EP0396966A1

EP0396966A1 - Portable radiometric data acquisition system

Info

Publication number: EP0396966A1
Application number: EP90107932A
Authority: EP
Inventors: Danny G. Snider
Original assignee: Santa Barbara Research Center
Current assignee: Raytheon Co
Priority date: 1989-05-08
Filing date: 1990-04-26
Publication date: 1990-11-14
Also published as: KR900018888A; BR9002026A; AU5480490A; CA2014654A1; KR930003454B1; JPH0334096A

Abstract

A data acquisition system (10) which can store environmental data at periodic intervals of time. In a preferred embodiment, the data acquisition system (10) is used as a fire sensor, and the stored signals are available to assist in determining the cause of the fire.

Description

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to radiometric data acquisition systems and more particularly to a portable radiometric data acquisition system that can be used as a fire sensor.

2. Discussion

Data acquisition systems are employed to detect and record ambient environmental data such as radiometric, photometric and temperature data. In addition, data acquisition systems can be used to collect and record information from other sensors such as pressure, acceleration, flow, etc. Prior radiometric data acquisition systems are generally bulky and do not function well in harsh environments. These prior systems typically included a sensor which would be placed in the desired location to be sensed, with wires connecting the sensor to an amplifier and further wiring connecting the amplifier to a recorder. This configuration results in systems which require considerable space as well as conditioned power.
These disadvantages have limited the usefulness of prior radiometric data acquisitions systems. For example, when prior radiometric data acquisition systems were placed in a vehicle, the vehicle sometimes could not be operated in its normal operating mode because the system would require personnel to monitor it and and also the system might not withstand the harsh environment of the vehicle under operation. Another disadvantage is that the bulk of such systems prevented them from being used in certain confined areas. Even where space is available, the cabling necessary to connect the various components might prevent normal operation of the vehicle.
It is another disadvantage with prior radiometric data acquisition systems that they require frequent attention and cannot be left for extended periods of time unattended.
Thus it would be desirable to provide a radiometric data acquisition system which is small and portable so that it can operate in a confined space. Also it would be desirable to provide a data acquisition system that can operate unattended for long periods of time. It is further desirable to provide a data acquisition system which can withstand harsh environments and not interfere with the normal operation of the surrounding apparatus.
Fire sensors are devices which detect radiometric information from one or more sensors and process this information to determine if it is indicative of a fire. Microprocessor controlled fire sensors have been developed to reduce the size of the system and to refine the analysis of the sensor data and thereby improve the detection of fires and the avoidance of false detections. See, for example, U.S. Patents No. 4,679,156 and 4,769,775, both issued to M. T. Kern et al. However, while such systems are able to successfully detect the existence of fire, once the fire is extinguished, a great deal of effort goes into trying to determine the cause of the fire. The fire sensor merely signals that there was a fire but does not provide any information regarding the cause of the fire. Thus, it would be desirable to provide a fire sensor which can also provide information useful in determining the cause of the fires it detects.

SUMMARY OF THE INVENTION

The present invention is a portable radiometric data acquisition system that is capable of collecting and storing data from sensors. The sensors may be located in a single or a plurality of locations and may sense such environmental information as radiometric, photometric, and temperature data, and/or other types of information such as pressure, acceleration, flow, etc. Because of its small size (a self-contained embodiment may fit in the palm of one's hand) the present invention can be placed in areas of difficult access. It can also operate unattended for extended periods of time without interfering with the surrounding vehicle or equipment.
The data acquisition system according to the present invention utilizes a microprocessor with one or more detectors connected to its input. The detector signal may be amplified and connected to an analog to digital converter before being transmitted to the CPU of the microprocessor. The microprocessor contains read only memory, random access memory and erasable programmable read only memory. The program for the CPU may be contained, in part, in both the read only memory and the erasable programmable read only memory. Typically, subroutines will be contained within the read only memory. The data acquisition system may be programmed through the erasable programmable read only memory to accept and store detected data at predetermined intervals of time. The frequency of the storing of detected data will depend on the application and may vary widely.
In one embodiment, the portable data acquisition system is adapted to be used as a fire sensor. In this embodiment, the detector, or detectors, are chosen and the detector signals processed to yield the desired information indicative of a fire. In this way, the portable radiometric data acquisition system of the present invention not only can detect a fire but also record environmental parameters leading up to the fire. This information is particularly useful to assist in investigations of the cause of the fire.

