Force reflection with compliance control
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorWon S. Kim
Life of this patent
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Abstract
Two classes of systems for force-reflecting control that enable high force-reflection gain are presented: position-error-based force reflection and low-pass-filtered force reflection, both combined with shared compliance control. In the position-error-based class, the position error between the commanded and the actual position of a compliantly controlled robot is used to provide force reflection. In the low-pass-filtered force reflection class, the low-pass-filtered output of the compliance control is used to provide force reflection. The increase in force reflection gain can be more than 10-fold as compared to a conventional high-bandwidth pure force reflection system, when high compliance values are used for the compliance control.
Claims4
In a system for teleoperation of a robot arm providing an operator with force reflection through a force-reflecting hand controller in combination with a shared compliance control for each Cartesian coordinate axis of the teleoperation system, a force-reflecting control architecture combined with shared compliance control architecture in one system comprising,
- means for transmitting from said hand controller a commanded position signal, HC, with gain, G.sub.ps,
- a robot servo system at said robot arm responsive to a servo control input signal for driving said robot arm to an actual commanded position, and producing a signal representative of actual position of said robot arm,
- a signal mixer coupling said servo control input signal for a commanded position to said robot servo system, said signal mixer modifying said servo control input signal in response to a low-pass filtered contact force signal to produce an actual servo control signal that is a function of the difference between said servo control input signal and said low-pass filtered contact force signal with compliance control feedback gain, G.sub.cc, for actual positioning of said robot arm,
- means for sensing contact force generated by said actual positioning of said robot arm for producing a contact force signal proportional to a force of reaction due to contact or torque when said arm is in contact with an object,
- a low-pass filter coupling said contact force signal to said mixer with said compliance control feedback gain as said low-pass filtered contact signal,
- means for producing a force reflection signal that is a function of said commanded position signal, HC, with gain G.sub.ps, transmitted to said robot arm and a selected one of two signals, namely a signal representing actual position of said robot arm effected by said robot servo control signal, and said force contact signal without compliance control feedback gain, G.sub.cc, and
- means for transmitting said force reflection signal to said hand controller, whereby said operator responds to said force reflection hand controller for producing a following commanded position signal for transmittal to said robot servo system.
Dependencies are inferred from the claim text.