Reset control for active vibration isolation in the presence of wide-band disturbances

This paper explores the use of reset control in systems subjected to wide-band disturbances. Such excitation may result in too rare or excessive resetting, leading to deteriorated performance. Moreover, the commonly used Describing Function (DF) approximation for the frequency-domain design of reset systems does not sufficiently represent the reset element’s behavior under such conditions as it is defined for sinusoidal excitation. To address this, we present a design approach based on analyzing the power spectral densities (PSD) of the signals in the system and using the Best Linear Approximations (BLA) of reset elements. In the first step, the dominant components in the PSD of the reset triggering signal are related to the frequency domain properties of the reset element. To benefit from resetting, it should lead to an increase in phase margins near the cross-over frequency. This is the case where the components at the cross-over frequency dominate the reset triggering signal. To ensure this, the use of a bandpass shaping filter is proposed. In the second step, the BLA of the reset element is used to represent its response to the signal with a specific PSD in the frequency domain. This information is used to tune both the reset element and the shaping filter to achieve the desired performance and minimize loss of gain at low frequencies. Closed-loop simulations show the method’s feasibility in achieving the desired behavior of the reset element, leading to improved resonance peak damping in the example studied.