Actuator Saturation Compensation for Fast Tool Servo Systems With Time Delays

• Published in: IEEE access Vol. 9; pp. 6633 - 6641
• Main Authors: Liu, Pengbo, Song, Yuanyuan, Yan, Peng, Sun, Yujing
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: actuator saturation; Actuators; anti-windup compensation; Antiwindup compensators; Capacitive sensors; Control systems; Delay effects; fast tool servo; Mathematical model; Nanopositioning; Nonlinearity; Optimization; Robustness; Saturation compensators; Servocontrol; Servomotors; Stability criteria; time delay; Uncertainty
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2020.3048377

Fast tool servo systems with high precision and high speed pose significant challenges to servo control at the nano-scale. The saturation of the control actions, time delays and system uncertainties further complicate the control challenges. To address these problems, we propose a Smith predictor based robust anti-windup scheme in this article, such that high performance servo with nano-accuracy can be achieved in the case of saturations, time delays and model uncertainties. According to the input/output based equivalent representation, the saturation nonlinearity is transformed to the dead zone nonlinearity fulfilling a sector condition. Based on the Popov criterion, the stability conditions for the anti-windup compensator are derived, which are further formulated as an <inline-formula> <tex-math notation="LaTeX">H_\infty </tex-math></inline-formula> optimization problem with robustness against model uncertainties. The effectiveness of the proposed control architecture is verified through real-time experiments, where excellent servo performance, saturation compensation and robustness are demonstrated, outperforming existing results.