Ding Han

Cross-coupled controller design for triaxial motion systems based on second-order contour error estimation

The cross-coupled control (CCC) is widely applied to reduce contour errors in contour-following applications. In such situation, the contour error estimation plays an important role. Traditionally, the linear or second-order estimation approach is adopted for biaxial motion systems, whereas only linear approach is available for triaxial systems. In this paper, the second-order contour error estimation, which was presented in our previous work, is utilized to determine the variable CCC gains for motion control systems with three axes. An integrated stable motion control strategy, which combines the feedforward, feedback and CCC controllers, is developed for multiaxis CNC systems. Experimental results on a triaxial platform indicate that the CCC scheme based on the second-order estimation, compared with that based on the linear one, significantly reduces the contour error even in the conditions of high tracking feedrate and small radius of curvature.

Pseudo minimum translational distance between convex polyhedra (I)

Based on the concept of gauge function, the pseudo minimum translational distance (PMTD) between two convex objects is defined in this paper. PMTD not only provides a measure of the clearance between two separating objects, but also quantifies the penetration of two objects intersecting each other. It is proved that the PMTD is differentiable almost everywhere w. r. t. the configuration variable of the objects. Algorithms for calculating PMTD and its derivative are also presented.

Optimization of manipulator dynamics in non extreme design case

This paper is concerned with the dynamic merit of robot manipulators and method for the optimization of manipulator dynamics in the case of an extremely bad design, which can be put into three categories:n 1. Acceleration performance: minimize 2. Velocity performance: minimize 3. Comprehensive performance: minimize , and are the dynamics indices of API, VPI and CD PI under various conditions respectively. The exchange algorithm is presented and a procedure is developed to solve this kind of Minimax problem. An example is discussed to illustrate the application of the optimization method. The large uniform magnitude of a joint relative driving torque provided by this dynamics optimization procedure will be made into a large work space and large torques.