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Design of control system for ailaunch vehicle

Abstract : This thesis addresses the problem of the stabilization of an (unmanned) airlaunch system. Air launching consists in bringing a satellite and its launcher (rocket) to a certain height using an aircraft, and then launching it from the air (often by dropping the rocket), in a similar way of launching a missile from a fighter. The main difference is that the envisaged mass ratio is much closer to one (heavy rocket compared to aircraft mass). It is then composed of two stages: the first stage called carrier aircraft consists of an aerial vehicle that carries the launcher which constitutes the second stage (rocket). This thesis starts by introducing the problem and objectives, continues by presenting several approaches to model the airlaunch system, and ends by developing different advanced control methods to stabilize it after the launching phase. In the modeling part we propose a firstly approach called the initial condition model which assumes that the separation phase is instantaneous, and then the airlaunch system is composed of an aircraft model after the launching phase but with large initial conditions on its state variables, caused by a non-perfect split phase. A second approach assumes that the separation phase itself is modeled by a disturbance on aerodynamic forces and moments (from a worst case) during a time interval. In the control part a modified conditional integrator controller for a class of nonlinear multi-input multi-output systems is first developed starting from the conditional integrator theory developed by Khalil and co-workers. It is then extended to a modified conditional servocompensator control for a class of nonlinear multi-input multi-output systems. Both control strategies were then applied to stabilize the airlaunch system after the separation phase. They have the advantage of being very robust, and they don't depend so much on reliable models. Even if these control strategies gave good results, it was investigated in this thesis another control approach much more dependent on detailed and reliable models. This approach was based on dynamic feedback linearization theory, and the main idea is to obtain better performance in trade off better models. Finally, all proposed control methods (plus some standard ones) were compared and illustrated by simulations under Matlab/Simulink on a nonlinear F-16 model. These simulations have shown that the results were as expected, and that each control strategy was well fit for a particular situation.
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Submitted on : Thursday, December 11, 2014 - 5:37:15 PM
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  • HAL Id : tel-01094178, version 1



van Cuong Nguyen. Design of control system for ailaunch vehicle. Automatic. Université d'Evry Val d'Essonne, 2013. English. ⟨tel-01094178⟩



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