FLIPPER MOTORS GEARHEAD SELECTION FOR DRIVE AND FLIPPER MOTORS MAXON MOTOR SELECTION PROGRAM COMPONENTS OF THE VEHICLE DRIVE AND FLIPPER MOTOR SYSTEMS VEHICLE ELECTRONICS C.1 SENSORS C.2 WIRELESS DATALINK C.3 THE PC/104 SINGLE BOARD COMPUTER D MISSION CONTROL CONSOLE D.1 D.2 D.3 D.4 MISSION CONTROLLER MODULE USER CONTROLLER MODULE MISSION CONTROLLER SOFTWARE MODULE SYSTEM INTEGRATION OF MCC A7 A7 A7 A9 A18 A18 A19 A19 A21 A21 A22 A22 A23 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot E MODULAR PAYLOADS E.1 PAN-TILT MECHANISM E.2 VIEWING CAMERA E.3 THERMAL IMAGER F ASSEMBLY DRAWINGS Page vi A24 A24 A24 A24 A25 D LIST OF FIGURES FIGURE 2.1: LEGGED ROBOTS: (A) TITAN VIII FROM TOKYO INSTITUTE OF TEHNOLOGY, (B) PARAWALKER FROM TOKYO INSTITUTE OF TEHNOLOGY, (C) ROBOT III FROM CASE WESTERN RESERVE UNIVERSITY, AND (D) HEXAPOD III FROM LYNXMOTION INC FIGURE 2.2: WHEELED ROBOTS: (A) LYNX FROM AB POOLE, (B) HOBO FROM KENTREE, (C) RATLER ROVERS FAMILY FROM NASA, AND (D) SOJOURNER FROM NASA FIGURE 2.3: TRACKED ROBOTS: (A) BRAT FROM KENTREE, (B) CYCLOPS FROM AB POOLE, (C) URBIE FROM IROBOT, (D) MICRO VGTV FROM INUKTUN, (E) MINI-ANDROS II FROM REMOTEC, AND (F) LURCH FROM SANDIA FIGURE 2.4: RE-CONFIGURABLE ROBOTS: (A&B) POLYBOT FROM PARC, (C&D) POLYPOD FROM PARC FIGURE 2.5: PROPOSED ILLUSTRATION OF ARTICULATED TRACKED ROBOT FIGURE 3.1: ILLUSTRATION OF ROBOT RETRACTED (LEFT) AND FULLY EXTENDED (RIGHT) 10 FIGURE 3.2: SIX TYPES OF OBSTACLES 11 FIGURE 4.1: VEHICLE PLATFORM HARDWARE CONFIGURATION TREE 15 FIGURE 4.2: ARTICULATED TRACK MECHANISM 16 FIGURE 4.3: VEHICLE DRIVE MECHANISM 16 FIGURE 4.4: VEHICLE FLIPPER MECHANISM 17 FIGURE 4.5: COAXIAL ROTATION OF VEHICLE DRIVE MECHANISM AND VEHICLE FLIPPER MECHANISM 18 FIGURE 4.6: MOST STRINGENT OPERATING (TEST AND EVALUATION) CONDITION FOR DRIVE MOTOR 19 FIGURE 4.7: FREE BODY DIAGRAM TO DETERMINE MAXIMUM DRIVE MOTOR TORQUE REQUIREMENT 19 FIGURE 4.8: MOST STRINGENT OPERATING (TEST AND EVALUATION) CONDITION FOR FLIPPER MOTOR 20 FIGURE 4.9: FREE BODY DIAGRAM TO DETERMINE MAXIMUM FLIPPER MOTOR TORQUE REQUIREMENT 20 FIGURE 4.10 TWO MAN-PORTABLE MODULES VS THREE MAN-PORTABLE MODULES 22 FIGURE 4.11: COTS T10 SERIES TIMING BELT 23 FIGURE 4.12: CUSTOMIZED VEHICLE TRACK PROFILE 23 FIGURE 4.13: SYMMETRY OF MOTOR PLACEMENT WITHIN THE ROBOT 24 FIGURE 4.14: SYMMETRY WITHIN THE ROBOT 25 FIGURE 4.15: USE OF VIBRATION ABSORBING PADS WITHIN THE ROBOT 26 FIGURE 4.16: LIMITED SPLASH-PROOF OF THE ROBOT 27 FIGURE 5.1: PR1 VEHICLE PLATFORM 28 FIGURE 5.2: PR1 VEHICLE CHASSIS 29 FIGURE 5.3: PR1 FLIPPER COMPARTMENT 30 FIGURE 5.4: PR1 ARTICULATED TRACK MECHANISM 31 FIGURE 5.5: PR1 VEHICLE DRIVE MECHANISM 32 FIGURE 5.6: PR1 VEHICLE FLIPPER MECHANISM 32 FIGURE 5.7: PR1 VEHICLE ELECTRONICS MODULE 33 FIGURE 5.8: PR1 VEHICLE POWERPACK: 12V, 3.2AH LEAD ACID BATTERY 34 FIGURE 5.9: SCHEMATIC OF PR1 POWER DISTRIBUTION CONFIGURATION 34 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot Page vii FIGURE 5.10: GROUND CLEARANCE OF PR1 36 FIGURE 5.11: COTS TIMING BELT PROFILE 36 FIGURE 5.12: PR2 VEHICLE PLATFORM 37 FIGURE 5.13: FRAMEWORK STRUCTURE OF PR2 VEHICLE CHASSIS 40 FIGURE 5.14: PR2 VEHICLE DRIVE MECHANISM 41 FIGURE 5.15: PR2 VEHICLE FLIPPER MECHANISM 42 FIGURE 5.16: PLACEMENT OF FLIPPER MOTOR OF PR1 VS PR2 42 FIGURE 5.17: PR2 FLIPPER ARMS ALIGNMENT IN FLIPPER SHAFT 43 FIGURE 5.18: FRAMEWORK STRUCTURE OF PR2 FLIPPER COMPARTMENT 44 FIGURE 5.19: TRACK COVERAGE OF PR2 44 FIGURE 5.20: PR2 VEHICLE ELECTRONICS MODULE 