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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. Source


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. Source


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. Source


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. Source


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. Source

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