三自由度苹果采摘机械臂动力学分析与轻量化设计

针对工业机械臂苹果采摘时运动规划复杂、自由度多、控制难等问题，本文研制了一款轻量化结构的三自由度苹果采摘机械臂。首先，针对苹果采摘工作要求完成了机械臂的结构设计与运动学分析。机械臂采用平行四边形结构，通过后置动力源减小整机转动惯量，且臂展长，工作空间大，运动时树枝干扰小，更适用于苹果采摘。其次，采用牛顿-欧拉方程建立动力学模型，完成机械臂苹果采摘仿真，通过动力学模型的理论数据，以减轻机械臂自身质量为优化目标，对臂及其关键部件应力及应变进行分析，计算不同轻量化方案下的应力、应变，从而选取最优的轻量化方案。通过对比轻量化前后机械臂仿真数据，骨棒型轻量化方案驱动力矩峰值分别降低21 N·m和15 N·m,均降低约20%,整机质量下降1.8 kg,降低32.1%,且轻量化后机械臂保持良好工作能力。根据优化结果，搭建了三自由度苹果采摘机械臂物理样机，通过试验得到大、小臂最大驱动力矩为92、63 N·m,基本符合仿真结果，验证了动力学模型的正确性。

Dynamic Analysis and Lightweight Design of 3-DOF Apple Picking Manipulator

Aiming at the problems of complex motion planning, multiple degrees of freedom and difficult control of industrial manipulator apple picking, human hand picking was simulated and a lightweight 3-DOF apple picking manipulator was developed. Firstly, the structural design and kinematic analysis of the manipulator were completed for the requirements of apple picking. The mechanical arm adopted a parallelogram structure, which reduced the rotational inertia of the whole machine through a rear power source, and had a long arm span, a large working space, and small branch interference during movement, which was more suitable for apple picking. Secondly, the Newton-Euler equation was used to establish the dynamic model, and the apple picking simulation of the manipulator was completed. Through the theoretical data of the dynamic model, the stress and strain of the arm and its key components were analyzed to reduce the mass of the manipulator itself. The stress and strain under different lightweight schemes were calculated to select the optimal lightweight scheme. By comparing the simulation data of the manipulator before and after lightweight, the peak driving torque of the bone rod lightweight scheme was reduced by 21N·m and 15N·m, respectively, both of which were reduced by about 20%. The weight of the whole machine was reduced by 1.8kg, which was reduced by 32.1%, and the lightweight manipulator maintained good working ability. According to the optimization results, a physical prototype of a 3-DOF apple picking manipulator was built. The maximum driving torques of the large and small arms were 92N·m and 63N·m through experiments, which basically conformed to the simulation results and verified the correctness of the dynamic model.