High-precision fuzzy-based force measurement and control with a novel air-suspended frictionless polishing pneumatic end-actuator

This study presents a force measurement and control system that integrates a novel air-suspended frictionless pneumatic polishing end-actuator with a fuzzy adaptive controller. The end-actuator employs a hydrostatic air suspension structure with multiple rows of throttle holes to eliminate sliding seal contact, enabling low-distortion normal force transmission with sub-Newton-level resolution. In-situ calibration using ISO-traceable standard weights achieves an expanded uncertainty of approximately ±0.55 N (k = 2) based on ISO Fundamental Metrology uncertainty budgeting. The controller, specifically designed to address pneumatic nonlinearity and model uncertainty, achieves bounded rapid tracking of low-frequency force references relevant to flexible polishing. Experimental validation includes repeatable tracking performance under constant, sinusoidal, and variable-frequency and amplitude reference force signals, spindle speed sensitivity assessment, and testing on flat, curved, and edge-bent workpieces. Compared with traditional sealed pneumatic cylinders, this design achieves shorter settling times and smaller steady-state force errors while maintaining safe contact flexibility. The results demonstrate that this metrology-driven pneumatic polishing end-effector provides quantifiable uncertainty and establishes a reusable protocol for evaluating dynamic force measurement and control in flexible surface interactions.