Wheel condition monitoring system and wheel position detection method

• US 7,800,488 B2
• Filed: 05/30/2007
• Issued: 09/21/2010
• Est. Priority Date: 05/31/2006
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Sugiura, Shinya, Ide, Nobuhiro, Iizuka, Hideo
• Primary Examiner(s): Lee; Benjamin C
• Assistant Examiner(s): Pham; Quang
• Application Number:
  US11/755,332
• Publication Number:
  US 20070279205A1
• Time in Patent Office: 1,210 Days
• Field of Search: 340442-448, 340/10.1, 343/443, 343/444, 343/445, 343/446, 343/447, 343/448, 343/449, 343/833, 116/34.A, 116/34.B, 116/34.R, 731/46, 731462-1466, 152/152.1, 152/415
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0416 allocating a corresponding wheel position on vehicle, e.g. front/left or rear/right
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B60C 23/0444 Antenna structures, control or arrangements thereof, e.g. for directional antennas, diversity antenna, antenna multiplexing or antennas integrated in fenders

Abstract

A wheel condition monitoring system includes a plurality of transmitters; a receiver; an antenna directivity control unit; a memory unit; and a wheel position determination unit. The transmitters are at each wheel of the vehicle, and transmit signals that include wheel condition data and identification data of themselves. The receiver receives the transmission signals so that the wheel condition monitoring system monitors the conditions of the respective wheels based thereon. The antenna directivity control unit controls the antenna directivity of the receiver. The memory unit stores the identification data by assigning relations between the identification data and the position of the corresponding wheel. The wheel position determination unit determines the position of the wheel at which the transmitter is installed based on the relations.

Claims

1. A wheel condition monitoring system that includes a plurality of transmitters, respectively installed at a plurality of wheels of a vehicle, that transmit wheel condition data that indicates the conditions of a corresponding wheel of the plurality of wheels, and a receiver, installed on a main body of the vehicle, that receives the wheel condition data transmitted from the respective transmitters, the wheel condition monitoring system monitoring the condition of each wheel of the plurality of wheels based on the wheel condition data transmitted from the transmitters and received by the receiver, comprising:

an antenna directivity control unit that controls an antenna directivity of the receiver;

a memory unit that assigns relations between the identification data of each transmitter, received by the receiver, and the position of the corresponding wheel, and stores the assigned relations when the antenna directivity of the receiver is changed by the antenna directivity control unit so that an antenna gain is sequentially maximized based on the position and orientation of each wheel; and

a wheel position determination unit that determines the position of the wheel at which one of the plurality of transmitters that has transmitted a transmission signal including the wheel condition data and the identification data thereof, is installed, when the receiver receives the transmission signal, based on the relations between the identification data of the each transmitter and the position of the corresponding wheel stored in the memory unit, wherein

the antenna directivity control unit includes;

a normal reception antenna directivity changing unit that changes, after relations between the identification data of all the transmitters and the positions of the corresponding wheels are stored in the memory unit, the antenna directivity of the receiver so that the receiver is able to receive the wheel condition data transmitted from all the transmitters,

a relation confirmation antenna directivity changing unit that changes the antenna directivity of the receiver such that the antenna gain is sequentially maximized based on the position and orientation of each wheel in order to store the relations between the identification data of each transmitter and the position of the corresponding wheel in the memory unit when an ignition switch of the vehicle is turned on or a predetermined switch is manipulated by an occupant of the vehicle, and

a changing stop unit that stops a change in the antenna directivity of the receiver by the relation confirmation antenna directivity changing unit when a time interval between a previous turn-off and a current turn-on of the ignition switch or a time interval between a previous and a current manipulation of the predetermined switch is shorter than a predetermined time that is required to exchange the wheels.

2. The wheel condition monitoring system according to claim 1, wherein the receiver includes:

a feed antenna element; and

a plurality of parasitic antenna elements, each having a controllable reactance.

3. The wheel condition monitoring system according to claim 2, wherein the parasitic antenna elements are respectively disposed in directions running toward the wheel positions when viewed from the feed antenna element.

4. The wheel condition monitoring system according to claim 1, wherein the antenna directivity control unit changes the antenna directivity of the receiver in at least all-but-one directions among directions toward the wheel positions.

5. The wheel condition monitoring system according to claim 1, wherein, if the relation between the wheel position and the identification data, which is received by the receiver and transmitted from each transmitter disposed in initial one or two wheel directions after starting a change of the antenna directivity, is identical to a previous relation stored in the memory unit, the antenna directivity control unit stops a further change of the antenna directivity.

