Mobile 6‐SPS Parallel Manipulators

Abstract

Abstract In this paper some special constructions of 6‐SPS parallel manipulators are presented whose platforms, with fixed actuators, are shaky in all possible positions and consequently mobile within their prospective workspace—a behavior which has been called “architectural mobility.” Constructions of such manipulators should be known to the designer of working platform mechanisms in order to avoid them beforehand in the design process. Although “closeness to a singularity position” can hardly be defined reliably, it certainly seems better to abstain even from platform constructions which geometrically resemble any one of the architecturally mobile platforms which we are going to describe. As we assume the points of attachments of the actuators (the S‐joints) in the basis as well as in the platform as located in planes, we can apply the method of synthesizing recently published in Advances in Robotic Kinematics (Kluwer, Netherlands, 2002); simultaneously we take the opportunity to reformulate a proposition made in that work which cannot be maintained in the generality stated there. Four examples of architecturally mobile 6‐SPS platforms are described: no special relation between the coordinates of the points of attachement in the two planes are assumed in the first example while in the following examples it is assumed that the S‐joints in their planes form specific polygons: triangles, quadrangles and trapezia. © 2003 Wiley Periodicals, Inc.