46 FIGURE 5.21: PR2 VEHICLE TRACK MODULE 46 FIGURE 5.22: PR2 VEHICLE POWERPACK MODULE 47 FIGURE 5.23: SCHEMATIC OF PR2 POWER DISTRIBUTION CONFIGURATION 48 FIGURE 5.24: PR2 VEHICLE TRACK PROFILES (A) THICK, (B) THIN 49 FIGURE 5.25: PR3 VEHICLE PLATFORM 53 FIGURE 5.26: PR3 NICKEL METAL HYDRIDE POWERPACK, 24V, 4AH 54 FIGURE 5.27: SCHEMATIC OF PR3 POWER DISTRIBUTION CONFIGURATION 55 FIGURE 5.28: PR3 VEHICLE ELECTRONICS MODULE 57 FIGURE 5.29: PR3 VEHICLE TRACK MODULE 57 FIGURE 5.30: PR4A AND PR4 VEHICLE PLATFORM 60 FIGURE 5.31: PR4A VEHICLE CHASSIS 61 FIGURE 5.32: PR4A GROUND CLEARANCE FOR PR4A AND PR4 61 FIGURE 5.33: PR4A FLIPPER COMPARTMENT 62 FIGURE 5.34: PR4A PC/104 MODULE 63 FIGURE 5.35: PR4A VEHICLE ELECTRONICS MODULE 64 FIGURE 5.36: PR4A VTM HOLDER AND DETACHABLE DRIVE PULLEY/IDLER 64 FIGURE 5.37: PR4A MAIN AND ARTICULATED TRACK COVERS 65 FIGURE 5.38: PR4A VEHICLE TRACK PROFILE 66 FIGURE 5.39: THE SCHEMATIC OF PR4A POWER DISTRIBUTION CONFIGURATION 67 FIGURE 5.40: PR4A VARIANTS 67 FIGURE 6.1: VEHICLE CHASSIS WITHOUT COVERS 68 FIGURE 6.2: THREE MODULES OF VEHICLE CHASSIS 70 FIGURE 6.3: FRAMEWORK STRUCTURE OF VEHICLE CHASSIS 70 FIGURE 6.4: COMPONENTS WITHIN A FLIPPER COMPARTMENT 71 FIGURE 6.5: FLIPPER COMPARTMENT FRAMEWORK STRUCTURE AND MOTOR MOUNTINGS 72 FIGURE 6.6: VEHICLE GROUND CLEARANCE, COAXIAL ROTATION AND MOTOR PLACEMENTS 72 FIGURE 6.7: BEARINGS FOR (A) VEHICLE DRIVE MECHANISM (B) VEHICLE FLIPPER MECHANISM 73 FIGURE 6.8: EASE OF ASSEMBLY/DISASSEMBLY OF FLIPPER COMPARTMENT 74 FIGURE 6.9: VEHICLE ELECTRONICS MODULE 75 FIGURE 6.10: COMMERCIAL PC/104 RACK WITH THE VARIOUS ELECTRONICS 76 FIGURE 6.11: VARIOUS COMPARTMENTS WITHIN THE VEHICLE ELECTRONICS MODULE 77 FIGURE 6.12: PHYSICAL AND ELECTRICAL CONNECTIONS BETWEEN SUB-MODULES OF THE VEHICLE CHASSIS 78 FIGURE 6.13: VEHICLE TRACK MODULE 78 FIGURE 6.14: THE FIVE FUNCTIONS OF VTM HOLDER 79 FIGURE 6.15: THE TWO FUNCTIONS OF DRIVE PULLEY HUB 79 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot Page viii FIGURE 6.16: THE CROSS SECTION VIEW OF DRIVE PULLEY AND DRIVE IDLER 80 FIGURE 6.17: THE CROSS SECTION VIEW OF FLIPPER PULLEY 80 FIGURE 6.18: THE FLIPPER ARM 81 FIGURE 6.19: ARTICULATED TRACK COVER 81 FIGURE 6.20: MAIN TRACK COVER WITH ROLLERS 82 FIGURE 6.21: VEHICLE POWERPACK MODULE 82 FIGURE 6.22: DIVISION OF VEHICLE DRIVE MECHANISM AMONG THE SUB-MODULES 83 FIGURE 6.23: DIVISION OF VEHICLE FLIPPER MECHANISM AMONG THE SUB-MODULES 84 FIGURE 6.24: QUICK RELEASE FEATURES OF VTM HOLDER 84 FIGURE 6.25: QUICK RELEASE FEATURES OF FC SIDE PLATES 85 FIGURE 7.1: THE SCHEMATIC OF THE ROBOT POWER DISTRIBUTION CONFIGURATION 88 FIGURE A1: OBSTACLE NEGOTIATING STRATEGIES – UNEVEN DITCH A1 FIGURE A2: OBSTACLE NEGOTIATING STRATEGIES – STEP A2 FIGURE A3: OBSTACLE NEGOTIATING STRATEGIES – LOG A3 FIGURE A4: OBSTACLE NEGOTIATING STRATEGIES – RAMP A5 FIGURE A5: OBSTACLE NEGOTIATING STRATEGIES – STAIRCASE A6 FIGURE B1: MAXON SELECTION PROGRAM GUI A8 FIGURE B2: SPEED, TORQUE AND VOLTAGE INPUT FOR DRIVE MOTOR SELECTION GUI A8 FIGURE B3: SUITABLE DRIVE MOTORS GUI A8 FIGURE B4: SPEED, TORQUE AND VOLTAGE INPUT FOR FLIPPER MOTOR SELECTION GUI A9 FIGURE B5: SUITABLE FLIPPER MOTORS GUI A9 FIGURE C1: OVERALL CONFIGURATION OF ON-BOARD ELECTRONICS A18 FIGURE C2: MAIN FUNCTIONS OF THE MICROPROCESSOR A19 FIGURE D1: OVERALL CONFIGURATION OF THE MCC A23 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot D.2 Page A22 USER CONTROLLER M ODULE This module provides the interface between the operator