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A novel 6-DOF PSS parallel manipulator

English Abstract

In this thesis, a novel 6 degrees of freedom (DOF) parallel manipulator is investigated with a general method. This manipulator is constructed by the following components: a fixed base, three triangle trusses, six limbs, six sliders and a moving platform. Prismatic joints and spherical joints are used to connect the major components. The main advantages of this parallel manipulator are that all of the actuators can be mounted on the triangle trusses which are telescoped to fixed base. This method on one hand reduces the inertia of the moving platform and on the other hand, improves the positioning accuracy. Closed-form solutions for the inverse kinematic problems are presented, and based on the analysis results, the forward kinematic problems are also conducted with the Newton-Raphson method. By using a numerical technique, the solutions of the forward kinematic problems can be reduced to an unique real one. Some case studies are simulated by using the MATLAB software, in which the structural models of the manipulator are drawn with the dimentional parameters. Since the actuators are mounted on the triangle trusses, the angle of the actuators layout is adjustable. The manipulator workspace volume with a constant orientation is analyzed in different actuators layout. Using the results, we can find the relationship between the reachable workspace volume and the angle of actuators layout, and the layout angle with respect to the largest volume is found. Another characteristic of this manipulator called kinematic singularity is investigated based on the kinematic analysis. Some special positions of the singularity are found, which is essential to avoid such positions in real application. The principle of virtual work is adopted to analyze the manipulator dynamics, with a new method to construct the link Jacobian matrix. This method can also be used to analyze other closed-loop mechanical structures. The results are obtained by the MATLAB software and two simulations for the dynamic problems are proposed with two given trajectories. This model is useful for the single-input and single-output type control strategy. A basic control prototype is established with a 6-axis Motion Controller, a DC brushless servo motor and a corresponding motor driver. By using the Visual C++ (VC++) 6.0 software, we develop an interface that is convenient for the user to control the motor. The research presented in this thesis designs this parallel manipulator as a viable robotic device for the 6 DOF manipulation. This manipulator offers the advantages including both the ones of traditional parallel manipulators and the others such as the adjustable angle of the actuators layout on the fixed base, which can make the manipulator have wider application field.

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Xu, Wei Yuan,


Faculty of Science and Technology


Department of Electromechanical Engineering





Machinery, Kinematics of

Robotics -- Mathematical models


Li, Yang Min

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