Iranian Journal of Electrical and Electronic Engineering

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In this paper, after defining pure proportional navigation guidance in the 3-

dimensional state from a new point of view, range estimation for passive homing missiles is

explained. Modeling has been performed by using line of sight coordinates with a particular

definition. To obtain convergent estimates of those state variables involved particularly in

range channel and unavailable from IR trackers, nonlinear filters such as sequential U-D

extended Kalman filter and Unscented Kalman filter in modified spherical coordinate

combined with a modified proportional navigation guidance law are proposed. Simulation

results indicate that the proposed tracking filters in conjunction with the dual guidance law

are able to provide the convergence of the range estimate for both maneuvering and nonmaneuvering

targets.

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When the process is highly uncertain, even linear minimum phase systems must sacrifice desirable feedback control benefits to avoid an excessive ‘cost of feedback’, while preserving the robust stability. In this paper, the problem of supervisory based switching Quantitative Feedback Theory (QFT) control is proposed for the control of highly uncertain plants. According to this strategy, the uncertainty region is suitably divided into smaller regions. It is assumed that a QFT controller-prefilter exits for robust stability and performance of the individual uncertain sets. The proposed control architecture is made up by these local controllers, which commute among themselves in accordance with the decision of a high level decision maker called the supervisor. The supervisor makes the decision by comparing the candidate local model behavior with the one of the plant and selects the controller corresponding to the best fitted model. A hysteresis switching logic is used to slow down switching for stability reasons. Besides, each controller is designed to be stable in the whole uncertainty domain, and as accurate in command tracking as desired in its uncertainty subset to preserve the robust stability from any failure in the switching.