MULTI-SENSE ENVIRONMENTAL MONITORING DEVICE AND METHOD

• US 20150204830A1
• Filed: 04/01/2015
• Published: 07/23/2015
• Est. Priority Date: 06/25/2010
• Status: Active Grant

• Current Assignee: Industrial Scientific Corporation (Fortive Corp.)
• Original Assignee: Industrial Scientific Corporation (Fortive Corp.)
• Inventors: Arunachalam, Raghu
• Granted Patent: US 9,575,043 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 33/0006 Calibrating gas analysers
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array
• CPC Class Codes: G01N 33/0063 using a threshold to release an alarm or displaying means
• CPC Class Codes: G08B 21/14 Toxic gas alarms G08B21/16 takes precedence
• CPC Class Codes: G08B 21/16 Combustible gas alarms
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold
• CPC Class Codes: G08B 29/16 Security signalling or alarm systems, e.g. redundant systems
• CPC Class Codes: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components
• CPC Class Codes: G08B 29/26 by updating and storing reference thresholds
• CPC Class Codes: G08B 5/22 using electric transmission; using electromagnetic transmission

Abstract

An environmental monitoring device for detecting and warning users of unhealthy levels of a given substance is disclosed having more than one sensor for each substance to be detected. Each sensor for each substance detected may be positioned in more than one plane or surface on the device. The device may be capable of auto or self calibration. Methods for reading substance levels and auto calibrating are also disclosed.

Claims

1. A monitoring device for monitoring substances, the monitoring device comprising:

a plurality of sensors, each of the at least two sensors being configured to detect a same substance separately from all other sensors of the monitoring device and to generate an output signal in response to a detection of the same substance;

a processing unit operably coupled to the at least two sensors, the processing unit being configured to;

receive each of the output signals from the at least two sensors, determine a detection signal for the same substance based on the output signals, and

generate a calibration action responsive to at least two of the output signals deviating by a threshold amount, the calibration action comprising at least one of performing self-calibration and generating a calibration request; and

a display operably coupled to the processing unit, the display being configured to show a detection condition for the same substance in accordance with the detection signal.

2. The monitoring device of claim 1, wherein the processing unit is configured to determine a display reading based on a respective concentration detected by each of the plurality of sensors.

3. The monitoring device of claim 1, wherein the calibration action comprises self-calibration by adjusting a gain of a sensor to minimize variance among the sensors for the substance.

4. The monitoring device of claim 1, further comprising a user interface configured to provide control signals to said processing unit, the user interface comprising at least one of a button, key, or touch screen.

5. The monitoring device of claim 1, wherein the calibration action comprises self-calibration by adjusting a gain of a sensor according to the relationship:

6. The monitoring device of claim 1, wherein the processing unit is configured to determine a difference between signals from at least a portion of the plurality of sensors and to generate a sensor fail signal responsive to the difference being outside of a threshold amount.

7. A method for monitoring a substance using a monitoring device operably coupled with a plurality of sensors, wherein each of the plurality of sensors is configured to detect the same substance, the method comprising the steps of, by a processor:

detecting a concentration of the substance based on output signals from each of the at least two sensors comprising concentration information associated with detection of the same substance;

determining a detection signal for said same substance based on the output signals;

calculating a display reading of the substance, the display reading being determined based on an aggregate of the output signals;

generating a calibration action responsive to the output signals deviating by a threshold amount, the calibration action comprising at least one of performing self-calibration and generating a calibration request;

comparing the display reading to a threshold limit; and

actuating an alarm in response to the display reading deviating from the threshold limit by a predetermined value.

8. The method of claim 7, further comprising determining a gain of a majority of sensors, wherein the calibration action comprises self-calibration by adjusting a gain of a deviating sensor to correspond with the gain of the majority of sensors.

9. The method of claim 7, wherein the detection signal is determined based at least partially on at least one of historic sensor data, span reserve of the respective sensors, gain of the respective sensors, or ambient temperature.

10. The method of claim 7, wherein the detection signal is determined according to the relationship:

11. The method of claim 7, further comprising generating an aggregate substance concentration according to the relationship:

12. The method of claim 11, wherein w_i is proportional to a span reserve of sensor i.

13. The method of claim 11, wherein w_i is proportional to a gain of sensor i.

14. A monitoring device for monitoring substances, the monitoring device comprising:

at least two sensors configured to detect a same substance and to generate an output signal in response to a detection of the same substance; and

a processing unit operably coupled to the at least two sensors, the processing unit being configured to;

receive each of the output signals from the at least two sensors,

determine a weight of each of the at least two sensors configured to indicate a reliability of each of the at least two sensors, and

determine an aggregate substance concentration reading by aggregating the output signals from the at least two sensors biased toward output signals from sensors indicated as being more reliable based on the weights.

15. The monitoring device of claim 14, wherein the weight is determined based on at least one of gain, span reserve, historic calibration performance, and historic bump test performance.

16. The monitoring device of claim 14, further comprising a display operably coupled to the processing unit, the display being configured to show a detection condition for the same substance in accordance with the detection signal.

17. The monitoring device of claim 14, wherein the processing unit is further configured to generate a calibration action responsive to at least two of the output signals deviating by a threshold amount, the calibration action comprising at least one of performing self-calibration and generating a calibration request.

18. The monitoring device of claim 17, wherein the calibration action comprises self-calibration by adjusting a gain of a sensor to minimize variance among the sensors for the substance.

19. The monitoring device of claim 17, further comprising a user interface configured to provide control signals to said processing unit, the user interface comprising at least one of a button, key, or touch screen

20. The monitoring device of claim 17, wherein the calibration action comprises self-calibration by adjusting a gain of a sensor according to the relationship: