Coordinated motion control of a pneumatic-cylinder-driven biaxial gantry for contour tracking tasks

In this paper, coordinated motion control of the pneumatic-cylinder-driven biaxial gantry for precise contour tracking is investigated. An adaptive robust coordinated motion controller is developed by incorporating the task coordinate formulation into the adaptive robust control architecture. Specifically, a task coordinate frame is used to approximately calculate the contour error, which is utilized for controller design to generate coordination between two axes. Furthermore, the proposed controller utilizes online parameter adaptation to estimate some important unknown model parameters, and employs a robust control law to attenuate the effects of parameter estimation errors, unmodelled dynamics and external disturbances. Therefore, certain transient contouring performance and steady-state contour tracking accuracy can be guaranteed. Extensive comparative experimental results obtained verify the effectiveness of the proposed coordinated motion control strategy and its performance robustness to sudden disturbances in practical implementation.