一般三支链并联机构正解算法

针对含复合铰链的3RPS并联机构在制造装配中实际结构参数不等于名义结构参数的问题，设计了一种考虑全部结构参数的一般三支链并联正解算法.一般三支链并联机构是3条支链共同支撑1个平台，每个支链结构均为一般5自由度串联机器人，其中只有一个运动副是主动副驱动的三支链并联机构.算法基于对偶四元数和DH方法表达支链方程，该算法考虑了一般三支链并联机构总共78项几何参数.可用于一般三支链并联机构的精度分析、精度综合、精度补偿和精确的运动仿真.算法经过反复计算验证，具有准确、稳定、速度快的特点，并且将3RPS，3_5R，3_RPUR，3_RPRRR等构型统一在一个数学模型中.

General forward kinematic algorism for three-chain parallel manipulator

To solve the problem that actual geometric parameters are not equal to nominal ones in parallel manipulator, a general forward kinematic algorism, containing all of the geometric parameters, was proposed. The general 3RPS parallel manipulator, with compound spherical joints, was taken as an example. The manipulator consists of a base platform, a mobile platform and three chains, and every chain is a 5-DOF serial manipulator with only 1-DOF being active. The algorism is based on dual quaternion and DH method and contains a total of 78 geometric parameters, and hence it is able to be used for accuracy analysis, accuracy synthesis, accuracy calibration and accurate kinematic simulation of parallel manipulator. Finally, the precise, stability and rapidness of the algorism were verified through iterative calculation. The forward kinematic algorism of 3RPS, 3_5R, 3_RPUR, 3_RPRRR,and so on can be expressed in a same form on the basis of the proposed algorism.