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10.26.2009 - Ferst Symposium on Controls

Grizzle
  • Mabel - controls leg length and leg position (LIKE Yueng-He!)
    • Uses "virtual holonomic constraints"
    • Assume there is a "crank" that drives all of the kinematics forward, then when various segments diverge minimize the error on the constraints.
  • Utilizing mechanics gives a 4:1 improvement in efficiency based on:
    • PositiveWork / Mass / Distance
  • For control utilize hybrid zero-dynamics
    • When controlling stiffness adding a deadbeat improves robustness
Petros Ioannou
  • Robust adaptive control
  • Identifier based control
    • Try and find appropriate control based on measured output
    • This makes the open-loop LTI system into a non-linear time-varying closed loop system
  • Use feedforward control to move the position of the zeros of the closed loop system
  • Using ARMA or backward-difference Euler is equivalent
Kahlil
  • High gain observers
  • Two problems in high gain observers
    • Peaking phenomenen
    • Saturation
  • In high gain you have the possibility of destabilizing the system with faster control than measurement
  • Have the possibility of recovering the actual trajectory of the system
  • Can you use these techniques for system identification?
Krstic
  • Stochastic averaging and extremum seeking
  • You can reach the global optimum through using stochastic averaging
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