Denise; Sideways Stability

Abstract

One of the grand challenges in biped walking is to find the key to stability in three dimensions. In addition to the fore-aft motions (pitch), in 3D also sideways motions (lean) and rotations around the vertical axis (yaw) are possible. It is the interaction between all three of these that makes the problem of 3D stability so difficult. Consequently, most of the known solutions to this problem are successful because they reduce the interaction in one way or another:

• Ignore yaw by assuming sufficient yaw resistance in the foot contact [96, 127].

• Apply large moments of inertia against yaw [33, 32].

• Walk with short steps [160, 33, 150].

• Counteract yaw with a counter-rotating body [181] or with counter-swinging arms [36].

In this chapter, however, we aim not at a reduced interaction between the degrees of freedom, but conversely we show how a purposefully induced interaction between lean and yaw can actually improve the stability of the walking motion.