Multimodal Active Vibration Suppression Control of Flexible Cantilever-Type Structure via Piezoelectric Electrode Configuration: Bending and Torsion Mode

This article introduces innovative methods for controlling vibration suppression in a flexible cantilever beam’s bending and torsion modes utilizing a piezoelectric electrode configuration. The modal analysis demonstrates that implementing electrode configurations, such as the full electrode configuration, enhances the excitation efficiency at the bending mode frequency, while the top-bottom electrode configuration improves the excitation efficiency at the torsional mode frequency of the piezoelectric cantilever beam. Based on the above-mentioned electrode configuration, this article presents two novel multimodal active vibration suppression control strategies, integrated with positive position feedback (PPF) control as the fundamental controller to manage simultaneous bending and torsion vibrations. These strategies are: (1) Superposition control and (2) Electrode switching control (ESC). The first control scheme that superposes control inputs of bending and torsional mode PPF controllers, proves highly effective in simultaneously suppressing both vibrations. In contrast, the ESC control scheme is developed with our designed electrode configuration switching circuit module and basic PPF control algorithms, enabling it to manage real-world scenarios involving time-varying single-mode vibrations in real-time (either bending or torsion mode). Experimental comparisons and analysis show that the newly proposed multimodal vibration control schemes are highly effective in suppressing simultaneous bending-torsion and time-varying bending/torsion vibrations. These schemes offer a significant advantage by reducing the need for additional actuators, making them suitable for various applications involving structural systems that experience both bending and non-bending mode vibrations. In the single-mode active vibration control experiments, the full-electrode mode combined with the bending-mode PPF control law suppressed 96.6% of the cantilever beam’s bending-mode resonance, while the upper and lower electrode modes reduced torsional-mode resonance by 88.6%. Multi-mode control experiments further demonstrated that the control-input superposition and electrode-switching methods achieve effective vibration suppression when bending and torsional disturbances act simultaneously or interactively.