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Ghosh S.,Indian Institute of Science | Ghosh S.,Control Decision Systems Laboratory | Ghose D.,Indian Institute of Science | Ghose D.,Control and Decision Systems Laboratory | And 2 more authors.
Journal of Guidance, Control, and Dynamics | Year: 2014

This paper proposes a variation of the pure proportional navigation guidance law, called augmented pure proportional navigation, to account for target maneuvers, in a realistic nonlinear engagement geometry, and presents its capturability analysis. These results are in contrast to most work in the literature on augmented proportional navigation laws that consider a linearized geometry imposed upon the true proportional navigation guidance law. Because pure proportional navigation guidance law is closer to a realistic implementation of proportional navigation than true proportional navigation law, and any engagement process is predominantly nonlinear, the results obtained in this paper are more realistic than any available in the literature. Sufficient conditions on speed ratio, navigation gain, and augmentation parameter for capturability, and boundedness of lateral acceleration, against targets executing piecewise continuous maneuvers with time, are obtained. Further, based on a priori knowledge of the maximum maneuver capability of the target, a significant simplification of the guidance law is proposed in this paper. The proposed guidance law is also shown to require a shorter time of interception than standard pure proportional navigation and augmented proportional navigation. To remove chattering in the interceptor maneuver at the end phase of the engagement, a hybrid guidance law using augmented pure proportional navigation and pure proportional navigation is also proposed. Finally, the guaranteed capture zones of standard and augmented pure proportional navigation guidance laws against maneuvering targets are analyzed and compared in the normalized relative velocity space. It is shown that the guaranteed capture zone expands significantly when augmented pure proportional navigation is used instead of pure proportional navigation. Simulation results are given to support the theoretical findings. Copyright © 2014 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Kumar S.R.,Indian Institute of Science | Kumar S.R.,Control and Decision Systems Laboratory | Rao S.,Indian Institute of Science | Rao S.,Control and Decision Systems Laboratory | And 2 more authors.
Journal of Guidance, Control, and Dynamics | Year: 2012

In this paper, sliding-mode-control-based guidance laws to intercept stationary, constant-velocity, and maneuvering targets at a desired impact angle are proposed. The desired impact angle, which is defined in terms of a desired line-of-sight angle, is achieved in finite time by selecting the missile's lateral acceleration to enforce terminal sliding mode on a switching surface designed using nonlinear engagement dynamics. The conditions for capturability are also presented. In addition, by considering a three-degree-of-freedom linear-interceptor dynamic model and by following the procedure used to design a dynamic sliding-mode controller, the interceptor autopilot is designed as a simple static controller to track the lateral acceleration generated by the guidance law. Numerical simulation results are presented to validate the proposed guidance laws and the autopilot design for different initial engagement geometries and impact angles. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.


Mukherjee D.,Indian Institute of Science | Mukherjee D.,Control and Decision Systems Laboratory | Ghose D.,Indian Institute of Science | Ghose D.,Control and Decision Systems Laboratory
Journal of Guidance, Control, and Dynamics | Year: 2013

Two strategies for shifting the right half-plane (RHP) zero(s) of a non-minimum-phase interceptor to the left half-plane (LHP) were proposed. Some neoclassical approaches were adopted using the small-gain theorem and the method of adjoints to obtain small miss distances. One of these neoclassical laws, zero miss distance proportional navigation guidance (ZMD PNG), achieves this objective for any flight time against both deterministic and random target maneuvers. The controllers proposed do not ensure strict positive realness (SPR) conditions, but merely shifting the right half-plane zero to the left half-plane reduced the miss distance considerably. Although not exactly zero (as SPR conditions are not met), these miss distance values are of the same order as those obtained for minimum-phase interceptors using zero miss-distance proportional navigation guidance.

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