Adaptive Robust Posture Control of a 3-RPS Pneumatic Parallel Platform with Unknown Deadzone

Abstract EN

An adaptive robust controller integrated with online deadzone estimation is proposed.

This controller provides trajectory tracking control for pneumatic parallel mechanisms.

Due to the air compressibility and nonlinear characteristics of the pneumatic system, unknown parameters in the model are selected to build online estimation matrices with the robust parts considered in the design.

As each proportional valve has specific values of deadzone boundary points, the deadzone parts are integrated into the online estimator, and an inverse deadzone compensator is used to overcome nonlinear limitations.

The effectiveness of the method was verified by simulation and experiment, and theoretical stability was demonstrated using the Lyapunov method.

Experiments in an actual plant with the proposed controller indicated that the performance of the pneumatic platform can be as good as that of ideal deadzone inverse compensation.

The deadzone estimated parameters converged to the real values quickly.

Additionally, this algorithm was effective under a compound reference input trajectory; thus, the controller is expected to perform well in actual working situations.