采用视觉伺服的月球样品容器夹持控制方法

A Gripping Control Method for Lunar Sample Container Using Visual Servoing

嫦娥五号探测器月面采样封装任务需利用采样机械臂及其末端执行机构夹持样品容器,为克服非结构化月面环境对机械臂控制造成的不可知影响,确保精确夹持样品容器,提出并设计了一种视觉伺服样品容器夹持的控制方法和系统。系统通过固定安装相机和“眼在手”相机协同获取机械臂末端执行机构以及样品容器特征,采用扩展卡尔曼滤波算法对机械臂末端执行机构位姿的控制参数进行估计,消除控制位姿的轨迹抖动,实现了对样品容器的精确夹持。最后,通过分析在轨月球样品容器被夹持过程的数据和图像,验证了该视觉伺服控制方法和系统设计正确有效。

The lunar surface sampling and encapsulation mission of Chang’e-5 probe requires the use of a sampling manipulator and its terminal actuator to grip the lunar surface soil sample container.In order to overcome the adverse effects of the unstructured lunar surface environment on manipulator control and to solve the control problem of precise gripping sample container,a gripping decision system of sample container based on visual servo is proposed and designed.The system adopts the fixed position camera and the“eye in hand”camera to obtain the characteristics of the actuator at the end of the manipulator and the sample container,and the extended Kalman filter(EKF)algorithm is used to estimate the control parameters of the manipulator terminal actuator’s position and attitude,so as to eliminate the trajectory jitter of the control,and realize the accurate clamping of the sample container.Finally,through analyzing the on-orbit data and images,the results show that the proposed visual servo control method is correct and effective.