Three uses for springs in legged locomotion
International Journal of Robotics Research
International Journal of Robotics Research
Efficient dynamic simulation of a quadruped using a decoupled tree-structured approach
International Journal of Robotics Research
Modern C++ design: generic programming and design patterns applied
Modern C++ design: generic programming and design patterns applied
Nonlinear Control Systems
Toward a coherent framework for the control of planar biped locomotion
Toward a coherent framework for the control of planar biped locomotion
IEEE Spectrum
A Simplified Stability Study for a Biped Walk with Underactuated and Overactuated Phases
International Journal of Robotics Research
Fast Biped Walking with a Sensor-driven Neuronal Controller and Real-time Online Learning
International Journal of Robotics Research
Control Strategy for the Robust Dynamic Walk of a Biped Robot
International Journal of Robotics Research
Ankle Actuation for Limit Cycle Walkers
International Journal of Robotics Research
MABEL, a new robotic bipedal walker and runner
ACC'09 Proceedings of the 2009 conference on American Control Conference
Effects of compliant ankles on bipedal locomotion
ICRA'09 Proceedings of the 2009 IEEE international conference on Robotics and Automation
Modeling and control of the monopedal robot thumper
ICRA'09 Proceedings of the 2009 IEEE international conference on Robotics and Automation
Stabilizing monopedal robot running: reduction-by-feedback and compliant hybrid zero dynamics
Stabilizing monopedal robot running: reduction-by-feedback and compliant hybrid zero dynamics
International Journal of Robotics Research
A partially observable hybrid system model for bipedal locomotion for adapting to terrain variations
Proceedings of the 16th international conference on Hybrid systems: computation and control
International Journal of Robotics Research
Human like trajectory generation for a biped robot with a four-bar linkage for the knees
Robotics and Autonomous Systems
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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 hybrid zero dynamics, originally developed for rigid robots with a single degree of underactuation, to MABEL, a bipedal walker with a novel compliant transmission and multiple degrees of underactuation. A time-invariant feedback controller is designed such that the closed-loop system respects the natural compliance of the open-loop system and realizes exponentially stable walking gaits. Five experiments are presented that highlight different aspects of MABEL and the feedback design method, ranging from basic elements such as stable walking and robustness under perturbations, to energy efficiency and a walking speed of 1.5â聙聣mâ聙聣sâ聢聮1 (3.4â聙聣mph). The experiments also compare two feedback implementations of the virtual constraints, one based on PD control of Westervelt et al., and a second that implements a full hybrid zero dynamics controller. On MABEL, the full hybrid zero dynamics controller yields a much more faithful realization of the desired virtual constraints and was instrumental in achieving more rapid walking.