ABSTRACT
This chapter provides two additional control features: the ability to serially compose designing controllers in order to obtain walking at several discrete walking rates with guaranteed stability during the transitions and the ability to regulate the robot’s average walking rate to a continuum of values, while rejecting modest disturbances. The control design involves the choice of a set of holonomic constraints that are asymptotically imposed on the robot via feedback control. The chapter aims to design an event-based controller that adjusts the parameters in the output so as to achieve walking at a continuum of rates instead of some finite set of rates, as would be achieved with the switching design. The event-based controller provides PI-action to adjust parameters of a within-stride controller that, for fixed parameter values, induces an exponentially stable, periodic orbit. Event-based PI control is used to maintain the designed average walking rate in the presence of parameter mismatch between the design model and the actual model.
