Post on 18-May-2015
description
Two-Legged Robot Design, Simulation and Realization
(Sep-2006 to May 2007)
Guided By: Prepared By:
Dr. S N. Pradhan Nirav A. Patel
Prof. K D. Shah ( 05mce011)
April 12, 2023 M.Tech Major Project 2
Architecture of two-legged robot
April 12, 2023 M.Tech Major Project 3
Subsystems of the robot
• Mechanical subsystem
• Electronics subsystem
• Software subsystem
April 12, 2023 M.Tech Major Project 4
Mechanical subsystem
• This subsystem focuses on• Actuators• CAD drawing of robot• Torque and speed calculation• Dimensional specification of the robot
April 12, 2023 M.Tech Major Project 5
Mechanical Subsystem
• Consists of • Stepper motor for open loop control of different
joints• Gearbox for increasing torque• CAD model showing placement of different
components
April 12, 2023 M.Tech Major Project 6
Stepper Motors
• Provides good open loop control by means of rotating one step per signal applied
• Types• Unipolar
• Less torque
• Easy to control
• Bipolar• Greater torque
• Harder to control compared to Unipolar motors
April 12, 2023 M.Tech Major Project 7
Stepper motors from precision motors
Specifications D-48-42-B20 D-48-42-B25 D-48-42-B28
Units BipolarMedium Torque
BipolarHigh Torque
BipolarHigh Torque
Operating Voltage V 6 12 24
Resistance per phase ohmsohms 2.7 6 15
Inductance per phase mH 3 6 12
Holding Torque mNm(oz-in) 94.9 (13.47) 148 (21.1) 164 (23.3)
Detent Torque mNm(oz-in) 18.5 (2.67) 18.5 (2.67) 18.5 (2.67)
Rotor Inertia g-m2 25.6 x 10-4 25.6 x 10-4 25.6 x 10-4
Weight gms (oz) 185 (6.52) 185 (6.52) 185 (6.52)
Step Angle degrees 7.5 7.5 7.5
Step angle accuracy o +/- 0.5o +/- 0.5o +/- 0.5o
Max. operating temperature
oC 100 100 100
Dielectric strength - 1000 VAC for 1 min. 1000 VAC for 1 min. 1000 VAC for 1 min.
End play mm (in) 0.2 (0.008) 0.2 (0.008) 0.2 (0.008)
April 12, 2023 M.Tech Major Project 8
Torque characteristics
April 12, 2023 M.Tech Major Project 9
Locations of Degrees of Freedom
• figure shows position of all motors
• ML1:Clock-AnticlockRotation of Ankle joint.
• ML2:Up-Down movement of Ankle joint.
• ML3: Movement of Knee joint.• ML4:Up-Down movement of
Pelvis joint.• ML5: Clock-Anticlock rotation
of pelvis joint
April 12, 2023 M.Tech Major Project 10
Values for torque calculations
• Motor Weight = 185 gram
• Gearbox Weight = 350 gram
• Controller Weight = 50 gram
• Other material weight = 1 kg
• We also assume that total height will be 60 cm so distance of CG from any motor will not be more than 30 cm.
April 12, 2023 M.Tech Major Project 11
Torque required by ML1
Since this is the motor requiring maximum torque when it has to lift rest of the body to maintain CG.So weight required to be lifted by this motor is
W = No of Motors *(Motor Weight + Controller Weight Gearbox weight) + Other Material Weight. (in gram)
= 9 * (185 + 50 + 350) + 1000 =6265 gram =6.265 KgNow maximum torque required by this motor is
T = W * 30 = 6.265 * 30
=187.95 Kg-cm
April 12, 2023 M.Tech Major Project 12
Torque required by ML5
Weight required to be lifted by this motor isW = No of Motors *(Motor Weight + Controller Weight
Gearbox weight) + Other Material Weight. (in gram) = 5 * (185 + 50 + 350) + 1000 = 3925 gram = 3.925 KgNow maximum torque required by this motor is
T = W * 30 = 3.925 * 30
= 117.75 Kg-cm
April 12, 2023 M.Tech Major Project 13
Motor and gearbox specifications
• Stepper Motor• Motor Model : D-48-42-B28
• Weight = 185 gram
• Holding Torque = 1.24 Kg-cm
• Operating Voltage = 24V
• Step Angle = 7.5 degree
• Gearbox• Gearbox Model:GB4
• Maximum torque = 200 Kg-cm
• Gear efficiency = 0.6
April 12, 2023 M.Tech Major Project 14
Available torque calculation…
• Suppose we assume that• N is Gear Ratio• To is Output torque at gearbox shaft• Ti is input torque to gearbox• Tm is torque produced by motor• Ge is gearbox efficiency
• Then,• To = Ti * Ge * N or To = Tm * Ge * N
because Tm=Ti
April 12, 2023 M.Tech Major Project 15
Available torque calculation
• Here,• Tm = Ti = 1.24 Kg-cm• Ge = 0.6• To = 187.95 Kg-cm
• So,• 1.87.95 = 1.24 * 0.6 * N• =>N = 252.62
April 12, 2023 M.Tech Major Project 16
Dimensional specifications of robot
April 12, 2023 M.Tech Major Project 17
Mechanical CAD drawing
April 12, 2023 M.Tech Major Project 18
Factors affecting the design
• Weight of motors.• Should be less enough so that it meets torque
requirements
• Weight of Gearbox• Should be less enough compared to maximum
torque at output shaft
• Torque of Motors• Should be high enough to lift the whole body
when combined with gearbox
April 12, 2023 M.Tech Major Project 19
Electronics subsystem
• This subsystem focuses on• Microcontroller development board and its
connection with stepper motor controllers• Microcontroller and its interfacing with
computer
April 12, 2023 M.Tech Major Project 20
Electronics subsystem
• Consists of• Microcontroller development board
• Atmel 89S52 In system programmable Microcontroller
