Hierarchical Optimal Contour-Position Control of Motion Control Systems

Contour control is critical in many motion control systems (e.g., manufacturing, robotics). A contour control algorithm is implemented in many applications to drive the contour error to zero; however, the additional algorithm significantly increases the complexity of the overall control system. In this paper, a hierarchical optimal control methodology is developed to design a single servomechanism control system capable of simultaneously driving contour error and individual servomechanism position errors to zero. The designer can systematically trade-off the importance of contour error and servomechanism position errors without the increased complexity of an additional algorithm. The methodology is applied to a two-axis motion control system and simulation studies are conducted for linear, circular, and elliptical contours. The results demonstrate the excellent tracking ability of the proposed motion control methodology and its utility for complex contours.