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== ПЕРЕВОДИМ_Оглавление ==
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Оглавление
 
Оглавление
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Благодарности
 
Благодарности
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Аннотация  
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Аннотация
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Глава I. ВВЕДЕНИЕ  
 
Глава I. ВВЕДЕНИЕ  
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1.1 Background  
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:1.1 Background  
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1.2 Purpose and Overview  
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:1.2 Purpose and Overview  
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Chapter II. Braided Pneumatic Actuators   
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2.1 Physical Characteristics
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Глава II. Braided Pneumatic Actuators   
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2.2 Geometric and Static Model
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:2.1 Physical Characteristics
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2.3 Static Model Verification
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:2.2 Geometric and Static Model
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2.4 Dynamic Model
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:2.3 Static Model Verification
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Chapter III. Simulation
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:2.4 Dynamic Model
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3.1 Simulation Overview
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3.2 Equations of Motion
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Глава III. Simulation
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3.3 Valve Model
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:3.1 Simulation Overview
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3.4 Dynamic Model Verification  
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:3.2 Equations of Motion
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Chapter IV. Robot Hardware  
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:3.3 Valve Model
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4.1 System Overview  
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:3.4 Dynamic Model Verification  
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4.2 Leg Design  
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4.3 Valves
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Глава IV. Robot Hardware  
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4.4 Force Sensors  
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:4.1 System Overview  
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4.5 Angle Sensors
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:4.2 Leg Design  
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Chapter V. Control
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:4.3 Valves
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5.1 Control Architecture and Control Laws
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:4.4 Force Sensors  
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5.2 Control Program
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:4.5 Angle Sensors
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5.3 Inverse Kinematics
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Chapter VI. Results and Discussion
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Глава V. Control
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6.1 Desired Walking Behavior
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:5.1 Control Architecture and Control Laws
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6.2 Tuning  
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:5.2 Control Program
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6.3 Walking Results  
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:5.3 Inverse Kinematics
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6.4 Robot Limitations
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6.5 Derivative Control
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Глава VI. Results and Discussion
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Chapter VII. Conclusion  
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:6.1 Desired Walking Behavior
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7.1 It Walks!
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:6.2 Tuning  
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7.2 Semi-Observed Speculation
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:6.3 Walking Results  
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7.3 Future work  
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:6.4 Robot Limitations
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Appendix A: Simulation Code  
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:6.5 Derivative Control
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A.1 Actuator.cpp  
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Appendix B: Controller Code  
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Глава VII. Conclusion  
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B.1 Control.cpp  
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:7.1 It Walks!
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B.2 Def.h
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:7.2 Semi-Observed Speculation
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B.3 Hardware.cpp
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:7.3 Future work  
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B.4 Predict.dat
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----
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B.5 Gain.dat
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Appendix C: Robot Hardware
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Приложение A: Simulation Code  
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C.1 Strain Gage Amplifier  
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:A.1 Actuator.cpp  
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C.2 Wiring
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C.3 Mechanical Drawings
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Приложение B: Controller Code  
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Bibliography
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:B.1 Control.cpp  
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:B.2 Def.h
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:B.3 Hardware.cpp
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:B.4 Predict.dat
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:B.5 Gain.dat
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Приложение C: Robot Hardware
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:C.1 Strain Gage Amplifier  
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:C.2 Wiring
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:C.3 Mechanical Drawings
  
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'''Литература'''
 
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'''Список таблиц'''
 
'''Список таблиц'''
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Table 4.1 : Transducer sensitivity and error
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Table 6.1 : Joint range of motion  
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:Таблица 4.1 : Transducer sensitivity and error
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Table 6.2 : Time parameters for walking motion
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:Таблица 6.1 : Joint range of motion  
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Table 6.3 : Walking motion control gains
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:Таблица 6.2 : Time parameters for walking motion
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Table 6.4 : Passivity and average duty cycles of each valve
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:Таблица 6.3 : Walking motion control gains
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:Таблица 6.4 : Passivity and average duty cycles of each valve
  
