Initiating device for use with telemetry systems

• US 6,332,400 B1
• Filed: 01/24/2000
• Issued: 12/25/2001
• Est. Priority Date: 01/24/2000
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Meyer, Steven J.
• Primary Examiner(s): Poon, Peter M.
• Assistant Examiner(s): Copier, Floris C.
• Application Number:
  US09/488,595
• Time in Patent Office: 701 Days
• Field of Search: 102/26, 102/215, 102/276, 102/264, 102/380, 102/222
• US Class Current: 102/264
• CPC Class Codes: F42C 15/40 wherein the safety or arming action is effected electrically

Abstract

A substitute solid state device for safely initiating a sustainer motor is provided. The substitute device replaces a mechanism that is integral to a warhead. The substitute device interfaces to a telemetry package and is suitable for insertion into small housings. A specific embodiment is a substitute interface to a telemetry system incorporating a circuit for firing a sustainer motor of a small missile or rocket. The substitute interface replaces the interface and firing circuit associated with the warhead in a missile of 2.75-inch diameter, such as the STINGER missile.

Claims

1. An action enabling apparatus, comprising:

a device, having inputs and outputs, for timing activities and for activating signals based on the occurrence of a pre-determined sequence of events;

a programmable logic device (PLD), incorporating timers and a first switch, and having inputs and outputs;

a clock, having inputs and outputs, operably connected to said PLD;

a first set of signal paths from said device to a first system, incorporating a sensor and having access to a power source, said first set of signal paths operably connected to said inputs of said PLD, said first set of signal paths comprising,

a first signal path, operably connecting said clock and said PLD, for carrying a signal from said clock,

a second signal path, operably connecting said PLD and said first system, for carrying a signal representative of event status as measured with said sensor,

a third signal path incorporating a reset circuit, operably connecting said PLD and said power source associated with said first system, for carrying a reset signal; and

a fourth signal path, operably connecting said PLD and said power source, for powering said PLD by said power source;

a second set of signal paths from said first system to a second system, said second system incorporating an initiator;

a third set of signal paths from said device to said initiator;

a second switch,

a thermal relay operably connected to said PLD through said second switch; and

a third switch operably connecting said PLD to said second system,

wherein said action enabling apparatus initiates an action in said second system only upon a proper occurrence of said pre-determined sequence of events, and

wherein said PLD has the outputs of said PLD set to a pre-determined value at receipt of said reset signal, initiated upon power up of said first system by said power source.

2. The action enabling apparatus of claim 1 wherein said first system comprises a telemetry system and said second system comprises a sustainer motor incorporating an initiator.

3. The action enabling apparatus of claim 1 wherein said second set of signal paths comprises:

a fifth signal path from said first system to said second system through said PLD, said second switch and said thermal relay for removing a path to electrical ground across the input of said initiator associated with said second system;

a sixth signal path from said first system to said second system for providing power to said initiator; and

a seventh signal path from said first system to said second system for monitoring said power provided to said initiator,

whereupon the removal of said path to electrical ground and insertion of a pre-determined signal on said seventh signal path provides energy to said initiator for activating said second system.

4. The action enabling apparatus of claim 1 wherein said third set of signal paths comprises:

a first subset of signal paths for providing event status signals to said first system from said PLD; and

a second subset of signal paths for providing an electrical ground for said PLD and for providing an enabling signal from said PLD to a third switch operably connected to said initiator.

5. The action enabling apparatus of claim 4 wherein said first subset of signal paths comprises:

an eighth signal path from said PLD for providing clock information to said first system;

a ninth signal path from said PLD for providing status about a switch signal to said first system;

a tenth signal path from said PLD for providing a signal to said first system related to providing power to said initiator of said second system;

an eleventh signal path from said PLD to said first system for providing a signal related to triggering a timing action associated with a pre-determined level of output of said sensor;

a twelfth signal path from said PLD to said first system for providing status associated with the default condition of said initiator; and

a thirteenth signal path from said PLD to said first system for providing status about an enabling signal,

wherein said first subset of signal paths provides timing and control status concerning signal paths among said PLD, said second system, and said first system.

