In precision positioning systems, lightly damped higher-order resonance modes can induce undesirable vibrations that degrade system performance and accuracy. These resonances pose additional challenges in non-collocated dual-stage positioning systems, where they significantly limit control bandwidth. Although conventional notch filters are commonly used alongside tracking controllers to enhance bandwidth, they lack robustness when faced with system parameter uncertainties. Moreover, the effects of the delimiting resonance on disturbance rejection remain. Active damping control has been successfully used to mitigate issues related to the primary resonance mode, but its application to higher-order modes has not been explored. This paper introduces a novel control strategy, High-Pass Positive Position Feedback (HP-PPF), inspired by existing methods but designed specifically for active damping of higher-order, non-collocated modes in positioning systems. The proposed method incorporates a second-order high-pass filter within a positive feedback loop, effectively attenuating the delimiting resonance. Integrated with a PID tracking controller in a dual-loop configuration, this method enhances disturbance rejection and robustness against model uncertainties, overcoming limitations of traditional notch filter-based methods while achieving comparable bandwidth improvements. The proposed control architecture is validated through a proof-of-concept experimental setup that demonstrates the effectiveness of the underlying mathematical framework.

In non-collocated compliant positioning systems, the parasitic resonance peak induces undesirable vibrations, limiting control bandwidth. Despite conventional notch filters being employed alongside PID controllers for improving bandwidth, parasitic resonance effects persist in disturbance rejection. This paper introduces an overactuation-based solution, utilizing additional actuators for active damping control to enhance closed-loop disturbance rejection within a PID-based control architecture. Integrating distributed piezoelectric bender actuator sensor pairs in a collocated configuration further improves damping. A formulated mathematical framework substantiates the benefits, validated by an experimental setup serving as a proof of concept. The proposed solution effectively suppresses parasitic resonance, enhances end-effector disturbance rejection, and achieves higher control bandwidth in the positioning system.