偏置式冗余空间机械臂逆运动学求解的参数化方法

针对肩、肘、腕均有偏置的空间站遥操作机械臂（SSRMS）型7DOF冗余机械臂，提出了逆运动学求解的关节角参数化及臂型角参数化两种方法。前者根据机械臂的臂型特征，推导以θ1、θ2、θ6、θ7中的一个作为给定参数时其他关节角的表达式，得出8种可能解；后者首先构造与SSRMS型机械臂相对应的零偏置球关节-旋转关节-球关节（SRS）机械臂，然后以臂型角为参数求解SRS机械臂的逆运动学，再根据SSRMS与SRS机械臂的关系，得到SSRMS的8组逆解。仿真算例校验了所提方法的有效性。

Parameterized Inverse Kinematics Resolution Method for a Redundant Space Manipulator with Link Offset

Aiming at the Space Station Remote Manipulator System （SSRMS） type 7DOF redundant manipulator, with link offsets at the shoulder, elbow, and wrist parts, two parameterized methods, joint angle parameterized and arm angle parameterized, are proposed to solve the inverse kinematic problem analytically. For the former, any joint variable of  θ 1,  θ 2,  θ 6 and  θ 7 can be taken as parameters to be defined; then analytical expressions of other joint angles are derived according to the configuration characteristics, and 8 possible solutions can be obtained. For the latter, a zero-offset Spherical-Revolution-Spherical (SRS) manipulator corresponding to the SSRMS-type manipulator is first constructed. A parameter called arm angle is used to describe the redundancy of the SRS manipulator, then its inverse kinematics equation is solved for a given arm angle. According to the relationship between the SRS and SSRMS manipulators, eight solutions of the SSRMS-type manipulator’s inverse kinematics are determined. The proposed methods are verified by a case study.