BRIEF DESCRIPTION OF THE DRAWINGS

The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and by reference to the following drawings in which:

FIG. 1 is a block diagram of the preferred embodiment of the portable data acquisition system of this invention;
FIG. 2 is a flow diagram of the portable data acquisition system program for storing data; and
FIG. 3 is a flow diagram of a program for the portable data acquisition system as employed in a fire detection system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A data acquisition system according to the present invention is shown in FIG. 1. The portable data acquisition system 10 is shown controlled by a microprocessor 12. This microprocessor 12 may be, for example, a Motorola MC68HC11. In this embodiment, the microprocessor 12 is connected to four detectors. First and second radiometric detectors, 14 and 16, respectively, are capable of sensing radiation of a wavelength of a particular spectral band. These detectors are also capable of producing an analog signal that is proportional to the detected energy. The detection of two discrete regions of wavelengths may be accomplished, for example, by utilizing identical detectors for the first and second detectors 14 and 16, and then placing appropriate filters 18 and 20 in front of each detector 14 and 16. Each filter 14 and 16 will then filter out all but the desired wavelengths of energy. Alternatively, different kinds of detectors with inherently different spectral sensitivities may be employed.
In addition, a temperature sensor 22 is also connected to the microprocessor 12 input. The temperature sensor 22 is capable of producing an analog signal that is proportional to the surrounding temperature. The data acquisition system 10 also is capable of accepting signals from a fourth detector (not shown) along an external sensor line 24. The external detector may be located at a point remote from the data acquisition system 10. Depending on the application, the external sensor may sense information such as pressure, acceleration, flow, etc., and transmit an analog signal to the external sensor line 24.
Since the signal along the external sensor line 24 may not be of sufficient strength for processing by the microprocessor 12, the signal is amplified by an amplifier 26 which has its output connected to one input line 28 of the microprocessor 12.
Likewise, the first detector 14 output is connected along conductor 30 to an amplifier 32 which is connected to a microprocessor input 34. The second detector 16 output is connected along conductor 36 to an amplifier 38 which transmits its output to a microprocessor input 40. Finally, the temperature sensor 22 output is fed along conductor 42 to an amplifier 44 which is connected to an input 46 of the microprocessor 12.
The analog signals from the detectors must be digitized for processing by the microprocessor 12. Thus, a series of analog to digital converters 48, 50, 52 and 54 respectively, are connected to the four input lines 34, 40, 46 and 28. The digitized signals produced by the analog to digital converters are then transmitted to a CPU 56 for processing.
As shown in FIG. 1, the microprocessor 12 also includes a program line 58 which is used to put the CPU into the programming mode for loading programs into the microprocessor 12 as will be discussed in more detail below. The program for the CPU is stored in both a read only memory (ROM) 60 and an electrically erasable programmable read only memory (EEPROM) 62. Typically the ROM 60 will be programmed with the communications program routines and the EEPROM 62 will contain the programming routines. By the use of subroutines that are stored in the ROM 60 the program space required for the EEPROM 62 is kept to a minimum. In addition, a random access memory (RAM) 64 is provided for storing of both data and program information.
A serial communication interface 66 is provided in the microprocessor 12 to input and retrieve data from the CPU 56. The serial communication interface 66 is connected to a status/data line 68 and to an interrogate/data line 70. The serial communication interface 68 is also connected to the CPU 56.
When the program line 58 is held low, the CPU 56 is placed under the control of the ROM 60 program and the serial communication interface 66 can be used to input and retrieve data from the CPU 56. In addition, with the program line 58 low, programs can be loaded in the EEPROM 62 by means of an industrial standard RS-232 port from any external source which is connected to the status/data line 68. A status line 72 is also provided which can be programmed to provide an output to external signaling or activation devices. Power to the Data Acquisition System 10 is provided by a power supply 74 which may be an internal battery or an external source of electrical power may be provided. When the program line 58 is not pulled low (ground potential) the CPU 56 is operated under program control of the EEPROM 62. The program in the EEPROM 62 may also make use of subprograms within the ROM 60 to conserve memory locations in the EEPROM 62 for data storage.
