Operation of a Two-Motor Robot Wrist to Achieve Three-Dimensional Manoeuvres with Minimum Total Rotation

Abstract

By use of a friction drive, two motors can be used alternately to reproduce a three-degree-of-freedom wrist manoeuvre. The algorithms required to achieve this are developed. In particular the efficiency of the resolution of the desired rotation is defined and simple approximations are derived for optimum operation, that is for which the total rotation required by the two motors for a given manoeuvre is minimized. Results are presented of optimum resolution for a wide range of manoeuvres. The time for calculation is also studied. Resolution time is insignificant on a mainframe computer, but for a 286 PC the approximate analysis would have to be used unless the manoeuvres were preprogrammed or a rapid response was not needed, as in a rehabilitation application.