Apparatus and method for measuring concentrations of a chemical/biological/nuclear agent in an environment

• US 6,539,311 B1
• Filed: 10/30/2000
• Issued: 03/25/2003
• Est. Priority Date: 10/30/2000
• Status: Expired due to Fees

• Current Assignee: Mitre Corporation
• Original Assignee: Mitre Corporation
• Inventors: Berger, Eugene L.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/698,108
• Time in Patent Office: 876 Days
• Field of Search: 702/19, 702/22, 702/23, 702/24, 702/25, 702/26, 702/30, 702/32, 435/4, 340/600, 340/603, 250/482.1, 250/472.1, 250/484.5, 436/58, 436/902, 700/52, 706/14
• US Class Current: 702/23
• CPC Class Codes: G01N 33/0065 using more than one threshold

Abstract

An apparatus and method for measuring chemical, biological, nuclear agents in an environment includes several detectors capable of measuring concentrations of the agents in the environment and a processor capable of operating an algorithm which, based on two sequential measures of concentration of the agent, estimates decay or elevation rate of the concentrations of the agent and feeds this estimated change rate to a Kalman filter which predicts the next measurement. The predicted next measurement of concentration is compared with the measured concentration and the error is calculated based on the discrepancy between the measured and predicted concentrations of the agent in the environment. Using this error, the attributes of the Kalman filter are adjusted to lower noise signals and improve further predictions of the concentration of the agent during the mission time.

Claims

1. An apparatus for measuring behavior of a chemical/biological/nuclear agent in an environment, comprising:

(a) at least one detector adapted to measure concentration of said agent at predetermined time instances,

(b) first means coupled to said at least one detector for estimating change rate of the concentration of said agent in said environment based on two consequent measurements of the concentration taken at time t₁ and time t₂, wherein t₂>

t₁,

(c) a Kalman filter receiving said estimated change rate of the concentration for predicting the concentration of said chemical/biological/nuclear agent in said environment at time t₃, wherein t₃>

t₂,

(d) second means having one input thereof coupled to said Kalman filter for receiving said predicted concentration corresponding to said time t₃, and further having another input for receiving a data corresponding to a concentration measured at said time t₃ by said at least one detector, said second means outputting data representative of an error causing discrepancy between said predicted concentration and said measured concentration measured at said time t₃, and

(e) third means coupled between the output of said second means and the input at said Kalman filter for adjusting parameters of said Kalman filter, thereby increasing accuracy of prediction of said agent behavior in said environment.

2. The apparatus of claim 1, further comprising dosage prediction means coupled to the output of said Kalman filter for integrating a plurality of said predicted concentrations of said agent accumulated over a predetermined period of time.

3. The apparatus of claim 2, further comprising comparing means for comparing said predicted dosage accumulated over said predetermined period of time with a predetermined threshold dosage level.

4. The apparatus of claim 3, further including warning means actuated when said predicted dosage accumulated over said predetermined period of time approaches said threshold dosage level for indicating the need for initiating protective measures.

5. The apparatus of claim 4, further including dewarning means actuated when said predicted dosage accumulated over said predetermined period of time is below said threshold dosage level for indicating termination of protective measures.

6. The apparatus of claim 1, further including a plurality of said detectors.

7. The apparatus of claim 1, wherein said change rate of the concentration represents decay rate of said agent in said environment.

8. The apparatus of claim 1, wherein said change rate of the concentration represents rising rate of said agent in said environment.

9. The apparatus of claim 1, wherein said environment is represented by a plurality of environment parameters including:

initial level of said agent, initial concentration of said agent, evaporation rate of said agent, air exchange rate in said environment, and duration of a mission.

10. The apparatus of claim 9, wherein said error output by said second means is determined by measurement errors inherent to said at least one detector and by deviations in at least one of said environmental parameters.

11. A method of measurement of concentration of a chemical/biological/nuclear agent, comprising the steps of:

(a) providing an environment represented by a plurality of environment parameters,

(b) measuring first, second and third concentrations of said agent in sequence at a first time, a second time, and a third time, respectively,

(c) providing a Kalman filter having Kalman filter parameters,

(d) predicting, by means of said Kalman filter a predicted concentration of said agent corresponding to said third time, said prediction being made based on said first and second concentrations measured at said first and second times,

(e) comparing said predicted concentration and said measured third concentration,

(f) calculating system errors causing discrepancies between said predicted concentration and said measured third concentration, and

(g) adjusting said Kalman filter parameters on the basis of said system errors, thus improving further predictions of concentrations by said Kalman filter.

12. The method of claim 11, further comprising the steps of:

providing at least one detector for measurement of said first, second and third concentrations of said agent in said environment.

13. The method of claim 12, further comprising the steps of:

providing a plurality of said detectors, and

placing said detectors within said environment at predetermined locations.

14. The method of claim 11, further comprising the step of:

predicting a dosage of said agent accumulated over a predetermined time duration by integrating said predicted concentrations of said agent over said predetermined time duration.

15. The method of claim 14, further comprising the steps of comparing said predicted accumulated dosage of said agent with a predetermined dosage threshold.

16. The method of claim 15, further comprising the steps of:

actuating warning indicia when said predicted accumulated dosage reaches said predetermined dosage threshold.

17. The method of claim 15, further comprising the steps of:

actuating dewarning indicia when said predicted accumulated dosage falls below said predetermined dosage threshold.