 
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'''Список иллюстраций'''
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:Иллюстрация 1.1 : Dimensionless force-length properties of actuators and biological muscles
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:Иллюстрация 2.1 : Photograph of inflated and uninflated actuators
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:Иллюстрация 2.2 : Actuator dimensions
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:Иллюстрация 2.3 : Geometric schematic of actuators
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:Иллюстрация 2.4 : Mesh geometry
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:Иллюстрация 2.5 : Revised actuator geometry schematic
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:Иллюстрация 2.6 : Pressure, Length, Force, Stiffness Relationship for a BPA
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:Иллюстрация 2.7 : Static model verification schematic
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:Иллюстрация 2.8 : Plot of Force vs. Length for a BPA with constant internal mass of air
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:Иллюстрация 2.9 : Pressure Increase vs. Length – constant mass system
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:Иллюстрация 2.10 : Plot of Force vs. Length – constant air mass – Exp. vs. Theor. results
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:Иллюстрация 2.11 : Plot of Effectiveness vs. Pressure
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:Иллюстрация 2.12 : Plot of Force vs. Length – Exp. vs. Theor. Results – (effectiveness)
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:Иллюстрация 2.13 : Plot of Force vs. Length – Constant Pressure System
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:Иллюстрация 2.14 : Dynamic model schematic
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:Иллюстрация 3.1 : Simulation overview schematic
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:Иллюстрация 3.2 : Detailed simulation schematic
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:Иллюстрация 3.3 : Actuator equation of motion schematic
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:Иллюстрация 3.4 : Flow curve for Matrix 758 3-way valve
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:Иллюстрация 3.5 : Dynamic model verification schematic
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:Иллюстрация 3.6 : Length vs. Time – 60 psi constant mass – 6 lb load - measured
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:Иллюстрация 3.7 : Length vs. Time – 60 psi constant mass – 6 lb load - simulation
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:Иллюстрация 3.8 : Length vs. Time – 80 psi constant mass – 11 lb load - measured
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:Иллюстрация 3.9 : Length vs. Time – 80 psi constant mass – 11 lb load - simulation
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:Иллюстрация 3.10 : Length vs. Time – 60 psi constant mass – 11 lb load - measured
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:Иллюстрация 3.11 : Length vs. Time – 60 psi constant mass – 11 lb load - simulation
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:Иллюстрация 3.12 : PWM valve model verification schematic
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:Иллюстрация 3.13 : Commanded vs. Actual duty cycles – Matrix 758 3-way valve
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:Иллюстрация 3.14 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - measured
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:Иллюстрация 3.15 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - simulation
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:Иллюстрация 3.16 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - measured
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:Иллюстрация 3.17 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - simulation
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:Иллюстрация 3.18 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - measured
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:Иллюстрация 3.19 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - simulation
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:Иллюстрация 3.20 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - measured
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:Иллюстрация 3.21 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - simulation
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:Иллюстрация 3.22 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - measured
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:Иллюстрация 3.23 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - simulation
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:Иллюстрация 4.1 : Robot hardware schematic
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:Иллюстрация 4.2 : Photograph of robot
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:Иллюстрация 4.3 : CAD model and photograph of robot leg
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:Иллюстрация 4.4 : CAD model and photograph of hip translational joint
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:Иллюстрация 4.5 : CAD model and photograph of hip rotational joint
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:Иллюстрация 4.6 : Schematic of inlet valve
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:Иллюстрация 4.7 : Schematic of exhaust valve
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:Иллюстрация 4.8 : Current vs. time for inlet valve
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:Иллюстрация 4.9 : Current vs. time for exhaust valve
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:Иллюстрация 4.10 : Force sensor classic analysis schematic
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:Иллюстрация 4.11 : Force sensor FEA results
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:Иллюстрация 4.12 : Photograph of force sensors
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:Иллюстрация 4.13 : Photograph of strain gage amplifier
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:Иллюстрация 4.14 : Transducer calibration plot
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:Иллюстрация 4.15 : Photograph of completed force measurement system
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:Иллюстрация 4.16 : Photograph of completed angle measurement systems
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:Иллюстрация 5.1 : Labeled schematic of a joint
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:Иллюстрация 5.2 : Block diagram of the control algorithm
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:Иллюстрация 5.3 : ISR schematic
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:Иллюстрация 5.4 : Inverse kinematics schematic
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:Иллюстрация 6.1 : Desired foot positions for walking motion
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:Иллюстрация 6.2 : Sequential video frames of the leg during walking motion
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:Иллюстрация 6.3 : Desired and actual x-y foot paths: Test 1
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:Иллюстрация 6.4 : Desired and actual joint angles vs. time: Test 1
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:Иллюстрация 6.5 : Actuator force vs. time
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:Иллюстрация 6.6 : Desired and actual joint stiffness vs. time
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:Иллюстрация 6.7 : Joint torque vs. time
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:Иллюстрация 6.8 : Ground reaction forces during walking vs. time
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:Иллюстрация 6.9 : Trolley motion vs. time
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:Иллюстрация 6.10 : Hip joint valve duty cycles vs. time
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:Иллюстрация 6.11 : Knee joint valve duty cycles vs. time
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:Иллюстрация 6.12 : Desired and actual joint angles vs. time: Test 2
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:Иллюстрация 6.13 : Desired and actual x-y foot paths: Kicking motion
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:Иллюстрация 6.14 : Desired and actual joint angles vs. time: Kicking motion
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:Иллюстрация 6.15 : Calculated angular velocity vs. time
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:Иллюстрация 6.14 : Desired and actual joint angles vs. time: Derivative control
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:Иллюстрация 7.1 : Desired and actual x-y foot paths: Angle feedback only
  
