# US 9,517,665 B2 · Apparatus and method for compensating for atmospheric pressure in a TPMS system

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- Number: US 9,517,665 B2
- Document ID: US9517665B2
- Status: Granted
- Kind: B2
- Application number: 14/576,894
- Filed: 2014-12-19
- Published: 2016-06-23
- Granted: 2016-12-13
- Earliest claimed: 2014-12-19
- Assignees: Continental Automotive Systems, Inc.
- Applicants: Continental Automotive Systems, Inc.
- Inventors: Jean-Christophe Deniau; Alexander Fink
- Web page: https://patentgrep.com/patent/US9517665B2

## CPC

- B60C 23/0433: {Radio signals}
- B60C 23/0408: {transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver}
- B60C 23/0476: {Temperature compensation of measured pressure values}
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES

## Abstract

An altitude of the vehicle from an external electronic source and an external temperature is received from a temperature sensor are received. An external relative humidity is determined. Based upon the altitude, the temperature, and the external relative humidity, an estimated barometric pressure is determined. An air pressure of a tire is received. An adjustment is made to the received pressure to obtain a corrected pressure. The amount of adjustment is based upon the estimated barometric pressure and the adjustment is applied to the air pressure to obtain a corrected tire pressure. An evaluation is made of the corrected tire pressure to determine when an alert should be presented to a user. When the alert is determined, the alert to the user is presented to the user.

## Claims

### Claim 1

A method, the method comprising:
receiving an altitude of the vehicle from an external electronic source;
receiving an external temperature is received from a temperature sensor;
determining an external relative humidity;
based upon the altitude received from the external electronic source, the temperature, and the external relative humidity, determining an estimated barometric pressure;
receiving an air pressure of a tire;
determining an adjustment to the air pressure of the tire, the adjustment based upon the estimated barometric pressure, the adjustment applied to the air pressure of the tire to obtain a corrected tire pressure;
evaluating the corrected tire pressure to determine when an alert should be presented to a user;
when the alert is determined, presenting the alert to the user.

### Claim 2 (depends on 1)

The method of claim 1 wherein the corrected tire pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.

### Claim 3 (depends on 1)

The method of claim 1, wherein the air pressure of the tire is received from a message from the TPMS sensor.

### Claim 4 (depends on 1)

The method of claim 1, wherein the altitude is received from a global positioning satellite (GPS) system.

### Claim 5 (depends on 1)

The method of claim 1, wherein determining an external relative humidity comprises receiving the external relative humidity from a external relative humidity sensor.

### Claim 6

An electronic control unit (ECU), the comprising:
an electronic interface having an input and output, the input configured to receive an altitude of the vehicle from an external electronic source and an external temperature is received from a temperature sensor;
a controller coupled to the electronic interface, the controller configured to determine an external relative humidity, the controller configured to based upon the altitude received from the external electronic source, the temperature, and the external relative humidity, determine the estimated barometric pressure, the controller configured to receive a pressure of a tire at the input of the electronic interface, the controller configured to determine an adjustment to the air pressure of the tire, the adjustment based upon the estimated barometric pressure, the adjustment being applied to the air pressure of the tire to obtain a corrected tire pressure, the controller configured to evaluate the corrected tire pressure to determine when an alert should be presented to a user and when the alter is determined, presenting the alert to the user via the output of the electronic interface.

### Claim 7 (depends on 6)

The ECU of claim 6 wherein the corrected tire pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.

### Claim 8 (depends on 6)

The ECU of claim 6, wherein the air pressure of the tire is received from a message from the TPMS sensor.

### Claim 9 (depends on 6)

The ECU of claim 6, wherein the altitude is received from a global positioning satellite (GPS) system.

### Claim 10 (depends on 6)

The ECU of claim 6, wherein the external relative humidity is determined from a measurement received from an external relative humidity sensor.

### Claim 11

A computer usable non-transitory medium having a computer readable program code embodied therein, said computer readable program code adapted to be executed to implement a method of determining atmospheric pressure, the method comprising:
receiving an altitude of the vehicle from an external electronic source;
receiving an external temperature is received from a temperature sensor;
determining an external relative humidity;
based upon the altitude, the temperature, and the external relative humidity, determining the estimated barometric pressure;
receiving a pressure of a tire;
determining an adjustment to the air pressure of the tire, the adjustment based upon the estimated barometric pressure, the adjustment applied to the air pressure of the tire to obtain a corrected tire pressure;
evaluating the corrected tire pressure to determine when an alert should be presented to a user;
when the alert is determined, presenting the alert to the user.

### Claim 12 (depends on 11)

The computer usable non-transitory medium of claim 11 wherein the corrected tire pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.

### Claim 13 (depends on 11)

The computer usable non-transitory medium of claim 11, wherein the air pressure of the tire is received from a message from the TPMS sensor.

### Claim 14 (depends on 11)

The computer usable non-transitory medium of claim 11, wherein the altitude is received from a global positioning satellite (GPS) system.

### Claim 15 (depends on 11)

The computer usable non-transitory medium of claim 11, wherein determining an external relative humidity comprises receiving the external relative humidity from a external relative humidity sensor.

### Claim 16 (depends on 1)

The method of claim 1 wherein the estimated barometric pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.

### Claim 17 (depends on 6)

The ECU of claim 6 wherein the estimated barometric pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.

### Claim 18 (depends on 11)

The computer usable non-transitory medium of claim 11 wherein the estimated barometric pressure is determined according to the equation
P
0
⁢
e
-
mgh
kT
,
where P0 is the barometric pressure at sea level; m is the molecular mass of air; g is the gravitational acceleration near Earth's surface, h is the altitude; k is the Boltzmann's constant; and T is the temperature.