University of Manitoba

Bradley Edwin Heinrichs

Nariman Sepehri

Amir Ali-Akbar Khayyat

A method and apparatus for controlling a hydraulic manipulator defines a position error signal (.theta..sub.e), defining a first control signal (U.sub.P, U.sub.PD) based on the position error (.theta..sub.e) and generating an improved position error integral signal (.theta..sub.I) based on a product of the position error (.theta..sub.e) integral signal and a velocity factor F.sub.V. The velocity factor F.sub.V is based on a derivative of the position error (.theta..sub.e) and a nonlinear function. An integral control signal (U.sub.I) is produced based on the improved position error integral signal (.theta..sub.I) and is combined with the first signal (U.sub.P, U.sub.PD) to provide an output control signal U to control the manipulator. The invention also preferably includes a system to further reduce overshoot by further modifying the position error signal (.theta..sub.e) depending on whether the velocity and acceleration of position are in the same direction and to accommodate stiction at deadband areas of the control by determining a stick induced velocity error signal (.theta..sub.e.sup.stiction) and modifying the control signal when required.

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Surrey, Canada

Bradley Edwin Heinrichs