Kinetostatic modeling of the clearance-affected prismatic pair

The presence of clearance in the kinematic pairs of mechanisms has a strong influence on the mechanism performances. Where positioning tasks are concerned, clearance can be considered as one of the most relevant error sources, since it affects both accuracy and repeatability. The development of predictive models then becomes relevant, suitable for assessing in advance the influence of clearance and for correcting unacceptable effects. Several deterministic techniques assessing the accuracy of clearance-affected mechanisms have been proposed in the literature; these techniques require the development of kinetostatic models for clearance-affected pairs. This paper presents a modeling for clearance-affected prismatic pairs. Such a model determines the three-dimensional displacement between the pairing elements in the prismatic pair, and relates it to the load acting on the pair. Since the displacement depends strongly on the actual pair design, the model is described in detail for a particular pair geometry; in principle, however, this approach could be used for any geometry. The proposed model may be implemented in kinematic, kinetostatic, or dynamic analyses as well, with the purpose of computing the influence of clearance on the position and orientation error of any link of a mechanism. (C) 2005 Wiley Periodicals, Inc.