Axiomatic Design of Hexapod-based Machine Tool Structures

Compared to the conventional serial structures of machine tools, hexapod-based structures are attracting increased attention because of their high rigidity and accuracy, less sliding surfaces, and light weight. There is no broadly accepted methodology by which one can determine the optimal structures of hexapodic parallel kinematic machines. This paper presents a systematic approach to design hexapod-based machine tools using axiomatic design. In the proposed formulation a set of function requirements (FRs) and a set of design parameters (DPs) are developed to study the coupling in the design. Modified FRs and DPs are suggested to reduce the coupling and thereby to design “good” hexapod based machine tools. Particular interests are given to those FRs-DPs mappings which are helpful in achieving an appropriate support for an arbitrary system of force and torque, as well as in getting a well-shaped workspace (i.e., maximizing the effective travels in all linear and angular directions).