multi degree-of-freedom hydraulic human power amplifier ... · • hpa control shown in dscc 2015,...
TRANSCRIPT
Multi Degree-of-Freedom Hydraulic
Human Power Amplifier with Rendering
of Assistive Dynamics
Sangyoon Lee, Perry Y Li
This work is performed within the Center for Compact and Efficient Fluid Power (CCEFP) supported by the
National Science Foundation under grant EEC-05040834. Donation of components from Takako Industries is
gratefully acknowledged.
Human Power Amplifier
• Tool that amplifies human force: in oar form
• Another example: exoskeleton
• Control objective: passive mechanical tool
• Physically connected to the task
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Human Power Amplifier
• Tool that amplifies human force: in oar form
• Another example: exoskeleton
• Control objective: passive mechanical tool
• Physically connected to the task
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Human
Environment
Control Objective
• Controlling the hydraulic actuator force
• Amplify the human force by a factor of
• resulting in the dynamics of target passive mechanical tool:
• ML: apparent inertia of the tool
• Achieved when
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a humanF F
Hydraulic Transformer
• Pressure control by metering
valve causes a significant
throttling losses
• Heat generation
• Transformer eliminates such
losses
• Constant power between input
A’ and load B
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• Hydraulic: high power density, precision, compactness
Flow
Pre
ssu
re
Output
Input
Load connected
to servo valve Load connected to transformer
Can we use transformer for
human power amplifier?
Outline
• Introduction
• System Dynamics
• Control Strategy
• Virtual coordination approach
• Guidance Control
• Experimental Results
• Conclusion
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System Description
• Generalized coordinate
• Hydraulic force from cylinder and motor
• Cylinder for pitch Motor for reach
• Connected to a transformer
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Virtual Coordination Approach
• Direct Force control [1]
• Positive velocity feedback effect
• Not robust
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[1] Li, P. Y., 2004. “Design and control of a hydraulic human power amplifier”. In ASME 2004 International Mechanical
Engineering Congress and Exposition, American Society of Mechanical Engineers, pp. 385–393.
0a dF F F
Virtual Coordination Approach
• Direct Force control [1]
• Positive velocity feedback
• Not robust
• Virtual coordination approach [2]
• Hydraulic actuator = ideal kinematic
actuator in series with nonlinear spring
• Compressibility
• Design controller to mimic the mass-
spring system
• Virtual + Actual
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[1] Li, P. Y., 2004. “Design and control of a hydraulic human power amplifier”. In ASME 2004 International Mechanical
Engineering Congress and Exposition, American Society of Mechanical Engineers, pp. 385–393.
[2] Li, P. Y., 2006. “A new passive controller for a hydraulic human power amplifier”. In ASME 2006 International Mechanical Engineering Congress and
Exposition, American Society of Mechanical Engineers, pp. 1375–1384.
0F
Virtual System
• Virtual inertia acts with
• If coordinated , then resulting
dynamics is
• The target dynamics!
• Guidance
• Passivity:
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Passive Decomposition - Transformation
• Transformation into the velocity spaces [5]
• Transformed dynamics:
• Then, design controller for shape system to
make sure VE 0!
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11 1( )
V
L
L v P
E
v p
M
M
M M M
MM M
Center of the mass
of combined system
Coordination error
[6] Lee, D. J., and Li, P. Y. 2004, “Passive decomposition of multiple mechanical systems under coordination requirements”. IEEE Transactions on
Automatic Control, 58, p. 230.
Locked System
Shape System
PVFC and Obstacle Avoidance
• Using the virtual coordination scheme, we
can add some additional control to the
virtual system such that the physical
system will be naturally guided
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Experimental System
• 2-DOF Human Power Amplifier with a
force handle
• Cylinder driven by transformer
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Computer controlled variable transformer prototype
based on 3.5cc micro-piston pumps
Human Power Amplification
• Wrestling
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Added force input
RMS ~3% with mean desired force
RMS 0.0094 m/s
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PVFC + Obstacle Avoidance
• Obstacle Avoidance + PVFC
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Other developments in Transformer
• Demonstrated controller performance
• Trajectory tracking shown in FPMC 2015
• HPA control shown in DSCC 2015, 2016
• Desire to show efficiency benefit experimentally
• Hardware-In-the-Loop?
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Simulated
Load
Conclusion
• 2-DOF Passive velocity coordination control using a transformer
• PVFC and Obstacle Avoidance to assist the human operator
• Demonstrates transformer need not sacrifice control performance
• Transformer efficiency will be shown
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