Referring now to FIG. 2, a flow diagram of a program for the data acquisition system 10 is shown. At the start, the program monitors the interrogate line 70 and if the line is not high the program will continue in a short loop. This interrogate line could be tied to the master switch of a vehicle in which the data acquisition system 10 has been installed. In such a case the only data of concern is that data occurring when the master switch is on. If the interrogate line is high, the program will cause the CPU 56 to read the analog to digital converters 48, 50, 52 and 54. After the analog to digital converters 48, 50, 52 and 54 are read, the data is stored in the EEPROM 66.
While not indicated in FIG. 2, it will be appreciated that the stored data could be compared to the previous data to determine if this data is higher. If the new data is higher it can be stored as the peak in one location within the EEPROM and replaced with new data when it exceeds this level. The time of the peak could also be stored. Also at this time, new data could be averaged in with the previous data and the average stored. The flow diagram in FIG. 2 shows that samples are taken every 100 milliseconds. This time could be changed to almost any value, for example, one every 100 microseconds, or one each year.
Referring now to FIG. 3, a flow diagram of the data acquisition system 10 programmed to be used as a fire sensor is shown. At the start of the program, the status line 72 is pulled low (reset). This line is used as a fire warning output signal line, which will go high in case of a fire. After the status line 72 is reset (turned off) the CPU 56 will check the signal level from the first detector 14. If this signal is over predetermined threshold then the CPU will check the signal from the number two detector 16, and if this signal is also over threshold the CPU 56 will cause the status line to go high indicating a fire. From there the CPU will branch back to test the signal levels from the detectors again. As soon as one detector goes below its threshold then the CPU will branch back to the start and reset the status line 72.
It will be appreciated that the program in FIG. 3 is for a very simple fire sensor which merely requires a simultaneous signal of sufficient amplitude from two detectors sensitive to different wavelengths. Much more complex fire sensor programs could be used such as those described in U.S. Patent Nos. 4,691,196; 4,639,598; 4,665,390; 4,679,156; 4,769,775; 4,647,776; 4,472,715; and 4,469,944. It will be appreciated that performing the more sophisticated signal processing as provided in some of the above patents will require more circuitry then delineated herein.
It is an important feature that the data acquisition system 10 can be used both as a fire detector as described in connection with FIGS. 1 and 3 above and as a data acquisition system 10 as described in connection with FIGS. 1 and 2 simultaneously. This may be accomplished by programming the data acquisition system 10 to perform both the data storage functions, shown in FIG. 2, as well as the fire detection functions shown in FIG. 3. It may be useful to have the fire output latch the memories 60, 62 and 64, so that the data stored therein is not displaced after the fire. Thus, once a fire is detected it will be possible to analyze the status of the detectors for a period of time preceding the fire. In this way a history of the events leading to the fire will be recorded. For example, it may be useful to know what changes took place preceding the fire in detected parameters such as radiometric, photometric, temperature, pressure, acceleration, etc. This information will be very useful for diagnosing cause of the fire and will save a great deal of time in conducting the post fire investigation.
From the foregoing it can be appreciated that the present invention provides a Data Acquisition System 10 that is portable, occupies little space, can be used in harsh environments and left for extended period of time unattended without interfering with the equipment or vehicle in which it is placed. A further advantage is that no power is necessary for the Data Acquisition System 10 to retain the recorded data due to the use of the EEPROM 62, so that the Data Acquisition System 10 could be disconnected from its site and sent to another location for the downloading of data. Those skilled in the art can appreciate that other advantages can be obtained from the use of this invention and that modification may be made without departing from the true spirit of the invention after studying the specification, drawings, and following claims.

