Missile Seeker Research Articles

Experimental validation and analysis of hybrid adaptive iterative learning sliding mode control for PMSM seeker coordinator

High-order nonlinearity, strong coupling, and external disturbances constrain the high-precision servo tracking control of the missile seeker coordinator, which compromises the guidance accuracy of guided weapons. The individual differences in the seekers cause model parameter perturbations, leading to uncertainty and time-varying disturbances, which reduces the tracking performance of the seeker servo system. To cope with these uncertainties various traditional Iterative learning control (ILC) strategies have been designed to suppress high-order nonlinear disturbances. However, these are very sensitive to system uncertainties, external disturbances and model parametric perturbations. In response to this challenge, this paper proposes a hybrid adaptive iterative learning sliding mode control (AILS) methodology. The iterative learning sliding mode control (ILSMC) strategy is used to reduce the impact of periodic disturbances in the system, ensuring a rapid system response. The enhanced adaptive learning law (EAL) strategy offers an estimation of the lumped disturbances of the system, encapsulating both parameter shifts and residual disturbances. Through this appropriate adaptive control, both disturbances compensation and the chattering effect due to sliding mode control are simultaneously minimized. Simulation and experimental results show that compared with the traditional open-loop iterative learning control, the learning convergence speed and convergence accuracy of the proposed hybrid AILS are highly significant. Experimental results also show that the control algorithm designed in this paper can also perform adaptively, has fast learning capability and ensures convergence while guaranteeing the tracking accuracy of the seeker coordinator servo system.

Microwave gain-assisted optical limiter in molecular magnets.

We investigate the optical properties of a crystal of molecular magnets within the microwave frequency range. It is shown that in the presence of a static magnetic field and applying a coupling laser field in the microwave region, reverse saturable absorption in the microwave domain can be induced in molecular magnets. Notably, the intensity and detuning of the coupling laser field are shown to exert significant control over electromagnetically induced optical limiting (OL). Thus, the OL behavior can safeguard the active sensors in seekers against the saturation as they approach microwave sources. What we believe to be a novel optical limiting phenomenon is introduced, wherein the crystal amplifies noiselessly weak input microwave fields in the linear region of the optical limiter while attenuating intense input fields. Consequently, these findings suggest the potential for actively controlling radars or seekers by exploiting a gain-assisted optical limiter to detect microwave sources with weak signals. The static magnetic field, acting as a pivotal parameter, significantly influences the attainment of OL performance across a broad spectrum of microwave frequencies. We anticipate that the outcomes of this investigation could be applied in microwave photonics to enhance the ranging capabilities of missile seekers or radars via the identification of weak signal targets. Additionally, the research highlights the protective capabilities of microwave sensors against high-power microwave signals. Finally, the open aperture Z-scan technique is employed to confirm the induced gain-assisted optical limiting behavior in molecular magnets.

Aeroacoustic Analysis of Rapid Position Changing Process of Missile Seeker Equipment

A two-dimensional CFD model of the rapid position-changing of missile seeker equipment is presented to study its aeroacoustic impact. By combining the computational fluid dynamics (CFD) with the Ffowcs Williams-Hawkings (FW-H) equation, the flow and related aeroacoustic features are analyzed under different flight Mach numbers and flight heights. The impact of seeker movement on the flow field and aerodynamic noise are highlighted. The results indicate that the spectrum peak of sound pressure level increases with the vortex shedding frequency as the flight Mach number increases. As the flight height of the missile increases, the sound pressure level is amplified while the frequency of vortex shedding decreases.

Research on the influence of time delay on combat effectiveness of aircraft fleet

Aiming at the influence of time delay on the combat effectiveness of aircraft fleet under the command of airborne warning and control system (AWACS), the process of beyond visual range air combat under the command of AWACS is analyzed, as well as the time delay characteristics in the combat information flow. The air combat situation threat of the aircraft by enemy aircraft is represented by the weighted fusion of the speed threat, angle threat, distance threat, and height threat of the aircraft. The threat matrix is proposed to represent the threat to the whole aircraft fleet. The threat matrix consists of the situational threat between each of our aircraft and each of the enemy aircraft. And the threat matrix of both sides is calculated to obtain the pre-enemy launch probability of both sides. With the two-step adjudication method and capturing the target probability of the missile seeker under the influence of time delay, the probability and number of being destroyed are calculated, as well as the combat effectiveness ratio. The opposing forces of both sides are set, and the calculation results in Matlab are consistent with the actual ones, which verifies the rationality and validity of the model, and can provide a theoretical reference for determining the time accuracy of the air-based network.

