LOW NOISE ZERO CROSSING DETECTION FOR INDIRECT TIRE PRESSURE MONITORING

• US 20160252543A1
• Filed: 03/23/2015
• Published: 09/01/2016
• Est. Priority Date: 02/27/2015
• Status: Active Application

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: ADNAN, Muhammad, HAMMERSCHMIDT, Dirk
• Granted Patent: US 10,254,129 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01P 3/487 delivered by rotating magnets
• CPC Class Codes: G01P 3/488 delivered by variable reluctance detectors
• CPC Class Codes: G01P 3/489 Digital circuits therefor
• CPC Class Codes: G01R 13/0254 for triggering, synchronisation
• CPC Class Codes: G01R 19/175 Indicating the instants of passage of current or voltage through a given value, e.g. passage through zero
• CPC Class Codes: G01R 23/02 Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage

Abstract

A magnetic speed sensor may comprise a digital component configured to estimate a zero crossing event based on a plurality of sensor signal samples. The digital component may output, to a control unit, a speed signal that is based on the estimated zero crossing event.

Claims

1. A magnetic speed sensor, comprising:

a digital component configured to;

estimate a zero crossing event based on a plurality of sensor signal samples; and

output, to a control unit, a speed signal that is based on the estimated zero crossing event.

2. The magnetic speed sensor of claim 1, where the digital component, when estimating the zero crossing event, is configured to:

interpolate the plurality of sensor signal samples in order to estimate the zero crossing event;

or

extrapolate the plurality of sensor signal samples in order to estimate the zero crossing event.

3. The magnetic speed sensor of claim 1, where the digital component is configured to obtain the plurality of sensor signal samples based on a constant buffer length technique associated with storing a particular quantity of sensor signal samples.

4. The magnetic speed sensor of claim 1, where the magnetic speed sensor is at least one of:

a giant magnetoresistance (GMR) sensor;

a colossal magnetoresistance (CMR) sensor;

an anisotropic magnetoresistance (AMR) sensor;

a tunnel magnetoresistance (TMR) sensor;

or

an extraordinary magnetoresistance (EMR) sensor.

5. The magnetic speed sensor of claim 1, where the plurality of sensor signal samples includes a first set of sensor signal samples and a second set of sensor signal samples,

the first set of sensor signal samples including sensor signal samples with values greater than a signal threshold, and

the second set of sensor signal samples including sensor signal samples with values less than the signal threshold.

6. The magnetic speed sensor of claim 1, where the plurality of sensor signal samples includes a first set of sensor signal samples and a second set of sensor signal samples,

the first set of sensor signal samples including sensor signal samples with values greater than a first signal threshold and less than a second signal threshold,

the first signal threshold being less than the second signal threshold, and

the second set of sensor signal samples including sensor signal samples with values less than the first signal threshold and greater than a third signal threshold,

the first signal threshold being greater than the third signal threshold.

7. The magnetic speed sensor of claim 1, where the plurality of sensor signal samples includes at least one sensor signal sample with a value above a signal threshold and at least one sensor signal sample with a value below the signal threshold.

8. A system, comprising:

a sensor module configured to;

estimate a zero crossing event based on a group of sensor signal samples,

the group of sensor signal samples including a sensor signal sample with a value above a signal threshold, and a sensor signal sample with a value below the signal threshold; and

provide, to a control unit, a speed signal that is based on the estimated zero crossing event.

9. The system of claim 8, where the sensor module, when estimating the zero crossing event based on the group of sensor signal samples, is configured to:

compute a fitted polynomial, associated with the zero crossing event, based on the group of sensor signal samples; and

estimate the zero crossing event based on the fitted polynomial.

10. The system of claim 9, where the fitted polynomial is a first order polynomial.

11. The system of claim 8, where the sensor module, when estimating the zero crossing event, is configured to:

interpolate the group of sensor signal samples in order to estimate the zero crossing event;

or

extrapolate the group of sensor signal samples in order to estimate the zero crossing event.

12. The system of claim 8, where the sensor module is configured to obtain the group of sensor signal samples based on a constant threshold level technique associated with storing sensor signal samples with values that lie between a first threshold and a second threshold.

13. The system of claim 8, where the sensor module, when providing the speed signal is configured to trigger a transition between a first output current level and a second output current level based on the estimated zero crossing event.

14. The system of claim 8, where the group of sensor signal samples includes a first set of sensor signal samples and a second set of sensor signal samples,

the first set of sensor signal samples including sensor signal samples with values greater than a first signal threshold and less than a second signal threshold,

the first signal threshold being less than the second signal threshold, and

the second set of sensor signal samples including sensor signal samples with values less than the first signal threshold and greater than a third signal threshold,

the first signal threshold being greater than the third signal threshold.

15. A method comprising:

identifying, by a digital component of a magnetic sensor, a zero crossing event based on a plurality of sensor signal samples; and

outputting, by the digital component of the magnetic sensor, a signal that is based on the identified zero crossing event.

16. The method of claim 15, where the plurality of sensor signal samples includes one or more sensor signal samples with values that satisfy a threshold and one or more sensor signal samples with values that do not satisfy the threshold.

17. The method of claim 15, further comprising:

obtaining the plurality of sensor signal samples based on a constant buffer length technique associated with storing a particular quantity of sensor signal samples.

18. The method of claim 15, where identifying the zero crossing event based on the plurality of sensor signal samples comprises:

computing a fitted polynomial, associated with the zero crossing event, based on the plurality of sensor signal samples; and

identifying the zero crossing event using the fitted polynomial.

19. The method of claim 15, further comprising:

obtaining the plurality of sensor signal samples based on a constant threshold level technique associated with storing sensor signal samples with values that lie between a first threshold and a second threshold.

20. The method of claim 15, where outputting the signal includes triggering a transition between a first output current level and a second output current level based on the identified zero crossing event.