Observer-corrector feedback is a control strategy which reduces destabilizing effects of unmodeled higher-order dynamics (e.g., structural resonances of a robotic manipulator) found in many systems subject to control. The fundamental idea is to synthesize a substitute feedback signal in order to extract dominant dynamic components (e.g., rigid body motion of a robotic manipulator) from the output of the controlled system. A band-limited state observer complemented by a low-pass filter corrector are employed for this purpose. The synthetic signal is used as a controller input, effectively eliminating destabilizing effects of unmodeled dynamics of the controlled system. In the presented work, the observer-corrector feedback mechanism is implemented for motion control of a three-axis direct-drive robotic manipulator for automated pick-place operations in semiconductor manufacturing applications. A detailed technical description of the robotic manipulator is provided, a control system with the observer-corrector arrangement is designed, and selected results of laboratory tests are presented. The tests demonstrate that the observer-corrector feedback mechanism leads to improved control performance, increased stability margin, and added robustness against variations in system parameters in comparison to usual control methods.

This content is only available via PDF.
You do not currently have access to this content.