Design of Guidance and Control Systems for Tactical Missiles

Qi Zaikang, Lin Defu

• Publisher: CRC Press
• Year: 2019
• Print ISBN: 9780367260415
• eBook ISBN: 9781000681215
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Design of Guidance and Control Systems for Tactical Missiles presents a modern, comprehensive study of the latest design methods for tactical missile guidance and control. It analyzes autopilot designs, seeker system designs, guidance laws and theories, and the internal and external disturbances affecting the performance factors of missile guidance control systems. The text combines detailed examination of key theories with practical coverage of methods for advanced missile guidance control systems. It is valuable content for professors and graduate-level students in missile guidance and control, as well as engineers and researchers who work in the area of tactical missile guidance and control.

1

The Basics of Missile Guidance Control

CONTENTS

1.1Overview

1.2Missile Control Methods

1.1 Overview

The purpose of missile control is to make the missile hit the target at the end of its flight. In order to achieve this goal, it is essential for the missile to constantly acquire the motion information of the target and of the missile itself in the course of the flight and adopt a tactic (that is a guidance law) to decide how to change the missile’s velocity direction based on the current missile and target relative motion, allowing the missile to finally hit the target. The relationship between the angular velocity θ˙ of the missile velocity vector and its normal acceleration a of the missile, is as follows:

θ˙=aV(Vis the missile velocity).	(1.1)

Therefore, the command of a guidance law that is generated to change the missile velocity vector direction is usually the normal acceleration a_c of the missile. This missile and target interception control loop is quite different from the conventional tracking control loop; the former is a time-varying control system, and its analysis method is completely different from the general linear time-invariant time-domain and frequency-domain analysis method. So a special term (guidance loop) has historically been given to this particular missile control outer loop.

With the help of autopilots, the missile output acceleration a will follow the above guidance acceleration command a_c. Under the assumptions of small perturbation, linearization and constant system parameter value, this autopilot loop is a linear time-invariant system and so different traditional control theory design methods can all be applied. Therefore, the autopilot loop that acts as the guidance inner loop historically is still referred to as the control loop.

The missile position and velocity information needed in the guidance process are obtained by an inertial navigation or integrated inertial navigation system. The process of obtaining the missile position and orientation information is called navigation. It is noteworthy that the term navigation here does not refer to the historical definition of directing the course of a ship or an aircraft. Fig. 1.1 shows the relationships between the terms navigation, guidance and control in missile control loops.

Fig. 1.1: Block diagram of the missile guidance and control loops

1.2 Missile Control Methods

It has been stated before that the task of a missile control system is to use missile normal acceleration to change the missile’s velocity direction according to the guidance law command. For tactical missiles flying in the atmosphere, this normal acceleration is generated by normal aerodynamic forces. As we know, when the missile has an angle of attack with respect to its velocity vector, the corresponding lift will produce a normal acceleration. However, for the missile to maintain a steady angle of attack, this angle of attack induced aerodynamic moment must be balanced by the control surface deflection induced control moment.

When the center of gravity of the missile is located in front of the center of pressure, the angle of attack generated aerodynamic moment will decrease the existing angle of attack and meanwhile, the x-axis of the missile body will try to coincide with the missile velocity axis. This type of aerodynamic layout is known as a statically stable aerodynamic configuration (Fig. 1.2). However, when the center of pressure of the missile is in front of its center of gravity, the existing angle of attack will continuously increase under the action of its corresponding destabilizing aerodynamic moment. Therefore, the missile is in a divergent state. This aerodynamic layout is called a statically unstable aerodynamic configuration (Fig. 1.3).

Fig. 1.2: Missile in a statically stable aerodynamic configuration

Fig. 1.3: Missile in a statically unstable aerodynamic configuration

In general, there are three types of aerodynamic configurations for the generation of a missile control moment:

(1) Normal aerodynamic configuration

In this aerodynamic configuration, the missile actuator is arranged at the tail of the missile (Fig. 1.4). The benefit of this configuration is that when the control moment is balanced by the angle of attack produced moment, the control surface incident angle is the difference between the control surface deflection angle and the angle of attack, which is the most efficient way of using the control deflection angle, thus allowing the use of a larger control surface deflection and larger angle of attack for maneuvering. But the drawback is that the position of the actuator in this configuration coincides with the rear end motor, which places certain restrictions on the size of the actuator. In addition, when the missile is to maneuver, the control surface force is in the opposite direction to the angle of attack produced normal force, which will cause some total normal force loss. However, taking these advantages and disadvantages into account, this configuration is still the most commonly used aerodynamic configuration for tactical missiles.

Fig. 1.4: Normal aerodynamic configuration

(2) Canard aerodynamic configuration

In this aerodynam...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Authors
• 1. The Basics of Missile Guidance Control
• 2. Missile Trajectory Models, Aerodynamic Derivatives, Dynamic Coefficients and Missile Transfer Functions
• 3. Basic Missile Control Component Mathematical Models
• 4. Autopilot Design
• 5. Guidance Radar
• 6. Line of Sight Guidance
• 7. Seekers
• 8. Proportional Navigation and Extended Proportional Navigation Guidance Laws
• Appendices
• Bibliography
• Index