Research of the FLC + PID switching control strategy based on real-time error for the pneumatic polishing force regulating system

Abstract

This paper designs an active pneumatic polishing force control system and investigates its control strategy. A straightforward method based on the experiments is proposed for identifying and modeling the pneumatic system and a convenient and effective control strategy based on real-time error is proposed for pneumatic polishing force regulating. Corresponding function between the input duty cycles and the output force values is created based on the experiment data tested by the system. Then the pneumatic force regulating system is modeled by the corresponding function. Base on the results of simulations and experiments, a FLC (Fuzzy Logic Control) + PID (Proportion-Integration-Differentiation) switching control strategy is designed with a switching mechanism to choose different control algorithm based on real-time error which can take the advantages of both PID and FLC. The FLC + PID switching controller can eliminate the steady state errors occurring in FLC controller and achieve the same accuracy as the PID controller but with a faster response speed. The approach effectively stabilizes the polishing force, resulting in polishing force errors that are distributed within ± 1 N. The mean errors are less than 0.2 N and the absolute mean errors hover around 0.3 N. The pneumatic polishing force control system regulated by the FLC + PID switching control exhibits effectiveness, stability, high control precision and fast response speed, and satisfies the force control requirements of polishing process.

Keywords

• Polishing force control
• Pneumatic system
• System identification
• FLC+PID switching control
• Real-time error