一种基于指数积公式的空间机械臂自标定方法

为了克服发射过程和在轨极端温度环境对空间机械臂末端位姿精度的影响，提出了一种基于指数积（POE）公式的空间机械臂运动学在轨自标定方法。该方法使用空间机械臂末端双目空间相机和棋盘式标定板测量空间机械臂末端位姿实际值。根据关节旋量理论值和实际值之间的伴随变换关系建立了空间机械臂实际运动学模型，对运动学模型取微分建立了线性化的运动学误差模型，给出了基于最小二乘法的运动学标定模型。进行了7自由度空间机械臂运动学自标定仿真，仿真结果表明运动学标定过程能快速收敛到稳定值，标定后空间机械臂末端位姿精度有明显提高。 

A self-calibration method for space manipulators based on POE formula

To overcome the influence of launching process and on-orbit extreme temperature environment on the tool pose accuracy of a space manipulator, a space manipulator kinematics on-orbit self-calibration method based on product of exponentials (POE) formula was presented. Using the binocular space camera fixed on the end-effector and a checkerboard calibration plate, the actual tool pose of the space manipulator was measured. According to the adjoint transformation between the theoretical value and actual value of joint twists, the actual kinematics model of the space manipulator was established. The linearized kinematics error model of the space manipulator was obtained by differentiating the kinematics model. A least-squares kinematics calibration model for the space manipulator was given. Kinematics self-calibration simulation of a seven-degree-of-freedom space manipulator was carried out. The simulation results show that the kinematics calibration process can converge to a stable value quickly and there is a significant improvement on the tool pose accuracy of the space manipulator after kinematics calibration.