Stiffness analysis of hexaslide machine tools

Authors: Rao, A. B. Koteswara; Saha, S.K.; Rao, P.V.M.

Source: Advanced Robotics, Volume 19, Number 6, 2005 , pp. 671-693(23)

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Abstract:

This paper presents stiffness analysis of hexaslides, a class of parallel manipulators with six constant length legs, the base joints of which move along six distinct rail-axes. In the design of hexaslides for machine tool applications, stiffness as well as its variation within the workspace is important. The stiffness of any parallel kinematic machine and, thus, the accuracy depends on the pose of the tool platform. A stiffness model of a generic hexaslide is developed here considering the flexibilities in both the actuator and the legs of the hexaslide. The methodology adopted is based on the concept of the determination of stiffness of a group of serially connected linear springs. Based on the proposed model, the average stiffness and its variation along and about the Cartesian coordinate axes offered by three typical hexaslides, having the same foot print size, are estimated and compared. Other typical performance indices, i.e. workspace volume, workspace volume index (ratio of workspace volume to machine size), global dexterity index and global stiffness index, are also compared.

Keywords: STIFFNESS MODEL; HEXASLIDE MACHINE TOOLS; PERFORMANCE INDICES

Document Type: Research article

DOI: http://dx.doi.org/10.1163/1568553054255673

Publication date: 2005-07-01