This paper is a continued investigation of a new concept for extending the payload-power range of electrical servoactuators. The fundamental idea is to combine small, high power motors with multispeed or continuously variable transmissions such that the effective torque-speed characteristics of the motor are "spread" across a wider output speed range. This has the effect of allowing smaller, high speed motors to also deliver high torque at low speeds. Use of a multispeed transmission allows motor size to be reduced while increasing overall actuator power density in the process. This power density increase can be used to allow a much greater range of electrically-actuated robots to be implemented with distributed actuators and can be used to drastically reduce overall manipulator complexity. This paper discusses the transmission-based actuator concept from a low-level control standpoint, and demonstrates that the "shifting action" of the transmission occurs in a way that is minimally obtrusive to the overall joint servo-control. It is shown that the gear-ratio only changes in situations where high acceleration is desired; the shifting of the transmission happens early in the move, occurs very rapidly, and settles to a final, fixed gear ratio very quickly. For the majority of the move, control objectives are essentially identical to those for available actuators. These results encourage further development of the concept for both robotics and automation applications.

Concerns a concept for extending the payload-power range of electrical servoactuators. The fundamental idea is to combine small, high power motors with multispeed transmissions such that the effective torque-speed characteristics of the motor are "spread" across a wider output speed range, This has the effect of allowing smaller motors to deliver high torque at low speeds. Use of a multispeed transmission allows motor size to be reduced while increasing overall actuator power density in the process. This increase can drastically reduce overall manipulator complexity and can be used to allow a greater range of electric robots to be implemented with distributed actuators. This paper discusses the transmission-based actuator concept from a low-level control standpoint, and demonstrates that the "shifting action" of the transmission occurs in a way that is minimally obtrusive to the overall joint servocontrol. It is shown that the gear-ratio only changes in situations where high acceleration is desired; the shifting of the transmission happens early in the move, occurs very rapidly, and settles to a fixed gear ratio very quickly. For the majority of the move, control objectives are essentially identical to those for available actuators. These results encourage further development of the concept for robot applications.

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.

Mobile robot work systems needed to do nuclear cleanup tasks exhibit complex structural and lost motion characteristics in their mechanisms which make them very difficult to automate. This research considers a macroscopic modeling technique which can be combined with sensor-guided manipulation schemes to achieve the needed in situ automation. A structural modeling method for flexible manipulators is used to optimize system control through sensor integration. The model detail is aimed at total system optimization, rather than maximum accuracy. The model reduces computational intensity of image processing, yet remains simple enough so as not to induce significant computational demands itself. Structural deflections are represented through homogeneous transforms inserted into the forward kinematic chain. The technique is being developed for full-scale evaluation at the Oak Ridge National Laboratory.