From Series Elastic Actuation to Series-Parallel Elastic Actuation

Actuators are key components for moving and con-
trolling a mechanism or system. However, the torque
to weight ratio and the energy efficiency of the current
state of the art actuators is much lower than in human
muscles. As a consequence, among others, manipula-
tors for human robot interaction in industry or service
applications have a low payload to weight ratio and a
low energy efficiency. Therefore, we developed a novel
actuation concept which we name Series-Parallel Elas-
tic Actuation (SPEA). The concept enables variable
recruitment and locking of multiple springs in par-
allel. After a problem analysis, the Series-Parallel
Elastic Actuator schematic will be introduced. Next,
a first prototype with the first results is discussed.
The experimental results endorse the practicability
of the SPEA concept and the modeled trend of a
lowered motor torque and increased energy efficiency.
A second prototype which is recently designed will be
introduced as well.