SIGNAL PROPERTY DETECTOR

• US 20130304261A1
• Filed: 05/10/2012
• Published: 11/14/2013
• Est. Priority Date: 05/10/2012
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Vass, Jiri, Rojicek, Jiri, Bicik, Vladimir
• Granted Patent: US 9,268,530 B2
• Time in Patent Office: Days
• US Class Current: 700/276
• CPC Class Codes: F24F 11/00 Control or safety arrangements
• CPC Class Codes: G05B 11/36 with provision for obtaining particular characteristics, e.g. proportional, integral, differential
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/0426 Programming the control sequence
• CPC Class Codes: G05B 2219/2614 HVAC, heating, ventillation, climate control
• CPC Class Codes: G05B 2219/37233 Breakage, wear of rotating tool with multident saw, mill, drill
• CPC Class Codes: G05B 23/00 Testing or monitoring of control systems or parts thereof monitoring of programme-control systems G05B19/048, G05B19/406
• CPC Class Codes: G06F 7/58 Random or pseudo-random number generators

Abstract

A property of a signal may be detected by sampling a signal and determining a scalar indicator of the samples. The samples can be transformed to create a transformed signal. A scalar indicator of the transformed signal may be determined and compared to the scalar indicator of the sample. If the comparison yields a number greater than a selected threshold value then the signal that was sampled may be deemed to include the property. A property indicator signal may be driven low or high to indicate that the signal has the property. The time and duration of time that the signal is deemed to include the property may be recorded. The recorded data may be reviewed and appropriate action may be taken.

Claims

1. A method comprising:

sampling an oscillation detector input signal to create a sampled signal;

transforming the sampled signal to create a transformed signal;

computing a scalar indicator of the sampled signal;

computing a scalar indicator of the transformed signal; and

comparing the scalar indicator of the transformed signal to the scalar indicator of the sampled signal to determine if the input signal is oscillating.

2. The method of claim 1, wherein comparing comprises determining a ratio of the scalar indicator of the sampled signal to the scalar indicator of the transformed signal.

3. The method of claim 2 and further comprising indicating the input signal is oscillating if the ratio is greater than a selected threshold.

4. The method of claim 1, wherein transforming the sampled signal includes band-pass filtering the sampled signal, and wherein the scalar indicator is the standard deviation.

5. The method of claim 1, wherein the oscillation detector input signal is received from a controller.

6. The method of claim 5, wherein the controller is a PID controller.

7. The method of claim 2, wherein the ratio is determined in accordance with the formula:

(first positive constant+scalar indicator of the sampled signal)/(second positive constant+the scalar indicator of the transformed signal).

8. The method of claim 1, wherein the oscillation detector input signal is a control signal in an HVAC system.

9. An apparatus comprising:

an oscillation detector comprising;

a sample module that samples an oscillation detector input signal to create a sampled signal;

a signal transformation module, wherein the signal transformation module transforms the sampled signal to create a transformed signal;

a scalar indicator module, wherein the scalar indicator module determines a scalar indicator of the transformed signal and a scalar indicator of the sampled signal; and

a comparison module, wherein the comparison module compares the scalar indicator of the transformed signal to the scalar indicator of the sampled signal to determine if the input signal is oscillating.

10. The apparatus of claim 9, wherein the comparing comprises determining a ratio of the scalar indicator of the sampled signal to the scalar indicator of the transformed signal.

11. The apparatus of claim 10, wherein the oscillation detector output comprises an oscillation indicator signal, wherein the oscillation indicator signal indicates if the ratio is greater than a selected threshold.

12. The apparatus of claim 9, wherein the signal transformation module band-pass filters the sampled signal, and wherein the scalar indicator is the standard deviation.

13. The apparatus of claim 9, wherein the oscillation detector input signal is received from a controller and the controller is a PID controller.

14. The apparatus of claim 10, wherein the ratio is determined in accordance with the formula:

(first positive constant+the scalar indicator of the sampled signal)/(second positive constant+the scalar indicator of the transformed signal).

15. The apparatus of claim 9, wherein the oscillation detector input signal is a control signal in an HVAC system.

16. A machine readable storage device that stores instructions, the instructions, which when performed by a machine, cause the machine to perform operations comprising:

sampling an oscillation detector input signal to create a sampled signal;

transforming the sampled signal to create a transformed signal;

computing a scalar indicator of the sampled signal;

computing a scalar indicator of the transformed signal; and

comparing the scalar indicator of the transformed signal to the scalar indicator of the sampled signal to determine if the input signal is oscillating.

17. The storage device of claim 16, wherein the instructions for comparing include instructions which when performed by the machine, cause the machine to perform operations comprising:

determining a ratio of the scalar indicator of the sampled signal to the scalar indicator of the transformed signal.

18. The storage device of claim 17, comprising instructions which when performed by the machine, cause the machine to perform operations comprising:

comparing the ratio to a selected threshold value, if the ratio is greater than the selected threshold value then indicating the input signal is oscillating.

19. The storage device of claim 18, wherein the transforming the sampled signal includes band-pass filtering the sampled signal, and wherein the scalar indicator is the standard deviation.

20. The storage device of claim 17, wherein the ratio is determined in accordance with the formula:

(first positive constant+the scalar indicator of the sampled signal)/(second positive constant+the scalar indicator of the transformed signal).