Sensor-based control of a nine-link biped
International Journal of Robotics Research
Biped Locomotion
Nonlinear Control Systems
Stable Bipedal Walking With Foot Rotation Through Direct Regulation of the Zero Moment Point
IEEE Transactions on Robotics
Experimental verification of 3D bipedal walking based on passive dynamic autonomous control
IROS'09 Proceedings of the 2009 IEEE/RSJ international conference on Intelligent robots and systems
Reduction-based Control of Three-dimensional Bipedal Walking Robots
International Journal of Robotics Research
Stable dynamic walking over uneven terrain
International Journal of Robotics Research
Human-data based cost of bipedal robotic walking
Proceedings of the 14th international conference on Hybrid systems: computation and control
Stability analysis and time-varying walking control for an under-actuated planar biped robot
Robotics and Autonomous Systems
Gait generation and control for biped robots with underactuation degree one
Automatica (Journal of IFAC)
Walking and steering control for a 3D biped robot considering ground contact and stability
Robotics and Autonomous Systems
International Journal of Robotics Research
International Journal of Robotics Research
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This paper presents three feedback controllers that achieve an asymptotically stable, periodic, and fast walking gait for a 3-D bipedal robot consisting of a torso, revolute knees, and passive (unactuated) point feet. The walking surface is assumed to be rigid and flat; the contact between the robot and the walking surface is assumed to inhibit yaw rotation. The studied robot has 8 DOF in the single support phase and six actuators. In addition to the reduced number of actuators, the interest of studying robots with point feet is that the feedback control solution must explicitly account for the robot's natural dynamics in order to achieve balance while walking. We use an extension of the method of virtual constraints and hybrid zero dynamics (HZD), a very successful method for planar bipeds, in order to simultaneously compute a periodic orbit and an autonomous feedback controller that realizes the orbit, for a 3-D (spatial) bipedal walking robot. This method allows the computations for the controller design and the periodic orbit to be carried out on a 2-DOF subsystem of the 8-DOF robot model. The stability of the walking gait under closed-loop control is evaluated witt the linearization of the restricted Poincare map of the HZD. Most periodic walking gaits for this robot are unstable when the controlled outputs are selected to be the actuated coordinates. Three strategies are explored to produce stable walking. The first strategy consists of imposing a stability condition during the search of a periodic gait by optimization. The second strategy uses an event-based controller to modify the eigenvalues of the (linearized) Poincare map. In the third approach, the effect of output selection on the zero dynamics is discussed and a pertinent choice of outputs is proposed, leading to stabilization without the use of a supplemental event-based controller.