Adaptive Robust Control for Rotation Tracking of a Soft Rotary Actuator with Hysteresis Compensation

Abstract

Precise control of soft pneumatic actuators is impeded by significant nonlinearities, particularly large internal volume variations during actuation---a factor often overlooked in conventional modeling. This paper proposes an adaptive robust control (ARC) framework designed for high-performance, energy-efficient control of soft actuators with non-negligible volume dynamics. The framework integrates a Modified Prandtl-Ishlinskii (MPI) model for hysteresis compensation with a real-time volume estimator using an internal Time-of-Flight (ToF) sensor. The ARC law then systematically handles uncertainties from both valve parameter variations and the volume estimation process. Experimental validation, through direct comparison with a conventional fixed-volume model, demonstrates that this volume-aware approach achieves robust trajectory tracking with significantly reduced control effort and energy consumption. This work establishes that explicitly modeling internal volume dynamics is crucial for developing high-performance control systems for a broad class of soft pneumatic actuators.