WO2003086788A1

WO2003086788A1 - System and method of recognition of transmitter identifiers for tires associated with a vehicle

Info

Publication number: WO2003086788A1
Application number: PCT/US2003/011152
Authority: WO
Inventors: Kurt L. Weaver; Loren D. Vredevoogd; Benjamin J. Algera; Brian S. Honeck
Original assignee: Johnson Controls Technology Company
Priority date: 2002-04-10
Filing date: 2003-04-10
Publication date: 2003-10-23
Also published as: AU2003228494A1

Abstract

A system for automatic recognition of transmitter identifiers transmitted from tires on a vehicle based on wireless messages received from the tire is described. The system includes a receiver circuit configured to receive the wireless messages, the wireless messages each including a unique transmitter identifier. The system further includes a memory configured to store a number of transmitter identifiers and a processing circuit configured to compare received transmitter identifiers with stored transmitter identifiers, and to identify whether a tire is associated with the vehicle based on said comparison during a training mode that occurs once per ignition cycle.

Description

SYSTEM AND METHOD OF RECOGNITION OF TRANSMITTER IDENTIFIERS FOR TIRES ASSOCIATED WITH A VEHICLE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 60/371 ,465, filed April 10, 2002, hereby incorporated by reference.

BACKGROUND OF THE DISCLOSURE

[0002] A typical tire pressure monitoring system can include a plurality of transmitter circuits coupled to each of a plurality of tires on a vehicle. Each transmitter circuit can include a tire pressure sensor configured to sense the tire pressure of an associated tire and a radio frequency transmitter. The transmitter circuits sense tire pressure and generate radio frequency signals in the form of a message. This message can include a transmitter identifier and the sensed tire pressure. The tire pressure monitoring system can also include a receiver circuit coupled to the vehicle for receiving the radio frequency signals. The receiver circuit processes the signals by, for example, displaying the tire pressures of each tire, providing warnings when tire pressures are outside predetermined parameters, etc.

[0003] The receiver circuit can further be configured to associate a tire position, i.e. a location of the tire on the vehicle, with a transmitter identifier. However, as tires on a vehicle are rotated or changed, a transmitter identifier associated with a tire position must be re-associated with a new tire position on the vehicle. Re-association can be performed by requiring the user to manually initiate a training mode and to stimulate successive transmissions from each transmitter circuit in a prescribed order. The transmitter identifiers received in the successive transmissions can be associated with tire positions based on the prescribed order. [0004] An alternative type of tire pressure monitoring system, referred to as a non-positional system, does not associate a transmitter identifier with a tire position. However, the receiver circuit must still be configured to recognize the transmitter identifiers that are associated with the vehicle's tires. Recognition of the transmitter identifiers associated with the vehicle's tires is necessary to distinguish between messages from the vehicle transmitter circuits and messages from transmitter circuits on other vehicles. For example, the receiver circuit must be able to distinguish between the transmitter identifiers on a first vehicle and the transmitter identifiers on a second vehicle driving or parked alongside the first vehicle.

[0005] According to one prior method of associating transmitter identifiers with the vehicle, an operator can initiate a manual train procedure. The user manually initiates a training mode such that the transmitter circuit in each tire is successfully stimulated to train the receiver circuit as to its location or association with the vehicle.

[0006] Accordingly, there is a need for detection of tire pressure monitor identifiers associated with vehicle tires without human intervention. Further, there is a need to eliminate manual training after a new transmitter circuit is installed or a spare tire is put into service. Further, there is a need for a system and method for distinguishing between wireless messages from tires associated with the vehicle and wireless messages from tires associated with other vehicles. The teachings hereinbelow extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.

SUMMARY OF EXEMPLARY EMBODIMENTS

[0007] According to an exemplary embodiment, a system for automatic recognition of transmitter identifiers transmitted from tires on a vehicle based on wireless messages received from the tires is described. The system includes a receiver circuit configured to receive the wireless messages, the wireless messages each including a unique transmitter identifier. The system further includes a memory configured to store a number of transmitter identifiers and a processing circuit configured to compare received transmitter identifiers with stored transmitter identifiers, and to identify whether a tire is associated with the vehicle based on said comparison during a training mode that occurs once per ignition cycle.

[0008] According to another exemplary embodiment, a method of automatic recognition of transmitter identifiers on a vehicle is described. The method includes receiving a plurality of wireless messages from a transmitter associated with the tire, determining transmitter identifiers from the received wireless messages, comparing received transmitter identifiers with current transmitter identifiers, and storing received transmitter identifiers not matching the current transmitter identifiers if received transmitter identifiers match candidate transmitter identifiers during a training mode.

[0009] According to yet another exemplary embodiment, a system for automatic recognition of tire pressure monitoring identifiers on a vehicle is described. The system includes means for receiving a plurality of wireless messages from a transmitter associated with the tire, means for receiving transmitter identifiers from the received wireless messages, means for comparing received transmitter identifiers with received transmitter identifiers, and means for storing received transmitter identifiers not matching the stored transmitter identifiers if received transmitter identifiers match candidate transmitter identifiers during a training mode.

