ADAPTIVE TUNING OF DEFENDING MISSILE UNDER ENVIRONMENTAL CONSTRAINTS

In this research, an adaptive controller is tuned and applied to proportional navigation system under environmental constraints. The purpose of this controller is to keep the stability of the missile during flight time, while the missile is affected by environmental effects such as gravity and drag force caused by the air. The proposed control system is tuned using particle swarm optimization (PSO) method, and the fitness function of the PSO technique is optimized to reduce the miss distance value of the missile at impact time, as well as to minimize the deviation error of the missile from the right track between the missile and the target The simulation results proved the stability of the missile in terms of trajectory stability during flight, miss distance, incidence angle, normal acceleration and radar’s gimbal angle stability and tracking performance. INTRODUCTION Proportional Navigation Guidance (PNG) is the most used system for guiding defending missiles, however, when dealing with missiles that changes its altitude during flight times, the gains of the proportional navigation guidance system should also be changed to accommodate to the environmental effects such as air drag force and gravity effects. It has been found that these effects could be obtained by knowing some states of the missile such as incidence angle, and attitude of the missile. In this research, an adaptive controller is applied to the proportional navigation system and tuned with particle swarm optimization in order to stabilize the missile during flight time. A two-dimensional look-up table is constructed for different values of incidence angles and missile speed. Then, a particle swarm optimization method is used to obtain the required gains for the three-loop proportional navigation guidance system. Research in [Shah, Samar, & Bhatti, 2010] aimed to design an adaptive control system for controlling the roll behavior of a short-range missile. The main problem investigated by this paper is to design a robust control system that could maintain the roll angle to a value near to zero. The adaptive controlling method is used to control the missile under varying launch angle as well as dynamic pressure. Also, the robustness of the control system is tested under aerodynamic effects and other disturbances. The simulation results proved the ability of the controller in rejecting aerodynamic effects and the other disturbances while keeping the roll angle to a value near to 1 GRA. in a Department, Email: murad.a.yaghi@gmail.com 2 Prof. in a Department, Email: onderefe@gmail.com AIAC-2019-030 Yaghi & Efe 2 Ankara International Aerospace Conference zero. In [Xiangrong Tong, Hongchao Zhao, & Guohu Feng, 2006] an overload control system is proposed to control an anti-warship missile. The purpose of this controller is to remove the non-minimum phase behavior of missile overload output. By this control technique, an adaptive global sliding mode method is proposed in order to control the missiles’ modified output system, and it’s used to evaluate the upper bound value of the lumped uncertainty. Also, a simulation example is performed to demonstrate the validity of the proposed system. In [Yang, Li, & Shi, 2009] a self-adaptive fuzzy proportional integral derivative control system is used to control a longitudinal channel for an autopilot system. This autopilot system is integrated within unmanned aerial vehicles (UAV) and combined with the traditional PID control system along with a fuzzy controlling method. The simulation results proved the simplicity of integrating the self-adaptive fuzzy PID. Also the proposed controller is compared with the traditional PID controller in terms of the dynamic performance of the controlled object, and the proposed controller also could be applied to a time-varying object and nonlinear systems such as UAV. In [Yue Zhang, 2011], the three-loop adaptive autopilot system is researched in order to guarantee the precision of the initial launching of the trajectory. By this research, the autopilot system is simplified and a three-loop adaptive control method and stability is designed. The simulation results showed that the proposed system was effective in controlling the disturbance of the initial launching and adapt to the change in dynamic characteristics as well as keeping the control stability. In [Shi & Zhao, 2017], the uncertain aerodynamics of the spinning projectile autopilot is investigated. A robust feedback adaptive control system is designed and applied for a double-channel spinning projectile. In order to accomplish that, the first step is to develop a dynamic model for the projectile, and an adaptive controller is applied to the autopilot system. Then a robust compensation system is designed and integrated to the adaptive controller to accomplish its robustness. The closed loop adaptive system performance is tested through simulations. In addition, the simulation results proved that the autopilot system eliminated the high frequency oscillations. Apart from these researches, our proposed intelligent tuning technique with its simple implementation method, proved to have a very good stability for the missile during flight time through the second norm minimization as well as excellent hitting accuracy by integrating the miss distance optimization technique into the fitness function of the PSO tuning method. The rest of the paper is organized as follows: Section 2 introduces the principles of the proportional navigation guidance system and the integrated adaptive controller. Section 3 includes the system design and tuning method. Section 4 contains the simulation results of the proposed control system.