Abstract
A hybrid approach to the design of the attitude control system for a launch vehicle (LV) in the atmospheric flight phase is proposed in this paper, where a structured <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller is tuned using a genetic algorithm (GA). The <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> synthesis relies on a classical architecture for the thrust vector control (TVC) system that features proportional-derivative loops and bending filters. Once a set of requirements on stability and robustness typical of industrial practice is specified, control design is carried out by parameterizing the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> weighting functions, and solving a two-layer max-min global optimization problem for the tuning parameters. The design methodology is applied to the model of a medium-size LV. The novel design is analyzed in off-nominal conditions taking into consideration model parameter scattering and wind disturbances. The results show that the automated design procedure allows to devise time-scheduled controllers providing adequate stability and performance, and appears as a viable and effective solution in order to reduce the burden of recurrent activities for controller tuning and validation conducted prior to each launch.
Highlights
This paper deals with a hybrid control synthesis technique based on a combination of genetic algorithm (GA) and structured H∞ in order to design a robust controller for a launch vehicle (LV) in atmospheric flight
Performances of the hybrid controllers developed according to GA-H∞ and GA-H∞ A methodologies are assessed with reference to the BC and H∞ designs
The major objective is to evaluate, using the LV model discussed in Section II, possible improvements due the GAbased syntheses in terms of robust stability and performance with respect to the manually tuned controllers, including consideration of reduced workload associated to the automated design procedures
Summary
This paper deals with a hybrid control synthesis technique based on a combination of genetic algorithm (GA) and structured H∞ in order to design a robust controller for a launch vehicle (LV) in atmospheric flight. The design problem is formulated as a structured H∞ control problem in standard form, and the weighting functions are defined so as to enforce the requirements This leads to the synthesis of a gain-scheduled manuallytuned structured H∞ controller with two operating modes, that is, drift-reduction and load-relief, which are enforced at different phases of flight in order to effectively deal with the variation of system parameters and, to some extent, design objectives along the vehicle ascent trajectory [25]. A second hybrid optimization procedure is proposed in order to design a controller, dubbed GA-H∞ A , obtained by exploiting the GA in combination with an augmented structured H∞ control synthesis technique, where the parametric structure of the model uncertainties is directly taken into account in the H∞ problem formulation, so as to improve robustness To this end, an LFT model of the flexible LV with uncertainty on rigid-body parameters and bending mode characteristics (i.e., frequency) is considered. An open source implementation of the mathematical model of the vehicle is available on GitHub.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
