Novel SPECTA Actuator to Improve Energy Recuperation and Efficiency

Abstract

The current state of the art in compliant actuation has already good performance, but this is still insufficient to provide a decent autonomy for the next generation of robots. In this paper, a next step is taken to improve the efficiency of actuators by tackling and enhancing the Series-Parallel Elastic Constant Torque Actuation (SPECTA) concept, which has previously been analyzed in simulations. In this work, the efficiency is increased further by decoupling the springs and their driving parts through the use of locking mechanisms, such that the motors are not always loaded and the springs can easily store energy from both input or output. Simulations have been performed to confirm this and they also showed that, in the SPECTA concept, it is always better to use high-speed motors instead of high-torque motors, even with non-efficient gearing. In this paper, the SPECTA concept is also validated experimentally with the use of a newly built test setup. In light of the obtained results, showing an increase in efficiency for almost all working points, it can be stated that SPECTA is a promising new actuation technology that allows for an increase in energy recuperation, efficiency, and autonomy.

Constant Torque Mechanisms: A Survey

“…The B-motor configuration, on the other hand, produces the highest torque of both types. This implies that this configuration is mostly used in applications requiring significant torque and energy (e.g., space applications [10][11][12]14] and robotics [3,5]). The torque of a constant torque spring in the B-motor configuration is given by…”

“…Performing this task can either be done using stiff actuators, i.e., when (a) motor(s) is directly coupled to the output, or by compliant actuators, i.e., when a compliant element or mechanism is placed between the motors and the output. The advantages of placing springs in the system is to decouple the inertia from the in-and output such that the transmission is protected from impacts coming from the output side [1] and to reduce the energy losses since a part of the energy can be delivered by the compliant element [2][3][4][5].…”