MULTIVARIABLE CONTROL SYSTEMS TOOLBOX

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NONLINEAR BACKSTEPPING CONTROL WITH OBSERVER
DESIGN FOR A 4 ROTORS HELICOPTER L. Mederreg, F.
Diaz and N. K. Msirdi LRV Laboratoire de
Robotique de Versailles, Université de Versailles
Saint Quentin en Yvelines, 10, avenue de
lEurope 78140, Vélizy, France.
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OUTLINE
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Introduction

• Thanks to its special configuration, the 4 rotor
  helicopter allows to achieve many tasks in
  different fields.
• Symmetry of the platform geometry
• Low weight
• Low cost
• Autonomous flight ? Non linear control law
  Synthesis.

• Complexity of the dynamical system
• Presence of Perturbations due to the wind
• Unavailability of some state variables

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4 rotors Helicopter model Presentation
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(No Transcript)
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The state representation is given by
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Back stepping controller synthesis
We consider that all the state vector is
measurable
System of 4 equations 4 unknowns
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SIMULINK bloc diagram of the controller
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Back stepping controller synthesis with observer

• We shall observe the absolute velocity vector

• We consider that all the other parameters are
  measurable

Where V is a LYAPUNOV candidate function

• We include in the expression of V the observing
  errors to be cancelled

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Simulation and results

• Simulation of a vertical helix trajectory flight
  in presence of perturbations (7 newton
  front wind blowing)
• The controller gains are adjusted by doing
  intensive simulations

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3D Tracking trajectory
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Tracking errors for the BACKSTEPPING controller
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Observation Errors for the BACKSTEPPING Observer
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Tracking Errors for the BACKSTEPPING controller
with Observer
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Conclusion

• This approach has shown
• Good robustness of the Controller
• Good convergence of the couple controller
  observer
• allows to decrease the number of the required
  sensors