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'''Список иллюстраций'''
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Figure 1.1 : Dimensionless force-length properties of actuators and biological muscles
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Figure 2.1 : Photograph of inflated and uninflated actuators
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== Глава1 ==
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Figure 2.2 : Actuator dimensions
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Figure 2.3 : Geometric schematic of actuators
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<center>'''Acknowledgements'''</center>
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Figure 2.4 : Mesh geometry
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Figure 2.5 : Revised actuator geometry schematic
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I would like to thank my wife Joni for being supportive of this crazy idea to go get a masters degree.  Without her support, I never would have been able to do it.  I
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Figure 2.6 : Pressure, Length, Force, Stiffness Relationship for a BPA
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would also like to thank my wonderful new son Boyd for helping me put priorities into perspective.
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Figure 2.7 : Static model verification schematic
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Figure 2.8 : Plot of Force vs. Length for a BPA with constant internal mass of air
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I want to thank Roger Quinn for providing an excellent work environment.  I have thoroughly enjoyed my experience working in the Biorobotics Lab. I also appreciate his patient and supportive leadership style.
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Figure 2.9 : Pressure Increase vs. Length – constant mass system
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Figure 2.10 : Plot of Force vs. Length – constant air mass – Exp. vs. Theor. results
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Gabe Nelson has given me invaluable counsel in robotics as well as life. In this thesis, you will see evidence of all the work he has done before me to make my work possible.  For this, I would like to thank him.
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Figure 2.11 : Plot of Effectiveness vs. Pressure
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Figure 2.12 : Plot of Force vs. Length – Exp. vs. Theor. Results – (effectiveness)
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I want to thank Rich Bachmann, Matt Birch, Jim Berilla, and Yuan Dao Zhang for using their time and talents to help me build the robot.
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Figure 2.13 : Plot of Force vs. Length – Constant Pressure System
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Figure 2.14 : Dynamic model schematic
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I would also like to express my gratitude to the other guys in the lab for being sounding boards for my half-baked ideas and providing a good political discussion at the drop of a hat.
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Figure 3.1 : Simulation overview schematic
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Figure 3.2 : Detailed simulation schematic
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I want to express my appreciation to my parents for raising me and giving me direction. I was taught many of the fundamentals of engineering while tinkering in the garage with my dad.
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Figure 3.3 : Actuator equation of motion schematic
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Figure 3.4 : Flow curve for Matrix 758 3-way valve
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I want to thank Dr. Joe Mansour and Dr. Steve Phillips for serving on my thesis committee.
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Figure 3.5 : Dynamic model verification schematic
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Figure 3.6 : Length vs. Time – 60 psi constant mass – 6 lb load - measured
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The work was supported by the Office of Naval Research under grant number
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Figure 3.7 : Length vs. Time – 60 psi constant mass – 6 lb load - simulation
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Figure 3.8 : Length vs. Time – 80 psi constant mass – 11 lb load - measured
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N0014-99-1-0378, and DARPA under contract number DAAN02-98-C-4027.
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Figure 3.9 : Length vs. Time – 80 psi constant mass – 11 lb load - simulation
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Figure 3.10 : Length vs. Time – 60 psi constant mass – 11 lb load - measured
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Finally, I want to thank God for life, and all these wonderful creatures that we study. Even with all our great technology, our understanding of the world is so limited.
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Figure 3.11 : Length vs. Time – 60 psi constant mass – 11 lb load - simulation
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As an engineer, His infinite wisdom and designs humble me. Without Him, we are nothing
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Figure 3.12 : PWM valve model verification schematic
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Figure 3.13 : Commanded vs. Actual duty cycles – Matrix 758 3-way valve
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Figure 3.14 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - measured
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Figure 3.15 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - simulation
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<center>'''Design and Control of a Robotic Leg With Braided Pneumatic Actuators'''</center>
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Figure 3.16 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - measured
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Figure 3.17 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - simulation
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<center>'''Abstract by ROBB WILLIAM COLBRUNN'''</center>
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Figure 3.18 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - measured
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Figure 3.19 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - simulation
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<center>'''A Braided Pneumatic Actuator is a device developed in the 1950’s by J.L.'''</center>
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Figure 3.20 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - measured
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Figure 3.21 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - simulation
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Figure 3.22 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - measured