6. The action enabling apparatus of claim 4 wherein said second subset of signal paths comprises:

a fourteenth signal path to electrical ground from said PLD;

a fifteenth signal path from said PLD to said second switch; and

a sixteenth signal path from said PLD to said third switch;

wherein, the appearance of a first and second pre-determined signal on each of said fifteenth and sixteenth signal paths, respectively, in concert with a third pre-determined signal on said sixth signal path, removes said path to electrical ground across the input of said initiator and energizes said initiator.

7. The action enabling apparatus of claim 1 wherein said clock comprises a first RC circuit and a feedback path from said PLD.

8. The action enabling apparatus of claim 1 wherein said sensor is an accelerometer.

9. The action enabling apparatus of claim 1 wherein said second signal path incorporates an attenuator circuit.

10. The action enabling apparatus of claim 9 wherein said attenuator circuit comprises:

a voltage divider, operably connected to a power distribution board of said first system, for attenuating an input signal;

a comparator, operably connected between said voltage divider and electrical ground and further connected to said power source and a reference voltage source, and

a capacitor,

wherein said attenuator circuit provides an input to said PLD necessary to enable said timers.

11. The action enabling apparatus of claim 1 wherein said initiator is a squib.

12. The action enabling apparatus of claim 1 wherein said second and third switches are MOSFETs.

13. A substitute initiating device to be deployed with a telemetry system incorporating a power source and a power distribution board interfacing to a sustainer motor in cooperation with said device, said sustainer motor incorporating an initiator having an input and an output, comprising:

a programmable logic device (PLD), incorporating a first switch and timers, said PLD having inputs and outputs;

a clock, for providing a timing reference, operably connected to said PLD;

a signal conditioning circuit, for conveying an input from a sensor, operably provided between the power distribution board and said PLD;

a shorting circuit incorporating a thermal relay, for establishing an electrical path to ground across an electromagnetically activated initiator, said shorting circuit operably connected to said initiator, said PLD through a second switch, and the power distribution board;

an enabling circuit, operably connected to said initiator, the power distribution board, and said PLD through a third switch, for enabling said initiator;

a reset circuit for enabling said outputs of said PLD to be set to a pre-determined level upon power up of said telemetry system, said outputs set to said pre-determined level by said reset circuit upon power up of the telemetry system;

a power circuit for providing power to said PLD from said telemetry system; and

signal paths provided for communication of status, said signal paths operable between said PLD and the power distribution board,

wherein said substitute initiating device fires said sustainer motor only upon the proper occurrence of a pre-determined sequence.

14. The initiating device of claim 13 wherein the status of said first switch is operably communicated between said PLD and the power distribution board.

15. The initiating device of claim 13 wherein feedback from a sustainer counter internal to said PLD is ANDed with input from said first switch and provided to said third switch,

wherein, energy is provided to the initiator along a path in said enabling circuit from the power distribution board to the initiator through said third switch.

16. The initiating device of claim 13 wherein said clock comprises a first RC circuit and a feedback path from said PLD.

17. The initiating device of claim 13 wherein said sensor is an accelerometer.

18. The initiating device of claim 13 wherein said second and third switches are MOSFETs.

19. The initiating device of claim 13 wherein said signal conditioning circuit also serves as an attenuator circuit.

20. The initiating device of claim 19 wherein said signal conditioning and attenuator circuit comprises:

a voltage divider, operably connected between said PLD and the power distribution board, for attenuating an input signal to said PLD;

a comparator, operably connected to said voltage divider and incorporating a built-in reference voltage referenced to electrical ground, said comparator provided power from the power source, and

a capacitor,

wherein said attenuator circuit provides an input to said PLD necessary to enable said timers.

21. The initiating device of claim 13 in which the shorting circuit comprises:

a first connection from the power distribution board to said thermal relay; and

a second connection from said PLD to said second switch,

wherein insertion of a signal of proper level on each of said first and second. connections results in removal of said electrical path to ground across said initiator.

