Force Analysis Method Of Some Parallel Robots Based On Screw Theory

The force analysis of parallel mechanism is a difficult problem of the mechanism theory. Nowadays, in most literature, only the active forces are studied in the force analysis process of the complicated mechanism especially the parallel mechanism; the constraint reactions of kinematic pair rarely were talked about. The study about the constraint reactions is of great importance to the mechanism theory and the engineering applications. The force analysis is very necessary to the designing of new mechanisms and to the using of the existing ones. The constraint reactions and the result of the force analysis are necessary to application in engineering.In this paper, using the new force analysis method based on screw theory proposed by Huang and the work done by Zhao, the forces of some different kinds of mechanisms are studied to proof and develop this method. The advantages of this method lie in that it can solve the active forces and the constraint reactions simultaneously, make the number of simultaneous equilibrium equations not more than six every time and widely used in the general parallel mechanisms. If only the active forces need to be solved, the influence coefficient method can also make the problem simple and applied to the general parallel mechanisms.These mechanism include the typical determinate spatial RSUR mechanism, which has only one degree of freedom and is considered as a parallel mechanism in the force analysis process; these mechanisms also include two indeterminate mechanisms, and in the process of the force analysis of the indeterminate mechanism, the connections between the model and the screw theory are studied, some new approaches are proposed.