Transmission-based electrical actuators: a concept for improving robot manipulator performance

This paper explores a new approach for extending the operating range of electrical servoactuators in applications such as high payload robotics and remote handling systems where, at present, only hydraulic systems are used. The fundamental idea is to incorporate a multi-speed transmission to “spread” a servomotor´s torque-speed characteristics across a wider output speed range. This has the effect of allowing smaller high power motors to also deliver high torque at low speeds. Incorporating a multi-speed transmission allows motor size to be reduced while increasing the overall actuator power density in the process. The hypothesis of this research was that this power density increase would be sufficient to allow a greater range of electrically-actuated robot manipulators to be designed with distributed actuators such that the cost and complexity of centralized actuators with power transmissions could be avoided. An existing articulated manipulator design is used as a baseline to evaluate potential benefits of this concept for robotics. Among these are increased performance, dramatic reductions in manipulator complexity and reduced manufacturing and implementation costs