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Zhang Z.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Luo S.,Luoyang Optoelectro Technology Development Center
Aerospace Science and Technology | Year: 2013

The terminal guidance problem for missiles intercepting maneuvering targets with terminal impact angle constraints is investigated. Regarding the target acceleration as an unknown bounded disturbance, novel guidance laws based on integral sliding mode control (ISMC) method technique are developed. The first one is a linear integral sliding mode (ISM) guidance law, which can guarantee the line-of-sight (LOS) angular rate and the LOS angle asymptotical convergence with infinite time. To further improve the convergence characteristics of guidance system, a nonlinear ISM guidance law is developed, which guarantees the LOS angular rate and LOS angle finite-time convergence characteristics. However, to guarantee the guidance system has a good performance for dealing with target acceleration, the switch gains of both linear and nonlinear ISM guidance laws need to be chosen larger than the bound of the target acceleration. It will lead to chattering problem. To reduce the chattering phenomenon and improve the performance of system, nonlinear disturbance observer (NDOB) is employed to estimate the target acceleration. The estimated acceleration is used to compensate to actual target acceleration. Then, two novel composite guidance laws combining linear and nonlinear ISM guidance laws with feedforward compensation terms based on NDOB are developed. Finally, simulation comparison results are provided to demonstrate the effectiveness of the proposed methods. © 2013 Elsevier Masson SAS. All rights reserved.


Zhang Z.,Nanjing Southeast University | Li S.,Nanjing Southeast University | Luo S.,Luoyang Optoelectro Technology Development Center
Transactions of the Institute of Measurement and Control | Year: 2013

For the terminal phase of tactical missiles intercepting maneuvering targets, the terminal guidance problem is studied. Based on an integral sliding mode (ISM) control method and nonlinear disturbance observer technique, a novel composite guidance law is designed in the case of constrained impact angle and a first-order-lag autopilot. Regarding the target acceleration and the external disturbance of autopilot as unknown bounded disturbance, a nonlinear ISM guidance law is designed. The obtained guidance law guarantees the line-of-sight (LOS) angular rate and LOS angle a finite-time convergence characteristics. Then, to alleviate the chattering problem and guarantee the disturbance rejection performance, the composite guidance law combining the ISM guidance law with feedforward compensation terms based on nonlinear disturbance observers is obtained. Finally, simulation comparison results are provided to demonstrate the effectiveness of the presented methods. © The Author(s) 2013.


Wei P.,Luoyang Optoelectro Technology Development Center | Wei P.,CAS Shanghai Institute of Technical Physics | Li X.,CAS Shanghai Institute of Technical Physics | Li T.,CAS Shanghai Institute of Technical Physics | And 4 more authors.
Infrared Physics and Technology | Year: 2014

The surface passivation of low-temperature-deposited SiNx films has been investigated in PIN type In0.83Ga0.17As photodiodes. In contrast to SiNx films (330 C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiNx films (75 C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In 0.83Ga0.17As photodiodes, which caused reductions of dark current as large as 2-3 orders of magnitude at the same test temperature 200 K. The effects of low-temperature-deposited SiNx passivations with lowrate (∼16 nm/min) model were compared to the ones with highrate (∼100 nm/min) model. SiNx films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiNx films were studied by SIMS. The results show that the content of oxides in SiN x layer fabricated by PECVD is 2 orders of magnitude more than that in SiNx layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiNx passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiNx passivations does not show the dependence on the perimeter-to-area(P/A) of the junction. © 2013 Elsevier B.V. All rights reserved.


Zhang G.,Luoyang Optoelectro Technology Development Center | Duan C.,Luoyang Optoelectro Technology Development Center | Liao Z.,Luoyang Optoelectro Technology Development Center
Applied Mechanics and Materials | Year: 2011

Morphing wings for winged tactical missile are gaining increasing concern for their potential to improve flight performance. However, morphing wings bring some new challenges to modeling flight dynamics due to movable components. This paper develops a set of complete nonlinear model, where some additional inertial terms are included. These terms account for the impact of morphing wing on flight states and make it difficult to study dynamic characteristics of missile. Therefore, a simplified model is deduced based on some reasonable assumptions. As a result, a longitudinal dynamic model is decoupled from the complete model. To verify the model, a numerical simulation is completed. The results show that the speed of wing changing has a notable effect on motion parameters during transition from one configuration to another, that is, the rapid wing changing means the larger amplitude and the higher frequency of motion vibration. © (2011) Trans Tech Publications.