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McKibben. In recent years, robotics engineers have begun to rediscover these fascinating devices, and use them as actuators for their robots. These actuators exhibit non-linear force-length properties similar to skeletal muscle, and have a very high strength-to-weight ratio. In this thesis, emphasis was placed on understanding the actuator properties so that this knowledge could be used in simulation and control of legged robots. Static and dynamic mathematical models were developed for the actuators, and verified through testing and simulation. A four-degree of freedom robotic leg was designed, constructed, and controlled. The leg provided stable, sensible forward walking for the robot, and was capable of operating 94% passively.  Though these actuators have a few limitations, their muscle-like properties including high strength-to-weight ratio, passive characteristics, and self-limiting force properties make them ideal for legged robots.
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Figure 3.23 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - simulation
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Figure 4.1 : Robot hardware schematic
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Figure 4.2 : Photograph of robot  
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Figure 4.3 : CAD model and photograph of robot leg
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'''Chapter I: Introduction'''
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Figure 4.4 : CAD model and photograph of hip translational joint
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'''1.1 Background'''
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Figure 4.5 : CAD model and photograph of hip rotational joint
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Figure 4.6 : Schematic of inlet valve
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Much ink has been used to explain the benefits of legged locomotion over wheeled locomotion for robots. As with most things, there is always a trade off. A wheeled robot might go faster and be easier to build, but tell it to climb a flight of stairs and its shortcomings become apparent quickly. Upon observation of all the creatures around us, we see the legged design as the locomotion method of choice. The purpose of this thesis, however, is not to show why it should be done, but how it can be done.
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Figure 4.7 : Schematic of exhaust valve
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Figure 4.8 : Current vs. time for inlet valve
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Legged locomotion is the beginning of the biologically inspired approach to robotics.  However, putting legs on a frame is not enough to have a walking robot. Arguably, the most important part of any motion device is the mechanism that does the moving: the actuators. In the past, CWRU walking robots have used DC motors to generate leg movement. With the move toward physical autonomy (operation without an umbilical), the poor strength to weight ratio of DC motors became far too prohibitive. The next generation of robot used pneumatic cylinders to increase this ratio. Air cylinders’ strength to weight ratio is much better than electric motors, but there is still room for improvement. The total weight of Robot III was 29.5 lbs. with 76% of that being actuator and valve weight (Bachmann, 2000). A lighter weight actuator that was just as strong would increase the robot’s payload capacity. The biologically inspired approach led the group to look at the prime movers that are designed into natural walking “machines”: muscles. Using real muscle tissue is technologically not practical at this time (Shimoyama, 1997), so an artificial muscle is necessary. This actuator is known as a Braided Pneumatic Actuator or a McKibben Artificial Muscle. These actuators can have a power-to-weight ratio as high as 25 times greater than DC motors (Shadow, 2000). These actuators also have experimentally been shown to have force-length properties similar to skeletal muscle (Klute et al.,1999).
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Figure 4.9 : Current vs. time for exhaust valve
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Figure 4.10 : Force sensor classic analysis schematic
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[[Изображение:Figure1-1.jpg]]
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Figure 4.11 : Force sensor FEA results
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Figure 4.12 : Photograph of force sensors
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''Figure 1-1: The dimensionless relationship between force and length under isometric conditions at maximal activation for various animals as well as a McKibben actuator pressurized to 5 bar (Klute et al.,1999).''
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Figure 4.13 : Photograph of strain gage amplifier
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Figure 4.14 : Transducer calibration plot
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This muscle-like stiffness and their structural flexibility present real advantages over air cylinders.  In this thesis, these braided pneumatic actuators will be referred to as “McKibbens” or BPA.
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Figure 4.15 : Photograph of completed force measurement system
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Figure 4.16 : Photograph of completed angle measurement systems
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'''1.2 Purpose and Overview'''
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Figure 5.1 : Labeled schematic of a joint
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Figure 5.2 : Block diagram of the control algorithm
+
The focus of this project involves the investigation of using McKibbens as the prime mover in a walking robot.  This work is divided into six sections. Each chapter builds upon the other to explain the process and methods of using BPA to make a robotic leg walk. Chapter two explains all the properties of the BPA as well as the mathematical model formulated for simulation and control. Chapter three describes the simple spring- mass-damper simulation that was written to dynamically validate the model. This simulation included a model of the actuator, and a model of a solenoid valve for controlling the mass of air in the actuator. The valve states were the only inputs, and the simulation calculated the remaining system properties. The next chapter describes all the hardware involved in making the robot walk. A system overview, the valves, the sensors, and the leg design are all presented. Chapter five delves into the control program and how the sensor feedback is turned into valve commands. Then, chapter six presents the results or quantification of the walking. The last chapter discusses the limits and shortcomings of using McKibbens. Finally, possible solutions and improvements are addressed as topics of future work.
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Figure 5.3 : ISR schematic
 
