Energy conservation in battery powered tag

• US 20030008692A1
• Filed: 07/03/2002
• Published: 01/09/2003
• Est. Priority Date: 07/05/2001
• Status: Active Grant

• Current Assignee: Goodyear Tire & Rubber Company
• Original Assignee: Goodyear Tire & Rubber Company
• Inventors: Phelan, John Roux
• Granted Patent: US 6,894,600 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• 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: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Method and apparatus for conserving energy in a battery powered tag which comprises a battery, one or more sensors, and a transmitter. Preferably, the tag is used in a pneumatic tire monitoring system which senses and transmits tire pressure and temperature readings. The method fundamentally comprises: hibernating between transmissions by the transmitter; and reading at least one of the sensors after each of a plurality of sleep periods while hibernating. Additionally, the sensors, and an analog-to-digital converter if present, can be enabled after each sleep period but before reading the sensors, and disabled again after reading. Along with reading the sensors, the battery may be tested to determine battery energy level after a specified number of sleep periods. A hibernation period may be ended if one of the sensor readings, preferably tire temperature, is very low, and at least one of a plurality of qualification criteria are met, wherein the qualification criteria include: one or more sensor readings being outside of a window of allowed values; or a sensor has a reading such that a transmitted value difference exceeds a specified threshold limit value, wherein the difference is the absolute value of the sensor reading minus the last transmitted reading of the same sensor. Optionally, the method further comprises the step of ending a period of hibernating if one of the sensor readings is not very low and none of the qualification criteria have been met after being checked for a specified limit number of times.

Claims

1. A method for conserving energy in a battery powered tag which comprises a battery, one or more sensors, and a transmitter, wherein the method comprises the steps of:

hibernating between transmissions by the transmitter; and

reading at least one of the one or more sensors after each of a plurality of sleep periods while hibernating.

2. A method according to claim 1, further comprising the steps of:

enabling the one or more sensors after each sleep period but before reading the one or more sensors; and

disabling the one or more sensors after reading the one or more sensors.

3. A method according to claim 1, wherein the tag further comprises an analog-to-digital converter (A/D), the method further comprising the steps of:

enabling the A/D after each sleep period but before reading the one or more sensors; and

disabling the A/D after reading the one or more sensors.

4. A method according to claim 1, further comprising the steps of:

testing the battery to determine battery energy level after a specified number of sleep periods.

5. A method according to claim 4, characterized in that:

a shorting way is utilized for testing the battery; and

the shorting way includes short circuiting the battery terminals for a specified limited amount of time before measuring the battery voltage level and un-shorting the battery terminals.

6. A method according to claim 1, further comprising the step of:

ending a period of hibernating if one of the sensor readings is very low and a specified hibernation time limit is reached.

7. A method according to claim 6, characterized in that:

the sensor with a very low reading is sensing temperature.

8. A method according to claim 1, further comprising the step of:

ending a period of hibernating if one of the sensor readings is not very low, and one or more sensor readings is outside of a specified window of allowed values.

9. A method according to claim 8, characterized in that:

the sensor with a not very low reading is sensing temperature.

10. A method according to claim 1, further comprising the step of:

ending a period of hibernating if one of the sensor readings is not very low, and at least one specific sensor has a reading such that a transmitted value difference exceeds a specified threshold limit value, wherein the transmitted value difference is the absolute value of the difference between the specific sensor reading and the last transmitted reading of the specific sensor.

11. A method according to claim 10, characterized in that:

the sensor with a not very low reading is sensing temperature.

12. A method according to claim 1, further comprising the step of:

ending a period of hibernating if one of the sensor readings is not very low, and at least one of a plurality of qualification criteria are met, wherein the qualification criteria include;

a criterion that one or more sensor readings is outside of a specified window of allowed values;

or

a criterion that at least one specific sensor has a reading such that a transmitted value difference exceeds a specified threshold limit value, wherein the transmitted value difference is the absolute value of the difference between the specific sensor reading and the last transmitted reading of the specific sensor.

13. A method according to claim 12, characterized in that:

the sensor with a not very low reading is sensing temperature.

14. A method according to claim 12, further comprising the step of:

ending a period of hibernating if one of the sensor readings is not very low and none of the qualification criteria have been met after being checked for a specified limit number of times.

15. A method according to claim 1, further comprising the steps of:

testing at least one of the sensor readings against one or more qualification criteria; and

ending a period of hibernating if one of the sensor readings is not very low and none of the qualification criteria have been met after testing sensor readings against the qualification criteria for a specified limit number of times.

16. A method according to claim 1, further comprising the steps of:

determining when a power-on reset (POR) has occurred, and whenever a POR occurs;

skipping a sleep period;

reading at least one of the one or more sensors;

testing the battery; and

ending the hibernating to allow transmission by the transmitter.

18. An energy conserving tag, according to claim 17, further comprising:

means for testing at least one of the sensor readings against one or more qualification criteria; and

means for ending a period of hibernation whenever one of the qualification criteria is met.

20. A monitoring system according to claim 19, characterized in that:

the object to be monitored is a pneumatic tire;

the one or more sensors are for sensing tire pressure and one or more temperatures of the tire carcass and of the tire pneumatic filling;

transmissions include a pressure reading, one or more temperature readings, and a battery test result; and

the qualification criteria include pressure or temperature sensor readings being outside of a specified window; and

pressure or temperature sensor readings being different from their last transmitted values by more than a specified threshold value.

17. An energy conserving tag, comprising:

a battery, one or more sensors, and a transmitter;

means to provide hibernation periods between transmissions by the transmitter;

means for reading at least one of the one or more sensors after each of a plurality of sleep periods while hibernating; and

means for testing the battery to determine battery energy level after a specified number of sleep periods while hibernating.

19. A monitoring system with an energy conserving battery powered active tag, comprising at least one object to be monitored, a system receiver, and an energy conserving tag mounted to the object to be monitored;

wherein the energy conserving tag comprises;

a battery, one or more sensors, and a transmitter;

means to provide hibernation periods between transmissions by the transmitter to the receiver;

means for reading at least one of the one or more sensors after each of a plurality of sleep periods while hibernating;

means for testing the battery to determine battery energy level after a specified number of sleep periods while hibernating;

means for testing at least one of the sensor readings against one or more qualification criteria; and

means for ending a period of hibernation whenever one of the qualification criteria is met.