Preliminary Experiments of Series Elastic Actuator Prototype utilizing Mechanical Resonance

This study proposes large force generation by a robotic manipulator by means of providing series elastic actuators exploiting mechanical resonance to it instead of powerful actuators. To this end, the authors designed and assembled a prototype of series elastic actuator that resonates at around 1.0 Hz on the basis of its model and identified parameters, and carried out preliminary experiments with it and a load. The prototype actuator consists of a geared DC motor with an encoder and an elastic element. The elastic element is made of two torsion springs so that it can generate torque in both directions. It was confirmed in the preliminary experiments that the prototype actuator resonated at around 0.7 Hz. In addition, in order to prove efficacy of mechanical resonance for large force generation, output torque of the prototype actuator with the elastic element and without it was estimated using their identified physical parameters and dynamics, and compared them. The estimation results showed that the prototype actuator exploiting mechanical resonance generated 2.24 times larger torque than the one without the elastic element.