Papers by Keyword: Parallel Manipulator

Abstract: The modal analysis was carried out to investigate the proposed improved curvature based finite element method (ICFE) for parallel manipulator with flexible links. The flexible link was discretizatied with ICFE first, and with the proposed rigid-flexible coupling technique, the flexible displacement of the moving platform and passive links was obtained, then through Lagrange equation, the structural model was derived. At last, to investigate the accuracy and efficiency of the ICFE and rigid-flexible coupling technique, modal analysis of ICFE model with different nodes and comparison studies with CFE and the ABAQUS model was carried out.

Abstract: This paper concerns with the control system design for a teleoperated endoscopic surgical manipulator system that uses PHANTOM Omni haptic device as the master and a 4-DOF parallel manipulator (2-PUU_2-PUS) as the slave. PID control algorithm was used to achieve the trajectory tracking, but the error in each actuated joint reached 0.6 mm which is not satisfactory in surgical application. The design of a control algorithm for achieving high trajectory tracking is needed. Simulation on the virtual prototype of the 4-DOF parallel manipulator has been achieved by combining MATLAB/Simulink with ADAMS. Fuzzy logic controller is designed and tested using the interface between ADAMS and MATLAB/Simulink. Signal constraint block adjusted the controller parameters for each actuated prismatic joint to eliminate the overshoot in most of position responses. The simulation results illustrate that the fuzzy logic control algorithm can achieve high trajectory tracking. Also, they show that the fuzzy controller has reduced the error by approximately 50 percent.

Abstract: A geometric and kinematic study between two structures of robots was performed, respectively a mechanical anthropomorphic structure, with bars and gears, with four degree of freedom, (dof), redundant (4R), which can avoid obstacles and a parallel manipulator with translation on three axes (3T). This 3T structural solution allows rapid and precise movements, which are important characteristics for machine building industry. All these features make the parallel manipulator to be an attractive alternative to the serial ones for high precision operations in a limited workspace.

Abstract: A kinematic optimization method of parallel manipulators is presented in this paper. A desired workspace for a parallel manipulator is usually an essential requirement in a practical application. Additionally, a good kinematic performance and/or a relatively small physical size would be of great significance. A dexterity index is utilized to measure the kinematic performance of parallel manipulators. A method to define the physical size of a parallel manipulator is introduced. The cost function is then formulated as a linear combination of a dexterity index and a physical size measurement. The Optimization Tool Box of MATLAB is applied to solve the optimization problem. Finally, a general Stewart-Gough platform is taken as an example to specify the design methodology.

Abstract: In order to improve the response effectiveness, extend the workspace of parallel manipulator and make it more conveniently to be used in realistic tasks, this paper has introduced an improved mechanism based on the traditional 6-PUS, which applied the rails leaning outside and the linear motor as its driving system. This has optimized the initial parameters of the improved mechanism, and analyzed its workspace in the software Matlab using the method of cylindrical coordinate search. The result has a guiding significance in optimization of traditional parallel manipulators and the manufacturing of the new prototype.

Abstract: This paper studied the novel 3-PRRR manipulator, the non-singularity workspace was deduced, satisfying various constrains, containing the angle scales of driving pairs, the travelling limits of driven pairs and the singular position conditions. Stepwise refinement method was employed and acceleration approaching method were put forward to improve the performance evaluation solving speed.

Abstract: To meet the increasing demands on the control performance of parallel manipulator, servo control strategy for parallel manipulator was researched systematically. Combined 2-DOF control with Internal Model Control, the servo controller for parallel manipulator was optimized as smoothly and efficiently as possible. On the basis of the original current loop and speed loop, the position loop was redesigned to have both good position tracking characteristics and anti-disturbance capacity. The synchronous control strategy combined position signal and force signal was proposed. The actual experiments show that 2-DOF synchronous control has better stability and position tracking performance compared with the traditional PID control. The control performance of parallel manipulator is improved effectively.

Abstract: A geometric and kinematic study between two structures of robots was performed, respectively a mechanical anthropomorphic structure, with bars and gears, with four degree of freedom, (dof), redundant (4R), which can avoid obstacles and a parallel manipulator with translation on three axes (3T). This 3T structural solution allows rapid and precise movements, which are important characteristics for machine building industry. All these features make the parallel manipulator to be an attractive alternative to the serial ones for high precision operations in a limited workspace.

Abstract: The singular configurations of a type of redundantly actuated parallel manipulator are studied in view of manipulability. Considering the non-square characteristics of Jacobian matrix of redundant input parallel machine, Laplace Theorem and its correlative theorems in Matrices Theory are introduced to avoid the problem that there is no determinant for non-square matrix. Singularity configuration distribution characteristics of this redundant input parallel machine are also depicted for different surfaces and orientations. These results provide pivotal foundations for its valid workspace selection.

Abstract: The construction and kinematic computing of the manipulator of the parallel structure with flexible links are given in the papers [1, 2] («Cable crane» [3]). It is reasonable to use the construction of the manipulator of similar type suggested below under the conditions with the rugged relief of the terrain and expanded service area. The problem of the research of manipulators with flexible links lies in the feedback effect of the lading dynamics on the links dynamics. The non-linearity of the kinematic structure of the manipulator expects the emergence of the feedback effects on the links in the dynamics which can exclude one or several links out of the structure (due to the flexibility of the construction). This makes difficult to use the purely analytical method of problem solving for simulation. The obtaining of the dependences of free and forced oscillations in modes of acceleration, steady motion and deacceleration under the exertion of the perturbation influence on the fixing point in the form of the force, the magnitude and direction of which is known should be considered as the main task of the research for the reviewing system.