TIRE ROTATION DETECTION SYSTEM AND METHOD

• US 20090204361A1
• Filed: 02/03/2009
• Published: 08/13/2009
• Est. Priority Date: 02/04/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Watasue, Toshiaki
• Granted Patent: US 7,930,132 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A method for determining whether a tire is in rotation is provided. A measured acceleration is compared to a first threshold after a first timer indicates that a first period has lapsed, and indication that the tire is in rotation is provided if at least one of the measured accelerations is greater than the first threshold. If an absolute difference between consecutive measured accelerations is greater than a second threshold, an indication that the tire is in rotation is also provided. Additionally, the second timer is started if the absolute difference is greater than the second threshold and if a second timer is not running, and indication that the tire is rotating is provided if the absolute difference is less than a predetermined threshold and if the second timer is running.

Claims

1. An apparatus comprising:

a first timer that indicates when a first period has lapsed;

a second timer that operates for a second period;

an accelerometer that measures the an acceleration of a tire after each first period has lapsed; and

a processor having a computer program embodied thereon, the computer program including;

computer code for indicating that the tire is in rotation if at least one of the measured accelerations is greater than a first threshold;

computer code for indicating that the tire is in rotation if an absolute difference between consecutive measured accelerations is greater than a second threshold;

computer code for starting the second timer if the absolute difference is greater than the second threshold and if the second timer is not running; and

computer code for indicating that the tire is rotating if the absolute difference is less than a predetermined threshold and if the second timer is running.

2. The apparatus of claim 1, wherein the apparatus further comprises a radio frequency (RF) output device that communicates information from the processor.

3. The apparatus of claim 1, wherein the apparatus further comprises a pneumatic pressure sensor that measured a tire pressure.

4. The apparatus of claim 1, wherein the apparatus further comprises a battery that supplies power to the apparatus.

5. The apparatus of claim 4, wherein the apparatus further comprises a battery voltage sensor that measures the voltage of the battery.

6. The apparatus of claim 1, wherein the computer program further comprises computer code for indicating that the tire is not in rotation if the absolute difference is less than the second threshold and the second timer is not running.

7. A system comprising:

a radiator;

a receiver that is mounted in the body of a vehicle and that is coupled to the radiator;

a plurality of sensing unit, wherein each sensor is secured to at least one tire of the vehicle, and wherein each sensing unit includes;

a first timer that indicates when a first period has lapsed;

a second timer that operates for a second period;

an accelerometer that measures the an acceleration of a tire after each first period has lapsed;

a processor having a computer program embodied thereon, the computer program including;

computer code for indicating that the tire is in rotation if at least one of the measured accelerations is greater than the first threshold;

computer code for indicating that a tire is in rotation if an absolute difference between consecutive measured accelerations is greater than a second threshold;

computer code for starting the second timer if the absolute difference is greater than the second threshold and if the second timer is not running; and

computer code for indicating that the tire is rotating if the absolute difference is less than a predetermined threshold and if the second timer is running; and

an RF output device that is coupled to the processor and that communicates information from the processor to the radiator.

8. The system of claim 7, wherein the system further comprises a display that is coupled to the receiver.

9. The system of claim 7, wherein the sensing unit further comprises a pneumatic pressure sensor that measured a tire pressure.

10. The system of claim 7, wherein the sensing unit further comprises a battery that supplies power to the apparatus.

11. The system of claim 10, wherein the sensing unit further comprises a battery voltage sensor that measures the voltage of the battery.

12. The system of claim 7, wherein the computer program further comprises computer code for indicating that the tire is not in rotation if the absolute difference is less than the second threshold and the second timer is not running.

13. The system of claim 7, wherein the radiator is an antenna.

14. A processor having a computer program for determining whether a tire is in rotation embodied thereon, the computer program comprising:

computer code for comparing a measured acceleration to a first threshold after a first timer indicates that a first period has lapsed;

computer code for indicating that the tire is in rotation if at least one of the measured accelerations is greater than the first threshold;

computer code for indicating that the tire is in rotation if an absolute difference between consecutive measured accelerations is greater than a second threshold;

computer code for starting the second timer if the absolute difference is greater than the second threshold and if a second timer is not running; and

computer code for indicating that the tire is rotating if the absolute difference is less than a predetermined threshold and if the second timer is running.

15. The computer program of claim 14, wherein the computer program further comprises computer code for receiving a measured tire pressure from a pneumatic pressure sensor.

16. The computer program of claim 14, wherein the computer program further comprises computer code for receiving a measured voltage of a battery from a battery voltage sensor.

17. The computer program of claim 14, wherein the computer program further comprises computer code for indicating that the tire is not in rotation if the absolute difference is less than the second threshold and the second timer is not running.