Robust adaptive tracking control for a class of mechanical systems with unknown disturbances under actuator saturation

• Published in: International journal of robust and nonlinear control Vol. 29; no. 6; pp. 1893 - 1908
• Main Authors: Hu, Xin, Wei, Xinjiang, Zhang, Huifeng, Han, Jian, Liu, Xiuhua
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.04.2019
• Subjects: actuator saturation; Actuators; adaptive backstepping method; Adaptive control; adaptive disturbance observer; Control stability; Control systems; Control theory; Disturbance observers; Mathematical analysis; Matrix methods; Mechanical systems; Robot arms; Robust control; Saturation; Tracking control; unknown disturbances
• ISSN: 1049-8923; 1099-1239
• DOI: 10.1002/rnc.4465

Summary A robust adaptive tracking control scheme is presented for a class of multiple‐input and multiple‐output mechanical systems with unknown disturbances under actuator saturation. The unknown disturbances are expressed as the outputs of a linear exogenous system with unknown coefficient matrices. An adaptive disturbance observer is constructed for the online disturbance estimation. An actuator saturation compensator is introduced to attenuate the adverse effects of actuator saturation. The adaptive backstepping method is then applied to design the robust adaptive tracking control law. It is proved that the designed control law makes the system outputs track the desired trajectories and guarantees the global uniform ultimate stability of the closed‐loop control system. Simulations on a two‐link robotic manipulator verify the effectiveness of the proposed control scheme.