• Stepper motor controllers• A3982 from Allegro Microsystems
April 12, 2023 M.Tech Major Project 21
Microcontroller
• Used to control movements of stepper motors and to communicate with PC
• Easy to program with the help of development boards available in the market
• 89S52 is one of the most popular 8-bit Microcontroller which have 4 output ports so provides enough no of pins to control more no of motors
• 89S52 can easily interfaced with PC
April 12, 2023 M.Tech Major Project 22
AT89S52 PCB layoutAT89S52 PCB layout
April 12, 2023 M.Tech Major Project 23
AT89S52 development board
April 12, 2023 M.Tech Major Project 24
Stepper Motor Controller
• Controlling stepper motor just by 2 signals instead of one for each coil which ranges from 4 to 8
• Reduced programming complexity• Two signals per motor
• Step
• Direction (CW/ACW)
April 12, 2023 M.Tech Major Project 25
Functional block diagram of A3982
April 12, 2023 M.Tech Major Project 26
Block diagram representation of A3982
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Microcontroller Development board and stepper motor controllers
April 12, 2023 M.Tech Major Project 28
Software subsystem
• This subsystem focuses on• Controlling stepper motors to establish stable
walking• Generating stable walking pattern
• It consists of• Two-legged robot simulator• Application Specific Compiler• Torque Analyzer
April 12, 2023 M.Tech Major Project 29
Two-Legged Robot simulator
• Simulates movements of different parts of body
• Can be used to analyze movements and their effects on centre of gravity
• Shows 3D model on computer screen
• Provides GUI with buttons for applying movements to different parts.
April 12, 2023 M.Tech Major Project 30
Need for Two-Legged Robot Simulator.
• Development of humanoid costs a lot so its better to use computer for simulation at low cost.
• It can simulate almost all possibilities.
• Can go for applying different algorithms without applying much more changes in design.
April 12, 2023 M.Tech Major Project 31
Snapshots of the simulator
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Isometric view of robot
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Front view of robot
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Side view of the robot
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Top view of the robotTop view of the robot
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Application specific compiler(ASC)
• Special type of compiler having application specific instruction set
• Developed compiler is for two-legged robot which have instructions like• MOVE LEFT LEG UP BY 5• ROTATE LEFT ANKLE CLOCKWISE BY 34
• Generates assembly language code for 8051 family of microcontrollers
April 12, 2023 M.Tech Major Project 37
Flowchart of ASCFlowchart of ASC
April 12, 2023 M.Tech Major Project 38
Instructions supported by ASCInstructions supported by ASCInstruction Joint Actuated
ROTATE LEFT ANKLE CLOCKWISE BY Left Ankle(Rotate)
ROTATE LEFT ANKLE ANTI-CLOCKWISE BY Left Ankle(Rotate)
MOVE LEFT ANKLE UP BY Left Ankle(Move)
MOVE LEFT ANKLE DOWN BY Left Ankle(Move)
MOVE LEFT KNEE UP BY Left Knee
MOVE LEFT KNEE DOWN BY Left Knee
ROTATE LEFT LEG CLOCKWISE BY Left Leg(Rotate)
ROTATE LEFT LEG ANTI-CLOCKWISE BY Left Leg(Rotate)
MOVE LEFT LEG UP BY Left Leg(Move)
MOVE LEFT LEG DOWN BY Left Leg(Move)
ROTATE RIGHT ANKLE CLOCKWISE BY Right Ankle(Rotate)
ROTATE RIGHT ANKLE ANTI-CLOCKWISE BY Right Ankle(Rotate)
MOVE RIGHT ANKLE UP BY Right Ankle(Move)
MOVE RIGHT ANKLE DOWN BY Right Ankle(Move)
MOVE RIGHT KNEE UP BY Right Knee
MOVE RIGHT KNEE DOWN BY Right Knee
ROTATE RIGHT LEG CLOCKWISE BY Right Leg(Rotate)
ROTATE RIGHT LEG ANTI-CLOCKWISE BY Right Leg(Rotate)
MOVE RIGHT LEG UP BY Right Leg(Move)
MOVE RIGHT LEG DOWN BY Right Leg(Move)
April 12, 2023 M.Tech Major Project 39
Snapshot of ASCSnapshot of ASC
April 12, 2023 M.Tech Major Project 40
Complete flow of Simulator and Complete flow of Simulator and CompilerCompiler
• 1: Write high level code in ASC• 2: Verify the code using simulator for desired
functionality• 3: Compile the verified code to generate Assembly
language code for specific Microcontroller• 4: Compile Assembly code using Assembler to
generate Hex file• 5: Load the Hex file in the Microcontroller
April 12, 2023 M.Tech Major Project 41
High Level Language ProgramHigh Level Language Program
April 12, 2023 M.Tech Major Project 42
Verify the programVerify the program
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Compile the verified programCompile the verified program
April 12, 2023 M.Tech Major Project 44
Load in the KeilLoad in the Keil
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Logic AnalyzerLogic Analyzer
April 12, 2023 M.Tech Major Project 46
Torque AnalyzerTorque Analyzer
• Torque analyzer• Records torque required by each joint of robot while
program is being executed by ASC.• Shows recorded data in form of graphs.
