A new type of 2R1T 3-P z P x S parallel mechanism is presented in this paper to satisfy the needs of configuration innovation for multi-axis machining platform. The limb configuration with a planar pantograph unit and the 3-P z P x S mechanism configuration are proposed and optimized. The analytical solutions of the forward and inverse position for the mechanism are derived, which are convenient to subsequent motion planning and control. After obtaining the workspace of the mechanism by the boundary search algorithm, the influence of key scale parameters on the rotation capacity of the mechanism in the whole workspace is investigated, and the reasonable ranges of the scale parameters required for large rotation capacity of the mechanism are confirmed. Furthermore, based on the Jacobian matrix condition number, the global performance indices of the angular velocity and the angular acceleration of 3-P z P x S parallel mechanism are defined, and ultimately the optimal ranges of the scale parameters are determined according to these two performance indices. The above results lay a theoretical foundation for the further development of high-efficiency hybrid NC machining center.
A new walking riveting robot based on 6-SPU parallel mechanism is designed to meet the needs of high precision and high efficiency machining for large, thin-walled and complex curved surface workpieces in aviation industry and automotive industry. After modeling and solving the position inverse solution of the robot, the riveting trajectory planning is carried out, and the correct positions and orientations of riveting holes are determined. For the workpiece with large thin-walled cylindrical surface, the riveting hole process of the robot is simulated by finite element analysis software, the maximum deformations in all orientations and the maximum equivalent stresses of the moving platform corresponding to riveting points are obtained. The above results provide the necessary theoretical basis for the structure optimization and performance analyses of the automatic riveting robot.
In this paper, a new type of 4PRR-P hybrid machining mechanism is presented. Based on the screw theory, the degree of freedom of the mechanism is verified. We solve the inverse position model of the the mechanism. The workspace of the mechanism is solved by the boundary search algorithm. The reasonable ranges of key scale parameters are obtained by investigating the influence of the parameters of the mechansm on its workspace. The above kinematic analyses and solving results can provide corresponding references for subsequent mechanism dynamics analysis and structural design.
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