Modern Technologies, Quality and Restructuring (TMCR 2007), Kishinev/Moldawien, May 31st-June 3rd, 2007, Tagungsband S. 21-27
In serial machine tools the motion of the machine axes are directly translated to the tool center point (TCP), but in most PKM the motion is transformed to the TCP nonlinearly. In this paper, the tracking error transformation from joint space to the TCP and the resulting contour error are modeled. As in machining processes the contouring accuracy depends on motion precision, the generation of the contour error in circular trajectory in PKM is presented. In contrast to conventional kinematics the radial deviation in PKM machining is not constant. Radial error in PKM is a function of the programmed radius, transformed drive tracking error, velocity gain and velocity transformation. A formula for the radial deviation with PKM is given and calculated for a bipod and a tripod example mechanisms.