机械臂初始构型对航天器姿态干扰力矩的影响研究

Research on Influence of Initial Configuration of Manipulator on Disturbance Torque of Spacecraft Attitude

针对机械臂在笛卡尔空间的轨迹规划,文章提出一种初始构型的最优化方法。首先,采用牛顿-欧拉法建立七自由度空间机械臂的逆动力学方程,从而得到机械臂的反作用力、力矩和机械臂的运动学参数之间的对应关系。其次,利用关节角参数法得到七自由度冗余机械臂的各种初始构型,并基于速度级逆运动学对机械臂进行不同初始构型下的轨迹规划。仿真表明:在不同的初始构型下对机械臂末端进行轨迹规划,机械臂在运动过程中对基座产生的反作用相差较大。因此,通过调整机械臂的初始构型,能大大减小其在运动过程中对航天器的干扰力矩。最后,给出算例验证了方法的有效性,按此方法可找到一种使航天器所受反作用力矩峰值最小的初始构型。

An optimization method for initial configuration is proposed to plan the trajectory of the manipulator in Cartesian space in this article.The Newton-Euler method is employed to model the inverse dynamics of seven degrees of freedom manipulator,so that the relationship between the reaction force,torque,and the kinematic parameters of the manipulator is obtained.The joint angle parameterized method is utilized to get various initial configurations of 7-DOF redundant manipulator.The trajectories of manipulator with different initial configurations are planned based on inverse kinematics of different initial configurations.The simulation results show that the base reaction caused by the manipulator is quite different when we plan path for the manipulator based on different initial configurations.Therefore,the disturbance torque of spacecraft attitude can be greatly reduced by adjusting the initial configurations of the manipulator.An illustrative example verifies the validity of the method.According to the method in this paper,the initial shape of the manipulator that minimizes the peak of the reaction moment on the spacecraft can be obtained.