MXPA99006061A - Method and apparatus for the identification of remote sending units in a vehic - Google Patents

Abstract

A remote tire pressure monitoring system includes a shipping unit for each monitored tire, and the sending units transmit RF signals, each including an ID identifier (i) and a pressure indicator P (i), a receiver operates in a learning mode in which the receiver associates specific identifiers, either with the vehicle or with the specific tires, during the learning mode, the vehicle is driven at a speed higher than the minimum value speed, for example, forty and eight kilometers per hour, and the identifiers are associated, either with the vehicle or the respective tires of the vehicle, only if they persist for a selected number of signs or racks during the learning period, in one example, the tires are inflated to different pressures in accordance with a predetermined pattern, and the pressure indicators of the received signals are used to associate the individual tire positions with the shipping units respectiv

Description

METHOD AND APPARATUS FOR IDENTIFICATION OF REMOTE SENDING UNITS IN A VEHICLE BACKGROUND OF THE INVENTION This invention relates to the programming of a central receiving unit for identifying shipping units such as radio frequency tire pressure delivery units associated with a vehicle. The patent of E.U.A. 5,600,301 assigned to the assignee of the present invention, discloses a tire pressure monitoring system that includes shipping units associated with each tire of a vehicle and a central receiving unit. Each of the sending units includes a respective radio frequency transmitter that transmits an RF signal that includes both an identifier code and a tire pressure indicator. Additionally, each of the shipping units includes a magnet sensor. When the receiving unit is placed in a learning mode, a magnet is used to activate each sending unit of the vehicle in a predetermined order. The receiver learns the identifiers associated with the respective tires based on the activation sequence of the sending units. It has been found that this approach has a reliable use, but requires the user to have a suitable magnet to sequentially activate the shipping units.

The patent of E.U.A. 5,731, 516 discloses a receiver that identifies the transmitters associated with a vehicle, first registering the identification codes received from the transmitters. After registering the identification codes, the receiver verifies that the identified transmitters are installed in the vehicle, ensuring that the tire data was also received from the transmitters previously identified. A problem with the prior art is that physically adjacent vehicles could include shipping units that transmitted similar identification codes and pressure indicators on the same frequency or a similar one. In this case the receiver may mistakenly register the identification code from an adjacent vehicle, instead of the desired identification code associated with the vehicle on which the receiver is mounted.

BRIEF DESCRIPTION OF THE INVENTION The present invention is directed to an improved method and apparatus for allowing a receiver to automatically identify the shipping units associated with the vehicle. This invention is defined by the following claims, and nothing found in this section should be taken as a limit for those claims. By way of introduction, the receiver described in the following detailed description automatically learns the identifiers associated with the vehicle's shipping units. In one method, the receiver receives the radiofrequency signals transmitted by the sending units, and the receiver stores only the information indicative of the chosen identifiers that persist during a learning period, while the vehicle is in motion. Because the vehicle is in motion, the possibility of a neighboring vehicle remaining close to the vehicle that has the receiver during the learning period is substantially reduced. In an embodiment described below, the tires of the vehicle are inflated to separate respective tire pressures, which are chosen to conform to a predetermined pattern. For example, pressures coming clockwise from the front left tire may decrease in a monotone style. The radiofrequency signals transmitted by the sending units are then received and the identifiers of the respective shipping units are associated with the respective rims based on the associated pressure indicators. In this way, the receiver automatically learns the identifiers associated with specific tires of the vehicle, and the operator is not required to use magnets or other selection devices.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a remote tire pressure monitoring system incorporating a preferred embodiment of this invention. Figure 2 is a block diagram of one of the shipping units of Figure 1. Figure 3 is a block diagram of one of the RF signals generated by the shipping unit of Figure 2. Figure 4 is a block diagram of the receiving unit of Figure 1. Figure 5 is a block diagram of a memory matrix included in the signal processor of Figure 4. Figure 6 is a flowchart of a method put in practice by the reception unit of Figure 4. Figures 7 through 14 are flow diagrams of a computer program implemented by the signal processor of Figure 4.

