Seeker-body decoupling system

• US 4,508,293 A
• Filed: 07/12/1982
• Issued: 04/02/1985
• Est. Priority Date: 07/12/1982
• Status: Expired due to Term

• Current Assignee: Hughes Missile Systems Company
• Original Assignee: General Dynamics
• Inventors: Jones, Richard W.
• Primary Examiner(s): Jordan, Charles T.
• Application Number:
  US06/397,255
• Time in Patent Office: 995 Days
• Field of Search: 244/3.15, 244/3.16, 244/3.19, 244/3.2, 244/3.21, 318/648
• US Class Current: 244/3.15
• 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 7/226 Semi-active homing systems, i.e. comprising a receiver and involving auxiliary illuminating means, e.g. using auxiliary guiding missiles
• CPC Class Codes: F41G 7/2286 using radio waves
• CPC Class Codes: G05D 1/12 Target-seeking control

Abstract

An improved airframe body decoupling system for a body gimballed sensor on an interceptor aircraft or guided missile. Body rate gyro information is employed for internal decoupling so as to eliminate decoupling match sensitivity to receiver errors. The true measure of sensor position from the gimballed antenna potentiometer is differentiated and then externally decoupled to produce the desired line-of-sight rate for use by the guidance/control section of the proportional navigation guidance system.

Claims

1. A method for body motion decoupling of a body gimballed antenna in a proportional navigation missile guidance system for a missile airframe, said guidance system comprising a track loop, a guidance/control section and a body rate gyro having a body rate output ψ

, said track loop having inputs representing body angle ψ and

LOS angle δ and

deriving antenna angle θ

, said track loop including a loop gain K.sub.ε and

measurement errors which together comprise a receiver, said method comprising the steps of;

combining angles δ and

θ

at a first combining point to provide an output signal ε

representing the antenna pointing error;

multiplying the angle ε

by said measurement errors and said loop gain to provide a first measured LOS rate σ

'"'"' at the output of said receiver;

combining LOS rate σ

'"'"' and body rate ψ

'"'"' at a second combining point to provide antenna command signal β

_c =σ

'"'"'-ψ

'"'"';

applying said command signal to a gimbal rate servo to position said antenna, the output of said gimbal rate servo being the antenna position with respect to the airframe or look angle β

where β

=σ

"-ψ

'"'"';

coupling said body angle ψ and

said look angle β

at a third combining point to provide said antenna angle θ

;

differentiating said look angle β

to provide σ

"-ψ

'"'"'; and

combining said body rate ψ

'"'"' with σ

"-ψ

'"'"' at a fourth combining point to provide a refined second LOS rate

σ

" for use by said guidance/control section of said guidance system.

2. The method recited in claim 1 wherein said body rate ψ

is multiplied by decoupling gain G_I prior to combining with σ

'"'"'.

3. The method recited in claim 2 wherein said body rate ψ

is multiplied by decoupling gain G_E prior to combining with σ

"-ψ

'"'"'.

4. The method recited in claim 3 wherein said gimbal rate servo includes a servo rate loop and said missile guidance system includes an autopilot for controlling the missile airframe, wherein the response time of said servo rate loop is in the order of ten times faster than the response time of said autopilot/airframe.

5. The method recited in claim 4 wherein said decoupling gains G_I and G_E have a value of unity.

6. Apparatus for decoupling body motion in a proportional navigation missile guidance system having a body gimballed antenna, a track loop signal processor and a guidance/control section which includes an autopilot for controlling the missile airframe, said track loop having inputs representing LOS angle σ

and antenna angle θ

, the receiver output of said track loop being a measured of LOS rate σ

'"'"', the LOS angle being applied to a gimbal rate servo, the output of said servo being a measure of the antenna look angle β

where β

is a function of LOS angle σ and

missile body angle ψ

, in the form β

=σ

"-ψ

'"'"', the look angle being combined with the body angle ψ

to provide said antenna angle θ

, wherein the improvement comprises;

a first combining point connected between the output of said receiver and said servo;

a body rate gyro having an output signal ψ

'"'"' coupled to said first combining point to combine body rate ψ

'"'"' with LOS rate σ

'"'"' at the input of said rate servo, thereby internally decoupling said body rate from said track loop;

a differentiator coupled to the output of said rate servo to differentiate the look angle signal σ

"-ψ

'"'"' to provide σ

"-ψ

'"'"';

a second combining point connected to the output of said differentiator;

said body rate gyro being coupled to said second combining point to combine body rate ψ

'"'"' with σ

"-ψ

'"'"', thereby externally decoupling said body rate from said track loop;

whereby the output of said second combining point is a refined LOS rate σ

" which is adapted to be employed by said guidance/control section of said guidance system.

7. The apparatus recited in claim 6 wherein said gimbal rate servo comprises a servo rate loop, the response time of said servo rate loop being in the order of ten times faster than the response time of said autopilot/airframe.

8. The apparatus recited in claim 6 wherein the input signal to said gimbal rate servo is β

_c =σ

'"'"'-ψ

'"'"', the positioning command signal for said antenna.