Unidirectional virtual inerter for high-bandwidth robot motion control

Abstract

This paper introduces a Unidirectional Virtual Inerter (UVI) as a novel feedback control element in conjunction with a traditional PD controller for high-bandwidth robot motion control. Designed to harness the beneficial properties of a physical inerter within a digital framework, a UVI overcomes the limitations inherent in the physical domain, such as mechanical design complexity, significant weight and size, and maintenance requirements. The research emphasizes the exploitation of the energy dissipation capability that emerges as the inerter transitions from a physical to a discrete setting. Although inerters are traditionally viewed as energy storage devices, their adaptation to the digital domain reveals a promising energy dissipation function. Moreover, by utilizing the features of the VI in a unidirectional manner, this study delves into the UVI’s unique advantages in the digital realm, especially its remarkable energy dissipation ability and the dynamic adjustment of gains based on the system’s kinetic energy. This innovative approach, designed to enhance the performance of existing derivative controllers, significantly improves system convergence speed and enhances stability by dissipating the system energy. The paper includes a stability proof using a common Lyapunov function and validates the effectiveness of the UVI in enhancing system stability and tracking accuracy through simulations and experiments with a multi-DoF robotic manipulator. The findings particularly underscore the controller’s efficacy in regulation and trajectory-tracking tasks.