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Adaptive Pulse Width Control of Structurally Flexible Systems
Project Abstract
Pulse Width Control (PWC) applies a series of fixed-height rectangular force pulses, in a feedback fashion, to move the end-effector of an electromechanical system subject to mechanical friction to its desired position. For point-to-point position control of the end-effector of a rigid body plant, under mild assumptions regarding the accuracy of the values assumed for the plant parameters, including the Coulomb friction and stiction levels, limit-cycle-free operation and zero steady-state position error are guaranteed.
When PWC is applied to control the position of the end-effector of a flexible-body plant, the result can be a position-error limit cycle. This project's investigators have shown that this limit cycle can be avoided, and that zero steady-state end-effector position error can be achieved, by use of a piecewise-linear-gain (PLG) PWC law. When applied to a six-axis industrial robot, their PLG PWC law achieved a more than order-of-magnitude improvement in end-effector position control accuracies compared to what could be achieved with proportional-integral-derivative controllers.
This project seeks to extend their earlier PWC work, to make it possible to achieve order-of-magnitude improvements in point-to-point end-effector position control accuracy in industrial robots and machine tools in bona fide industrial settings.
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