In the last years, several control theories have been widely developed.1–3 They are generally applied to control task such as trajectory tracking and optimization. In most cases, the control approaches are based on linear methods and on the assumption that precise analytical model of the controlled system is available. However, relationships between physical variables are non linear and only represented by discrete numerical tables. Recently, neural networks have been proposed as feed-forward inverse dynamics controllers. In addition, a number of flight control applications illustrated the online learning capability of neural networks.4,5 This paper presents the design of a flight controller using neural networks. Emphasis is placed on the use of a command and stability augmentation system using an off-line trained network. The application is focused on a remotely piloted vehicle (RPV). The paper is organized as follows: Section 2 presents the longitudinal dynamics of a rigid airplane. The third section outlines the principles of a linear controller. The design of a neural controller is given in section 4. The effectiveness of the proposed approach is displayed by simulation results in the case of a longitudinal control.

Flight control system design using neural networks

It is proposed a translation methodology applied to temporal transient response characteristics to obtain parameters of the typical second order transfer function, in the frequency domain. This method based on automatic successive approximations, applying an inverse interpolation, will minimize overdesign and manual iteration in the process of searching for a controller in frequency. For each type of requirement, specific techniques are recommended to obtain specification translation, using the “ascending and descending differences Newton’s procedure” due to its practice advantages, compared to other interpolation procedures. It will be used as interpolation functions those describing step signal or pulse signal, with subcritical damping and approached with a second order transfer function.

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Inverse Interpolation Techniques for Temporary Specifications Translation to Frequency Domain

In order to obtain a method of temporary specification translation to the frequency domain, which minimizes overdesign and manual iteration in the process of searching for a controller in frequency, it is proposed to use successive approximations automatically, applying any inverse interpolation. In this regard, specific techniques are recommended to obtain specification translation for each type of requirement, based on the “ascending and descending differences Newton method of 5th order” due to its practice advantages, compared to other interpolation procedures. For this, it will be used as interpolation functions those describing step signal or pulse signal, with subcritical damping and approached with a second order model.

https://polipapers.upv.es/index.php/RIAI/article/download/9236/9265

Interpolación inversa de características de respuesta transitoria temporal a parámetros de la función de transferencia típica de segundo orden

Nonlinear quantitative feedback theory (QFT) is used to design a flight control system for the nonlinear model of the YF-16 aircraft (A/C) with C* as the controlled output. The resulting closed loop stability augmentation system (SAS), Pe(S), becomes part of the outer loop containing the pilot. The Neal-Smith pilot model for a compensatory tracking task is used to develop a technique which allows the designer to synthesize compensation in the outer loop, which includes a free compensator Fp(S). The latter is chosen to minimize pilot workload, increase system bandwidth, and improve handling qualities ratings as per the Neal–Smith criteria, for the tracking task. The available pilot compensation abilities are then available for further increasing of system bandwidth to improve overall capabilities. This approach can be used at the early stages of flight control design, thus saving time and money over the current practice. Simulations in the time and frequency domains demonstrate that the desired performance is attained.

I. M. Horowitz

Papers

Flight controller design for uncertain and nonlinear plants with pilot compensation