Fumiaki Imado

High-g Barrel Roll Maneuvers Against Proportional Navigation from Optimal Control Viewpoint

Our previous studies showed that the high- g barrel roll (HGB) maneuver generally produces very large miss distanceagainstproportionalnavigationmissiles.Theperformanceofthismaneuverisdiscussedfromtheviewpoint of optimal control. Numerically obtained three-dimensional optimal evasive maneuvers of a e ghter against a proportional navigation missile were those of vertical-S type and horizontal-S type, which are two dimensional in nature. It is shown that the HGB is regarded as a kind of approximation of these optimal maneuvers; however, the HGB is easier to implement than the optimal maneuvers, and we may still insist on the practical effectiveness of the HGB. Nomenclature acmax = missile lateral acceleration command limit ap, ay, apc, ayc = missile pitch- and yaw-axis lateral accelerations and their command signals at = aircraft normal acceleration g = acceleration of gravity h = altitude

A Study on the Optimal Flight Control for an Autonomous UAV

This paper proposes a method, which employs the optimal flight controls of a point mass model to a rigid body model, in order to realize the optimal flights for an autonomous UAV. All parameters of the point mass model need to be decided by the comparison of both models simulation results with a flight simulator, of which the point mass model as well as the rigid body model is incorporated into the simulation programs. The 4 control inputs for the rigid body model have to be produced properly in the attitude control systems. Some simulation results showed good correspondence and justified our approach. Both flight trajectories also corresponded approximately only in the case of the moderate flight maneuvers

The Application of an UAV Flight Simulator - The Development of a New Point Mass Model for an Aircraft

This paper proposes a new point mass model for an aircraft. The model was developed in order to realize realistic flight maneuvers utilizing the side-slip condition of an UAV precisely. Unlike a traditional point mass model, it has 4 control variables, that is, the side-slip angle is chosen as one more control variable in addition to 3 control variables: the angle-of-attack, bank angle, and total engine thrust. The model as well as a traditional point mass model with 3 control variables was incorporated into the simulation programs of an UAV flight simulator. The comparison results of the landing approach maneuvers with the flight simulator demonstrated the effectiveness of our proposed point mass model

A Study about Optimal Orbit Control of Dive and Ascent Satellite

Dive and ascent satellite (DAS) is a kind of satellite that can approach very close to the Earth, which was designed by National Aerospace Laboratory (NAL) of Japan in later 1970s. Now we noted the function of the satellite that can descend and ascend, and proposed to use it for getting detailed information of the area stricken by a natural disaster. In this paper optimal orbit control of DAS is discussed, where the Earth is treated as an ellipsoid of revolution, and the atmosphere drag and the second zonal coefficient is considered. The optimal orbit control problems are treated as nonlinear two point boundary value problems, and solved by the steepest ascent method (STP)

A METHOD TO SOLVE MISSILE-AIRCRAFT PURSUIT-EVASION DIFFERENTIAL GAMES

Abstract This paper shows; that, in some conditions we can obtain the exact solution for a missile and an aircraft differential games which minimizes and maximizes the essential pay-off of the problem: the miss distance, without employing any linearized approximation. The idea of our method is, by starting from the aircraft one-sided optimal control solution against a PNG missile, which maximizes the miss distance, and then optimize the missile control to minimize the miss distance. The obtained minimax solution shows the resultant miss distance is far smaller than that of the PNG missile. Although it is impossible to obtain the solution in real time, however, if the results are incorporated into the missile guidance system as a knowledge base, the performance will be fairly improved. The extension of the study into more general cases is also explained.

Is the augmented proportional navigation really useful

Augmented proportional navigation requires the information of a target acceleration, which must be estimated by a filtering logic. The process necessary accompanies a time lag, which degrades the guidance performance. A trade-off study between augmented and conventional proportional navigation is conducted with the time lag taken into consideration. The result shows that, the augmented proportional navigation has good performance even if a time lag exists in estimating the target acceleration, and is particularily useful against the target out-of coplane maneuvers.

The optimal orbital control of the dive and ascent earth observing satellite

In this paper, we propose observing the particular area which is in the emergency situation or suffered by a natural disaster with the Dive and Ascent earth observing Satellite (DAS). We selected the forces of the thrusters fixed to the satellite body three axes as the control variables, and obtained the optimal thrust patterns by using the Steepest Descent Method (SDM). Some of new ideas and study results are presented.

The Development of Three-Dimensional Scale Model UAV Simulator

This is the study about the development of a three-dimensional UAV scale model flight simulator (SMS). In a conventional flight simulator, the target configuration viewed from the cockpit is exhibited in a two dimensional screen, while the purpose of the SMS is to exhibit the movement of the target in a three-dimensional space. The SMS is composed of a conventional UAV simulator and manipulators to express the movement of the target. In this study, a small miniature aircraft is mounted on the end effector of a 6-link manipulator. The model aircraft is drived to follow the output of the UAV simulator, and reproduce the three-dimensional maneuver of the aircraft. The purpose is to give a geometrical insight of a UAV to the operator. In this paper, some basic study results are shown, which assured the feasibility of this SMS

SOME FEATURES OF THE GAME BETWEEN THE SUPERSONIC ASM AND THE COUNTERATTACK AMM

An advanced RF surface-to-air missile (SAM) system is accompanied by ground radars, missiles, and launchers, which are very vulnerable to air-to-surface missiles (ASMs). This paper studies the threat of ASMs and an IR homing anti-missile-missile (AMM) system which defends the SAM site. A supersonic highly maneuverable ASM is assumed and the performance required for this counterattack AMM is briefly studied. The interception problem between the ASM and the AMM is considered as a game and some features of the game are discussed and an approach is explained.

An elementary study on a guidance of a rotating high speed vehicle

A method of controlling a spinning missile by gas jet impulses is studied and presented. The spinning effect of the vehicle is to average the uncertain aerodynamic force and give the stability by its gyro momentum. However, the missile spin axis has the minimum moment of inertia, therefore the induced nutation will diverge unless it is actively dumped. The principle of the induction of the nutation and its active damping algorithm are explained first. An attitude control system of a missile by gas jet impulses is designed and simulations are conducted. The result showed fine performance. However, in a practical application, many problems are left to be solved.