[0010] According to yet another exemplary embodiment, a method of recognition of transmitter identifiers on a vehicle is described. The method includes determining that a transmitter identifier previously associated with the vehicle is no longer being received, determining that a received transmitter identifier that has not been previously associated with the vehicle has been received, determining that the vehicle has reached a predetermined speed, and associating the received transmitter identifier with the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention will become more fully understood from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like parts, and in which:

[0012] FIG. 1 is a schematic diagram of a tire monitoring circuit having a system for automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment;

[0013] FIG. 2 is a block diagram of the system for automatic recognition of tire pressure transmitter identifiers on a vehicle of FIG. 1 , according to an exemplary embodiment;

[0014] FIG. 3. is a flowchart of a method of automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment;

[0015] FIG. 4 is a flowchart of a method of automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment;

[0016] FIG. 5 is a flowchart of a method of automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment;

[0017] FIGs. 6A and 6B are tables used in the implementation of the method of automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment; and [0018] FIGs. 7-9 are flowcharts illustrating methods for updating timers and counters used in the method of automatic recognition of tire pressure transmitter identifiers on a vehicle, according to an exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0019] Referring first to FIG. 1 , a tire monitoring system 10 is illustrated on a vehicle 1 2. Tire monitoring system 10 is configured to monitor one or more characteristics of one or more tires 14, 1 6, 1 8, 20, such as, tire pressure, temperature, alignment, tread wear, etc. According to alternative embodiments, more or fewer tires may be associated with vehicle 1 2. Tire monitoring system 10 is a wireless system, which utilizes radio frequency, infrared, or other wireless signal transmission technology to provide tire characteristic data from tires 1 4-20 to a receiver circuit 22.

[0020] Tire monitoring system 10 further includes a plurality of transmitter circuits 24, 26, 28, 30, each associated with one of tires 14-20. More or fewer transmitter circuits may be included as needed. Transmitter circuits 24-30 include at least one sensor configured to determine at least one tire characteristic of an associated tire. Transmitter circuits 24-30 are configured to provide the tire characteristic data in a wireless message transmitted to receiver circuit 22.

[0021 ] Receiver circuit 22 includes a single antenna 32 in this exemplary embodiment for receiving wireless messages from one or more of transmitter circuits 24-30. According to alternative embodiments, multiple antennas may be coupled to receiver circuit 22 for receiving wireless messages at a plurality of locations on vehicle 1 2. For example, receiver circuit 22 may include four antennas, one disposed in the vicinity of each of transmitter circuits 24-30.

[0022] According to yet another exemplary embodiment, receiver circuit 22 may be coupled to a vehicle data bus. The vehicle data bus may coupled to transmitter circuits 24-30 to receive messages. The vehicle data bus may be further coupled to other vehicle systems to receive data. For example, a vehicle data bus may be coupled to a speedometer to receive a vehicle's current speed. Receiver circuit 22 may be coupled to the vehicle data bus independent of whether receiver circuit 22 is configured to received wireless or wired messages.

[0023] Receiver circuit 22 is configured to receive wireless messages from one or more of transmitter circuits 24-30, to monitor the tire characteristic data on the wireless messages, and to selectively display tire characteristic data to an operator of vehicle 1 2. For example, receiver circuit 22 may receive tire pressure data from transmitter circuits 24-30 and may monitor the tire pressure data to determine if the tire pressure of any of tires 14-20 is greater than or less than predetermined maximum and/or minimum thresholds and may provide a display and associated alarm (visible, audible, etc.) to the operator of vehicle 1 2. The alarm indicates to the operator that maintenance of the tire causing the alarm may be needed.

[0024] Each of transmitter circuits 24-30 is configured to transmit a transmitter identifier in each wireless message. The transmitter identifier may be any type of identifier uniquely identifying the transmitter circuit. For example, a transmitter identifier of "OOOf", in hexadecimal representation, may indicate a first transmitter circuit, while a transmitter identifier of "01 af" may identify a different transmitter circuit. Receiver circuit 22 may be configured to receive the transmitter identifier on the wireless message and to identify a location of the transmitter circuit and the associated tire on vehicle 1 2. Identifying a location allows receiver circuit 22 to provide more meaningful tire data to the operator of vehicle 1 2. For example, receiver circuit 22 may associate a transmitter identifier of "OOOf" with the vehicle position of "left front", and display the tire pressure data for the tire associated with transmitter identifier "OOOf" along with a display indicating that the tire is the left front tire, such as, "LF 28". In this manner, useful information can be provided to the operator of vehicle 1 2 to determine alarm conditions, such as, "LF LOW", "RR LOW", etc.

