Novel control strategy for the plus SPEA: A redundant actuator with reconfigurable parallel elements

We developed a new actuator, the plus Series-Parallel Elastic Actuator (+ SPEA), which is a redundant actuator using brakes. This actuator can achieve additional objectives, other than performing a given task, such as minimum electrical energy consumption. In this paper, we developed a novel control strategy which consists of solving an optimal control problem. Solving this problem allows to use the redundancy of the actuator, as the brakes, in order to achieve lower electrical consumption. The results are then compared to the consumption of an equivalent non-redundant stiff actuator. The results highlight the capability of the actuator to reduce energy consumption in comparison with the latter actuator.