Nonlinear proportional integral controller

摘要

A method and apparatus for controlling a hydraulic manipulator defines a position error signal ( theta e), defining a first control signal (UP, UPD) based on the position error ( theta e) and generating an improved position error integral signal ( theta I) based on a product of the position error ( theta e) integral signal and a velocity factor FV. The velocity factor FV is based on a derivative of the position error ( theta e) and a nonlinear function. An integral control signal (UI) is produced based on the improved position error integral signal ( theta I) and is combined with the first signal (UP, UPD) 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 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 estiction) and modifying the control signal when required.