Authors

Abstract

To solve the problem that the moving trajectory and operating trajectory are relatively independent and time-consuming when robots transfer agricultural products from harvesting fields to warehouses or transport vehicles, a type of agricultural materials handling robot was designed, the optimal trajectory planning method for the collaborative operating time of agricultural materials handling robots was proposed, and the time optimal trajectory under the collaborative operation of robot operating system and traveling system was acquired. Specifically, the kinematic model and dynamic model for the collaborative operation of robots were established to perform time optimal trajectory planning for materials handling robots, the Beta distribution was then applied to the Whale Optimization Algorithm (WOA) for population initialization, and a nonlinear convergence factor was introduced to prevent local optimum in the later stage of iterations. Finally, WOA was improved combining the variable neighborhood algorithm to enhance the diversity of the neighborhood structure, and this improved algorithm was applied to model solving. The results reveal that the proposed trajectory planning method can facilitate robots to obtain a smooth and time optical moving trajectory in collaborative operations of materials grabbing and discharging and obstacle avoidance. The displacement, speed, acceleration, and force/torque curves of each joint of the robots change gently, and the double-crawler traction can meet the requirements of the robots and rapidly stabilize and track the time optical trajectory.

Abstract in Chinese

为了解决机器人将农产品从收获场所转移到仓库或运输车辆存在的移动轨迹和作业轨迹相对独立且耗时长的问题，本文设计一种农业物料移运机器人，并提出一种农业物料移运机器人协同作业时间最优轨迹规划方法，获得机器人作业系统和行驶系统协同作业的时间最优轨迹。该方法建立机器人协同作业的运动学模型和动力学模型，对物料移运机器人开展时间最优轨迹规划，并将Beta分布应用于鲸鱼优化算法(Whale Optimization Algorithm，WOA)进行种群初始化，再引入非线性收敛因子改善迭代后期陷入局部最优的情况，最后结合变邻域算法改进了鲸鱼优化算法来增加邻域结构的多样性，并将此算法应用于该模型求解。结果表明，提出的轨迹规划方法可使机器人在抓放料协同作业和避障协同作业中取得平滑且时间最优的运动轨迹，机器人各关节的位移、速度、加速度、力/力矩曲线变化平缓，两履带牵引力满足机器人的要求且可快速稳定跟踪时间最优路径。