球形水果采摘机械手的高精度控制仿真

High-Precision Control Simulation of Spherical Fruit Picking Robot

为了提高球形水果采摘机械手的轨迹跟踪精度和稳态性能、减小球形水果采摘机械手在执行采摘任务过程中造成的水果破碎率,提出了基于LQ理论的球形水果采摘机械手控制方法,设计了具有3自由度的包括手爪、手腕和手臂3个关键部位的球形水果采摘机械手,并分析了各个部位具体功能.假设球形水果采摘机械手为刚性理想模型,设置了3个坐标系,成功实现了机械手在各个坐标系之间的矢量转化,通过计算机械手运动边界条件,建立了球形水果采摘机械手任意运动情况模型.以上述模型为研究对象,设计了模型离散线性控制系统,并计算了具有扰动补偿的离散LQ最优轨迹跟踪控制器最优性能指标,得到了系统最优轨迹跟踪控制器参数,实现了球形水果采摘机械手控制.仿真结果显示,所提方法设计的机械手控制器较好地补偿了系统扰动,能够准确、稳定地执行球形水果采摘任务,大大降低了球形水果采摘机械手在执行采摘任务过程中造成的水果破碎率.

In this article,a method to control the spherical fruit picking manipulator based on LQ theory was proposed. Firstly,we designed the spherical fruit picking manipulator with 3-DOF,including three key parts such as the claw,wrist and arm. Secondly,we analyzed the specific function of each part. Assuming that the spherical fruit picking manipulator was a rigid ideal model,we set three coordinate systems,so that vector transformation of manipulator between each coordinate system was successfully realized. By calculating the boundary condition of manipulator,we built the model of arbitrary motion of spherical fruit picking manipulator. Based on above model,we designed the discrete linear control system. Meanwhile,we calculated the optimal performance index of discrete LQ optimal trajectory tracking controller with disturbance compensation,so as to get the optimal trajectory tracking controller parameters. Finally,we achieved the control of spherical fruit picking manipulator. Simulation results show that the manipulator controller designed by the proposed method compensates the system disturbance. Meanwhile,it can accurately and stably perform the spherical fruit picking task. In this way,the fruit broken rate caused by the spherical fruit picking manipulator during the picking task can be greatly reduced.