Claims

1. A system for recording environmental information comprising:
at least one detector means for detecting said environmental information and generating a detector signal responsive to the detected environmental information;
microprocessor means for operating on and storing data applied to its inputs and generating information thereto at its outputs, said microprocessor means including a central processing unit (CPU), a read only memory, a random access memory, and programmable read only memory;
output means for providing an output of said environmental information after processing by said microprocessor;
first coupling means for coupling the detector output to an input of the microprocessor means; and
second coupling means for coupling the microprocessor outputs to the output means.

2. The system of Claim 1 wherein said at least one detector means comprises a first detector means for detecting energy having a wavelength with a first spectral band and at least one additional detector means for detecting energy having a wavelength in a different second spectral band.

3. The system of Claim 1 wherein said first coupling means further comprises an amplifier means and an analog to digital converter means.

4. The system of Claim 1 wherein said second coupling means further comprises a serial communication interface means.

5. The system of Claim 1 wherein said programmable read only memory comprises an electrically erasable programmable read only memory.

6. The system of Claim 1 wherein at least one of said read only memory, or programmable read only memory has a program stored therein for causing said CPU to accept and store environmental information sensed by said detector means at predetermined intervals of time.

7. The system of Claim 1 wherein at least one of the detector means is remotely disposed from the microprocessor means and one detector means comprises a temperature sensor.

8. The system of Claim 1 wherein said microprocessor means is programmed to analyze said environmental information and to transmit a signal to said output means when said environmental information is indicative of a fire.

9. A fire sensor system comprising:
at least one detector means for detecting environmental information and generating a detector signal responsive to the detected environmental information;
microprocessor means for analyzing and storing data applied to its inputs and generating information thereto at its outputs, said microprocessor means including a central processing unit (CPU), a read only memory, a random access memory, and programmable read only memory;
output means for providing a signal in response to said environmental information;
first coupling means for coupling the detector output to an input of the microprocessor means;
second coupling means for coupling the microprocessor outputs to the output means; and
said microprocessor means being programmed to transmit a signal to said output means when said analyzed data is indicative of a fire.

10. The system of Claim 9 wherein said at least one detector means comprises a first detector means for detecting energy having a wavelength with a first spectral band and at least one additional detector means for detecting energy having a wavelength in a different second spectral band.

11. The system of Claim 9 wherein said first coupling means further comprises an amplifier means and an analog to digital converter means.

12. The system of Claim 9 wherein said second coupling means further comprises a serial communication interface means.

13. The system of Claim 9 wherein said programmable read only memory comprises an electrically erasable programmable read only memory.

14. The system of Claim 9 wherein at least one of said read only memory, or said programmable read only memory has a program stored therein for causing said CPU to accept and store environmental information sensed by said detector means at predetermined intervals of time whereby, changes in the environmental information preceding a fire are stored.

15. A fire sensor system comprising:
at least one detector means for detecting environmental information and generating a detector signal responsive to the detected environmental information;
means for storing said detector signal at periodic intervals;
means for analyzing said detector signal to determine if said detected environmental information is indicative of a fire;
means for transmitting an output signal when said means for analyzing determine that a fire is present, whereby said stored detector signals preceding a fire are available to assist in determining the cause of the fire.

16. A method of determining the cause of a fire comprising the steps of:
detecting environmental information with at least one detector at periodic intervals, said detector capable of generating a signal in response thereto;
storing said information at said periodic intervals in an information storage means;
analyzing said detected environmental information to determine if said signal is indicative of the presence of a fire;
generating a signal to an output means when said analysis indicates the presence of a fire; and
analyzing the information stored at periodic intervals prior to the existence of the fire, to assist in determining the cause of the fire.