面向农情信息采集的足式机器人水田行走机理研究

An effective way to mitigate the problem of soil compaction is adopting legged robots to collect field information instead of large agricultural equipment. However, the interaction mechanism between propulsion system of legged robot and rheological soil is still un-clear, and the design principles and optimization methods of robot legs are also missing or imperfect, which restrict the application of legged robots in paddy fields. In this project, mechanical properties of terra soil will be measured, and the basic interaction mechanism will be subsequently revealed. Applying the theory of multi-body dynamics analysis and methods of ANSYS explicit dynamics analysis and to study and establish the legged robot propulsion system simulation model, and control algorithms, and coming up with the optimal design scheme of the propulsion device through simulation and optimization. After performing large members of experiments on the soil-bin test-bed, multi-factor mathematical models of the motion performance indexes will be established. Applying kinds of research methods and means including virtual simulation, high-speed photography, multi-factor model prediction and experimental verification, the comprehensive optimization and design method on legged robot propulsion device are to be explored and established, and the optimal combination of soil parameters, structural parameters and motion parameters will be achieved finally. This study will provide theoretical basis and new methods for the research and development of farmland legged robots, accelerating the technological progress and industrial applications of farmland legged robots.

与大型农业设备相比，采用足式机器人进行农情信息采集可以缓解土壤机械压实问题，然而，足式机器人与具有复杂流变特性的水田土壤之间的相互作用机理不明晰，其腿部设计与优化缺乏理论依据，制约着足式机器人在水田中的应用。针对我国南方水田土壤，测定其力学特性，探索足式机器人推进机构与流变型土壤之间的相互作用机理；综合多体动力学理论和有限元分析方法，构建足式机器人水田行走仿真模型及控制算法，获取最优设计方案；多因素、多指标的系统开展运动特性试验，建立运动性能多因素数学模型；综合虚拟仿真、高速摄影、多因素模型预测与试验验证等方法和手段，实现机器人腿部结构形式、运动参数与各种土壤参数间的最佳组合。本研究可为足式农田机器人的研发提供理论基础和新方法，对推进足式农田机器人技术进步和产业化应用等均具有重要意义。

开展足式机器人腿部结构与流变型土壤间相互作用的动态仿真与试验研究，对于推进农田足式机器人技术进步和产业化应用等均具有重要意义。本项目通过研制一套足式机器人单腿土槽试验台系统及构建一套与实际环境相一致的单腿足-地作用虚拟仿真测试平台，分析系统能耗大小及运动特性，揭示足式机器人推进机构与流变型土壤间的相互作用机理，为农田足式机器人腿部设计及优化提供科学依据。通过研究，本项目取得以下研究成果：（1）优选与实际情况比较吻合的扩展D-P模型来构建水田土壤仿真模型，得到足部与土壤的作用机理模型。（2）利用ABAQUS有限元软件建立刚柔耦合的多体动力学及足－地接触仿真，揭示了水田土壤上典型步态及其参数对足式机器人能耗的影响，得到机械腿最优的步态和足端结构。分析表明足端形状对试验结果影响较为显著，选取椭圆型运动轨迹和柱形足端结构、优化腿部的入土过程将有利于降低能耗。(3)为了减小腿部转动惯量，提高机器人续航能力，设计了五连杆和双四杆机构的机器人腿部模型，对腿部运动学和动力学进行分析，建立关节电机峰值力矩、峰值角速度、单个步态周期内总能耗与连杆尺寸参数间的函数关系，构建面向机器人连杆尺寸参数的多目标优化模型，分别采用遗传算法和Gamultiobj算法实现机器人腿部最优设计。在保障腿部强度的基础上，利用有限元分析软件对腿部进行轻质化处理，减轻腿部质量，降低腿部转动惯量；利用仿生学机理增加弹性带设计，缓冲地面冲击，改善腿部受力情况。（4）研制了足式机器人水田行走土槽试验台1套及四足机器人样机多款。项目的研究成果为足式机器人水田行走的结构设计、控制参数选取提供了依据。