DETAILED DESCRIPTION OF CURRENTLY PREFERRED MODALITIES Referring now to the drawings, Figure 1 shows a schematic view of a vehicle V, which includes in this example four rims. The vehicle V includes a remote tire pressure monitoring system 10, which in this example includes four sending units 12 and a receiving unit 14. Each of the sending units 12 includes a radio frequency transmitter powered by a battery that periodically transmits radiofrequency signals indicative of the pressure in an associated rim. In this example, the tires are labeled T (1), T (2), T (3), T (4), and the associated rim pressures are identified as P (1), P (2), P (3) ), P (4). The receiving unit 14 receives radio frequency signals from the sending units 12 and issues a warning to the operator of the vehicle V when the indicated tire pressure of either tire is outside a predetermined range. This invention can be used with the widest variety of shipping units 12 and receiving units 14, and for this reason these components will be described only briefly herein. As best shown in Figure 2, each of the shipping units 12 may include a pressure sensor 16 and a magnet sensor 18 that provide input signals to a signal processor 20. The signal processor generates output signals transmitting an RF transmitter 22. A battery 24 provides electrical power to the remaining components of the sending unit 12. In this example, the RF signals transmitted by the RF transmitter 22 can take the form shown in Figure 3 As shown in Figure 3, the RF signal 26 includes three components: an identifier 28, a pressure indicator 30, and a magnetic frame indicator 32. The identifier 28 in this embodiment includes a digital variable ID (i) that it is set equal to an identification code assigned to the respective sending unit 12. Each of the shipping units 12 of the vehicle V will then have a different identifier 28. The pressure gauge 30 provides an indication of rim pressure in the respective rim. Preferably, the pressure indicator 30 takes the form of a digital variable P (i) equal to a measure of the tire pressure, although it is possible to apply other techniques. For example, the pressure indicator 30 may take the form of a carrier frequency, where the carrier frequency is chosen to indicate the associated rim pressure. Alternatively, pressure gauge 30, in some embodiments, may be based on a minimum value instead of providing an absolute measure of pressure. The magnet frame indicator 30 may be a single bit variable M (i) which identifies the RF signal (sometimes referred to as a frame in this description), either generated in response to a magnetic field that detected the magnet sensor 18. , or not.

In this example, each of the sending units 12 transmits 8 RF signals or frames per block, and a block of frames is transmitted every minute, while the vehicle is in motion. When a magnet is used to start the operation of one of the shipping units, the respective shipping unit transmits 40 racks within a short period. As shown in Figure 4, the receiving unit 14 includes an RF receiver 34 operative to receive the RF signals 26 described above in conjunction with Figure 3 and to provide the received RF signals to a signal processor 36. The processor of signal 36 controls a screen 40 and responds to a switch 38 of learning mode. For example, the signal processor 36 may automatically provide a display if the received signals indicate that one of the tires T (1) ... T (4) is outside a predetermined range. The learning mode switch 38 is used to place the receiving unit 14 in a learning mode, in which the receiving unit 14 automatically associates the identifiers of each of the sending units 12 associated with the vehicle V with respect to to the tires. As used herein, the term "rim" has a broad meaning and in some cases is used to give importance to the rim position (for example, the left front rim) when compared to a specific rim. During the learning mode, the signal processor automatically loads the identifiers ID (1) -ID (4) in the respective rows of a memory block 42 as shown in figure 5. Once the memory block 42 is automatically loaded, the memory block 42 records the association between the individual tires T (1) -T (4) and the corresponding identifiers ID (1) -! D (4). Then the signal processor 36 can use the memory block 42 to determine which of the received RF signals is associated with the vehicle (while it is in opposition to other physically adjacent vehicles) and the rim or rim position associated with each received signal which is associated with the vehicle. Figure 6 provides a high-level flow diagram of a method implemented by the receiving unit 14 in learning mode. As shown in Fig. 6, the receiving unit is located in a learning mode in step 50 in response to the activation of the learning mode switch 38 of Fig. 6. Either before or after activating the circuit breaker. learning mode, the user inflates the four tires of the vehicle T (1) -T (N) to the pressures P (1) -P (N), where P (1) <; P (2) < ... < P (N-1) < P (N), as indicated in step 52. Then the user guides the vehicle at a speed greater than the speed chosen (for example, 24 kilometers per hour) for at least 3 minutes in step 54. During this period the receiving unit receives radiofrequency signals S (i) from the sending units in step 56, where each RF signal S (i) includes an identifier ID (¡), a pressure indicator P (i), and an indicator of magnet frame M (¡), as described above. In step 58 the receiving unit then associates the chosen identifiers ID (i) that persist during the learning period while the vehicle is in motion with specific tires T (j), based on the respective pressures P (i). This completes the learning procedure. It should be noted that because step 58 only associates the identifiers that persist during the learning period, there is a reduced opportunity for the sending units of other, physically adjacent vehicles to be confused with the shipping units of the vehicle of interest. This is because the vehicle of interest moves at a speed greater than the chosen speed, and therefore a parked vehicle, which was initially close to the vehicle of interest, will not remain near the vehicle of interest during the learning period. In addition, in step 58 the specific chosen identifiers are associated with the specific rims based on the respective pressure indicators. Since the tires were inflated in a pressure sequence specified in step 52, the pressure indicators received by the receiving unit provide an accurate association between the specific identifiers and the respective tires. Table 1 is a list of constants and variables of a digital computer program implemented by the signal processor of Figure 4.