[0025] According to an exemplary embodiment, receiver circuit 22 may be further configured to receive the transmitter identifier on the wireless message and to classify the tire that is the source of the wireless message based on the transmitter identifier. Based on this classification, the transmitter identifier can be stored in a table associated with the classification that is maintained by receiver circuit 22. Exemplary classifications may include current tire and candidate tire.

[0026] A tire that has previously been recognized as being associated with the vehicle can be classified as a current tire. Generally, this classification describes tires that have been in use on vehicle 1 2 and/or a spare tire carried in or on vehicle 1 2. A transmitter identifier associated with a current tire is referred to as a current transmitter identifier hereinafter.

[0027] A tire that has not previously been recognized as being associated with vehicle 1 2 but may or may not need to be may be classified as a candidate tire. An example of a candidate tire may be a tire that has recently been added to vehicle 1 2, such as a replacement tire. Another example may be a tire associated with a vehicle that is driving alongside vehicle 1 2. A transmitter identifier associated with a candidate tire is referred to as a candidate transmitter identifier hereinafter. The classifications and associated tables are discussed below with reference to FIGs. 3-6B.

[0028] According to yet another exemplary embodiment, the wireless message may further include a function code. A function code may be an instruction or information to be acted upon by the receiver circuit 22. Examples of function codes may include a wake code, a low battery code, etc. The wake code can provide an indication to receiver circuit 22 that vehicle 1 2 has reached a predetermined speed; such that receiver circuit 22 should begin training the tires on vehicle 1 2 as described below with reference to FIGs. 3-5. In some embodiment, it is desirable to only train while the vehicle is moving to avoid erroneously training to a tire on a vehicle that is parked next to the vehicle to be trained. A low battery code can indicate that a transmitter circuit needs a replacement battery.

[0029] Referring now to FIG. 2, a block diagram of receiver circuit 22 is illustrated according to an exemplary embodiment. Receiver circuit 22 includes a receiver 34, a signal strength circuit 36, a processing circuit 38, and a memory 40. Receiver 34 may additionally be a circuit including a receiver coupled to additional components. Receiver 34, circuits 36 and 38, and memory 40 are illustrated in block form to indicate that these elements are functional units which may be embodied in hardware circuitry, software, or other processing elements. For example, receiver 34, circuits 36 and 38, and memory 40 may be disposed on one or more integrated circuits, and may be part of a system-on-chip (SOC), and may further include programmable logic, microprocessors, microcontrollers, or other control circuitry. Furthermore, memory 40 may include volatile memory portions and non-volatile memory portions, and may include random access memory, read-only memory, or any other memory type.

[0030] Receiver 34 is configured to receive wireless messages via antenna 32 from transmitter circuits 24-30. Portions of receiver 34 may be duplicated to receive wireless messages from a plurality of antennas simultaneously. Transmitter circuits 24-30 are configured to transmit blocks of wireless messages, each block including eight identical frames of data, in this exemplary embodiment. Due to interference, multipath, and other sources of error, transmitter circuits 24-30 send duplicative data in each of the frames of each block. Transmitter circuits 24-30 are configured to transmit blocks of data periodically, wherein the rate of transmissions is greater when vehicle 1 2 is in motion than when vehicle 1 2 is idle. For example, when vehicle 1 2 is in motion, a block of data may be sent from each of transmitter circuits 24-30 at a rate of one transmission per 60 seconds, and when vehicle 1 2 is idle, transmitter circuits 24-30 are each configured to send a block of data at a rate of one transmission per 60 minutes. Receiver 34 may include amplifying circuitry, filtering circuitry, buffering circuitry, demodulating circuitry, and/or other circuit elements necessary to receive wireless messages from transmitter circuits 24- 30 via antenna 32.

[0031] Signal strength circuit 36 is coupled to receiver 34 and is configured to determine the signal strengths of the wireless messages. In this exemplary embodiment, signal strength circuit 36 generates a received signal strength indicator (RSSI) for each frame of each block of data. In particular, the RSSI of the first bit in each frame of each block is used to determine the RSSI for the frame. If additional signal strength values are required, signal strength circuit 36 may be configured to measure a plurality of signal strength values for each frame. Signal strength circuit 36 may measure signal strength values for one or more of the first bit of each frame, the last bit of each frame, or any other bits in the frame or message.

[0032] Processing circuit 38 is configured to store the signal strengths provided by signal strength circuit 36 in memory 40. Processing circuit 38 may be configured to identify the positions of the tires on vehicle 1 2 (e.g., left front, right front, right rear, left rear) based on the signal strengths of the wireless messages. In one exemplary embodiment, processing circuit 38 is configured to provide a pattern of the signal strengths (e.g., a statistical distribution such as, a frequency distribution), to compare the pattern of the signal strengths to one or more predetermined patterns (e.g., frequency distributions) stored in memory 40 and to determine the position of the tire on the vehicle based on the comparison. The frequency distributions may include one or more counts of signal strengths that provide sufficient data to correlate a new frequency distribution with one of a plurality of stored frequency distributions. In this example, frequency distributions include the number of samples per bit. The above described system to identify the positions of the tires on a vehicle based on the signal strengths of the wireless messages is further described in a U.S. Patent Application entitled "SYSTEM FOR MONITORING THE PRESSURE OF TIRES OF A MOTOR VEHICLE", filed April 2, 2003, incorporated herein by reference.

