Observer-based Adaptive Fuzzy Force Control for the Pneumatic Polishing System End-actuator with Uncertain Dynamic Contact Model

In the field of flexible polishing, the accuracy of contact force control directly affects processing quality and material removal uniformity. However, the complex dynamic contact model and inherent strong hysteresis of pneumatic systems can significantly impact the force control accuracy of pneumatic polishing system end-effectors. To enhance responsiveness and control precision during the flexible polishing process, this study proposes an observer-based fuzzy adaptive control (OBFAC) scheme. To ensure control accuracy under an uncertain dynamic contact model, a fuzzy state observer is designed to estimate unmeasured states, while fuzzy logic approximates the uncertain nonlinear functions in the model to improve control performance. Additionally, the integral barrier Lyapunov function is employed to ensure that all states remain within predefined constraints. The stability of the proposed control scheme is analyzed using the Lyapunov function, and a pneumatic polishing experimental platform is constructed to conduct polishing contact force control experiments under multiple scenarios. Experimental results demonstrate that the proposed OBFAC scheme achieves superior tracking control performance compared to existing control schemes.