TABLE 1 A. Constants PMIN 1.05 Kg / cm2 PMAX 2.11 Kg / cm2 MINFRAME 1.41 Kg / cm2 MINTIME 0.21 Kg / cm2 DELTA 0.07 Kg / cm2 MAX 0.70 Kg / cm2 B LearnArray Variables (0 ... MAX) List used to store data for the transmitter's emitted signals Time Time in minutes since the learning mode was started Account Number of different transmitter IDs stored from in Leam array Index Loop Counter B. Structure of LearnArray LearnArray (i) = RecTime (i), RecFrame (i), RecID (i), RecMagnetFrame (i), RecPressure (i) RecTime = Time since the last frame was received From the transmitter (i) , RecFrame = Total number of frames received from the Transmitter (i), RecID ID of the transmitter (i), RecMagnetFrame = Total number of magnet frames received from The transmitter (i), RecPressure = Last pressure reading received from the Transmitter ( i).

Table 1 and figures 7 through 14 provide more information for a computer program to implement the method in Figure 6. Table 1 provides introductory information on the constants and variables that are used in the program flow. shown in figures 7 to 14. As shown in table 1, various constants are used in the program of figures 7 through 14. The PMIN and PMAX constants define the minimum and maximum pressures of the rim that are accepted as valid pressure readings, respectively. The MINFRAME constant defines the minimum number of frames or separate RF signals that are required from a particular sending unit before it is considered that the sending unit has persisted through the learning period. The MINTIME constant defines the minimum time (in minutes) that must be included from the last rack from a shipping unit before the shipping unit can be considered overdue and removed from the buffer section as described below. The DELTA constant defines the maximum differential pressure that will be accepted between two consecutive data frames from a single sending unit. The MAX constant defines the size of the buffer section that is used to store the information of the sending unit. The program shown in figures 7 to 14 uses four main variables as shown in table 1. The LearnArray variable is a buffer section that stores a list of records, each record stores data from RF signals received and has a respective identifier, the LearnArray buffer section is referred to as a list for this description. As shown in Table 1, each record in the LearnArray buffer section includes five separate variables. The variable RecTime is set equal to the time (in minutes) since the last frame of the associated sending unit was received. The RecFrame variable is set equal to the total number of racks that are received from the associated sending unit during the learning period. The variable Recldf is set equal to the identifier of the associated sending unit. The RecMagnetFrame variable is set equal to the total number of magnet frames received from the associated sending unit, and the RecPressure variable is set equal to the last pressure indicator received from the associated sending unit. The timer routine in Figure 7 runs once per minute, and operates to increment the RecTime variable for each record in the LearnArray buffer section. After doing this, the garbage routine in Figure 9 is executed. This routine removes the LearnArray records in certain circumstances. In particular, the garbage routine evaluates the RecTime and RecFrame variables for each of the registers in LearnArray. In the case that (1) at least one of the records in LearnArray has a RecTime greater than three (indicating that no frame has been received from the associated shipping unit in three minutes) and (2) that the record has a value of RecFrame <; 20 (indicating that the associated sending unit has not transmitted enough RF signals and the record is incomplete), then (3) the garbage routine discards the incomplete record in LearnArray having the highest value of RecTime, or one of the records incomplete in LearnArray associated with the highest RecTime value and the smallest number of frames (as indicated in the RecFrame variable). This way the backlog records are removed from LearnArray. Each time a new RF signal or rack is received, the rack routine of Figure 8 is called. This routine compares the rack pressure indicator associated with PMIN and PMAX, and only allows the process to continue if the indicator of the magnet frame is set, or the pressure indicator indicates a pressure between PMIN and PMAX. If so, the control is transferred to the update routine in Figure 12. This routine checks to determine if the identifier of the associated rack has already been stored in LearnArray. If so, the associated LearnArray record is updated. Otherwise, a new entry is added to LearnArray. The final loop of the updated routine in Figure 12 runs only if LearnArray is full. In this case, the final loop of the update routine deletes a record from LearnArray having the RecFrame variable equal to one (if such a record is present), thus maintaining only the new record. The new and rectified record routines called by Fig. 12 are shown in a flow chart