Two configurations of series elastic actuators for linearly actuated humanoid robots with large range of motion

We have developed two different configurations of series elastic actuators to be used in the lower body of THOR, a full scale humanoid developed for the DARPA Robotics Challenge. Both designs utilize a ball screw transmission but use different output mechanisms. The THOR-Linear actuator uses a simple lever output while the THOR-Hoekens actuator uses a novel inversion of a Hoekens Linkage. The simpler design of the THOR-Linear actuator makes it well suited for parallel actuation applications while the THOR-Hoekens actuator features a larger range of motion and nearly constant mechanical advantage. In this video, we show early tests of the two actuator designs used in the THOR lower body. The video shows the two actuator designs, their range of motion on THOR, and a series of performance tests.