Liu Y, Sun Y, Zhang Y T,et al.Model-free iterative learning control of a pneumatic six-degree-of-freedom platform robot[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(6):136-146.

doi:10.16186/j.cnki.1673-9787.2023120004

Received:2023/12/01

Revised:2024/04/08

Published:2026/10/09

Model-free iterative learning control of a pneumatic six-degree-of-freedom platform robot

Liu Yu, Sun Yan, Zhang Yuting, Yang Jie

Department of Automation， Beijing Institute of Petrochemical Technology， Beijing 102617，China

Abstract: Objectives Parallel robots possess advantages such as high stiffness， strong load-carrying capacity， high precision， and excellent dynamic performance， offering broad development prospects. To further improve the pose control accuracy of a pneumatic six-degree-of-freedom （6 DOF） platform robot， this study focuses on model-free adaptive iterative learning control.  Methods First， a third-order mathematical model is established for the metal-clearance-sealed cylinder to provide a roughly accurate reference model for subsequent control algorithms. Second， based on an in depth analysis of the pneumatic servo system driven by the metal-clearance-sealed cylinder， a pose control strategy for the 6-DOF platform robot based on model-free adaptive iterative learning control is proposed and its controller is designed. Finally， the effectiveness of the controller is verified using MATLAB. Results Simulation results demonstrate that the model free iterative learning control method exhibits stronger robustness. In step response simulations， compared with the PID method， the model-free iterative learning control method reduces the average rise time by approximately 59% and shortens the average settling time by about 40%，the average reduction in the mean square error is approximately 31%，the average reduction in the maximum error is approximately 63%. In sinusoidal tracking experiments， compared with the PID method， the model-free iterative learning control method achieves average reductions of approximately 56%~57% in the mean square error and 47%~52% in the maximum error.  Conclusions For the pneumatic 6-DOF platform robot， the model-free iterative learning control method exhibits superior control performance compared to traditional PID control and shows promising application prospects.

Key words: six-degree-of-freedom platform robot; model-free control; iterative learning control; PID control; metal clearance-sealed cylinder