Authors

Abstract

To address the requirements for automation and intelligence of agricultural robots, this paper develops a 14-degree-of-freedom dynamic model for wheeled agricultural robots. The model aims to provide a dynamic modeling foundation under the framework of modern control theory for the automation and intelligence of wheeled agricultural robots. It incorporates the Ackermann steering mechanism, MacPherson independent suspension system, tire model, and deformable soil model based on Bekker's formula. The vertical tire pressure is calculated using the deformable soil model via Bekker's formula, while tire forces are predicted by combining the tire slip angle and slip ratio with the Magic Formula Tire Model. By analyzing the force transmission effect of the suspension system, integrating the center-of-mass coupling effect analysis and the robot body model equations, the precise prediction of the attitude and motion trajectory of the wheeled agricultural robot is achieved. A co-simulation experiment using MATLAB and CarSim under the double lane change (DLC) condition is designed for validation. Experimental results demonstrate that the proposed model exhibits high consistency with the CarSim simulation results. The mean absolute errors (MAE) are 0.327° for steering wheel angle, 0.677°/s for yaw rate, 0.691° for body roll angle, and 0.944 m/s² for lateral acceleration. All errors are less than 1.5, meeting the requirements of dynamic simulation. This model can effectively predict the body attitude of wheeled agricultural robots and lay a foundation for the subsequent development of optimal control algorithms for agricultural robots.

Abstract in Chinese

针对农业机器人自动化与智能化的需求，本文构建了一套十四自由度轮式农业机器人动力学模型，旨在为轮式农业机器人的自动化与智能化提供现代控制学理论框架下的动力学模型基础。该模型涵盖了阿克曼转向机构、麦弗逊独立悬架系统、轮胎模型以及Bekker公式的可变形土壤模型等。通过Bekker公式的可变形土壤模型计算轮胎正压力，将轮胎侧边角和滑移率结合魔术公式轮胎模型（Magic Formula Tire Model）预测轮胎力，分析悬架系统对力的传递效应，结合重心耦合效应分析及机器人身体模型公式，实现了对轮式农业机器人姿态及运动轨迹的精准预测。设计双移线（DLC）工况下 MATLAB 与 CarSim 联合仿真实验进行验证，实验结果表明：该模型与 CarSim 仿真结果一致性较高，转向盘转角平均绝对误差（MAE）为 0.327°、横摆角速度为 0.677°/s、车身侧倾角为 0.691°、侧向加速度为 0.944 m/s²，所有误差均小于 1.5，满足动力学仿真需求。该模型可有效预测轮式农业机器人机身姿态，为后续农业机器人最优控制算法开发奠定基础。