Novel Serial Elastic Actuator Elastic module without friction hysteresis
Martin Mallwitz, Christian Oekermann
series DFKI Documents, volume 15-02, Jun/2015. DFKI GmbH.
A serial elastic actuator (SEA) includes a physical compliance. Thereby the actuator provides the following
characteristics: sensible for external mechanical impacts, decoupling loads from the motor side, low-pass filter
behavior for loads and it stores energy. This characteristics privilege the actuator for applications with a
direct human-robot contact like industrial, rehabilitation or teleoperation scenarios and for walking robots.
The talk gives an overview of common applications and designs. It gives a more detailed view on SEAdevelopment
at the DFKI project ’Capio’. Generally the implementation of a compliance cause hysteresis
problems by friction or material characteristics. Depending of the positioning of elasticity it complicates
the design development and increases the actuator size. To solve these problems a customized torsional disc
spring is implemented in a serial elastic actuator module. The iterative spring design workflow from the CAD
model to the large displacement FEM simulation is described. The DFKI design of a serial elastic module
for a 5 Nm actuator is shown beside other research designs.