Sharif Digital Repository

In this paper, midcourse guidance strategies are derived considering approximate models for drag and thrust in the presence of gravity and autopilot dynamics. The guidance/control system is assumed as a linear time-varying and of arbitrary-order. The zero-effort miss differential equation is obtained in a way that three classes of guidance laws, namely optimal fuel, optimal energy, and closed-loop explicit strategy, can be derived by available methods for minimum and nonminimum phase autopilots. The resulting guidance laws have the structure of a guidance gain multiplied by the zero-effort miss. Several thrust/drag models arc also considered and discussed to obtain the effective navigation... 

In this paper a novel non-rotating space tethered configuration is introduced which its relative positions controlled using electromagnetic forces. The attitude dynamics is controlled by three reaction wheels in the body axes. The nonlinear coupled orbital dynamics of a dumbbell tethered satellite formation flight are derived through a constrained Lagrangian approach. These equations are presented in the leader satellite orbital frame. The tether is assumed to be mass-less and straight, and the J2 perturbation is included to the analysis. The forces and the moments of the electromagnetic coils are modeled based on the far-filed model of the magnetic dipoles. A guidance scheme for generating... 

A heuristic predictive line-of-sight (LOS) guidance law is introduced to intercept a high-speed maneuvering target. A combination of continuous ant colony system and tabu search optimization algorithms is proposed to generate the optimal predictive commands of LOS guidance law. Prediction is driven by the previous positions of the target to estimate the next positions of it. Thus, the guidance system is continually solving a dynamic optimization problem in order to determine the acceleration commands by minimizing a cost function subject to actuators saturation. This innovation distinguishes the proposed guidance law from the classic LOS guidance, described by a simple relation between the... 

This paper is concerned with the problem of guidance filter design for a homing air defense missile using measurements of an on-board pitch-yaw gimballed seeker mechanism. This problem possess a highly nonlinear dynamic which is influenced by various error sources such as seeker's stabilization loop torque disturbances originated from pursuer's accelerations and angular velocities, significant channel couplings, time-delayed and noisy measurements of optical sensor besides the unknown target maneuvers. To handle the inherent nonlinearity of problem a wide variety of assumptions are made in literature to derive simplified engagement kinematics. In present work, performance degradations which... 

In this study, the guidance and control problem of a single-channel spinning missile is investigated. The missile utilizes a single ON-OFF actuator to drive a pair of control surfaces (e.g. elevators) and consequently to perform all required lateral maneouvers. An approximated linear response of the so-called non-rotating frame to ON-OFF input, applied to the rotating frame, is derived using the multiple-input describing function technique. It is shown that there is a relationship between the response of the non-rotating frame and that of the equivalent non-rotating body. It is also shown that the two-channel flight controller, designed for the equivalent non-rotating body, can be reduced to... 

To achieve an exact three-dimensional command to line of sight (CLOS) guidance law, a novel control scheme comprising feed-forward terms (to exactly compensate known kinematics) accompanied by an adaptive nested saturated feedback strategy is presented. A square-root cubature Kalman filter is designed as the CLOS non-linear guidance filter. Performance of the proposed guidance law is compared with the augmented proportional navigation (APN), at the absence and presence of target maneuvers, autopilot dynamics and non-ideal tracking filter. Simulation results demonstrate the satisfactory performance of proposed strategy. © 2018 Concern CSRI Elektropribor, JSC  

Two-dimensional engagement of a pursuer and a maneuvering target, affected by matched uncertainties, is formulated as a nonlinear differential game. The uncertain guidance problem is converted into a nonlinear model predictive control problem by introducing an appropriate cost function. The objective is to calculate the best guidance commands of the pursuer and the worst possible target maneuvers simultaneously, over a receding horizon. The proposed cost function penalizes the line-of-sight rate, the pursuer acceleration, and the uncertainties. It also rewards the target maneuver. A particle swarm-based dynamic optimization algorithm is developed to solve the nonlinear model predictive... 

Herein, a novel type of multifunctional magnetic nanoparticles with dual thermal and pH-responsive behavior was fabricated as the carrier for delivery of doxorubicin (DOX). Fe3O4@SiO2 magnetic nanoparticles, were grafted with polymer brushes consisting of poly (NIPAM-co-GMA) (PNG) chains via surface initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. The polymer brushes were then modified with hydrazine groups as DOX binding sites. The prepared multifunctional magnetic nanoparticles were characterized by FT-IR, 1H NMR, XPS, TGA, DLS, VSM, GPC, TEM, and XRD analysis. The in vitro drug release of the multifunctional magnetic nanoparticles was examined at 37 °C...