and the vehicle It basically consists of main components: the Remote Controller Unit (RCU) and the Head Mounted Display (HMD) It is an extremely crucial module as it enables the operator to carry out the desired control actions such as the movement of the vehicle, control of the manipulator arm or camera and payload activation The RCU is handheld and relatively lightweight It consists of the necessary joysticks and switches to enable the user to operate the vehicle with relative ease An additional handheld input device known as the Twiddler 2, which comprises of a mouse and a keypad, is also included for text input The HMD used in this case is the commercially available Sony LDI-100 Glasstron It can either be worn on the user’s head or mounted on an appropriate headgear, with the viewing screen positioned directly in front of the user’s eyes It provides a VGA display at 640x480 resolution with see through display capability It also incorporates audio output such as a pair of earphones so that the operator is able to listen to the sounds that are picked up by the microphone onboard the vehicle Thus, the HMD enables the operator to have a spatial awareness of the environment that the vehicle is currently operating in, through feedback of the video images and audio output from the vehicle D.3 M ISSION CONTROLLER SOFTWARE M ODULE The Mission Controller Software module (hereby known as MCS) is developed in-house At this stage, the MCS is developed under the Windows 95/98 operating system environment using Microsoft Visual C++ Such an approach is in line with the design guidelines mentioned earlier, which emphasises on the usage of COTS products Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot Page A23 The MCS is loosely divided into two main portions as shown below a Human Machine Interface (HMI) The HMI portion consists of the status display screens of the vehicle and its various essential onboard components b System Executive (SE) and Communications It handles all the data transaction and processing logic including wireless data transfer with vehicle and video images from framegrabber D.4 SYSTEM I NTEGRATION OF MCC Refer to Figure D1 for the overall system integration diagram of the MCC Figure D1: Overall Configuration of the MCC Through the entire operation, there are constant video and audio outputs from the vehicle to the MCC In addition, data containing the status of the vehicle is constantly updated to the MCC through the wireless data modem The video stream received by the RF receiver contains image from the pan/tilt camera on the vehicle This is then fed into the video input channels on the PC/104 based framegrabber The provided SDK from the framegrabber is used to display a constant real-time video image at about 30 fps through the HMD Besides the video image, the audio output from the RF receiver will also be sent to the earphones on the HMD through the embedded computer From the remote controller unit, the movements of the joysticks and the status of the various panel switches are captured by the embedded computer through the RS-232 ports From the information gathered from these controls, the embedded computer is able to determine the action desired by the operator and in turn transmits the corresponding control action to the vehicle through the wireless data modem In addition, the various status gathered from the vehicle are displayed on the HMD so that the operator is aware of his surroundings (with the see-through mode of the HMD) than to spend time looking down at the remote controller unit to retrieve the necessary information Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot E Page A24 MODULAR PAYLOADS The implementation of payloads introduces the task capabilities of the robotic vehicle They determine the manipulative functions to be performed by the robotic vehicle Various payloads are in the initial process of research and development Presently, the surveillance payload that involves a pan-tilt mechanism, a viewing camera for daytime operation and thermal imager for nighttime operation has been identified for the robotic vehicle E.1 PAN-TILT M ECHANISM The pan-tilt-zoom camera is mounted on a pan-tilt mechanism to provide the basic manoeuvrable capability of the viewing camera The maximum load capacity of the mechanism is 1kg The minimum pan and tilt speeds are determined at 180° per second and 90° per second respectively The pan-tilt mechanism is connected to the platform electronics via a RS232 link E.2 VIEWING CAMERA The viewing camera is a colour CCD camera with zoom capabilities E.3 THERMAL I MAGER The thermal imager operates in a long-wavelength infrared spectrum, which enables applications like ground-based night surveillance It provides analog video in monochrome and the images are generated at 30 frames per second The field of view is 40° x 30° and minimum focus range is 0.3 metres Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot F Page A25 ASSEMBLY DRAWINGS Master of Engineering Thesis PR04 ROBOT WITH PAN-TILT-UNIT 2-ISOMETRIC PR04A ROBOT WITH PAN-TILT-UNIT 2-ISOMETRIC PR04 VEHICLE CHASSIS PR04 VEHICLE ELECTRONICS MODULE PR04 VEM VIDEO ASSEMBLY PR04 VEM MODEM ASSEMBLY 4-ISOMETRIC PR04 COTS PC104 ASSEMBLY PR04 VEHICLE ELECTRONICS MODULE COMPONENTS PR04 FLIPPER COMPARTMENT PR04 DRIVE MOTOR (150W) ASSEMBLY PR04 FC TOP ASSEMBLY LARGE PR04 FLIPPER MOTOR (150W) ASSEMBLY 4-ISOMETRIC PR04 FC FRAMEWORK ASSEMBLY V2 PR04 FC SHAFT ASSEMBLY PR04 FLIPPER COMPARTMENT COMPONENTS PR04 VEHICLE TRACK MODULE PR04 FLIPPER ARM LEFT ASSEMBLY PR04 FLIPPER ARM RIGHT ASSEMBLY 4-ISOMETRIC PR04 VTM COVER ASSEMBLY V2 PR04 VEHICLE POWERPACK MODULE PR04 VEHICLE TRACK MODULE COMPONENTS PR04A VEHICLE TRACK MODULE PR04A FLIPPER ARM LEFT ASSEMBLY PR04A FLIPPER ARM RIGHT ASSEMBLY 4-ISOMETRIC PR04A VTM COVER ASSEMBLY PR04 VEHICLE POWERPACK MODULE PR04A VEHICLE TRACK MODULE COMPONENTS [...]... traverse on flat terrain 2.2.2 PAYLOADS Payloads refer to the additional weight that can be carried by robot Both wheeled and tracked robots can support high payloads while legged and re-configurable robots can only support low payloads Re-configurable robots can only carry payloads that can be packed inside them Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot 2.2.3 Page... Illustration of Robot Retracted (Left) and Fully Extended (Right) The proposed robot consists of a pair of main driving tracks, a pair of articulated front tracks and a pair of articulated rear tracks as shown in Figure 3.1 There are two motors to drive the left and right main tracks, and another two motors to rotate the front and rear articulated tracks Master of Engineering Thesis Mechanical Design of a. .. and staircase Finally, both the literature survey and the obstacle negotiating strategy suggested that an articulated tracked robot should be chosen for the exploratory development Figure 2.5: Proposed Illustration of Articulated Tracked