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Figure 5.4 : Inverse kinematics schematic
 
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Figure 6.1 : Desired foot positions for walking motion
 
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Figure 6.2 : Sequential video frames of the leg during walking motion
 
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Figure 6.3 : Desired and actual x-y foot paths: Test 1
 
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Figure 6.4 : Desired and actual joint angles vs. time: Test 1
 
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Figure 6.5 : Actuator force vs. time
 
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Figure 6.6 : Desired and actual joint stiffness vs. time
 
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Figure 6.7 : Joint torque vs. time
 
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Figure 6.8 : Ground reaction forces during walking vs. time
 
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Figure 6.9 : Trolley motion vs. time
 
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Figure 6.10 : Hip joint valve duty cycles vs. time
 
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Figure 6.11 : Knee joint valve duty cycles vs. time
 
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Figure 6.12 : Desired and actual joint angles vs. time: Test 2
 
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Figure 6.13 : Desired and actual x-y foot paths: Kicking motion
 
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Figure 6.14 : Desired and actual joint angles vs. time: Kicking motion
 
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Figure 6.15 : Calculated angular velocity vs. time
 
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Figure 6.14 : Desired and actual joint angles vs. time: Derivative control
 
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Figure 7.1 : Desired and actual x-y foot paths: Angle feedback only
 

