基于虚功原理的Stewart机构逆动力学模型修正

Modification of the Inverse Dynamics Model of Stewart Robot by the Principle of Virtual Work

针对Stewart机构动力学模型传统推导中没有考虑分支角速度及角加速度轴向分量的问题,采用虚功原理对Stewart机构的动力学模型进行修正,加入轴向分量的影响,并与未考虑轴向分量时的模型进行了比较和误差分析。从仿真结果可以看出,当机构低速运动或者分支轴向惯量较小时,误差较小,可以近似忽略,这也是传统建模方法在大多数情况都能够适用的原因,但在机构高速运动以及分支轴向惯量较大时,应对传统模型进行修正以满足现今对机构运动高速性和定位精确性的更高要求。

Aiming at the problem that the axial angular velocity and acceleration of branches were not considered in traditional deducing Stewart mechanism dynamic models, the inverse dynamics model of Stewart manipulators was modified by calculating axial vectors based on the principle of virtual work. Comparison and errors analysis were devel- oped between modified and non-modified models. Simulation results show that when platform moves in a low velocity and branches have small axial inertia, the errors were small and can be neglected, which is a main reason why tradi- tional models are appropriate in most cases. However, when platform moves in a high velocity or branches have large axial inertia, models should be modified to satisfy the higher demands for moving velocity and positioning accuracy of manipulators.