The control of nonholonomic and underactuated systems with symmetry is illustrated by the problem of controlling a bicycle. We derive a controller which, using steering and rear-wheel torque, causes a model of a riderless bicycle to recover its balance from a near fall as well as converge to a time parameterized path in the ground plane. Our construction utilizes new results for both the deriva...

An open-loop control for underactuated mechanical systems using oscillatory inputs with amplitude and frequency modulations is investigated. Once all actuated joints are moved to their desired positions, oscillatory inputs are applied to an actuated joint to move the remaining unactuated joints. The steering force of the unactuated joints is achieved by utilizing the dynamic coupling between ac...

Recent advances have been made in learning of grasps for fully actuated hands. A typical approach learns the target locations of finger links on the object. When a new object must be grasped, new finger locations are generated, and a collision free reach-to-grasp trajectory is planned. This assumes a collision free trajectory to the final grasp. This is not possible with underactuated hands, wh...

In this paper, stability analysis of walking gaits and robustness analysis are developed for a five-link and four-actuator biped robot. Stability conditions are derived by studying unactuated dynamics and using the Poincaré map associated with periodic walking gaits. A stable gait is designed by an optimization process satisfying physical constraints and stability conditions. Also, considering ...

This paper addresses the control of a planar, biped robot with one degree of underactuation. Previous work has designed controllers that induce provably, exponentially stable, periodic walking motions at fixed, pre-determined walking rates. These controllers operate in continuous-time during the single support phase of the robot. The present paper shows how to design an event-based PI controlle...

The planar bipedal testbed MABEL contains springs in its drivetrain for the purpose of enhancing both energy efficiency and agility of dynamic locomotion. While the potential energetic benefits of springs are well documented in the literature, feedback control designs that effectively realize this potential are lacking. In this paper, we extend and apply the methods of virtual constraints and h...

Dexterous, within-hand manipulation, in which an object held in the fingertips is manipulated by the fingers, shares many similarities with parallel robots. However, their mathematical formulations appear to be substantially different. This paper introduces a formulation typical from parallel manipulators to model the kinetostatics of a handplus-object system, including thefingertip forces form...

This paper seeks insight into stabilization mechanisms for periodic walking gaits in 3D bipedal robots. Based on this insight, a control strategy based on virtual constraints, which imposes coordination between joints rather than a temporal evolution, will be proposed for achieving asymptotic convergence toward a periodic motion. For planar bipeds with one degree of underactuation, it is known ...