The Human Centered Robotics Laboratory at UT Austin and Meka Robotics, present Hume, a bipedal robot for rough terrain locomotion. Hume has been designed to achieve the skill of Human Centered Hyper-Agility (HCHA). In particular the extrema of HCHA includes free-running-like capabilities on near-vertical surfaces. HCHA is a very important capability because of its direct impact in the design of human assistive devices for all terrains and the design of next generation semi-autonomous bipedal robot. To design Hume, we conducted computational simulations of rough terrain locomotion, compared them with human subjects moving nimbly in the same terrains, designed a high performance modular Series Elastic Actuator (SEA), and built a 6 Degree of Freedom, 15 Kg biped, that can achieve 10 rad/s of angular speeds and 100 Nm of joint torques. The robot is designed for interacting with human scale environments at human like speeds. To facilitate this capability, each actuator utilizes series elastic elements for high bandwidth force sensing and rugged impact tolerance. To maintain low leg mass and allow for quick maneuvers, the actuators are located as high and near the center of mass as possible.
Packed into the center of the torso are the leg abduction/adduction actuators while the hip ﬂexion/extension actuators ride just above the hip's center of rotation. This conﬁguration keeps the knee ﬂexion/extension actuator as the only mechanism located on the leg and thus minimizes swing inertia and provides for an overall lighter leg. Each joint of the biped is driven by a modular series elastic actuator (SEA). The design utilizes a ball screw as the major transmission component providing an efﬁcient high gear reduction while maintaining a low rotational inertia.
The ball screw drives a set of stiff springs that decouple impacts and provide force sensing. This whole spring assembly rides along on special linear bushings that are able to auto compensate for any misalignment thereby reducing friction. For the ﬂexion/extension joints, the SEA output is then attached to cables that drive the joint while the abduction/adduction actuators use push/pull rods to maneuver the leg.