Robot Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot 3 Page 10 OBSTACLE NEGOTIATING STRATEGIES As mobility is one of the key features of. .. Design of a Small All- Terrain Robot Page 12 The main concept of ONS is that the configuration of the articulated tracks and the main track should follow the shape of the terrain (formed by the obstacles and the ground) as closely as possible This can prevent drastic motion of the robot because of its weight distribution, as well as enable the robot to have maximum traction on the terrain Whenever there are... computer (WC) together with a wireless data modem, a wireless video receiver, a head mounted display (HMD) and remote control unit (RCU) Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot 4.1.4 Page 15 M ODULAR PAYLOADS Two modular payloads, a pan-tilt zoom camera and a pan-tilt thermal imager have been designed for the robot 4.2 VEHICLE PLATFORM The scope of this project is only... conducted for obstacles such as ditch, uneven ditch, step, log, ramp and staircase The obstacle negotiating capability of a dual articulated track robot was animated for the above-mentioned obstacles In appendix A, Figure A1 , A2 , A3 , A4 and A5 show the “snapshots” of the animation of the proposed robot using Obstacle Negotiating Strategies to negotiate uneven ditch (ditch is just a special case of uneven ditch),... TABLE 7.3: SUMMARY OF WEIGHT ESTIMATE OF VEHICLE PLATFORM 90 TABLE B1: REQUIREMENT OF MOTORS A7 TABLE B2: COMPARISON BETWEEN NEUGART AND MAXON PLANETARY GEARHEAD A7 TABLE B3: COMPONENTS OF THE VEHICLE DRIVE AND FLIPPER MOTOR SYSTEMS A9 Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot F Page x LIST OF ABBREVIATION COTS - Commercial-off-the-shelf FC... stepmultiple of the distance between two adjacent profiles The height of the profile affects the vehicle ground clearance Figure 4.12: Customized Vehicle Track Profile Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot 4.2.8 Page 24 SYMMETRY OF ROBOT During the design of the robot, symmetry is one of the major design considerations This is because symmetry of the robot means that there... – able to be remotely teleoperated via wireless communication with live video feedback; Endurance – able to carry its own battery and be continuously operated for an hour; Master of Engineering Thesis Mechanical Design of a Small All- Terrain Robot Page 2 The secondary objectives of this project are to develop the followings: Payloads – integration capability that allow easy mounting or removing of. . .Mechanical Design of a Small All- Terrain Robot E Page ix LIST OF TABLES TABLE 2.1: TECHNICAL SPECIFICATIONS OF TITAN VIII 4 TABLE 2.2: TECHNICAL SPECIFICATIONS OF LYNX 5 TABLE 2.3: TECHNICAL SPECIFICATIONS OF URBIE 6 TABLE 2.4: COMPARISON TABLE USING VARIOUS COMPARISON FACTORS 9 TABLE 3.1: PERFORMANCE SPECIFICATION OF THE PROPOSED ROBOT 12 TABLE 4.1: ... MCC A7 A7 A7 A9 A1 8 A1 8 A1 9 A1 9 A2 1 A2 1 A2 2 A2 2 A2 3 Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot E MODULAR PAYLOADS E.1 PAN-TILT MECHANISM E.2 VIEWING CAMERA E.3... UNIVERSITY OF SINGAPORE DEPARTMENT OF MECHANICAL ENGINEERING NATIONAL UNIVERSITY OF SINAGPORE 2002 Mechanical Design of a Small All-Terrain Robot A Page i ABSTRACT The project involved the exploratory... Illustration of Articulated Tracked Robot Master of Engineering Thesis Mechanical Design of a Small All-Terrain Robot Page 10 OBSTACLE NEGOTIATING STRATEGIES As mobility is one of the key features of