Papers by Author: Xiao Jun Yang

Abstract: To obtain better trajectory tracking, a new synchronous control with sliding mode surface is proposed. Based on Kane equation, the dynamics model of a planar 2-DOF redundantly actuated parallel mechanism was formulated. With trajectory contour error, the synchronization error was defined and the sliding surface was determined. After dynamic equation linearization, a robust adaptive sliding mode synchronous controller was designed with stability analysis. After Matlab simulation, figures of tracking errors and synchronization errors changing with time compared with computed torque method were plotted. Results show that the robust adaptive sliding mode synchronous control can be able to achieve good trajectory tracking compared with computed torque controller.

Abstract: The concept evaluation of mechanical product is essentially a multi-attribute decision making (MADM) problem in the fuzzy environment. In order to reduce the adverse impact of preference or judgments of decision makers on the final evaluation results, this paper attempts to propose an integrated fuzzy multi-attribute decision making methodology that combines the fuzzy TOPSIS technique and the objective weighting to evaluate mechanical product. The fuzzy TOPSIS technique is applied to rank the design alternatives, and the objective weighting method is integrated into the fuzzy TOPSIS technique to determine the appropriate criteria weights. Finally, a real application to pan mechanism selection for a cooking robot is demonstrated.

Abstract: In this paper the multi-objective optimization design of a preliminarily designed end-effector tool for robot-assisted automatic polishing system is presented. ADAMS and iSIGHT are integrated for the multi-objective optimization design, the overall procedure of which is shown in this paper. Design of Experiment is arranged before optimization. The global optimization methods provided by iSIGHT software- Exterior Penalty and Multi-Island Genetic are utilized to perform optimizing process. Simulation executed in ADAMS with model updating with optimized structural design parameters verifies the significance of the multi-objective optimization in improving the performance of preliminarily designed end-effector tool.

Abstract: A new 5-degrees-of-freedom hybrid kinematic machine(HKM) consisting of a 4-degrees-of-freedom PTS-based parallel kinematics platform with center constraint branch and a serial X axis is developed. The will-be-machined workpiece is mounted on the platform and the spindle movement is driven by the X axis. This new HKM is very different from a conventional serial-type machine. Therefore, a special algorithm that can transfer the cutter location data (CL-data) into machine specific NC commands is essential for the applications of the PTS-X based HKM in real machining of the workpiece with the complicated surface. The workpiece’s location approach on the platform and the orientation transformation of the moving platform relative to the machine coordination system are investigated.

Abstract: In this paper, a novel parallel mechanism (3-RRRS/UPR) used in flexible fixture with configuration composed of two parallel robots (2-RR and 3-RRRS/ UPR) is presented. First, system modeling including the mobility study is conducted. Then a novel methodology is proposed that makes use of screw theory to analyze the deformation and stiffness of the mechanism: firstly we identified the existence of the deformation of the subchain, in terms of the relationship between the effective screw and deformation screw; then we took the deformation as an infinitesimal motion of the mechanism, and the stiffness matrix corresponding to the deformation can be deduced. Finally the global stiffness matrix of the whole mechanism is modeled by assembling different stiffness characters based on the presented methodology.

Abstract: In this paper a novel constraint calibration technique for Stewart platform based Parallel Kinematics Machine(PKM) is presented. A commercial trigger probe and a developed double-ball bar gauge are employed to aid the calibration. In the measuring process the characterized errors can be obtained by comparing the nominal characterized size calculated by the function using the measuring data with the real size of the double-ball gauge. An optimization approach is used to calculate the PKM structural errors, and these errors can be finally compensated into the control model. The error transferring matrix with regard to the structural error of PKM can be formulated. The calibration efficiency can be improved by the automatic calibration operation with the doubleball bar gauge. The developed calibration system has been applied in the industry where the PKM is used for machining the turbine vane, and the machining quality can meet the requirements of the specifications. The presented calibration scheme is generic to be applied for the wide range of PKMs.