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

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 letter 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.