[0033] According to one alternative embodiment, receiver circuit 22 does not include signal strength circuit 36 and signals are provided from receiver 34 to processing circuit 38.

[0034] The components in FIG. 2 can be used to implement an exemplary method for recognition of transmitter identifiers on a vehicle, described below with reference to FIGs. 3-5. In an exemplary embodiment, receiver circuit 22 maintains tables of transmitter identifiers for vehicle 1 2 in memory 40. The tables include a current tire table, populated with current transmitter identifiers, and a candidate tire table, populated with candidate transmitter identifiers, described above with reference to FIG. 1 .

[0035] Referring now to FIG. 6A, a current tire table 200 is shown according to an exemplary embodiment. Current tire table 200 includes a current tire table entry for each tire associated with vehicle 1 2. For example, a first current tire table entry 202 may be associated with a first tire on vehicle 1 2, a second current tire table entry 204 may be associated with a second tire on vehicle 1 2, a third current tire table entry 206 may be associated with a third tire on vehicle 1 2, a fourth current tire table entry 208 may be associated with a fourth tire on vehicle 1 2, and a fifth current tire table entry 21 0 may be associated with a spare tire. More or fewer current tire table entries may be used to reflect more or fewer tires associated with vehicle 1 2, for example, if vehicle 1 2 includes multiple rear wheels or more than two axles.

[0036] According to an exemplary embodiment, each of the current tire table entries includes a plurality of data fields. Each data field is represented by a column in table 200. The data fields include a current transmitter identifier 21 2, a current tire counter 214, a current tire timer 21 6, an expired tire flag 21 8, a current tire wake flag 220, and an ID received flag 222. According to alternative embodiments, more or fewer fields can be included in each current tire table entry. For example, wherein tire pressure monitoring system 1 0 tracks the position of tires on vehicle 1 2, each current tire table entry may include a field indicating a position of the tire on vehicle 1 2. The data fields and table 200 are further described below with reference to FIGs 3-5.

[0037] Referring now to FIG. 6B, a candidate tire table 230 is shown according to an exemplary embodiment. Candidate tire table 230 includes a plurality of candidate tire table entries 232. The number of entries 232 included in tire table 230 may be varied to obtain optimal performance. For example, where not enough entries are included, it may be necessary to overwrite an entry that has not been referenced in a while, but may still be needed. However, if too many entries are included, excessive memory is consumed and table searching may be slow. According to an exemplary embodiment, candidate tire table 230 should include the same number of entries as there are tires on vehicle 1 2.

[0038] According to an exemplary embodiment, each of candidate tire table entries 232 also include a plurality of data fields. The data fields include a candidate transmitter identifier 234, a candidate tire counter 236, a candidate tire timer 238, and a candidate tire flag 240. These data fields and table 230 are also described below with reference to FIGs 3-5.

[0039] A method for processing a wireless message received at receiver circuit 22 will now be described. The method is described further below with reference to FIG. 3. As an overview, in operation, a wireless message is received at receiver circuit 22. The wireless message contains a transmitter identifier hereinafter referred to as the received transmitter identifier. Receiver circuit 22 compares the received transmitter identifier to transmitter identifiers stored in the tables in memory 40 and processes the wireless message based on this comparison. [0040] For example, a received transmitter identifier is stored in candidate tire table 230 if the received transmitter identifier does not match a current transmitter identifier stored in current tire table 200. Although the transmitter identifier is placed in candidate tire table 230, in this exemplary embodiment, the tire is not yet considered a candidate for placement in current tire table 200 because it has not been received continuously enough. Accordingly, if a predetermined number of messages are received that contain the same transmitter identifier, the transmitter identifier is marked as a candidate tire or candidate transmitter identifier and candidate tire flag 240, described with reference to FIG. 6B, is set.

[0041] Similarly, if a transmitter identifier that is stored in current tire table 200, i.e. a current transmitter identifier, is not received for a predetermined period of time, the current transmitter identifier can be flagged as an expired tire or expired transmitter identifier and expired tire flag 218, described with reference to FIG. 6A, is set. In at least one exemplary embodiment, the continuous period is five counts, or five minutes. If a current transmitter identifier becomes expired or a missing transmitter identifier is detected and a candidate transmitter identifier is available, the candidate transmitter identifier replaces the expired or missing transmitter identifier, thus becoming a new current transmitter identifier.

