Passive dynamic model for walking down stairs

This paper presents a passive dynamic walking model that can walk down stairs. Knee-bend mechanism which is inspired from the pattern of human´s walking down stairs is designed in the walking model. The stance knee is designed to be bent between knee-strike and heel-strike. The bending time of the stance leg after knee-strike is adjusted to adapt to the stair height. By traversing the bending time of the stance leg, the stable walking motion with a certain stair height could be found. The force at the stance foot and the eigenvalues of the Jacobian are analyzed to verify the walking motion. The results show that the periodic walking motion is stable when the stair height is less than 0.11. Furthermore, the features of the walking motion with different stair height are discussed.