SDRE and LQR Controls Comparison Applied in High-Performance Aircraft in a Longitudinal Flight

Guilherme P. Dos Santos (Federal University of Technology - Paraná (UTFPR), 84016-210, Ponta Grossa, PR, Brazil)
Adriano Kossoski (São Paulo State University, School of Engineering, 17033-360, Bauru, SP, Brazil)
Jose M. Balthazar (São Paulo State University, School of Engineering, 17033-360, Bauru, SP, Brazil)
Angelo Marcelo Tusset (Federal University of Technology-Paraná (UTFPR))

International Journal of Robotics and Control Systems
Vol 1, No 2 (2021)

This paper presents the design of the LQR (Linear Quadratic Regulator) and SDRE (State-Dependent Riccati Equation) controllers for the flight control of the F-8 Crusader aircraft considering the nonlinear model of longitudinal movement of the aircraft.  Numerical results and analysis demonstrate that the designed controllers can lead to significant improvements in the aircraft's performance, ensuring stability in a large range of attack angle situations. When applied in flight conditions with an angle of attack above the stall situation and influenced by the gust model, it was demonstrated that the LQR and SDRE controllers were able to smooth the flight response maintaining conditions in balance for an angle of attack up to 56% above stall angle.  However, for even more difficult situations, with angles of attack up to 76% above the stall angle, only the SDRE controller proved to be efficient and reliable in recovering the aircraft to its stable flight configuration.