[0042] Referring now to FIG. 3, FIG. 3 illustrates a first portion of a method for processing a wireless message received at receiver circuit 22. A second and a third portion are descπbed below with reference to FIGs. 4 and 5, respectively. It is understood that one or more of the steps in this exemplary method may be eliminated or rearranged in various embodiments. Advantageously, the described method allows recognition of transmitter identifiers without requiring any action by the driver.

[0043] At a starting step 68, tire pressure monitoring system 10 is initialized when the ignition for vehicle 12 is first turned on. During initialization, all timers and counters are reset and all flags are cleared with the exception of a "trained" flag. Further, candidate tire table 230 is cleared such that the table will not contain any entries.

[0044] Following initialization in step 68, any timers and/or counters can be activated in a step 69. A variety of timers and counters can be associated with the method described. The timers and counters can be used to track a history of received transmitter identifiers, the time of reception, an expected time of reception, etc. According to an exemplary embodiment, the timers and counters associated with a specific transmitter identifier can be implemented as data fields in a table entry associated with the specific transmitter identifier in current tire table 200 or candidate tire table 230. Other timers may be implemented independent of the tables.

[0045] Referring now to FIG. 7, a method for implementing a train mode timer 160 is illustrated according to an exemplary embodiment. In an exemplary embodiment, detection for new transmitter identifiers is enabled for a predetermined time period following ignition on and only once per ignition cycle to avoid excessive training.

[0046] The train mode timer is used to determine when training mode is done. A train mode time-out timer is set to an initial value upon entering train mode to provide sufficient time for detecting candidate and expired tires. The initial value can be empirically determined to allow sufficient time for all tires to be trained, but not be excessive. According to an exemplary embodiment, the timer can be set to 20 minutes. When timer 1 60 is initiated, the timer is decremented once per minute in a step 1 62. A determination is made in a step 1 64 whether timer 1 60 has reached zero. If timer 1 60 is not equal to zero and one minute has elapsed, step 1 62 is repeated. If timer 1 60 is equal to zero, a step 1 66 is performed wherein receiver circuit 22 exits training mode and a train mode enabled flag is cleared. After training mode is complete, receiver 22 performs normal monitoring functions at step 68, described above with reference to FIG. 3.

[0047] Referring now to FIG. 8, a method 1 70 for determining whether a current transmitter identifier has expired is illustrated according to an exemplary embodiment. A current tire expires when the transmitter identifier for the current tire has not been received for a predetermined period. Current tire timer 21 6, described above with reference to FIG. 6A, is used to monitor the amount of time that has elapsed since a transmitter identifier has been received that matches a current transmitter identifier stored in current tire table 200. If a predetermined amount of time has expired, a current tire counter 214 associated with the current transmitter identifier is incremented. The predetermined amount can be 70 seconds according to an exemplary embodiment. According to alternative embodiments, the predetermined amount can be configured based on a maximum time between transmissions for the transmitters. If the counter reaches a predetermined value and a matching transmitter identifier has still not been received, the current transmitter identifier can be reclassified as an expired transmitter identifier.

[0048] Prior to starting method 1 70, current tire timer 21 6 can be initialized to have a value of zero. Current tire timer 21 6 is incremented once per second in a step 1 72. After current tire timer 21 6 is incremented, a determination is made in a step 1 74 whether current tire timer 21 6 is greater than or equal to 70 seconds. If the current tire timer is not greater than or equal to 70 seconds, step 1 72 is repeated after one second. If current tire timer 21 6 is greater than or equal to 70, current tire timer 21 6 is reset to 1 0 seconds and current tire counter 214 associated with the current transmitter identifier is incremented in a step 1 76.

[0049] Current tire counter 214 is an updateable field in the current tire table entry for the current transmitter identifier. After current tire counter 214 is incremented in step 1 76, a determination is made in a step 1 78 whether the counter has exceeded a predetermined value, for example, five. If current tire counter 214 has exceed the predetermined value, the current transmitter identifier is marked as expired and the expired flag 21 8 is set in a step 1 79. Otherwise, step 1 72 is repeated after one second.

[0050] Referring now to FIG. 9, a method 1 80 for determining whether a new transmitter identifier is a candidate transmitter identifier is illustrated according to an exemplary embodiment. Upon receipt of a new transmitter identifier, i.e. one that is not stored in the tables in memory 40, the new transmitter identifier can be placed in candidate tire table 230 while it is determined whether the tire should be associated with vehicle 1 2. Method 1 80 can be used to determine whether the new transmitter identifier is being received often and continuously such that the transmitter identifier should be designated as a candidate transmitter identifier.

[0051 ] In method 1 80, candidate tire timer 238 is initialized to have a value of zero. Candidate tire timer 238 is incremented once per second in a step 1 82. After candidate tire timer 238 has been incremented, a determination is made in a step 184 whether the timer has reached 70 seconds. If not, step 1 82 is repeated after one second has passed. If timer 238 has reached 70, the elapsed time without a repeated reception of the new transmitter identifier indicates that the new transmitter identifier has not been continuously received. Accordingly, timer 238 and counter 236 are reset to zero, and candidate tire flag 240 is cleared in a step 1 86.

