This thesis explores an observed method used by humans when pushing a large object of unknown mass. Body motion and reaction forces are analyzed for feet-apart pushing with varying stance length. It is found that, via articulation of the waist, a human will push their static zero-moment point (ZMP) as far forward as possible prior to pushing. Along with an extended back leg, this provides a larger support region in which the ZMP can move before stability is lost. Using this motion, the subject can produce a larger force than if the waist is constrained. Further, in this stance the subject is stable without object contact and can exert a range of forces by controlling mass distribution at the feet. For this increases in force exertion and stability, a linearized double inverted pendulum model with a feet-apart stance is proposed for use in the humanoid robot pushing of an unknown mass. Using the human pushing data and our humanoid, HUBO+, the advantage of this model and the added degree of freedom is shown against the commonly used single inverted pendulum model for humanoid robot pushing.M.S., Mechanical Engineering and Mechanics -- Drexel University, 201
