西瓜采摘末端执行器夹持力精确控制  

Precise control of clamping force for watermelon picking end-effector

作　　者：胡志勇[1] 张学炜[1] 张伟 王琳[1] 

机构地区：[1]内蒙古工业大学机械学院,呼和浩特010051 [2]秦皇岛港股份有限公司,秦皇岛066002

出　　处：《农业工程学报》2014年第17期43-49,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：内蒙古自治区科技重大专项(ZD 20120636)

摘　　要：为实现西瓜的机械化采摘,该文提出了采用液压驱动型末端执行器采摘大型果实的思路。在抓取西瓜时,为避免末端执行器夹持力不稳定引起的果实损伤,需对夹持力进行精确控制,该文建立了末端执行器负载模拟平台和AMESim&Simulink联合仿真模型,模拟西瓜采摘夹持力的加载情况。针对执行器夹持力加载过程中位置控制系统对力控制系统产生干扰,影响夹持力精确加载的问题,该文基于速度同步控制原理,设计了简化的加载误差补偿环节,开展了加载误差补偿理论、仿真及试验研究。结果表明,速度同步控制方法能够有效地减小加载误差,提高末端执行器负载模拟精度。该研究可为末端执行器输出力的精确控制和抓取控制策略提供参考。Certain agricultural work requires a very stable robot end-effector to reduce vibration and damage to products. However, the structures of conventional articulated robots tend to be too weak to manipulate heavy objects, such as the watermelon. To achieve mechanized harvesting of the watermelon, we compared the characteristics of different end-effectors with the motor, pneumatic and hydraulic drives. By contrast, the hydraulic drive has many advantages, such as high power-weight ratio, compact structure and convenient layout. Therefore, the end-effector with hydraulic drive is more suitable for heavy fruit harvesting such as the watermelon. The hydraulic drive system based on force perception can output appropriate clamping force according to actual situation. When picking robot crawls and picks, it needs to avoid the damage to fruits and vegetables caused by unstable clamping force and to achieve the precise control of the clamping force for picking robot end-effector. Therefore, how to improve output force’s control precision of the valve control cylinder and reduce interference are key to improve the picking performance. Two identical small valve control cylinders were used to establish a load simulation test platform for simulating the loading condition of the clamping force in picking watermelons. There existed the question that position control system interfered the force system on load simulation test platform, which situation would affect the loading accuracy of the end-effector and result in the loading error;and hence in order to reduce the loading error, the control compensation method, which could produce a compensation effect by increasing the compensation algorithm link in the control program, was adopted in this paper. Through this method the loading error was effectively suppressed. Based on the load simulation test platform, the researches of the theory, simulation and experiment on the inhibition of the loading error were carried out. The mathematical relationship between position disturbance a

关 键 词：液压驱动 末端执行器 农业机械 西瓜采摘 负载模拟 加载误差补偿 夹持力 精确控制 

分 类 号：TP241[自动化与计算机技术—检测技术与自动化装置] S225[自动化与计算机技术—控制科学与工程]