[0052] Referring again to FIG. 3, in a step 70, receiver circuit 22 enters a reiterative loop awaiting reception of a wireless message. After receiving a wireless message in step 70, a step 71 is performed in which transmitter identifiers are verified. Verification can include checking for transmission errors, data integrity issues, etc. If an error condition exists or data integrity is compromised, the received wireless message can be discarded and the process will return to step 70. [0053] Whenever a valid wireless message has been indicated in step 71 , the received transmitter identifier from the wireless message is compared to current transmitter identifiers stored in the current tire table in a step 72. If a received transmitter identifier matches a current transmitter identifier for a particular tire, current tire timer 216 and current tire counter 214 for that tire are reset in step 74. Further, expired tire flag 218 is cleared and ID received flag 222 is set. ID received flag 222 indicates that the current transmitter identifier has been received at least once since initialization.

[0054] In a step 78, it is determined whether the wireless message contains a wake function code, indicative that the vehicle has reached a predetermined speed. If the wireless message does not contain a wake function code, i.e. the vehicle has not reached the predetermined speed, the process returns to step 70. If the wireless message contains a wake function code, the process continues with auto train triggered steps, described with reference to FIG. 5 at the starting point labeled (A). According to an alternative embodiment, a current vehicle speed could be received over a vehicle data bus to determine whether the vehicle has reached the predetermined speed.

[0055] Returning to step 72, if the received transmitter identifier in the wireless message does not match a current transmitter identifier, a check is made as to whether the received transmitter identifier matches a candidate transmitter identifier from the candidate tire table in a step 82. If the received transmitter identifier matches a candidate transmitter identifier, a determination is made in a step 84 whether the wireless message contains a wake function code. If the wireless message contains a wake function code, candidate tire wake flag 242 is set for the candidate transmitter identifier in a step 86.

[0056] If the wireless message does not contain a wake function code in step 84 or after the wake-up flag for the candidate transmitter identifier is set in step 86, a step 88 is performed in which a determination is made as to whether candidate tire timer 238 is greater than 35 seconds. If not greater than 35 seconds, the process returns to starting step 70. Checking the candidate tire timer helps to insure that transmissions are at one minute intervals and that abnormal timing is rejected. The candidate tire timer default of 35 seconds may be configured based on desired and/or current timing.

[0057] If the candidate tire timer is greater than 35 seconds, candidate tire counter 236 is incremented and candidate tire timer 238 is reset in a step 92. In a step 94, a determination is made as to whether candidate tire counter 236 has reached a consecutive count, such as five. If the consecutive count is met, representing a predetermined time interval, candidate tire flag 240 is set in a step 96. If candidate tire counter 236 has not reached the consecutive count limit in step 94 or after the candidate flag has been set in step 96, the process proceeds to steps to test for a trigger, described with reference to FIG. 4 at entry point B.

[0058] Returning to step 82, if the received transmitter identifier does not match a current or candidate transmitter identifier, the lowest count entry (represented by candidate tire counter 236) in candidate tire table 230 is identified as a target for replacement in a step 102. In a step 1 04, the received transmitter identifier is written to candidate tire table 230, overwriting the lowest count entry. Further, still in step 104, candidate tire counter 236 is set to one, and candidate tire timer 238 is set to zero. In a step 106, it is determined whether the wireless message includes a wake function code. If no wake function code is included, the process proceeds to steps to test for a trigger, described with reference to FIG. 4 at entry point B.

[0059] Referring now to FIG. 4 at entry point A, if the wireless message does contain a wake function code, a step 108 (FIG. 4) is performed in which candidate wake flag 242 is set for the candidate transmitter identifier. In a step 1 1 0, it is determined whether all current transmitter identifiers are untrained, which may indicate that a fast train mode should be used. If all current identifiers are untrained, a determination is made in a step 1 1 1 whether a fast train mode is enabled. If fast train mode is enabled, the expired flags are set for all tires in current tire table 200 and control passes to auto-train trigger step 130, described with reference to FIG. 5. Fast train is enabled based on a user input to system 10. Fast train mode can be used during development and manufacturing processes to test and configure system 1 0. Alternatively, fast train mode may be enabled, for example, when a user has placed new tires with new transmitter identifiers on the vehicle and wishes to speed the training process.

[0060] If all current identifiers are not untrained in step 1 1 0 or if fast train mode is not enabled in step 1 1 1 , control passes to steps to test for a trigger initiated at step 1 14. In step 1 14, a determination is made as to whether a train mode flag is set, indicating that system 10 is in a train mode. If in training mode, control proceeds to train mode described with reference to FIG. 5 at entry point B.

