Finite-time observer-based backstepping control of a flexible launch vehicle

Elodie Duraffourg (1) , Laurent Burlion (1) , Tarek Ahmed-Ali (2)

1 ONERA - The French Aerospace Lab [Toulouse]
2 ENSICAEN - École Nationale Supérieure d'Ingénieurs de Caen

In this paper, a longitudinal model of a space launch vehicle was developed using the Lagrange mechanism and a free–free Euler–Bernoulli beam model. The aim was to propose a model including one flexible mode plus a nonlinear aerodynamic coefficient for nonlinear control design. We then studied the output feedback problem raised by using such a nonlinear model. The main achievement is to propose a new finite-time state observer when the measured outputs are corrupted by an unidentified flexible mode. This effect may destabilize a classical backstepping control law applied to the rigid model. To achieve this, a backstepping control law was redesigned to damp out the flexible mode, once measured and characterized. Hence a new adaptive finite time observer was developed. Closed-loop simulations show the effectiveness of the observer in combination with a redesigned backstepping control law when sensors and the launcher nozzle are collocated.

Mots clés: NONLINEAR CONTROL; BACKSTEPPING; OBSERVER DESIGN; FLEXIBLE MODES

Domaines: Sciences de l'ingénieur [physics]; Physique [physics]; Mathématiques [math]; Informatique [cs]

Elodie Duraffourg, Laurent Burlion, Tarek Ahmed-Ali. Finite-time observer-based backstepping control of a flexible launch vehicle. Journal of Vibration and Control, 2016, 24 (8), pp.1535-1550. ⟨10.1177/1077546316664021⟩. ⟨hal-02315092⟩