In this paper, the full tracking problem in aircraft system identification and control is presented. Time domain output error method with maximum likelihood principle was used to perform system identification. The linear quadratic regulator (LQR)-based approach has been used for solving aviation full tracking problems in aviation. It has been shown that the generalized nonlinear LQR control is able to handle such problems even in case of inaccurate measurements and in the presence of moderate disturbances provided that the model of an aircraft is properly identified.
This paper presents a controller design process for an aircraft tracking problem when not all states are available. In the study, a nonlinear-transport aircraft simulation model was used and identified through Maximum Likelihood Principle and Extended Kalman Filter. The obtained mathematical model was used to design a Linear–Quadratic Regulator (LQR) with optimal weighting matrices when not all states are measured. The nonlinear aircraft simulation model with LQR controller tracking abilities were analyzed for multiple experiments with various noise levels. It was shown that the designed controller is robust and allows for accurate trajectory tracking. It was found that, in ideal atmospheric conditions, the tracking errors are small, even for unmeasured variables. In wind presence, the tracking errors were proportional to the wind velocity and acceptable for small and moderate disturbances. When turbulence was present in the experiment, state variable oscillations occurred that were proportional to the turbulence intensity and acceptable for small and moderate disturbances.
Purpose The purpose of this paper is to analyze the active suppression of the nonlinear aeroelastic vibrations of ailerons caused by freeplay by robust H∞ and linear quadratic Gauss (LQG) methods of control in case of incomplete measurements of the state of the system. Design/methodology/approach The flexible wing with nonlinear aileron with freeplay is treated as a plant-controller system with H∞ and LQG controllers used to suppress the aeroelastic vibrations. The simulation approach was used for analyzing the impact of completeness of measurements on the efficiency and robustness of the controllers. Findings The analysis shows that the H∞ method can be effectively used for suppression of nonlinear aeroelastic vibrations of aileron, although its efficiency depends essentially on completeness and types of measurements. The LQG method is less effective, but it is also able to prevent aileron vibrations by reducing their amplitudes to acceptable, safe level. Research limitations/implications Only numerical analysis was carried out for the problem described; thus, the proposed solution is of theoretical value at this stage of analysis, and its application to the real suppression of aeroelastic vibrations requires further research. Practical implications The work presents a potentially useful solution to the problem of interest and results are a theoretical basis for further research. Social implications This work may lead to a hot debate on the advantages and drawbacks of the active suppression of vibrations in the aeroelasticians community. Originality/value The work raises the important questions of practical stabilizability of the nonlinear aeroelastic systems, their dependence on completeness and types of measurements and robustness of the controllers.
Purpose The purpose of the paper is to analyze the active suppression of the aeroelastic vibrations of ailerons with strongly nonlinear characteristics by neural network/reinforcement learning (NN/RL) control method and comparing it with the classic robust methods of suppression. Design/methodology/approach The flexible wing and aileron with hysteresis nonlinearity is treated as a plant-controller system and NN/RL and robust controller are used to suppress the nonlinear aeroelastic vibrations of aileron. The simulation approach is used for analyzing the efficiency of both types of methods in suppressing of such vibrations. Findings The analysis shows that the NN/RL controller is able to suppress the nonlinear vibrations of aileron much better than linear robust method, although its efficiency depends essentially on the NN topology as well as on the RL strategy. Research limitations/implications Only numerical analysis was carried out; thus, the proposed solution is of theoretical value, and its application to the real suppression of aeroelastic vibrations requires further research. Practical implications The work shows the NN/RL method has a great potential in improving suppression of highly nonlinear aeroelastic vibrations, opposed to the classical robust methods that probably reach their limits in this area. Originality/value The work raises the questions of controllability of the highly nonlinear aeroelastic systems by means of classical robust and NN/RL methods of control.
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