[0061] If not in training mode, a determination is made whether training mode should be initiated in step 1 1 6 through 1 22. Initially, a check is made as to whether the candidate flag is set for the received transmitter identifier in a step 1 1 6. If a candidate flag is not set, a step 1 1 8 is performed in which control returns to starting step 70.

[0062] If the candidate flag is set for the received transmitter identifier, a determination is made whether the candidate wake flag 242 is set for the received transmitter identifier in a step 1 20. If the candidate wake flag is not set, a check is made in a step 1 22 as to whether there are four candidate tires with candidate flags set and all current tires are flagged as expired tires. This state indicates that all four tire have new transmitters and no wake function codes have been received. If such a condition is not met, step 1 18 is performed and control returns to starting step 70. If there are four candidate tires with candidate flags set and all current tires are marked as expired, control passes to auto train triggered steps described with reference to FIG. 5 at entry point B. Further, if in step 1 20 the candidate wake-up flag is set, control also passes to auto train triggered steps described with reference to FIG. 5 at entry point B.

[0063] Referring now to FIG. 5, at entry point A, a step 130 is performed in which a determination is made whether the train mode flag is set, indicative that system 10 is in training mode. If not currently in training mode, a step 1 32 is performed in which a determination is made whether the training mode is enabled. If the training mode is enabled, system 10 enters training mode and a step 1 34 is performed in which the train mode time out timer is set to a predetermined value as discussed above with reference to FIG. 7, the train mode flag is set, the current tire timers and counters are set to zero or their default value, the expired tire flags are cleared and candidate timers and counters are set to zero or their default value. After step 1 34 or if the training mode is not enabled in step 1 32, control passes to a step 1 36 and returns to starting step 70. Training mode is disabled when the train mode timer has expired.

[0064] Returning to step 1 30, if currently in training mode, a check is made in a step 1 40 to determine if all ID received flags are set. If all ID received flags are set, a step 142 is performed in which the train mode flag is cleared, train mode is disabled until the next ignition cycle and control passes to step 1 36 and returns to starting step 70. Having all ID received flags set indicates that all current tires are installed and there is no need for further training.

[0065] If all ID received flags are not set or if the train mode flag was determined to be set in step 1 14 in FIG. 4, a step 1 44 is performed in which a determination is made whether candidate tire table 230 includes any entry marked as a candidate, i.e. candidate tire flag 240 is set. If multiple candidate tire flags are set, a determination is made in a step 146 which flagged candidate identifier in candidate tire table 230 has the highest candidate tire counter. If no candidates are flagged, control passes to step 1 36 and returns to starting step 70. [0066] Following determination of the candidate tire having the highest candidate tire counter, a step 148 is performed in which a check is made as to whether the expired tire flag is set for any current tire table entry. If no expired flags are set, step 136 is performed and control returns to starting step 70. If expired tire flags are set, a determination is made in a step 1 49 which current tire table entry having a expired tire flag set has the highest value in the current tire counter. This determination indicates the entry for which a wireless message has not been received for the longest time.

[0067] Following step 149, a step 150 is performed to determine whether any other current identifiers have current tire counters equal to zero to determine whether other current tires are indeed transmitting. If the other current tire transmitters are not transmitting, the current tire may have "expired" because the vehicle is stationary and not because the current tire transmitter identifier should be replaced.

[0068] If no other current identifier counters are equal to zero, a step 1 52 is performed in which a check is made as to whether any entry in candidate tire table 230 having a set candidate tire flag also has a set candidate wake flags. If no candidate wake flags are set, a step 1 54 is performed and control returns to starting step 70.

[0069] If the candidate wake flag is determined to be set in step 1 52 or if any other current tire counters are equal to zero in step 1 50, a step 1 56 is performed in which the current identifier information and/or values are set to the candidate identifier. Accordingly, the candidate tire becomes a current tire in current tire table 200. For the new entry, the current tire counter 214 is set to zero, the current tire timer 21 6 is set to zero, the expired tire flag 21 8 is cleared, and the ID received flag 222 is set. Following step 1 56, step 1 54 is performed and control returns to starting step 70.

[0070] Advantageously, the method described with reference to FIGs. 3-5 assures that identifier training occurs at the optimum time, while the vehicle is moving. Further, the method improves the possibility that a candidate identifier is not a random identifier from another vehicle within receiver range. Further, the auto training of the identifiers is turned off after a certain time because re- association of identifiers is unnecessary while the vehicle is in motion. Accordingly, the auto train mode is disabled until the next ignition cycle.

