Parameter optimization and trajectory planning of 3P-Delta parallel mechanism

摘要

3P-Delta parallel mechanism is a spatial 3-DOF translational parallel mechanism which has the advantages of simple structure and easy to control. It can be used in sorting, handling, packaging and other automatic applications. In this paper, taking the 3P-Delta parallel mechanism as the research object, firstly the forward and the inverse kinematics of the mechanism are formulated by using closed-loop vector method. Through the Jacobian matrix of the mechanism, the velocity and acceleration expressions are derived. The singularity points of the mechanism are studied based on the Jacobian matrices and all singularity configurations of the mechanism are obtained. Secondly, based on the inverse kinematics of the mechanism, the workspace of the mechanism is solved by using the extreme limit boundary searching method and the stereoscopic graph of the workspace is plotted. Taking the Jacobian condition number of the mechanism as an index, the dexterity of the mechanism is analyzed, figuring out the Jacobian condition number of each point in the workspace. The global Jacobian condition number of the mechanism is obtained by MATLAB simulation. And taking the minimum global Jacobian condition number as the optimization objective, the structural parameters of the mechanism are optimized using the genetic algorithm to obtain the optimal dimension of the mechanism. Then, the virtual prototype model is established using ADAMS to simulate the mechanism and the velocity and acceleration curves of the mechanism are obtained. From the curve, it can be concluded that the mechanism has a good movement performance. Finally, the experimental prototype is constructed and the motion trajectory of the mechanism is planned by trapezoidal velocity curve. With the trajectory planning, the moving platform can pass through a given path with a good kinematics performance.