22. The initiating device of claim 13 in which said enabling circuit comprises:

a third connection, said third connection extending from the power distribution board to said inputs of said second and third switches, said third connection incorporating a resistor;

a fourth connection, comprising a second RC circuit having a pre-determined time constant, operably connecting said PLD and said input of said second switch; and

a fifth connection, comprising a third RC circuit having a predetermined time constant similar to said second RC circuit, operably connecting said PLD, said input of said third switch and a voltage from the telemetry system as reduced by a series resistor,

wherein said third connection energizes, said initiator, pending the proper occurrence of said predetermined sequence and removal of said electrical path to ground across said initiator.

23. The initiating device of claim 13 further comprising a power monitoring circuit operably connected to a first resistor, said first resistor having two ends, a first end connected to the power distribution board and a second end connected to said resistor in said enabling circuit, and a second resistor, having two ends, a first end connected to the power distribution board and said first end of said first resistor and a second end operably connected to electrical ground,

wherein power level in said monitoring circuit as provided from the power distribution board is monitored.

24. The initiating device of claim 13 which said signal paths between said PLD and the power distribution board comprise:

a sixth connection for carrying a signal representative of a function of said clock;

a seventh connection for carrying a signal representative of a function of said switch;

an eighth connection for carrying a signal representing a firing decision of said PLD;

a ninth connection for carrying a signal representative of event status as measured with said sensor;

a tenth connection for representing said default condition of said initiating device; and

an eleventh connection for carrying a signal permitting the enabling of said initiator,

wherein said sixth through eleventh connections provide status of activity among said PLD, said initiator, and said telemetry system.

25. A method for insuring safe and reliable initiation of a device, comprising:

detecting a sequence of events;

determining a proper order of occurrence of said sequence of events; and

initiating the device upon determination of said proper order of occurrence,

wherein said device is initiated within a few tenths of seconds after initiation of said sequence of events,

wherein inadvertent initiation of the device is prevented via an electrical path to an electrical ground across an initiator provided through a thermal relay operably connected to a second switch, and

wherein at a pre-determined event within said sequence of events, said second switch is closed permitting energy to flow from a power source through said thermal relay and interrupt said electrical path to said electrical ground across said initiator.

26. The method of claim 25 wherein a sustainer motor of a missile is initiated, said sustainer motor incorporating said initiator activated through cooperation among a first switch, said second switch, and a third switch.

27. The method of claim 26 wherein detecting a pre-determined sequence of events is achieved by a programmable logic device (PLD) operably connected between a first system, said system having access to a source of power and incorporating a sensor, a clock, and said second and third switches.

28. The method of claim 27 wherein said first system is an internally powered telemetry system, incorporating an accelerometer as said sensor and a power distribution board, and said clock is an RC circuit with a pre-determined time constant operably connected to said PLD and receiving feedback therefrom.

29. The method of claim 25 wherein said electrical path to said electrical ground is removed via provision of electrical energy from a source of power associated with said first system to a thermal relay maintaining said electrical path to said electrical ground when no signal is present,

wherein said electrical path is removed by applying sufficient energy to said thermal relay to interrupt said electrical path to said electrical ground.

30. The method of claim 26 wherein said the device is initiated upon determination of the proper occurrence of said sequence provided as a first signal from said first system, a second signal from said PLD to said second switch and a third signal from said PLD to said third switch,

wherein initiation of said first, second, and third signals is controlled by said PLD using a pre-determined timing sequence measured by timers internal to said PLD and said clock.

31. The method of claim 26 wherein said sequence is associated with times as follows:

t₀ is about the time of launch of said missile;

T₁ is a period of time about X milliseconds (ms) in duration occurring after said t₀;

T₂ is a period of time about Y ms in duration occurring after said t₀;

T₃ is a period of time about Z ms in duration occurring after said t₀ that includes said T₂ and T₁ periods, given that said sensor provides to said PLD a value at or above a pre-determined value for the duration of said T₁ period during said T₂ period,

T₄ is the total elapsed time, W, after t₀ in which an initiation signal is active;

wherein W>

Z>

Y>

X, and

wherein said first, second, and third signals are sent to open said first and second switches at about the end of period T₃, thus energizing said initiator and firing said sustainer motor, and

wherein said initiation signal is inactivated at T₄=W.

32. The method of claim 31 such that:

X is about 20;

Y is about 40;

Z is about 250;

W is about 500; and

said predetermined value is about 25 G.