International Journal of Robotics Research
International Journal of Robotics Research
Adding an Upper Body to Passive Dynamic Walking Robots by Means of a Bisecting Hip Mechanism
IEEE Transactions on Robotics
A Disturbance Rejection Measure for Limit Cycle Walkers: The Gait Sensitivity Norm
IEEE Transactions on Robotics
Controlling the Walking Speed in Limit Cycle Walking
International Journal of Robotics Research
Hardware design and gait generation of humanoid soccer robot Stepper-3D
Robotics and Autonomous Systems
The instantaneous leg extension model of virtual slope walking
IROS'09 Proceedings of the 2009 IEEE/RSJ international conference on Intelligent robots and systems
Analysis of a biped powered walking model based on potential energy compensation
ROBIO'09 Proceedings of the 2009 international conference on Robotics and biomimetics
Fully interconnected, linear control for limit cycle walking
Adaptive Behavior - Animals, Animats, Software Agents, Robots, Adaptive Systems
A Compliant Hybrid Zero Dynamics Controller for Stable, Efficient and Fast Bipedal Walking on MABEL
International Journal of Robotics Research
Linear reactive control for efficient 2D and 3D bipedal walking over rough terrain
Adaptive Behavior - Animals, Animats, Software Agents, Robots, Adaptive Systems
Applied Bionics and Biomechanics - Human-Robot Interaction/Interface
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Limit Cycle Walkers are bipeds that exhibit a stable cyclic gait without requiring local controllability at all times during gait. Well-known example are McGeer's “Passive Dynamic Walkers”, but the concept expands to actuated bipeds as involved in this study. Current state-of-the-art Limit Cycle Walkers excel in being very energy efficient, but their ability to handle disturbances (i.e. disturbance rejection) is still limited. A way to improve this ability while maintaining low energy consumption is the use of ankle actuation, which has so far seen few applications in this type of walker. In this paper we study the effect of (1) applying (passive) stiffness in the ankle joint, (2) applying control in the stance ankle based only on local sensor information and (3) modulating ankle push-off. For all three strategies the paper shows how they influence energy use and disturbance rejection of a simple point mass walking model, a more realistic model and a physical prototype. We find that applying a passive ankle spring that results in premature heel rise is energetically optimal and gives an actuation pattern that largely resembles that of humans. Local stance ankle control and ankle push-off modulation can improve the disturbance rejection of a Limit Cycle Walker by at least 60%, without increasing its energy use. These findings are substantiated by showing that our prototype is able to handle large disturbances such as a step-down of 5% of its leg length, while walking efficiently at a mechanical cost of transport of 0.09.