机构的位置分析是求解机构的输入与输出构件直接的位置关系。是机构运动分析最基本的任务,也是机构速度、加速度、受力分析、误差分析、工作空间分析、动力分析和机构综合等的基础。在实际应用中,解正解问题意味着决定机器人末端执行器当前实际的位姿。基于此,提出一种新型3支链6自由度并联机构3-U^rRS。采用球面2自由度五杆机构作为复合驱动装置。以机构上平台3个顶点之间的长度为约束条件,建立约束方程,研究该并联机构的正解的封闭解形式,得到一个16次方的一元多项式方程。以3-U^rRS自身的机构特点建立约束方程,得出反解的封闭解形式。最后对该正反解的研究结果进行数值验证,正解的计算结果与反解的计算结果十分吻合,仅有微小误差,这是由计算的累积误差引起的。
Position analysis of mechanism is to find the straightforward relations between the input and output component, which is elemental task for kinematics analysis and also the basic study of speed, acceleration, stress analysis, error analysis, workspace analysis, dynamic analysis and mechanism synthesis. In practice, solving the forward kinematics means to determine the current, real pose of the end-effectors of the mechanism. According to the reasons above, a new 6-DOF parallel mechanism with 3 limbs is presented. It uses 2-DOF spherical five-bar mechanism as the compound drive device. The length between the three vertexes of the platform is regarded as the restrict condition to obtain the constrained equations and thus the closed-form solution of the forward position problem of the parallel mechanism is studied. The resultant equation is a 16th polynomial. The inverse kinematics' closed-form solution can be obtained by solving the equations established by the mechanism's structure feature. At last, a numerical verification is put up to the results of the forward and inverse solutions. The forward solution is very coincident with the inverse solution but only minute error, which is caused by the accumulated computing error.