Synthesize the optimal control law for the antenna transmission system of the missile seeker

The appearance in the armed forces of some countries super-maneuverable aircraft has posed the problem of synthesizing the angle measuring equipment of the missile seeker with higher requirements for accuracy, fast acting, and stability when tracking the target. However, the operating principle of current angle measuring equipment does not allow simultaneous improvement of all the necessary criteria, even though such principles are based on the generation of the evaluation signals of angular coordinates and angular speed of line of sight in a loop circuit. Based on the application of optimal control theory, it is possible to synthesize the system’s many loop circuits, which simultaneously achieve the best criteria in terms of accuracy, impact speed, as well as tracking stability, and consumption energy for the control process.

Надувные радиолокационные отражатели: заметность на море

Object and purpose of research. Radar signatures of floating off-board decoys used by foreign navies for eluding anti-ship missiles of at sea are estimated. Materials and methods. Analysis of existing floating radar decoys are based on reviews of leading foreign experts. Signatures of these decoys at sea were calculated using a four-beam model of electromagnetic wave scattering on the underlying surface developed at KSRC. Main results. Quantitative assessments of floating decoy detection ranges by typical anti-ship missile radar seekers are made. Conclusion. The investigations showed that flying radar balloons are more effective in seduction of anti-ship missiles.

Computationally Efficient Ground-to-Air Missile Seeker Based on Camera Images

Computationally Efficient Ground-to-Air Missile Seeker Based on Camera Images

Design of a Compact Indirect Slot-Fed Wideband Patch Array with an Air SIW Cavity for a High Directivity in Missile Seeker Applications

This research proposes a compact indirect slot-fed wideband patch array antenna for a missile seeker application. The proposed single antenna consists of three dielectric layers for a radiator, an air substrate-integrated waveguide (SIW) cavity, and an indirect feeding network. The rectangular patch is used as a radiator on the first substrate layer, and the air SIW cavity (ASIWC) is employed to obtain high directivity and low mutual coupling characteristics in the second substrate layer. In the third layer, an indirect feeding structure is used to achieve the wideband characteristics in the Ka-band. The single element is extended to a 4 × 1 linear array with fabrication, and the fabricated array characteristics are measured in a full anechoic chamber. The measured operating fractional frequency bandwidth is 9.2%, and the measured array gain is 11.7 dBi at the bore-sight direction (θ0 = 0∘).

A compact, low-profile, and high-performance monopulse antenna array for missile seeker

In this paper, the authors presented a compact, low-profile, and high-performance ku-band monopulse antenna array (MAA) for missile seekers with reduced complexity involved in fabrication, assembly, and installation. They investigated a multilayered microstrip patch Antenna technology by systematically developing an efficient synthesis process, high-performance design of radiating elements as well a feed network integrated with monopulse circuitry, and innovative multiple layered joining processes, which overcome limitations of the existing MAA system. Optimum aperture distribution corresponding to desired radiation characteristics is synthesized using a hybrid synthesis technique in which collapse distribution (CD) is employed to initialize the Genetic Algorithm (CD-AvGA). The authors designed the proposed MAA with computed coefficient and carried out fabrication, assembly, and functional validation. The obtained experimental results are in close agreement with simulated ones and satisfy the missile seeker’s stringent functional and platform requirements.

Modeling and Simulation of Two Axes Gimbal Using Fuzzy Control

The application of the guided missile seeker is to provide stability to the sensor's line of sight toward a target by isolating it from the missile motion and vibration. The main objective of this paper is not only to present the physical modeling of two axes gimbal system but also to improve its performance through using fuzzy logic controlling approach. The paper is started by deriving the mathematical model for gimbals motion using Newton's second law, followed by designing the mechanical parts of model using SOLIDWORKS and converted to xml file to connect dc motors and sensors using MATLAB/SimMechanics. Then, a Mamdani-type fuzzy and a Proportional-Integral-Derivative (PID) controllers were designed using MATLAB software. The performance of both controllers was evaluated and tested for different types of input shapes. The simulation results showed that self-tuning fuzzy controller provides better performance, since no overshoot, small steady-state error and small settling time compared to PID controller.