[0071] While the exemplary embodiments illustrated in the FIGURES and descπbed above are presently preferred, it should be understood that these embodiments are offered by way of example only. For example, various techniques for comparing detected tire pressure monitor identifier signals with stored identifiers may be used. Further, the teachings herein may be applied to various types of vehicles, including cars, trucks, motorcycles, all-terrain vehicles, construction vehicles, etc. Accordingly, the present invention is not limited to a particular embodiment, but extends to various modifications that nevertheless fall within the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1 . A system for automatic recognition of transmitter identifiers transmitted from tires on a vehicle based on wireless messages received from the tire, comprising: a receiver circuit configured to receive the wireless messages, the wireless messages each including a unique transmitter identifier; a memory configured to store a number of transmitter identifiers; and a processing circuit configured to compare received transmitter identifiers with stored transmitter identifiers, and to identify whether a tire is associated with the vehicle based on said comparison during a training mode that occurs once per ignition cycle.

2. The system of claim 1 , wherein the wireless messages comprise tire pressure data, wherein the processing circuit is configured to generate an output signal representative of the tire pressure data and the position of the tire.

3. The system of claim 1 , wherein the memory includes a plurality of predetermined frequency distributions, each of the predetermined frequency distributions corresponding to one of a plurality of tire positions.

4. The system of claim 1 , wherein received transmitter identifiers are stored in a candidate tire table.

5. The system of claim 4, wherein the candidate tire table is cleared upon ignition of the vehicle.

6. The system of claim 1 , wherein the wireless messages include a wake function code transmitted when the vehicle reaches a pre-determined speed.

7. The system of claim 6, wherein wireless messages include a normal function code after the wake function code is transmitted.

8. The system of claim 1 , wherein the processing circuit is configured to receive a vehicle speed input over a vehicle data bus.

9. The system of claim 1 , wherein the processor circuit is configured to determine if the tire has been replaced on the vehicle based on the comparison of the received and stored transmitter identifiers.

10. A method of automatic recognition of transmitter identifiers on a vehicle, comprising: receiving a plurality of wireless messages from a transmitter associated with the tire; determining received transmitter identifiers from the received wireless messages; comparing received transmitter identifiers with current transmitter identifiers; and storing received transmitter identifiers not matching the current transmitter identifiers if received transmitter identifiers match candidate transmitter identifiers during a training mode.

1 1 . The method of claim 10, wherein the wireless messages each comprise tire pressure data, further comprising generating generate an output signal representative of display of the tire pressure data and the position of the tire.

1 2. The method of claim 10, wherein the predetermined time interval is approximately one minute.

1 3. The method of claim 1 0, further comprising storing received transmitter identifiers not matching current transmitter identifiers and not matching candidate transmitter identifiers as candidate transmitter identifiers.

14. The method of claim 13, wherein the storing detected transmitter identifiers includes replacing a candidate transmitter identifiers having the lowest count of the candidate transmitter identifiers.

1 5. The method of claim 1 0, wherein the transmitter has a stationary mode and a wake mode.

1 6. The method of claim 1 5, wherein the transmitter transmits once per hour in stationary mode and the transmitter transmits a wake function code upon entering a wake mode.

17. The method of claim 10, further comprising determining whether a vehicle has reached a predetermined speed prior to storing received transmitter identifiers not matching the current transmitter identifiers if received transmitter identifiers match candidate transmitter identifiers during a training mode.

1 8. The method of claim 10, further comprising determining if a tire has been replaced on the vehicle based on matching candidate transmitter identifiers during an auto train mode.

1 9. A system for automatic recognition of tire pressure monitoring identifiers on a vehicle, comprising: means for receiving a plurality of wireless messages from a transmitter associated with the tire; means for receiving transmitter identifiers from the received wireless messages; means for comparing received transmitter identifiers with stored transmitter identifiers; and means for storing received transmitter identifiers not matching the stored transmitter identifiers if received transmitter identifiers match candidate transmitter identifiers during a training mode.

20. The system of claim 1 9, further comprising means for storing received transmitter identifiers not matching stored transmitter identifiers and not matching candidate transmitter identifiers as candidate transmitter identifiers.

21 . The system of claim 20, wherein the means for storing received transmitter identifiers includes means for replacing a candidate transmitter identifier having the lowest count of candidate transmitter identifiers.

22. The system of claim 1 9, further comprising means for determining if a tire has changed position on the vehicle and for providing an output signal representative of the tire position change.

23. A method of recognition of transmitter identifiers on a vehicle, comprising: determining that a transmitter identifier previously associated with the vehicle is no longer being received; determining that a received transmitter identifier that has not been previously associated with the vehicle has been received; determining that the vehicle has reached a predetermined speed; and associating the received transmitter identifier with the vehicle.

24. The method of claim 23, further including determining that a train flag has been set prior to associating the received transmitter identifier with the vehicle.

25. The method of claim 23, wherein determining that the vehicle has reached a predetermined speed includes receiving a wake function code associated with the received transmitter identifier.

26. The method of claim 23, wherein determining that the vehicle has reached a predetermined speed includes receiving a vehicle speed input over a vehicle data bus.

27. The method of claim 23, wherein determining that a received transmitter identifier that has not been previously associated with the vehicle is being received includes determining that the received transmitter identifier has been received a plurality of times within a predetermined period.