For the step-down test, MABEL is put in motion, walking around the central tower on an initially flat floor. MABEL then walks up a stair-stepped ramp, takes at least one step on a flat platform, and then steps off the platform. The height of the platform is increased each lap. In her first attempt at walking over rough ground, in April 2010, MABEL appeared to have a terrible “accident,” severing her shin in two. Analysis of the experimental data showed how the disturbance at step-down caused the torso to pitch forward. The feedback system overreacted when correcting the torso angle, causing a second, rapid, forward-pitching motion of the torso. Because the angle of the swing leg is controlled relative to the torso, the swing leg rotates forward rapidly as well and impacts the ground with sufficient force to break the leg.
In this experiment, a refined control algorithm is being tested. Check out the results.
Duration : 0:1:42