奇异是并联机器人的固有性质,对机器人的工作性能有着种种影响,因此对于确定的机构,找出它的所有奇异位形具有重要的意义。从运动学角度分析,奇异位形有三类形式,每种形式都具有不同的物理意义。基于以上原因,研究一种新型6自由度3支链并联机器人3-U^rPS的奇异位形,其中U^r为复合胡克铰,即2自由度球面并联机构,P为移动副,S为球副。根据机构自身的几何特点,非常方便地得出反解的唯一解析形式。对机构的反解方程进行求导,得出有规律的速度雅可比矩阵,然后通过求解雅可比矩阵的行列式,使奇异位形的解析形式很容易得出。讨论该并联机器人的第1类和第2类奇异位形,并得出3种特殊位置的奇异位形。奇异位形的分析对该并联机器人的轨迹规划和控制具有重要的意义。
Since singularity is the inherent character of parallel manipulator and has various effects on manipulator's working performance, for certain mechanism, it has great significance to find out all of its singularities. From the view of kinematics, there exist three different types of singularities, each having a different physical interpretation. The singularity loci of a new 6-DOF parallel manipulator with 3 limbs 3-U^rPS are studied, where U^r is compound universal joint, i.e. a 2-DOF spherical parallel mechanism, P is prismatic joint and S is spherical joint. It is very expedient to obtain the unique inverse solution in analytical form by the mechanism's geometry character. Differentiating the inverse functions with respect to time can derive the regular speed Jacobian matrices. Singularities' analytical form can be achieved easily through solving the determinant of the matrices. The singularities of type I and type II of the parallel manipulator are discussed and 3 cases special singularities are obtained. The analysis of the singular configurations provided here has great significance for manipulator trajectory planning and control.