Robust velocity sliding mode control of mobile wheeled inverted pendulum systems
ICRA'09 Proceedings of the 2009 IEEE international conference on Robotics and Automation
Planar bipedal jumping gaits with stable landing
IEEE Transactions on Robotics
Optimal braking control for UW-Car using sliding mode
ROBIO'09 Proceedings of the 2009 international conference on Robotics and biomimetics
Sliding-mode velocity control of mobile-wheeled inverted-pendulum systems
IEEE Transactions on Robotics
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The purpose of this paper is to present a robust tracking control algorithm for underactuated biped robots capable of self-balancing in the presence of external disturbances. The biped is modeled as a five-link planar robot with four actuators located at hip and knee joints. A sliding mode control law has been developed for the biped to follow a human-like gait trajectory while keeping the torso nearly upright. The control forces are calculated by defining four first-order sliding surfaces as a linear combination of the torso and the four joint tracking errors. The control approach is shown to guarantee that all trajectories will reach and stay on these surfaces during each step, while the walking cycle stability is maintained through a Lyapunov function. The criteria for asymptotic stability of the surfaces are presented and a numerical search method is implemented for the selection of the corresponding surface parameters. The paper further investigates the robustness of the controller in response to disturbances. Numerical simulations demonstrate the tracking stability of the biped's multistep walk and its human-like response to an external disturbance.