in Figs. 13 and 14. The new record routine of Fig. 13 stores the ID identifier (!) From the most recently received RF signal in the Reid variable of the associated LearnArray register and resets the RecTime, RecFrame, and RecMagnetFrame variables for this record. The rectified routine in Figure 14 increments the RecFrame variable of the associated LearnArray register (to indicate that another frame has been received from the associated sending unit), resets RecTime to zero, and sets RecPressure equal to the pressure indicator P (i) of the most recently received RF signal. The MagnetFrame variable is incremented only if the magnet frame indicator M (i) is set in the associated frame. Returning to FIG. 8, after the updating routine has been called, the rack routine calls the complete routine of FIG. 10.

The full routine sets the total variable equal to the number of LearnArray entries, with the RecFrame variable greater than MINFRAME. Additionally, the Dlndex variable is set equal to the number of LearnArray entries having the RecMagnetFrame variable greater than half of MINFRAME. Then, the Total variable is compared to four. If the Total is less than four, LearnArray does not yet contain four entries that have an adequate number of frames. If TOTAL is equal to or greater than four, then the complete routine in Figure 10 compares Dlndex with four. If Dlndex is equal to four, indicating that the four LearnArray entries correspond to the sending units that transmit the magnet frames, then the routine extracted from Figure 11 is called. If this is not the case, the complete routine of the Figure 10 calls a sort routine that classifies LearnArray by RecPressure, the lowest pressure located in the first LearnArray record, the second lowest pressure located in the second LearnArray record, and so on. Then it is called the routine extracted from Figure 11. As shown in Figure 11, the extracted routine finds the first record of LearnArray with a RecFrame greater than MINFRAME and sets the first record equal to LEFT FRONT ID. In this way, the identifier associated with the shipping unit that sends the required number of frames and indicative of the lowest pressure is associated with the position of the left front tire T (1). The extracted routine then finds the next LearnArray record having RecFrame greater than MINFRAME and associates this LearnArray record with RIGHT FRONT ID. In this way, the next pressure towards the lowest received from a sending unit that sends at least one MINFRAME number of racks within the learning period is associated with the right front rim position. This continues until all four tires have been associated with the identifiers of the respective shipping units. Once all four tires have been associated with a respective dentifier, the entire routine ends the learning mode. Of course, many changes and modifications may be made in the preferred embodiment described above. For example, in embodiments where the receiving unit 14 does not identify which rim is outside the desired pressure range for the user, the association step 58 of Figure 6 can be revised in such a way that the chosen identifiers ID (i) are associate with the vehicle in the event that such identifiers are received repeatedly during the learning period. There is no need, in this case, to associate the chosen identifiers with the tires based on the respective pressures. Also, the system may additionally include conventional modes of operation in which a magnet is used to consecutively activate the sending units of a vehicle in a manual learning mode. As used herein, the term "Identifier" has a broad meaning and includes any aspect of a received signal that can indicate the source of the signal. As explained above, an identifier may contain a digital code such as a binary code or a frequency such as a carrier frequency. The term "Indicative of pressure" has a broad meaning and includes signals that vary progressively with pressure (either directly or inversely, linearly or non-linearly) or minimum value signals that have one of a limited number of states according to the pressure detected. The term "associated" has a broad meaning and includes any storage of information that links an identifier to a respective vehicle or rim. The term "extreme" has a broad meaning and includes the highest or lowest value in a sequence. An extreme value can be limited to the highest or lowest value that falls within an acceptable range, such as the pressure margin between the PMIN and PMAX variables of the previous example. The term "rim" has a broad meaning and includes the rim position, such as the left front rim of a vehicle. Although the above example has been mentioned in terms of a vehicle having four tires, it should be recognized that the embodiments described above can be easily adapted for use with vehicles having four or more tires. The above detailed description has described only some of the many forms that this invention may contain. For this reason, this detailed description has been created solely by way of illustration.

