Guidance system having a body fixed seeker with an adjustable look angle

• US 6,181,988 B1
• Filed: 04/07/1998
• Issued: 01/30/2001
• Est. Priority Date: 04/07/1998
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Coleman, Guy B., Schneider, Arthur J.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): GIBSON, ERIC M
• Application Number:
  US09/056,490
• Time in Patent Office: 1,029 Days
• Field of Search: 701/1, 701/3, 701/4, 244/3.14, 244/3.15, 244/3.16
• US Class Current: 701/3
• CPC Class Codes: F41G 7/2213 maintaining the axis of an orientable seeking head pointed at the target, e.g. target seeking gyro
• CPC Class Codes: F41G 7/2253 Passive homing systems, i.e. comprising a receiver and do not requiring an active illumination of the target
• CPC Class Codes: F41G 7/2293 using electromagnetic waves other than radio waves

Abstract

A missile guidance system with a fixed body missile seeker having an adjustable look angle. The missile seeker has a fixed camera whose look angle is adjustable to keep a moving target within the field of view of the camera. The target is tracked by a tracker to generate target angle and line of sight rate signals. The target angle signal is input to pointing angle adjustment apparatus which adjusts the look angle of the camera. The pointing angle adjustment apparatus may comprise a stepper motor that controls the angular position of a gimbal on which the camera is mounted. Alternatively, the pointing angle adjustment apparatus may comprise one or more stepper motors that control an adjustable zoom lens or a plurality of optical wedges, respectively. A body angular rate output signal of a body-fixed inertial measurement system is summed with the line of sight rate signals from the tracker to determine the inertial line of sight rate of the moving target. The inertial line of sight rate is driven to zero or a low fixed value by a control system to accurately track a target. The control system and missile dynamics generate a body angle signal that is input to a difference circuit along with a camera pointing angle signal output by the pointing angle adjustment apparatus. The difference circuit generates a desired camera pointing angle that is input to the pointing angle adjustment apparatus to point the camera at the target.

Claims

1. A missile guidance system for guiding a missile toward a moving target, said guidance system comprising:

a body fixed inertial measurement system disposed on the missile that outputs an angular rate signal indicative of the angular rate of the body of the missile;

a control system that processes an inertial line of sight rate signal to produce control signals that control the flight of the missile;

missile dynamics for processing the control signals from the control system to steer the missile toward the moving target and for generating a body angle output signal indicative of the body angle of the missile; and

a seeker comprising;

a camera that is fixed relative to the body of the missile and that has an adjustable pointing angle;

a target tracker coupled to the camera that processes video output signals therefrom to track the moving target, for generating a line of sight rate output signal indicative of the line of sight rate of the target relative to the body of the missile, and for generating a target angle output signal that is the difference between the pointing angle of the camera and the body angle of the missile that is input to the pointing angle adjustment apparatus;

pointing angle adjustment apparatus for controlling the pointing direction of the camera to have a predetermined number of fixed settings that define predetermined pointing directions of the camera, and wherein the pointing angle adjustment apparatus generates a camera pointing angle output signal that is indicative of the camera pointing angle to the target relative to the body of the missile;

a summing device having a first input for receiving the line of sight rate output signal from the tracker and a second input for receiving the angular rate signal output by the body fixed inertial measurement system, and for summing the signals to produce an inertial line of sight rate signal;

a difference circuit having a first input for receiving the camera pointing angle output signal and having a second input for receiving the body angle output signal, for generating a camera pointing angle signal indicative of the desired pointing angle of the camera;

and wherein the camera pointing angle signal is input to the pointing angle adjustment apparatus which adjusts the pointing angle of the camera to a selected one of the predetermined pointing angles that points the camera at the moving target.

2. The guidance system of claim 1 wherein the pointing angle adjustment apparatus comprises a stepper motor that is coupled to a gimbal.

3. The guidance system of claim 1 wherein the pointing angle adjustment apparatus comprises two stepper motors that are respectively coupled to two rotatable optical wedges.

4. The guidance system of claim 1 wherein the pointing angle adjustment apparatus comprises a stepper motor that is coupled to a zoom lens that is adjustable to stop at selected fields of view under control of the stepper motor.