Force sensor implementation for enhanced responsiveness of SMART non-linear actuators

SMART non-linear actuators have been designed to improve the performance of biped robots and other mechatronic devices. However, the practical use of these actuators presents some difficulties, due to their intrinsically non-linear characteristic, in particular when it is necessary to realise advanced control schemes. To overcome this problem it is demonstrated how a force sensor implemented in one of the four-bar linkages of the mechanism provides an extra sensitivity and could be used to obtain an enhanced responsiveness. This approach resulted in two main advantages: on first place it enables the full testing of the theoretical SMART actuator properties, and, on second place, it will also facilitate the further implementation of complex control strategies. Experimental results are presented and used to verify the advantages of the proposed approach.