Lv H.,Luoyang Optoelectro Technology Development Center
IET Conference Publications | Year: 2013

This paper proposes a novel alternating least squares (ALS) method for joint angle and Doppler frequency estimation in bistatic multiple-input multiple-output (MIMO) radar. Via iteratively estimating the transmitting, receiving and Doppler steering vectors of multiple targets from the received signals, ALS can simultaneously obtain the two-dimensional (2-D) angles and Doppler frequency of the target. Simulation results illustrate the rapid convergence rate and high estimation accuracy of this method.


Guan Y.,Luoyang Optoelectro Technology Development Center | Wang J.,Luoyang Optoelectro Technology Development Center | Ma D.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Based on the P-N-N-P type two-color infrared focal plane array(FPA) detector structure and its equivalent circuit, the principles and realization ways of a kind of 128×128 two-color infrared focal plane readout integrated circuit(ROIC) with successively integrating and simultaneously reading out have been proposed. The cell circuit using the direct injection (DI) structure as the input stage will acquire the larger integrating capacitors. This structure meets the demand that there are two independent signal channels for both the middle and short wavelength infrareds in a cell circuit. The simulation results show that the circuit meets the predetermined design requirements, the integrating time is adjustable, the readout rate is faster than or equal to 5 MHz, the linearity of the output voltages of MW and SW reach above 99%, the power dissipation is about 68 mW. © 2015 SPIE.


Zhang L.,Luoyang Optoelectro Technology Development Center | Zhang X.,Luoyang Optoelectro Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

InAs/GaSb superlattice material was grown on GaAs substrates by Molecular-beam epitaxy(MBE). To study the Ohmic contact and electrical property of InAs/GaSb superlattices, the Au//Ti/InAs/GaSb superlattices contact was fabricated using heated electron evaporation methods on the surface of InAs/GaSb superlattices. The Au//Ti/InAs/GaSb superlattices contact character was analyzed by transmission line model. The results show that Au//Ti/InAs/GaSb superlattices contact is the Ohmic contact with good contact resistivity. And it meets requirement of Ohmic contact with the perfect quality. The electrical properties of InAs/GaSb superlattices were tested by Van Der Pauw. That means the leak current decrease as the carriers density reaches to a lower level. At the meantime, the detector obtains a better background noise and energy resolution. © 2012 SPIE.


Guo C.,Northwestern Polytechnical University | Liang X.-G.,Luoyang Optoelectro Technology Development Center
International Journal of Aeronautical and Space Sciences | Year: 2014

This paper proposes a novel guidance law based on the block backstepping sliding mode control and extended state observer (ESO), which also takes into account the autopilot dynamic characteristics of the near space interceptor (NSI), and the impact angle constraint of attacking the maneuvering target. Based on the backstepping control approach, the target maneuvers and the parameter uncertainties of the autopilot are regarded as disturbances of the outer loop and inner loop, respectively. Then, the ESO is constructed to estimate the target acceleration and the inner loop disturbance, and the block backstepping sliding model guidance law is employed, based on the estimated disturbance value. Furthermore, in order to avoid the "explosion of complexity" problem, first-order low-pass filters are also introduced, to obtain differentiations of the virtual control variables. The stability of the closed-loop guidance system is also proven, based on the Lyapunov theory. Finally, simulation results demonstrate that the proposed guidance law can not only overcome the influence of the autopilot dynamic delay and target maneuvers, but also obtain a small miss distance. © The Korean Society for Aeronautical & Space Sciences.


Guo C.,Northwestern Polytechnical University | Liang X.-G.,Luoyang Optoelectro Technology Development Center
International Journal of Aeronautical and Space Sciences | Year: 2014

A novel robust H∞ switching tracking control design method with disturbance observer is proposed for the near space interceptor (NSI) with aerodynamic fins and reaction jets. Initially, the flight envelop of the NSI is divided into small subregions, and a slow-fast loop polytopic linear parameter varying (LPV) model is proposed, to approximate the nonlinear dynamic of the NSI, based on the Jacobian linearization and Tensor-Product (T-P) model transformation approach. A disturbance observer is then constructed, to estimate the modeled disturbance. Subsequently, based on the descriptor system method, a robust switching controller is developed, to ensure that the closed-loop descriptor system is stable with a desired H∞ disturbance attenuation level. Furthermore, the outcome of the proposed switching tracking control problem is formulated as a set of linear matrix inequalities (LMIs). Finally, simulation results demonstrate the effectiveness of the proposed design method. © The Korean Society for Aeronautical & Space Sciences.


Guo C.,Northwestern Polytechnical University | Liang X.-G.,Luoyang Optoelectro Technology Development Center
International Journal of Aeronautical and Space Sciences | Year: 2014

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closedloop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time. © The Korean Society for Aeronautical & Space Sciences.

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