Dynamics evaluation of parallel manipulators considering gravity and driving force uniformity

Abstract

Dynamics evaluation is one of the core research contents of robotics, especially for the parallel manipulators, which are usually working with high acceleration. The general dynamics evaluation methods mainly deal with the acceleration of end-effector and magnitude of driving force based on the general inertia/mass matrix, and ignore the gravity. However, with the change of the placement mode of a parallel manipulator, the gravity would have a great effect on the dynamics of a heavy parallel manipulator. On the other hand, there still some other properties should be evaluated, such as the acceleration sensitivity of each driving shaft caused by gravity, the driving force uniformity when driving force achieves its maximum value. For these reasons, this paper investigates a dynamics evaluation method considering gravity and driving force uniformity. First, the limitations of general evaluation methods are described; next, the proposed dynamics evaluation method is given, including acceleration sensitivity analysis and the driving force uniformity; finally, by taking a typical horizontal parallel tool head as an example of study, a complete dynamics evaluation work is performed by using the proposed method.