AMC26: VSSEA robust position control

TL;DR

This paper develops robust position control strategies for the novel VSSEA using state-space models, combining state-feedback and sliding mode controllers with disturbance observers to enhance robustness and performance.

Contribution

It introduces a unified control framework integrating disturbance observers with state-feedback and sliding mode controllers for VSSEA, improving robustness without sacrificing dynamic response.

Findings

DOb significantly enhances robustness against disturbances.

LQR controllers offer better robustness with slower dynamics.

Experimental results confirm real-world applicability.

Abstract

This paper presents robust position control strategies for the novel VSSEA. By employing a constructed state-space model, two control schemes are developed in a unified framework: a state-feedback controller and a sliding mode controller, both integrated with a second-order DOb. The proposed framework achieves high-performance motion control by precisely estimating and compensating for internal and external disturbances, while preserving the nominal dynamic response. Simulation results demonstrate that pole-placement-based controllers are highly sensitive to disturbances, whereas LQR-based controllers offer improved robustness at the expense of slower dynamics. By incorporating DOb, robustness is significantly enhanced without degrading time response, and the LQR controller can be tuned solely for performance optimization. Experimental results confirm that the proposed robust position controllers can be implemented in real world applications. These results highlight the effectiveness of the proposed approach and lay the foundation for future investigations on robust stability and performance under different stiffness settings.