Design and Simulation of Three-Degree-of-Freedom Wrist Structure of Picking Manipulator

Abstract

In order to solve the problem of poor flexibility of existing picking manipulators, a picking manipulator with a wrist joint has been designed, the wrist is capable of rotating 45° forward and backward around the x and y axes. Firstly, ANSYS was used to simulate the performance of different hoses under different conditions, and finally a 4*6 mm PVC hose was selected to replace the internal cardan joint as the transmission component. Secondly, the wrist structure was optimised using genetic algorithm to reduce the tendon rope variation differences to 0.31 mm and 0.24 mm. Finally, the results of orchard picking experiments indicate that the end-effector rotation of 720° can ensure that the fruit stalks can be unscrewed, the time required to complete the picking is 1.6 s, and the overall picking success rate was 100%. After 9 days of placing the harvested fruit, both the flesh and skin are intact, indicating that the manipulators can complete the non-destructive picking operation.