A modified direct adaptive robust motion trajectory tracking controller of a pneumatic system

• Published in: Frontiers of information technology & electronic engineering 2014-10, Vol.15 (10), p.878-891
• Main Authors: Qian, Peng-fei, Tao, Guo-liang, Meng, De-yuan, Liu, Hao
• Format: Article
• Language: English
• Subjects: Adaptation; Communications Engineering; Computer Hardware; Computer Science; Computer Systems Organization and Communication Networks; Control theory; Controllers; Directional control; Disturbances; Electrical Engineering; Electronics and Microelectronics; Instrumentation; Kalman filters; Mapping; Mathematical models; Networks; Parameter estimation; Pneumatics; Pulse duration modulation; Robust control; Solenoid valves; Synthesis; Tracking control; Trajectory control; Uncertainty; 参数不确定性; 未建模动态; 气动系统; 自适应鲁棒控制; 衍生物合成; 跟踪控制器; 运动轨迹; 鲁棒自适应
• ISSN: 1869-1951; 2095-9184; 1869-196X; 2095-9230
• DOI: 10.1631/jzus.C1400003

In this study, we developed and tested a high-precision motion trajectory tracking controller of a pneumatic cylinder driven by four costless on/off solenoid valves rather than by a proportional directional control valve. The relationship between the pulse width modulation （PWM） of a signal＇s duty cycle and control law was determined experimentally, and a mathematical model of the whole system established. Owing to unknown disturbances and unmodeled dynamics, there are considerable uncertain nonlinearities and parametric uncertainties in this pneumatic system. A modified direct adaptive robust controller （DARC） was constructed to cope with these issues. The controller employs a gradient type adaptation law based on discontinuous projection mapping to guarantee that estimated unknown model parameters stay within a known bounded region, and uses a deterministic robust control strategy to weaken the effects of unmodeled dynamics, disturbances, and parameter estimation errors. By using discontinuous projection mapping, the parameter adaptation law and the robust control law can be synthesized separately. A recursive backstepping technology is applied to account for unmatched model uncertainties. Kalman filters were designed sepa- rately to estimate the motion states and the derivative of the intermediate control law in synthesizing the deterministic robust control law. Experimental results illustrate the effectiveness of the proposed controller.