基于自运动的7-DOF机械臂逆运动学研究

针对一种7自由度典型机械臂构型的逆运动学问题，根据机构特点和自运动性质提出一种解析算法。首先对该冗余机械臂的自运动性质进行分析，其为平面四杆运动。采用冗余角对自运动进行描述，并分析机械臂末端位置和杆长对自运动的运动形式和冗余角变化范围的影响。然后基于自运动特性，将冗余角作为一个约束条件，结合位姿分离法，求出该机械臂的逆运动学解析算法。最后通过数值算例进行验证。该方法针对某一特定位姿求出所有的理论逆解。相对于传统的数值解法，该方法不存在理论误差，相邻位姿点相互独立，不存在误差积累。

Inverse Kinematics Algorithm of 7-DOF Manipulator Base on Self-motion

Aiming at the inverse kinematics problem of a typical manipulator with 7 degrees of freedom (DOF), an analytical algorithm is proposed based on characteristics of the mechanism and property of the self-motion. Firstly, the self-motion of the redundant manipulator is analyzed. It is a planar four-bar motion. The self-motion is described by the redundant angle and the influence of the location of the end-effector of the robotic manipulator and the length of the rod on the form of the self-motion is analyzed. Then based on the characteristics of the self-motion, the inverse kinematic analysis algorithm of the manipulator is obtained by separating the position and posture of end-effector and taking the redundant angle as a constraint. Finally, the numerical examples are given to prove the correctness of the algorithm of inverse kinematics. In theory, all solutions can be obtained by the method if the position and orientation of the robotics manipulator are given. Compared with the traditional numerical method, this method does not produce theoretical error and accumulation error. The position and posture point are independent of each other.