Текущая версия на 03:30, 28 апреля 2009


ПЕРЕВОДИМ_Оглавление

Оглавление

Благодарности

Аннотация

Глава I. ВВЕДЕНИЕ

1.1 Background
1.2 Purpose and Overview

Глава II. Braided Pneumatic Actuators

2.1 Physical Characteristics
2.2 Geometric and Static Model
2.3 Static Model Verification
2.4 Dynamic Model

Глава III. Simulation

3.1 Simulation Overview
3.2 Equations of Motion
3.3 Valve Model
3.4 Dynamic Model Verification

Глава IV. Robot Hardware

4.1 System Overview
4.2 Leg Design
4.3 Valves
4.4 Force Sensors
4.5 Angle Sensors

Глава V. Control

5.1 Control Architecture and Control Laws
5.2 Control Program
5.3 Inverse Kinematics

Глава VI. Results and Discussion

6.1 Desired Walking Behavior
6.2 Tuning
6.3 Walking Results
6.4 Robot Limitations
6.5 Derivative Control

Глава VII. Conclusion

7.1 It Walks!
7.2 Semi-Observed Speculation
7.3 Future work

Приложение A: Simulation Code

A.1 Actuator.cpp

Приложение B: Controller Code

B.1 Control.cpp
B.2 Def.h
B.3 Hardware.cpp
B.4 Predict.dat
B.5 Gain.dat

Приложение C: Robot Hardware

C.1 Strain Gage Amplifier
C.2 Wiring
C.3 Mechanical Drawings

Литература

Список таблиц

Таблица 4.1 : Transducer sensitivity and error
Таблица 6.1 : Joint range of motion
Таблица 6.2 : Time parameters for walking motion
Таблица 6.3 : Walking motion control gains
Таблица 6.4 : Passivity and average duty cycles of each valve

