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Two-level control scheme for stabilisation of periodic orbits for planar monopedal running

Sadati, N ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1049/iet-cta.2010.0512
  3. Publisher: 2011
  4. Abstract:
  5. This study presents an online motion planning algorithm for generating reference trajectories during flight phases of a planar monopedal robot to transfer the configuration of the mechanical system from a specified initial pose to a specified final one. The algorithm developed in this research is based on the reachability and optimal control formulations of a time-varying linear system with input and state constraints. A two-level control scheme is developed for asymptotic stabilisation of a desired period-one orbit during running of the robot. Within-stride controllers, including stance and flight phase controllers, are employed at the first level. The flight phase controller is a feedback law to track the reference trajectories generated by the proposed algorithm. To reduce the dimension of the full-order model of running, the stance phase controller is chosen to be a parameterised time-invariant feedback law that produces a family of two-dimensional finite-time attractive and invariant submanifolds. At the second level, the parameters of the stance phase controller are updated by an event-based update law to achieve hybrid invariance and stabilisation. To illustrate the analytical results developed for the behaviour of the closed-loop system, a detailed numerical example is presented
  6. Keywords:
  7. Analytical results ; Event-based ; Feedback laws ; Flight phase ; Full-order models ; Mechanical systems ; Motion planning algorithms ; Numerical example ; Optimal controls ; Periodic orbits ; Reachability ; Reference trajectories ; Second level ; Stance phase ; State constraints ; Submanifolds ; Time invariants ; Time varying linear systems ; Two-level control ; Algorithms ; Level control ; Linear systems ; Motion planning ; Phase control ; Robot programming ; Stabilization ; Controllers
  8. Source: IET Control Theory and Applications ; Volume 5, Issue 13 , Sept , 2011 , Pages 1528-1543 ; 17518644 (ISSN)
  9. URL: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5992560&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4079545%2F5992554%2F05992560.pdf%3Farnumber%3D5992560