Path Planning of a Robotic Manipulator for Pruning Apple Trees Based on RRT-Connect Algorithm

Abstract

<b><sc>Abstract.</sc></b> Robotic pruning is a solution to address the issues of labor shortages and high associated costs of pruning apple tree. According to the pruning requirements of high-spindle-shaped apple trees in the dormant period, the autonomous and precise operation of the robot is realized in the presence of obstacles. The kinematic model of the apple tree pruning manipulator was established by the DH-parameter method. The manipulator model and the virtual tree canopy model were established in MATLAB. The workspace and collision-free path planning of a six-rotational (6R) degrees of freedom (DoF) robotic manipulator with an end-effector was explored. A two-way rapid exploration random tree (RRT-connect) algorithm was applied to establish a collision-free path to the target pruning point. The path smoothing and optimization algorithms were used to reduce the path length and optimize the path. The length of the generated path and the planning time were recorded. Simulation results showed that the robotic manipulator can avoid obstacles to reach the trim point. This research was expected to provide a certain basis for the path planning of robots applied to fruit tree pruning.