Modelling and simulation of two axes gimbal fuzzy PI stabilization system in the presence of feedback sensors noise

The missile guidance in terminal phase is an optimization problem as the miss distance should be minimized. The optimization of missile miss distance is highly affected by the missile seeker performance. Design of gimbal control system suffers always from feedback sensors noise which leads to system instability. In this paper, a promising design of the fuzzy PID controller for a missile seeker gimbal is proposed considering the feedback sensor noise with practical gyro transfer function calculated based on real experimental measurements utilizing MATLB system identification toolbox. Also, the mathematical model of two stabilized axes gimbal. Stabilization is achieved considering the missile motion parameters such as rates, torques and coupling between yaw and roll channels. A Matlab simulation is carried out for evaluating the proposed system modelling and to test the robustness of the fuzzy PID controller in the presence of feedback sensor noise. A comparative analysis with PI based controller is conducted to evaluate the performance of the proposed controller which presents sufficient enhancement to the missile gimbal stability parameters.

Structural Design and Thermodynamic Analysis of a Missile Borne RF Module

The volume, weight and heat dissipation resources of missile borne SAR seeker are seriously limited, and the working environment is extremely harsh. Therefore, more stringent requirements are put forward on the structural design and thermal design of the electronic module on the missile borne SAR seeker. In this paper, the modular structure design and passive thermal control of a missile borne RF module are studied. In order to improve the interchangeability of products and simplify the design, a universal RF module based on JVPX connector is designed in this paper. In view of the high-speed and high-temperature physical working environment of the SAR seeker, the structure of phase-change heat sink is adopted in the module, which solves the thermal control problem of short-term reliable operation of the heating chip on the module. Finally, the effectiveness of the passive heat dissipation is verified by simulation analysis.

A Novel Self-Tuning Fuzzy Logic-Based PID Controllers for Two-Axis Gimbal Stabilization in a Missile Seeker

Tracking a target is an essential function of a seeker for missiles. The target tracking mechanism of a seeker consists of gimbals, mounted with gyroscopes, and an antenna or some other energy receiving devices such as radar, infrared (IR), or laser. Stabilization of such a gimbal is necessary for any guided missile to maintain the tracking device always pointing towards the target. For the stabilization of the gimbal system, several control methods have been employed for making the gimbal to follow an input rate command by eliminating all the gimbal disturbances. Here, a new self-tuning fuzzy logic-based proportional, integral, derivative (PID) controller is introduced for the stabilization of a two-axis gimbal for a manoeuvring guided missile. The proposed control method involves tuning the gains of the PID controller based on the fuzzy logic rule bases considering the missile body rotation. The performance of the stabilization loops has been verified through MATLAB simulations for fuzzy logic-based PID controller compared with the conventional PID controller. The simulation results show the response of the gimbal system with stabilization loops met the control requirements with fuzzy PID controllers but not with conventional PID controllers.

OBSCURANT AND EMISSION CHARACTERISTICS OF THE SCREENING SMOKE COMPOSITIONS USED IN NAVAL SHIPS

Obscurant and optronic decoy compositions are the pyrotechnic formulations that are an effective way to protect naval ships from optical guided missile seekers. In this work, the obscurant characteristics (i.e. the transmittance and the extinction coefficient) and the infrared emission characteristics (i.e. the infrared emission distribution and the radiance) of the obscurant and optronic decoy compositions were described. The results showed that the obscurant cloud made from the mixture of red phosphorus, Ba(NO3)2 and Viton rubber has a low transmittance, high extinction coefficient with 1.06 µm laser and strong infrared emission in the wavelength range of 8.0 to 14.0 µm. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 to 5.0 µm) of the optronic decoy composition based on Mg-Al, hexachloroethane and Viton rubber reaches maximum values (i.e. 17.77E-3 W.cm-2.Sr-1) at about 17 wt% Mg-Al. Finally, the above obscurant and optronic decoy compositions can be used combination in naval ships against the anti-ship missile.

Effects of Mg Al Alloy Powder on the Combustion and Infrared Emission Characteristics of the Mg Al PTFE Viton Composition

Metal-Fluorocarbon compositions are the pyrotechnic formulations which have been widely used in infrared decoy flares to protect aerial targets from infrared guide missile seekers. In this work, the effect of Mg-Al alloy powder (i.e. the particle size and the content) on the combustion and the infrared emission characteristics (i.e. the infrared emission distribution and the infrared radiance) of the pyrotechnic composition based on Mg-Al alloy, polytetrafluoroethylene (PTFE) and Viton rubber are described. The results show that the high burning rate (with the values of 4.0 mm.s-1 to 10.0 mm.s-1, depend on the compression density) of this composition is achieved with a high content of Mg-Al alloy or when using fine Mg-Al alloy particles as well as coarse PTFE particles. On the other hand, the infrared emission radiance (in the wavelength range of 2.5 μm to 5.0 μm) of Mg-Al/PTFE/Viton composition reaches maximum values (i.e. 17.7 W.cm-2.Sr-1 and 21.0 W.cm-2.Sr-1 with the size of Mg-Al particles are 20 μm and 120 μm, respectively) at 60 wt% Mg-Al alloy. Finally, the Mg-Al/PTFE/Viton composition has a similar combustion and emission characteristics as the Mg/PTFE/Viton composition.

