Observer-Based Control of Soft Manipulators with Hysteretic Elasticity

Soft robotic manipulators exhibit pronounced nonlinearities due to, for instance, hyperelastic materials and fluidic actuation. Hysteresis is one of the most challenging effects to model and compensate and can significantly degrade tracking accuracy. While data-driven and model-free techniques for hysteresis compensation have been explored, they require extensive experimentation that accelerates material fatigue and reduces long-term reliability. This work presents a model-based control scheme that estimates and compensates, in real time, the hysteretic elasticity of a soft manipulator. A state observer is designed to estimate the internal state in a Bouc–Wen hysteresis model. This is combined with a nonlinear controller designed with a Lyapunov-based approach. Simulation and experimental results demonstrate improved performance and better disturbance rejection compared to an adaptive baseline controller.