Список иллюстраций

Иллюстрация 1.1 : Dimensionless force-length properties of actuators and biological muscles
Иллюстрация 2.1 : Photograph of inflated and uninflated actuators
Иллюстрация 2.2 : Actuator dimensions
Иллюстрация 2.3 : Geometric schematic of actuators
Иллюстрация 2.4 : Mesh geometry
Иллюстрация 2.5 : Revised actuator geometry schematic
Иллюстрация 2.6 : Pressure, Length, Force, Stiffness Relationship for a BPA
Иллюстрация 2.7 : Static model verification schematic
Иллюстрация 2.8 : Plot of Force vs. Length for a BPA with constant internal mass of air
Иллюстрация 2.9 : Pressure Increase vs. Length – constant mass system
Иллюстрация 2.10 : Plot of Force vs. Length – constant air mass – Exp. vs. Theor. results
Иллюстрация 2.11 : Plot of Effectiveness vs. Pressure
Иллюстрация 2.12 : Plot of Force vs. Length – Exp. vs. Theor. Results – (effectiveness)
Иллюстрация 2.13 : Plot of Force vs. Length – Constant Pressure System
Иллюстрация 2.14 : Dynamic model schematic
Иллюстрация 3.1 : Simulation overview schematic
Иллюстрация 3.2 : Detailed simulation schematic
Иллюстрация 3.3 : Actuator equation of motion schematic
Иллюстрация 3.4 : Flow curve for Matrix 758 3-way valve
Иллюстрация 3.5 : Dynamic model verification schematic
Иллюстрация 3.6 : Length vs. Time – 60 psi constant mass – 6 lb load - measured
Иллюстрация 3.7 : Length vs. Time – 60 psi constant mass – 6 lb load - simulation
Иллюстрация 3.8 : Length vs. Time – 80 psi constant mass – 11 lb load - measured
Иллюстрация 3.9 : Length vs. Time – 80 psi constant mass – 11 lb load - simulation
Иллюстрация 3.10 : Length vs. Time – 60 psi constant mass – 11 lb load - measured
Иллюстрация 3.11 : Length vs. Time – 60 psi constant mass – 11 lb load - simulation
Иллюстрация 3.12 : PWM valve model verification schematic
Иллюстрация 3.13 : Commanded vs. Actual duty cycles – Matrix 758 3-way valve
Иллюстрация 3.14 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - measured
Иллюстрация 3.15 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 5 lb load - simulation
Иллюстрация 3.16 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - measured
Иллюстрация 3.17 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 1 lb load - simulation
Иллюстрация 3.18 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - measured
Иллюстрация 3.19 : Length vs. Time – 100 psi - 25 Hz, 50% PWM – 15 lb load - simulation
Иллюстрация 3.20 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - measured
Иллюстрация 3.21 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 1 lb load - simulation
Иллюстрация 3.22 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - measured
Иллюстрация 3.23 : Length vs. Time – 100 psi - 50 Hz, 50% PWM – 5 lb load - simulation
Иллюстрация 4.1 : Robot hardware schematic
Иллюстрация 4.2 : Photograph of robot
Иллюстрация 4.3 : CAD model and photograph of robot leg
Иллюстрация 4.4 : CAD model and photograph of hip translational joint
Иллюстрация 4.5 : CAD model and photograph of hip rotational joint
Иллюстрация 4.6 : Schematic of inlet valve
Иллюстрация 4.7 : Schematic of exhaust valve
Иллюстрация 4.8 : Current vs. time for inlet valve
Иллюстрация 4.9 : Current vs. time for exhaust valve
Иллюстрация 4.10 : Force sensor classic analysis schematic
Иллюстрация 4.11 : Force sensor FEA results
Иллюстрация 4.12 : Photograph of force sensors
Иллюстрация 4.13 : Photograph of strain gage amplifier
Иллюстрация 4.14 : Transducer calibration plot
Иллюстрация 4.15 : Photograph of completed force measurement system
Иллюстрация 4.16 : Photograph of completed angle measurement systems
Иллюстрация 5.1 : Labeled schematic of a joint
Иллюстрация 5.2 : Block diagram of the control algorithm
Иллюстрация 5.3 : ISR schematic
Иллюстрация 5.4 : Inverse kinematics schematic
Иллюстрация 6.1 : Desired foot positions for walking motion
Иллюстрация 6.2 : Sequential video frames of the leg during walking motion
Иллюстрация 6.3 : Desired and actual x-y foot paths: Test 1
Иллюстрация 6.4 : Desired and actual joint angles vs. time: Test 1
Иллюстрация 6.5 : Actuator force vs. time
Иллюстрация 6.6 : Desired and actual joint stiffness vs. time
Иллюстрация 6.7 : Joint torque vs. time
Иллюстрация 6.8 : Ground reaction forces during walking vs. time
Иллюстрация 6.9 : Trolley motion vs. time
Иллюстрация 6.10 : Hip joint valve duty cycles vs. time
Иллюстрация 6.11 : Knee joint valve duty cycles vs. time
Иллюстрация 6.12 : Desired and actual joint angles vs. time: Test 2
Иллюстрация 6.13 : Desired and actual x-y foot paths: Kicking motion
Иллюстрация 6.14 : Desired and actual joint angles vs. time: Kicking motion
Иллюстрация 6.15 : Calculated angular velocity vs. time
Иллюстрация 6.14 : Desired and actual joint angles vs. time: Derivative control
Иллюстрация 7.1 : Desired and actual x-y foot paths: Angle feedback only

Глава1

Acknowledgements

I would like to thank my wife Joni for being supportive of this crazy idea to go get a masters degree. Without her support, I never would have been able to do it. I would also like to thank my wonderful new son Boyd for helping me put priorities into perspective.

I want to thank Roger Quinn for providing an excellent work environment. I have thoroughly enjoyed my experience working in the Biorobotics Lab. I also appreciate his patient and supportive leadership style.

Gabe Nelson has given me invaluable counsel in robotics as well as life. In this thesis, you will see evidence of all the work he has done before me to make my work possible. For this, I would like to thank him.

I want to thank Rich Bachmann, Matt Birch, Jim Berilla, and Yuan Dao Zhang for using their time and talents to help me build the robot.

I would also like to express my gratitude to the other guys in the lab for being sounding boards for my half-baked ideas and providing a good political discussion at the drop of a hat.

I want to express my appreciation to my parents for raising me and giving me direction. I was taught many of the fundamentals of engineering while tinkering in the garage with my dad.

I want to thank Dr. Joe Mansour and Dr. Steve Phillips for serving on my thesis committee.

The work was supported by the Office of Naval Research under grant number

N0014-99-1-0378, and DARPA under contract number DAAN02-98-C-4027.