Deception Jamming Against Doppler Beam Sharpening Radars

Missile seekers are becoming increasingly more capable of using Doppler Beam Sharpening (DBS) modes as part of the homing cycle, which requires new countermeasures against this mode. One type of countermeasure, is to create false targets within the seeker DBS image. This paper proposes a jamming technique to generate false targets at a precise location within a seeker DBS image, by both delaying and adding a Doppler shift to received waveforms. The effects of tracking errors on the position of the false target are analysed, both analytically and with simulations and used to assess the practical implementation of the jamming scheme. An experimental DBS system was built to test the effectiveness of the jamming scheme against a platform moving in steps and assess errors caused by incorrectly estimating the seeker trajectory.

Tunable optical behavior of infrared filters with phase change material

We propose an asymmetric to quasisymmetric behavioral tunability of a structured filter operating in the mid-infrared (IR) spectral region, where the atmospheric transparency is high. The structure is designed through electromagnetic wave analysis using finite-difference time-domain computations. The behavioral tunability provides dynamic control of the optical behavior of the IR filter without geometric and structural changes and opens up a field of research area in the tunable IR devices. It is shown that optical characteristic can be switched from an optical diode (unidirectional isolator or asymmetric light transmission) to the bidirectional isolator (quasisymmetric behavior) based on the phase transition of vanadium dioxide in the entire mid-IR spectrum. The proposed structure can be fabricated with the current nano and microfabrication techniques and can be utilized in smart front IR windows for protecting delicate sensors in the IR imaging systems and IR missile seekers under strong IR laser radiation.

Infrared Spectra of Customized Magnesium/Teflon/Viton Decoy Flares

Infrared (IR) guided missile is known to cause 90% of aircraft damage. Magnesium/Teflon/Viton (MTV) decoy flares are customized materials, which are capable of yielding thermal signature to interfere with IR guided missile seekers. In this study, the IR-signature of an MTV flare is measured in a jet engine nozzle. The jet engine IR-signature is characterized with two characteristic peaks over the α-band (2–3 µm) and β-band (3–5 µm); this is correlated to black body emission at 690° C. The MTV decoy flare with 65% Mg offers an increase in the average intensity of the α- and β-bands by 21 and 4 times, respectively, to that of the jet engine. Quantification of emitting species in the combustion flame is conducted by using the ICT thermodynamic code. The developed MTV formulation offers the relative intensity ratio of the α- and β-bands equal to 0.96, which is comparable to that of an aircraft (0.7).

Design and Simulation of Air to Air Missile Homing System

This paper will talk about AIM 120 AMRAAM missile guidance for pursuing a moving target. The missile guidance system itself consists of missile dynamics, control system, seeker, and guidance methods. For general purpose, the missile dynamics approach will use non-linear equation of motions. The control surface that will be discussed follow the rule BTT (Bank-to-Turn) and control system that will be used is PID control system that widely used for control design. Lastly, the guidance method that will be studied here is proportional navigation and constant bearing course approach. The simulation will be conducted using MATLAB Simulink. The Simulink model consist of target dynamics, and guidance system. From the result of simulation, it will be shown that the missile can pursue its target quite well. Hence, the simulation system can be used well for preliminary design purpose.Keywords—Homing System, Control System, Proportional Navigation, Missile Dynamics, Seeker, Bank-to-Turn, Constant Bearing Course.

RADAR Cross Section Measurement And Imaging RRelated To Ship Target In The Sea Environment

Study on electromagnetic scattering related to ship target in the sea environment is always an important topic in anti-ship missile radar seeker detection. A airborne radar has developed for radar cross section (RCS) measurements and imaging. Studied the target tracking algorithm, which is based on the Global Position System and video image, by this means, the stable tracking technique based on mobile platform was solved. Compared the measured data with the numerical results, the result shows a good agree. It is indicated that the system can be used to measure and analyze wideband electromagnetic scattering characteristic for arbitrary shape targets.