System and method for detecting motion of an object

• US 7,197,921 B2
• Filed: 01/04/2005
• Issued: 04/03/2007
• Est. Priority Date: 01/04/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kramer, Bradley Allen
• Primary Examiner(s): Thompson; Jewel
• Application Number:
  US11/029,158
• Publication Number:
  US 20060144134A1
• Time in Patent Office: 819 Days
• Field of Search: 731/46, 731/462, 731/464, 731/468, 340/444, 340/426.11
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0477 Evaluating waveform of pressure readings

Abstract

Systems and methods are disclosed to for detecting movement of an object. In one embodiment, a system is disclosed to detect movement of an object (e.g., a tire). The system includes a sensor that is operative to sense at least a pressure condition within an enclosed space of the object based on an operating mode of the system. A control system controls the operating mode of the system based at least in part on whether movement of the object is detected. The movement of the object is detected based on a variation in the at least a pressure condition over time. The system can be implemented as part of a tire pressure monitoring system.

Claims

1. A system to detect movement of an object, comprising:

a sensor that is operative to sense at least a pressure condition within an enclosed space of the object based on an operating mode of the system;

a control system that controls the operating mode of the system based at least in part on whether movement of the object is detected, the movement of the object being detected based on a variation in the at least a pressure condition over time and

a variation detector that detects the movement of the object if the at least a pressure condition exceeds a predetermined level of variation over a plurality of samples.

2. The system of claim 1, further comprising memory that stores a value indicative of the at least a pressure condition for each of a plurality of samples.

3. The system of claim 1, further comprising memory that stores a value indicative of the at least a pressure condition for each of a plurality of samples, the variation detector being operative to determine a statistical variation in the values stored in the memory, the control system controlling the sensor in a first mode if the statistical variation exceeds the predetermined level of variation and controlling the sensor in a second mode if the statistical variation does not exceed the predetermined level of variation, such that the sensor is activated more often in the first mode.

4. The system of claim 1, wherein the control system controls the sensor to sense at a greater rate in a first operating mode corresponding to when the movement of the object is detected than in a second operating mode when the movement of the object is not detected.

5. The system of claim 1, further comprising a temperature sensor, the at least a pressure condition further comprising a pressure condition that is sensed by a pressure sensor and a temperature condition that is sensed by the temperature sensor.

6. The system of claim 1, further comprising

an evaluator that determines an indication of the variation based on each of a plurality of samples of the at least a pressure condition over time;

and

a comparator that compares the indication of variation relative to a predetermined variation level, the movement of the object being detected based on the comparison.

7. The system of claim 1, further comprising a transmitter, the control system causing the transmitter to transmit a signal that includes a value indicative of the at least a pressure condition based on the operating mode.

8. A tire pressure monitoring system comprising:

a plurality of tire pressure sensing modules, each of the plurality of tire pressure sensing modules including a system according to claim 1 that is operative to sense the at least a pressure condition associated with each of a plurality of respective tires mounted for movement on a vehicle; and

a central control system that receives signals from each of the plurality of tire pressure sensing modules.

9. A tire pressure monitoring system comprising:

a pressure sensor that is operative to sense a pressure condition associated with a tire;

a control system that controls the pressure sensor to sense the pressure condition at a sample rate that varies based on whether movement of the tire is detected; and

a variation detector that detects the movement of the tire based on determining at least a predetermined level of variation in the sensed pressure condition over a plurality of samples of the sensed pressure condition;

memory that stores a value indicative of the sensed pressure condition for each of a plurality of samples of the sensed pressure condition;

an evaluator that determines an indication of the variation in the sensed pressure condition based on the value stored in the memory for each of the plurality of samples of the sensed pressure condition; and

a comparator that compares the indication of variation relative to a predetermined variation level, the variation detector detecting the movement of the object based on the comparison.

11. The system of claim 9, further comprising a temperature sensor that senses temperature of the tire, the variation detector detecting the movement of the tire as a function of variation in the sensed pressure and the sensed temperature over a plurality of samples.

12. The system of claim 9, further comprising a transmitter, the control system controlling the transmitter to transmit a signal that includes a value indicative of the sensed pressure condition based on an operating mode of the system, the operating mode of the system varying based on whether the variation detector detects the movement of the tire.

10. A tire pressure monitoring system comprising:

a pressure sensor that is operative to sense a pressure condition associated with a tire;

a control system that controls the pressure sensor to sense the pressure condition at a sample rate that varies based on whether movement of the tire is detected;

a variation detector that detects the movement of the tire based on determining at least a predetermined level of variation in the sensed pressure condition over a plurality of samples of the sensed pressure condition; and

memory that stores a value indicative of the sensed pressure condition for each of a plurality of samples of the sensed pressure condition wherein the variation detector determines a statistical variation in the values stored in the memory for the plurality of samples, the control system controlling the pressure sensor to sense in a first mode if the statistical variation exceeds the predetermined level of variation and controlling the pressure sensor in a second mode if the statistical variation does not exceed the predetermined level of variation, the pressure sensor being activated more often in the first mode than in the second mode.

13. A tire pressure monitoring system comprising:

means for sensing pressure of a tire and for providing an indication of the sensed pressure;

means for controlling the means for sensing pressure to sense the pressure based on whether movement of the tire is detected; and

means for detecting movement of the tire solely as a function of variation in the indication of the sensed pressure over time.

14. The system of claim 13, further comprising means for storing a value for the indication of the sensed pressure for each of a plurality of samples.

15. The system of claim 13, further comprising means for controlling an interval between consecutive times when the means for sensing senses the pressure of the tire based on an operating mode of the system, the operating mode varying based on whether the movement of the tire is detected.

16. The system of claim 13, further comprising means for transmitting the indication of the sensed pressure from the system.

17. A method for detecting movement of a tire, comprising:

sensing at least a pressure condition associated with the tire;

determining a variation for the at least a sensed pressure condition over time; and

detecting movement of the tire based on the determined variation for the at least a pressure condition;

controlling an operating mode of a tire pressure monitoring system based on the detected movement of the tire, the tire pressure monitoring system operating in a first mode when the determined variation for the at least a pressure condition exceeds an expected value and operating in a second mode when the determined variation for the at least a pressure condition does not exceed the expected value, the sensing occurring more often in the first mode than in the second mode.

18. The method of claim 17, further comprising transmitting an indication of the at least a pressure condition based on the operating mode of the tire pressure monitoring system.