Linear Quadratic Gaussian/Loop Transfer Recover Control Flight Control on a Nonlinear Model

As part of the development of a 4D autopilot system for unmanned aerial vehicles (UAVs), i.e. a time-dependent robust trajectory generation and control algorithm, this work addresses the problem of optimal path control based on the flight sensors data output that may be unreliable due to noise on data acquisition and/or transmission under certain circumstances. Although several filtering methods, such as the Kalman-Bucy filter or the Linear Quadratic Gaussian/Loop Transfer Recover Control (LQG/LTR), are available, the utter complexity of the control system, together with the robustness and reliability required of such a system on a UAV for airworthiness certifiable autonomous flight, required the development of a proper robust filter for a nonlinear system, as a way of further mitigate errors propagation to the control system and improve its ,performance. As such, a nonlinear algorithm based upon the LQG/LTR, is validated through computational simulation testing, is proposed on this paper.

• T. Sanches
• K. Bousson

• Autonomous flight
• LQG/LTR
• nonlinear state estimator
• robust flight control and stability.

[1] T. Sanches. Longitudinal Flight Control with a Variable Span Morphing Wing. LAMBERT Academic Publishing, Balti, Moldova, 2017.
[2] B. N. Pamadi. Stability, Dynamics and Control of Airplanes. AIAA, Inc. Hampton, USA, 1998.
[3] E. E. Larrabee. Airplane Stability and Control. Cambridge University Press, Cambridge, UK, 2002.
[4] B. Etkin. Dynamics of Flight Stability and Control. John Wiley & Sons, Inc. s.l., 1996.
[5] J. B. Moore. Linear Optimal Controler. Prentice-Hall, s.l., 1989.
[6] Luo, J.; Lan, C.E.: 'Determination of Weighting Matrices of a Linear Quadratic Regulator'' Journal of Guidance, Control and Dynamics, Vol. 18 no. 6 (1995), pp. 1462-1463.
[7] R. C. Nelson. Flight Stability and Automatic Control. McGraw-Hill Book Company, New York, USA, 1989.
[8] K. Bousson. Unidade Curricular de Aviónica: Teoria dos Observadores e da Filtragem de Kalman-Bucy (No domínio contínuo). FEUBI-DCA, Covilhã, Portugal, 2016.
[9] Athans, M.: The role and use of the stochastic Linear-Quadratic-Gaussian problem in control system design'' IEEE Transaction on Automatic Control, (1971).
[10] Stein, G.; Athans, M.: "The LQG/LTR Procedure for Multivariable Feedback Control Design'' IEEE Transaction on Automatic Control, vol.AC-32 no. 2 (1984), pp. 105-114.
[11] Kozáková, A.; Hypiusová, M.: ''LQG/LTR based reference tracking for a modular servo'' Journal of Electrical Systems and Information Technology, no. 2 (2015), pp. 347-357.
[12] X. Chen. Advanced Control Systems II (ME233): Key Notes for Discussion 7, 2013.
[13] Lavretsky, E.: ''Adaptive Output Feedback Design Using Asymptotic Proprieties of LQG/LTR Controllers'' IEEE Transaction on Automatic Control, Vol. 57 no. 6 (2012), pp. 1587-1591.
[14] A. A. G. Siqueira. SEM 5928 – Sistemas de Controle: Aula 8 – Projeto LQG/LTR, Universidade de São Paulo, Brazil, 2014.
[15] X. Chen. Lecture 9(ME233): LQG/Loop Transfer Recovery (LTR), UC Berkeley, USA,2014.
[16] M. Aoki. Optimization of Stochastic Systems, Topics in Discrete-Time Systems. Academic Press, New York, USA, 1967.