Improved performance for robot manipulators via transmission re-design: the SPRINTA

Abstract

A new design philosophy for the transmission of robot manipulators is proposed and an example of a practical implementation is presented. The philosophy combines the advantages of conventional geared robots in terms of relocating the actuators away from the joints and the alternative direct-drive approach. The gimbal drive is an example of a non-linear transmission where there is negligible friction, no backlash or compliance and which provides a varying reduction ratio for gravity compensation and for some dynamic decoupling. The gimbal drive is implemented on the three degrees of freedom SPRINTA prototype. Static repeatability, as well as tracking error and dynamic repeatability for the industrial goalpost test are measured. The performance demonstrates the potential of such a type of robot.