Both-side drive of a ball screw feed axis - verification of the theoretical assumptions

A parallel run of two drives connected in synchronous position control is mainly used in feed axes of gantry machine tools in order to compensate skewing of the gantry. Other reasons for using this concept include increasing rigidity, improving dynamics or achieving thermal symmetry. In most cases these applications use separate position measuring for each drive. Therefore both drives are equivalent in terms of regulation conditions. Due to the mainly used symmetrical design of the axis, the mechanical structure of drives and regulation schema connected to them are also identical. This paper aims to show the results of using two permanent magnet synchronous motors (PMSM) as two drives of the ball screw axis, which is typically and sufficiently controlled with only one drive. The following topics are discussed in this paper: changes in the mechanical structure and its dynamic behavior, effects of this concept on drive regulation and improvements in regulation parameters.