| This thesis extends the theory of passive dynamic bipedal robots to the case of bipedal robots which walk by means of simple forms of actuation. Beginning with the study of the simplest possible mechanisms which could be described as actuated walking robots, we build up to more advanced walking machines, developing the tools along the way which are required to describe and control the possible gait behavior of a super-articulated, torso-driven, biped robot.; We are concerned with the actuation of the forward motion of the biped. Its motion is assumed to be restricted to the sagittal plane such that it can not fall over sideways. A novel design for a torso-driven biped robot is proposed which involves the use of just a single motor to input energy into the walking motion. A light-weight, active clutch mechanism selects which leg the torso reacts against. The other joints in the model are unactuated to reduce energy consumption and weight. The actuation of the controlled joint is planned such that the motion of the uncontrolled degrees of freedom sustain the walking behavior.; Specific contributions of this research include the study of the dynamics of super-articulated, torso-driven biped robot models via numerical simulation. The use of a homotopy method yielded a design parameter region which gives rise to the chaotic gait behavior characteristic of passive-dynamic bipeds. A control strategy is devised which stabilizes the equilibrium walking behavior of the torso-driven biped. This control strategy is used in conjunction with an actuation scheme to delay a saddle-node bifurcation which limits the basic performance of the system.; The walking mechanisms which are the focus of the thesis are part of a much larger class of super-articulated mechanical systems. In addition to the walking mechanisms, the thesis considers the problem of controlling a hanging kinematic chain by means of forced rotation about the vertical axis. It is shown analytically that, in the limit as the number of chain links goes to infinity, the speeds at which the vertical configuration of the chain loses stability approach those of a continuous, heavy string. |
