Underactuated approach for the control-based forward dynamic analysis of acquired gait motions

This paper presents a method to carry out the analysis of acquired gait motions through a control-based forward dynamic approach. Unlike some well-established control-based methods that consider inputs for all the system degrees of freedom, the current work proposes the more realistic alternative of having inputs at joint level only, thus leading to an underactuated system. The ground reactions come from a foot-ground contact model which is built in a pre-processing stage. Different sets of outputs to be tracked by the joint controllers are evaluated. It is observed that choosing as outputs the weighted trajectories of all the system degrees of freedom yields satisfactory results, and that including the weighted ground reactions provides only marginal improvement.