Simple friction-compensating control algorithm for high precision mechanisms

摘要

A high precision pointing mechanism (10), particularly for use in space applications. The precision mechanism includes a motor assembly (26) connected to a displaceable elbow (24). A controller (166) determines a motor torque command (170) in accordance with a position error (168). The position error is used to generate proportional gain (172), derivative gain (182), and integral gain (194) compensation terms. The sum of the proportional compensation component (172) and derivative compensation component (182) is used to generate a proportional- derivative compensation component. The proportional-derivative compensation component is input to a hyperbolic tangent function (188), which substantially models the friction characteristic of the high precision pointing mechanism (10). The output from the hyperbolic tangent function (188) is used in combination with the proportional- derivative compensation component and the integral compensation component to generate the motor torque command (170).