Only the following claims, including all equivalents, are those that define the scope of the invention.

Claims (12)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for identifying a team of radiofrequency sending units associated with a vehicle, said method consists of the following steps: (a) reception of the radiofrequency signals transmitted by the sending units, each radio frequency signal consists of an identifier associated with the respective shipping unit; and (b) storage of information indicative of the chosen identifiers that persist during a learning period while the vehicle is in motion.

2. The method according to claim 1, further characterized in that each detector consists of a respective digitally encoded signal.

3. The method according to claim 1, further characterized in that step (b) comprises the step of storing information indicative of those identifiers that are received repeatedly over a period of persistence greater than one minute while the vehicle is in motion.

4. The method according to claim 1, further characterized in that the radiofrequency signals transmitted by the sending units consist of pressure indicators of the rim.

5. - A method to identify and locate a team of remote tire pressure delivery units, each shipping unit associated with a respective tire of a vehicle, said method consists of the following steps: (a) inflate a set of tires consisting of tires T (1) ... T (N) with respective tire pressures separated P (1) ... P (N), further characterized because

P (1) < ... < P (N); (b) receiving the signals transmitted by the sending units, each signal consists of an identifier associated with the respective sending unit and a pressure indicator indicative of a respective detected pressure; (c) associate with the respective tire information indicative of the identifiers in accordance with the respective pressure indicators. 6. The method according to claim 5, further characterized in that N = 4; further characterized because the tire set consists of tires T (1), T (2), T (3), T (4); further characterized in that the tire pressures consist of pressures P (1), P (2), P (3), P (4); and further characterized in that P (1) < P (2) < P (3) < P (4).

7. The method according to claim 5, further characterized in that step (c) consists of the step of associating with the rim T (1) information indicative of the identifier associated with the pressure indicator indicative of the lowest rim pressure .

8. The method according to claim 5, further characterized in that the step (c) cost in addition to the step of associating with the rim T (n) information indicative of the identifier associated with the pressure indicator indicative of the lowest pressure n of rim.

9. - The method according to claim 5, further characterized in that the signals are radiofrequency signals.

10. An apparatus for identifying and locating a team of remote tire pressure delivery units, each associated with a respective tire of a vehicle, said apparatus consists of: means for receiving signals transmitted by the sending units, each signal it consists of an identifier associated with the respective sending unit a pressure indicator indicative of a respective detected pressure; means for associating with the respective rims the information indicative of the identifiers in accordance with the respective pressure indicators.

11. The apparatus according to claim 10, further characterized in that the association means consist of means for associating with the rim T (1) the information indicative of the identifier associated with the pressure indicator indicative of the lowest rim pressure. .

12. The apparatus according to claim 10, further characterized in that the association means consist of means for associating with the rim T (n) the information indicative of the identifier associated with the tire pressure indicator indicative of the tire pressure plus low.