Method Of Structrual Parameters Optimatization And Trajectory Planning For Delta Robot Under Driving Constranits

Delta robot is a kind of lower-mobility parallel robot, with characteristics of high speed, high accuracy, high load capacity. It’s widely used for high speed pick-and-place operation. A research in support of the national “863” project “economical handling robot development and industrialized application research” is carried out. Aiming at a better performance of the robot without increasing the request of the driving part, this paper has optimized the structural parameters and planned the tragedy of the robot. Concrete research contents are as followsFirst of all, the mechanical structure design and the characteristics of Delta parallel robot are introduced. Both of the direct and inverse kinematic models are established. Based on the results, a representation of the workspace and the Jacobian matrix are obtained. And then the various singular configurations of the parallel robot are analyzed. What’s more, a novel approximation for improved rigid dynamic model based on Lagrangian multiplier method is established. Comparison the calculation results of the lumped mass physical model and the homogeneous bar physical model show that the lumped mass physical model can not only reduce the amount of calculation but also improve the accuracy of it.Secondly,A novel method for structural parameters optimization design of it is proposed, with the workspace served as its dimensional constraints, the kinematic accuracy and flexibility of mapping characteristics between the joint space and the operation space as its kinematical constraints, a coupling function formed by the maximum driving power of a single active joint and the occupation ratio of workspace is established as the optimization objectives, and the rod sizes of the robot together with the differences of the semi-diameters between the moving platform and fixed base are determined as the optimization parameters. A set of structure parameters which comprehensively include the occupation ratio of workspace, kinematic and dynamic performances are obtained via an instance, and the comparison between the parameters and the results of the optimization targeted for minimizing the maximum driving torque of a single active joint show that the performances of workspace, kinematic accuracy and flexibility are significantly improved as well as the dynamic characteristics, the driving power is obviously reduced.Then, I proposed a method for pick and place operation trajectory planning base on lame curve. A optimization is developed with the maximum acceleration of a single active joint as its optimization objective. The degree of the lame curve was served as its optimization parameters together with the length of the linear motion. Compared with the result of Interpolation trajectory, it can effectively reduce the residual vibration.After the optimization work, the robot prototype is built and the test systems are carried out. The experiments based on the structural parameters optimization method and trajectory planning methods are carried on. The results show that the optimized structure can keep a high performance in the condition of power reduce by half. Then the test of the trajectory is carried out, which include the kinematic performance test and the vibration characteristics test of the two trajectories. The effectiveness of structural parameter optimization and trajectory planning method are verified.