Optical attitude reference

• US 4,072,281 A
• Filed: 12/27/1976
• Issued: 02/07/1978
• Est. Priority Date: 12/27/1976
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Miller, Walter E. Jr., Sitton, Robert L., Blackmon, Anthony D.
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Eisenzopf, Reinhard J.
• Application Number:
  US05/754,204
• Time in Patent Office: 407 Days
• Field of Search: 244/3.16, 244/171, 244/176, 244/190, 250/203 R, 250/225, 318/585, 318/640, 356/148
• US Class Current: 244/3.16
• CPC Class Codes: F41G 7/26 Optical guidance systems

Abstract

The optical attitude reference system provides missile attitude reference ing an optical beam in lieu of conventional gyroscopes. In the missile control systems autopilot, the system uses the properties of polarized light to determine missile roll angle relative to the beam transmitter reference axes at the launch site.

Claims

1. Apparatus for providing optical attitude reference for a missile comprising:

transmitter means for directing optical energy from a fixed station toward said missile;

optical detector means on said missile responsive to optical energy from said transmitter for providing electrical output signals;

a prism disposed on said missile adjacent said optical detector means and between said optical detector and said transmitter, said prism having an ordinary ray output and an extraordinary ray output, said prism being disposed for polarizing optical energy from said transmitter prior to said energy being received by said optical detector;

said optical detector means comprises first and second detectors disposed to receive said ordinary and extraordinary prism outputs respectively and provide an electronic output signal responsive thereto;

first and second amplifiers disposed respectively to receive inputs from said first and second detectors to provide output signals responsive thereto and a differential amplifier coupled to receive said first and second amplifier output signals for providing an output signal;

filter means disposed to receive the differential amplifier output for providing an output signal for coupling to indicator or load circuitry; and

ambiguity means coupled to the output of said filter means for selectively providing a predetermined output signal;

said ambiguity means comprising a limiting amplifier coupled to the output of said differential amplifier, a flip-flop coupled to the output of said limiting amplifier for providing a square wave frequency output at one-half the frequency output of said limiting amplifier, said flip-flop having both an inverted and a non-inverted output;

first and second signal channels having inputs coupled respectively to said flip-flop outputs;

an OR gate having first and second inputs and an output, said OR gate being coupled to receive output signals from said first and second channels and provide an output signal when said predetermined flip-flop output is present on either channel;

each of said channels comprising, in series, a first AND gate, a low pass filter, a comparator, a latching circuit, and a second AND gate, said first AND gate being coupled to respective outputs of said flip-flop and said second AND gate being coupled to provide an input to said OR gate;

each of said first AND gates being adapted to receive a reference signal input from an external source; and

inhibit means coupled to each of said latching circuits for preventing simultaneous operation of said latches.

2. An optical attitude reference apparatus as set forth in claim 1 wherein said first and second amplifiers are logarithmetic amplifiers.

3. Apparatus for providing optical attitude reference for a missile comprising:

transmitter means for directing optical energy from a fixed station toward said missile;

optical detector means on said missile responsive to optical energy from said transmitter for providing electrical output signals;

polarizing means on said missile disposed adjacent said optical detector means and between said optical detector and said transmitter, said polarizing means being disposed for polarizing optical energy from said transmitter prior to said energy being received by said optical detector;

amplifier means responsive to the output of said detector; and

filter means disposed to receive said amplifier output for providing an output signal for coupling to indicator or load circuitry; and

wherein said polarizer is a Nicol prism;

said optical detector means comprises first and second photodetectors, each having four outputs for indicating two axis light position on the surface of the respective detectors;

first and second summing circuits coupled to respective first and second photodetector outputs for summing said outputs; and

outputs from said first and second summing circuits being coupled to said amplifier means for providing said indicator output signal indicative of missile roll angle.

4. A optical attitude reference apparatus as set forth in claim 3 and further comprising a third summing network having inputs coupled to receive the outputs of said first and second summing networks for providing a total sum output indicative of the composite transmitter signal impinging on said optical detector.

5. An optical attitude reference apparatus as set forth in claim 4 and further comprising a body axis determination circuit comprising fourth and fifth summing circuits and a first difference circuit, said fourth and fifth summing circuits each having first and second inputs coupled respectively to first and second of said four outputs of said photodetectors respectively, and having respective outputs coupled as inputs to said first difference circuit;

said difference circuit providing an output indicative of light impinging on said photodetectors representing a missile attitude reference signal output.

6. Apparatus for providing optical attitude reference for a missile comprising:

transmitter means for directing optical energy from a fixed station toward said missile;

optical detector means on said missile responsive to optical energy from said transmitter for providing electrical output signals;

polarizing means on said missile disposed adjacent said optical detector means and between said optical detector and said transmitter, said polarizing means being adapted for polarizing optical energy from said transmitter prior to said energy being received by said optical detector;

amplifier means responsive to the output of said detector; and

filter means disposed to receive said amplifier output for providing an output signal for coupling to indicator or load circuitry; and

ambiguity means coupled to the output of said filter means for selectively providing a predetermined output signal;

said ambiguity means comprising a limiting amplifier coupled to the output of said filter means for providing a square wave output in response to the input thereto;

a flip-flop circuit coupled to the output of said limiting amplifier for providing a square wave frequency output at one-half the frequency output of said limiting amplifier, said flip-flop having both an inverted and non-inverted output square wave output frequency;

first and second signal channels having inputs coupled respectively to said flip-flop outputs;

an OR gate having first and second inputs and an output, said OR gate being coupled to receive output signals from said first and second channels and provide an output signal when said predetermined flip-flop output is present on either channel, and wherein each of said channels comprise, in series, a first AND gate, a lowpass filter, a comparator, a latching circuit, and a second AND gate, said first AND gate being coupled to an output of said flip-flop and said second AND gate being coupled to provide an input to said OR gate; and

each of said first AND gates being adapted for coupling to receive a reference signal input from an external source.

7. An optical attitude reference apparatus as set forth in claim 6 wherein each channel of said ambiguity circuit further comprises a NOR gate having an output coupled to said latching circuit and an input coupled to receive an output from the other channel latching circuit for allowing operation of only one of said latches.