Finally, I want to thank God for life, and all these wonderful creatures that we study. Even with all our great technology, our understanding of the world is so limited. As an engineer, His infinite wisdom and designs humble me. Without Him, we are nothing

Design and Control of a Robotic Leg With Braided Pneumatic Actuators
Abstract by ROBB WILLIAM COLBRUNN
A Braided Pneumatic Actuator is a device developed in the 1950’s by J.L.


McKibben. In recent years, robotics engineers have begun to rediscover these fascinating devices, and use them as actuators for their robots. These actuators exhibit non-linear force-length properties similar to skeletal muscle, and have a very high strength-to-weight ratio. In this thesis, emphasis was placed on understanding the actuator properties so that this knowledge could be used in simulation and control of legged robots. Static and dynamic mathematical models were developed for the actuators, and verified through testing and simulation. A four-degree of freedom robotic leg was designed, constructed, and controlled. The leg provided stable, sensible forward walking for the robot, and was capable of operating 94% passively. Though these actuators have a few limitations, their muscle-like properties including high strength-to-weight ratio, passive characteristics, and self-limiting force properties make them ideal for legged robots.

Chapter I: Introduction 1.1 Background

Much ink has been used to explain the benefits of legged locomotion over wheeled locomotion for robots. As with most things, there is always a trade off. A wheeled robot might go faster and be easier to build, but tell it to climb a flight of stairs and its shortcomings become apparent quickly. Upon observation of all the creatures around us, we see the legged design as the locomotion method of choice. The purpose of this thesis, however, is not to show why it should be done, but how it can be done.

Legged locomotion is the beginning of the biologically inspired approach to robotics. However, putting legs on a frame is not enough to have a walking robot. Arguably, the most important part of any motion device is the mechanism that does the moving: the actuators. In the past, CWRU walking robots have used DC motors to generate leg movement. With the move toward physical autonomy (operation without an umbilical), the poor strength to weight ratio of DC motors became far too prohibitive. The next generation of robot used pneumatic cylinders to increase this ratio. Air cylinders’ strength to weight ratio is much better than electric motors, but there is still room for improvement. The total weight of Robot III was 29.5 lbs. with 76% of that being actuator and valve weight (Bachmann, 2000). A lighter weight actuator that was just as strong would increase the robot’s payload capacity. The biologically inspired approach led the group to look at the prime movers that are designed into natural walking “machines”: muscles. Using real muscle tissue is technologically not practical at this time (Shimoyama, 1997), so an artificial muscle is necessary. This actuator is known as a Braided Pneumatic Actuator or a McKibben Artificial Muscle. These actuators can have a power-to-weight ratio as high as 25 times greater than DC motors (Shadow, 2000). These actuators also have experimentally been shown to have force-length properties similar to skeletal muscle (Klute et al.,1999).

Figure1-1.jpg

Figure 1-1: The dimensionless relationship between force and length under isometric conditions at maximal activation for various animals as well as a McKibben actuator pressurized to 5 bar (Klute et al.,1999).

This muscle-like stiffness and their structural flexibility present real advantages over air cylinders. In this thesis, these braided pneumatic actuators will be referred to as “McKibbens” or BPA.

1.2 Purpose and Overview

The focus of this project involves the investigation of using McKibbens as the prime mover in a walking robot. This work is divided into six sections. Each chapter builds upon the other to explain the process and methods of using BPA to make a robotic leg walk. Chapter two explains all the properties of the BPA as well as the mathematical model formulated for simulation and control. Chapter three describes the simple spring- mass-damper simulation that was written to dynamically validate the model. This simulation included a model of the actuator, and a model of a solenoid valve for controlling the mass of air in the actuator. The valve states were the only inputs, and the simulation calculated the remaining system properties. The next chapter describes all the hardware involved in making the robot walk. A system overview, the valves, the sensors, and the leg design are all presented. Chapter five delves into the control program and how the sensor feedback is turned into valve commands. Then, chapter six presents the results or quantification of the walking. The last chapter discusses the limits and shortcomings of using McKibbens. Finally, possible solutions and improvements are addressed as topics of future work.

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