Chattering-Free Sliding-Mode Control of a Soft Actuator for Precise Tracking Performance

The increasing wide popularity of Electro-Adhension actuation through Dielectric Elastomer is credited to their suitability in several bio-inspired applications such as flexible prosthetics, humanoid grasps, bio-mimicking robots etc. Virtually all DEAs suffer from precise positioning challenges due to their inherent strong nonlinear dynamics, namely: creep and hysteresis. As a consequence, there is a necessity to establish control-enabling DEA models and accompanying control strategies that eliminate these undesirable dynamics and allow for precise reference tracking. In this paper, an experimentally validated DEA model is employed to design a simple yet well-performing control strategy based on the Sliding Mode Control (SMC) philosophy. To further enhance the control performance and improve implementability, a technique to eliminate the inherent control input chattering present in typical SMC designs is also described. Extensive closed-loop simulations are performed, and tracking performances are quantified to justify the designed superiority of the control scheme performance.