A control strategy is presented which reduces destabilizing effects of unmodeled higher-order dynamics found in many systems subject to control. These effects are major limiting factors of conventional controllers, especially for high-performance machinery, such as precision machine tools and robotic manipulators. In the proposed strategy, a substitute feedback signal is synthesized in order to extract dominant dynamic components (e.g., rigid body motion of a flexible robotic manipulator) from the output of the controlled system. A unique arrangement of a band-limited state observer and a low-pass filter corrector is employed for this purpose. The synthetic signal is used as a controller input, effectively eliminating destabilizing effects of unmodeled dynamics of the controlled system. A simulation example demonstrates that the strategy results in improved control performance, increased stability margin, and added robustness against variations in system parameters in comparison to conventional methods adopted currently in engineering practice.

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