• Program to take first step from start positionrotate left ankle anti-clockwise by 35 , rotate left leg clockwise by 35 , rotate right leg anti-clockwise by 35 , rotate right ankle clockwise by 35;move right leg up by 60 , move right knee down by 30;move right leg up by 32 , move left leg down by 32 , move right knee down by 32 , move left ankle down by 40;move right knee up by 32 , move right ankle down by 40;
April 12, 2023 M.Tech Major Project 47
Torque required at right knee jointTorque required at right knee joint
April 12, 2023 M.Tech Major Project 48
Torque required by all the jointsTorque required by all the joints
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ConclusionConclusion
• For two-legged robots torque requirements are For two-legged robots torque requirements are very high compared to multi legged robots and very high compared to multi legged robots and wheeled robots.wheeled robots.
• Balancing is one of the most difficult tasks for Balancing is one of the most difficult tasks for two-legged robots.two-legged robots.
• In the Table 1 maximum torque required by robot In the Table 1 maximum torque required by robot without including dynamics of the robot are given without including dynamics of the robot are given for taking one step forward from rest condition.for taking one step forward from rest condition.
• From the table we can conclude that knee joint From the table we can conclude that knee joint requires highest torque.requires highest torque.
April 12, 2023 M.Tech Major Project 50
Table 1. Maximum torque required Table 1. Maximum torque required by joints of robot by joints of robot
Joint Name Maximum TorqueKg-cm
Left Ankle(Up/Down) 145
Left Ankle(Clock/Anti-clock) 43
Left Knee 0
Left Pelvis(Up/Down) 70
Left Pelvis(Clock/Anti-clock) 53
Right Ankle(Up/Down) 2
Right Ankle(Clock/Anti-clock) 43
Right Knee 34
Right Pelvis(Up/Down) 77
Right Pelvis(Clock/Anti-clock) 46
April 12, 2023 M.Tech Major Project 51
References
• Satoru Shirata, Atsushi Konno, and Masaru Uchiyama, “Design and Development of a Light-Weight Biped Humanoid Robot Saika-4”, Proceedings of IEEE/RSJ International Conference on Intelligent Robots and Systems, Sendai, Japan, September 28 - October 2, 2004, pp. 148-153.
• Rainer Bischoff and Tamhant Jain,”Natural Communication and Interaction with Humanoid Robots”, Second International Symposium on Humanoid Robots, Tokyo, Japan, October 1999.
April 12, 2023 M.Tech Major Project 52
References…
• Qiang Huang, Yoshihiko Nakamura, Hirohiko Arai, and Kazuo Tanie, “Development of a Biped Humanoid Simulator”, Proceedings of the lEEE/RSJ International Conference on intelligent Robots and Systems , Takamatsu, Japan, Vol. 3, 2000, pp. 1936-1942.
• Riadh Zaier, “Motion Generation of Humanoid Robot based on Polynomials Generated by Recurrent Neural Network”, Proceedings of the First Asia International Symposium on Mechatronics, Xi’an, China, September 27-30, 2004.
• Tetsuro Kitazoe, “Unsupervised Learning of Two Legged Robot”, IEEE International Workshop on Robot and Human Communication, Nagoya, Japan , 18-20 Jul, 1994, pp. 351-355.
April 12, 2023 M.Tech Major Project 53
References…
• Andre Senior, and Sabri Tosunoglu, “Design of a Biped Robot”, Florida Conference on Recent Advances in Robotics, Miami, Florida, May 25-26, 2006.
• Kazuo Tanie, “Humanoid Robot and its Application Possibility”, IEEE Conference on Multisensor Fusion and Integration for Intelligent Systems, 30 July-1 Aug, 2003, pp. 213 – 214.
• “ASIMO Technical Information”, American Honda Motor Co. Inc. Corporate Affairs and Communications, January 2003. ,http://asimo.honda.com/downloads/pdf/asimo-technical-information.pdf
April 12, 2023 M.Tech Major Project 54
References
• “History of ASIMO” http://asimo.honda.com/AsimoHistory.aspx
• “Stepper Motor Specifications”, Precision Motors, http://www.pmpl.co.in/d4842bi.pdf
• “Gearbox Specifications”, Mech-Tex Manufacturing Co., http://www.mechtex.com/PDF/gb4.pdf