Low line TPMS: sensor association using RSSI and doppler signatures with a single or multiple ECUs
A TPMS that uses a unique signature, such as RSSI signal levels and statistics or Doppler shift information, to identify the location of where the TPMS signal is being transmitted from. The TPMS includes a separate transmitter unit provided in each tire, where each transmitter unit transmits TPMS signals including an ID code identifying the tire and the pressure in the tire. The TPMS also includes a receiver unit that receives the TPMS signals from each of the transmitter units, where the receiver unit stores an average or other classification of the signature over time to identify the location of the transmitter unit for a particular ID code. The receiver unit compares the new received TPMS signals to the classified signals to identify whether the ID code indicates that the position of the tire has changed.
1. A tire pressure monitoring system (TPMS) for a vehicle having a plurality of tires, said system comprising:
a plurality of transmitter units where a separate transmitter unit is provided in each tire, and where each transmitter unit transmits TPMS signals including data identifying the tire and the pressure in the tire; and
at least one receiver unit receiving the TPMS signals from each of the transmitter units, said at least one receiver unit identifying a signature in each of the TPMS signals and classifying the signatures over time to provide a training set signature representing a location of the transmitter units, where the signature includes a Doppler frequency shift of the received signal associated with tire-rotation-induced cyclical changes in velocity of the transmitter unit in each tire relative to the receiver unit.
2. The TPMS according to claim 1 wherein the at least one receiver unit classifies the signature in the received TPMS signals as compared to the training set signatures to determine that the location of a tire has changed.
3. The TPMS according to claim 2 wherein the at least one receiver identifies a new location of a tire by identifying that the signature of a received TPMS signal for that tire matches the training set signature for a different signature of another tire.
4. The TPMS according to claim 3 wherein the data identifying the tire is an identification (ID) code, and wherein the at least one receiver unit determines that the location of a tire has changed if the signature of the tire is classified for the location of a training set signature of a tire having a different ID code.
5. The TPMS according to claim 1 wherein the at least one receiver is two receivers where both receivers receive the TPMS signals from each of the transmitter units, store the unique signatures of each of the TPMS signals over time to provide a separate classification of a location of the transmission of each of the signals, and classifies the received TPMS signals to the training set signatures.
6. The TPMS according to claim 5 wherein the two receivers are located at different locations on the vehicle.
7. The TPMS according to claim 1 wherein the signature includes a received signal strength indicator.
8. The TPMS according to claim 1 wherein the signature includes a phase of the signal.
9. The TPMS according to claim 1 wherein the signature includes a polarization of the signal.
10. A tire pressure monitoring system (TPMS) for a vehicle having a plurality of tires, said system comprising:
a plurality of transmitter units where a separate transmitter unit is provided in each tire, and where each transmitter unit transmits TPMS signals including an identification (ID) code identifying the tire and the pressure in the tire; and
at least one receiver unit receiving the TPMS signals from each of the transmitter units, said at least one receiver unit identifying a received signal strength indicator (RSSI) in each of the TPMS signals and classifying the RSSI over time to provide a training set RSSI identifying a location of the transmitter units, wherein the at least one receiver unit compares the RSSI in the received TPMS signals to the training set RSSIs to determine that the location of a tire has changed and identifies a new location of a tire by identifying that the RSSI of a received TPMS signal for that tire matches the training set RSSI for a different RSSI of another tire, where the at least one receiver unit also identifies a Doppler frequency shift of the TPMS signal associated with tire-rotation-induced cyclical changes in velocity of the transmitter unit in each tire relative to the receiver unit, and uses the Doppler frequency shift along with the RSSI to correlate received signals with training sets.
11. The TPMS according to claim 10 wherein the at least one receiver is two receivers where both receivers receive the TPMS signals from each of the transmitter units, store the RSSI signal levels and statistics referred to as RSSI signatures of each of the TPMS signals over time to provide a separate training set RSSI of a location of the transmission of each of the signals, and compare the received TPMS signals to the training set RSSIs to determine whether the signal has changed.
12. The TPMS according to claim 11 wherein the two receivers are located at different locations on the vehicle.
13. A method for identifying the location of a tire on a vehicle having a plurality of tires in a tire pressure monitoring system (TPMS), said method comprising:
transmitting TPMS signals from a plurality of transmitter units where a separate transmitter unit is provided in each tire, where the TPMS signals including data identifying the tire and the pressure in the tire;
receiving the TPMS signals by at least one receiver unit receiving the TPMS signals from each of the transmitter units;
identifying a signature in each of the TPMS signals and classifying the signatures over time to provide a separate training set signature of a location of the transmitter units, where the signature includes a Doppler frequency shift of the received signal associated with tire-rotation-induced cyclical changes in velocity of the transmitter unit in each tire relative to the receiver unit; and
comparing the signature in the received TPMS signals to the training set signatures to determine that the location of a tire has changed.
14. The method according to claim 13 wherein comparing the signature in the received TPMS signals to the training set signatures includes identifying a new location of a tire by identifying that the signature of a received TPMS signal for that tire matches the training set signature for a training set signature of another tire.
15. The method according to claim 14 wherein the data identifying the tire is an identification (ID) code, and wherein comparing the signature in the received TPMS signals to the training set signatures includes determining that the location of a tire has changed if the signature of the tire is classified for the location of a signature of a tire having a different ID code.
16. The method according to claim 13 wherein the signature includes a received signal strength indicator.
17. The method according to claim 13 wherein the signature includes a phase of the signal.
18. The method according to claim 13 wherein the signature includes a polarization of the signal.