6. The wheel condition monitoring system according to claim 1, wherein, after the identification data of each transmitter is stored in the memory unit by assigning the relations between the identification data of each transmitter and the position of the corresponding wheel, the antenna directivity of the receiver is changed such that the antenna gain of the receiver is substantially constant in all directions.

7. The wheel condition monitoring system according to claim 1, wherein, after the identification data of each transmitter is stored in the memory unit by assigning the relations between the identification data of each transmitter and the position of the corresponding wheel, the antenna directivity of the receiver is changed such that the antenna gain of the receiver is substantially constant in directions toward the wheel positions.

8. The wheel condition monitoring system according to claim 1, further comprising:

a body-mounted transmitter, installed on the main body of the vehicle, that transmits in a direction toward each wheel an instruction signal that requests each transmitter installed on each wheel to transmit the wheel condition data; and

a wheel-mounted receiver, installed on each wheel, that receives the instruction signal from the body-mounted transmitter,

wherein, when the wheel-mounted receiver receives the instruction signal from the body-mounted transmitter, each transmitter installed on each wheel transmits the transmission signal, including the wheel condition data representing a condition of the corresponding wheel, in response to the instruction signal.

9. The wheel condition monitoring system according to claim 1, wherein the relation confirmation antenna directivity changing unit changes the antenna directivity of the receiver such that the antenna gain is sequentially maximized based on the position and orientation of each wheel in order to store the relations between the identification data of each transmitter and the position of the corresponding wheel in the memory unit if the time interval between the previous turn-off and the current turn-on of the ignition switch is greater than the predetermined time that is required to exchange the wheels.

10. A wheel position detection method for a wheel condition monitoring system including a plurality of transmitters respectively installed on each wheel of a vehicle, that transmit wheel condition data representing a condition of the respective wheels, and a receiver installed on the main body of the vehicle for receiving the wheel condition data from the respective transmitters so that the wheel condition monitoring system monitors the condition of the corresponding wheel based on the wheel condition data received by the receiver, the wheel position detection method determining a position of the wheel at which the transmitters that has transmitted the wheel condition data is installed, the method comprising:

controlling an antenna directivity of the receiver;

storing identification data of each transmitter in a memory unit and assigning relations between the identification data of each transmitter and the position of the corresponding wheel, when the antenna directivity of the receiver is changed such that an antenna gain of the receiver is sequentially maximized in a direction toward each wheel; and

determining a position of a specific wheel at which the transmitter that has transmitted a transmission signal is installed, when the receiver receives the transmission signal that includes the wheel condition data and identification data from the transmitter based on the relations between the identification data and positions of the corresponding wheel stored in the memory unit, wherein

after storing relations between the identification data of each transmitter and the position of the corresponding wheel, the antenna directivity of the receiver is changed so that the receiver is able to receive the wheel condition data transmitted from all the transmitters,

the antenna directivity of the receiver is changed such that the antenna gain is sequentially maximized based on the position and orientation of each wheel in order to store the relations between the identification data of each transmitter and the position of the corresponding wheel if an ignition switch of the vehicle is turned on or a predetermined switch is manipulated by an occupant of the vehicle, and

the antenna directivity of the receiver is not changed if a time interval between a previous turn-off and a current turn-on of the ignition switch or a time interval between a previous and a current manipulation of the predetermined switch is shorter than a predetermined time that is required to exchange the wheels.

11. The wheel position detection method according to claim 10, wherein the receiver includes a feed antenna element and a plurality of parasitic antenna elements, each having a controllable reactance, and

wherein the antenna directivity is changed by controlling reactance of each of the parasitic antenna elements.

12. The wheel position detection method according to claim 11, wherein the parasitic antenna elements are respectively disposed in directions running toward the wheel positions when viewed from the feed antenna element.

13. The wheel position detection method according to claim 10, wherein the antenna directivity of the receiver is changed in at least all-but-one directions among directions toward the wheel positions.

14. The wheel position detection method according to claim 10, wherein if the relation between the wheel position and the identification data, which is received by the receiver and transmitted from each transmitter disposed in initial one or two wheel directions after starting a change of the antenna directivity, is identical to a previous relation stored in the memory unit, the antenna directivity is not further changed.

15. The wheel position detection method according to claim 10, wherein after the identification data of each of the transmitters is stored in connection with the wheel positions, the antenna directivity of the receiver is changed such that the gain is substantially constant in all directions.

16. The wheel position detection method according to claim 10, wherein, after the identification data of each of the transmitters is stored in connection with the wheel positions, the antenna directivity of the receiver is changed such that the gain is substantially constant in directions toward the wheel positions.

17. The wheel position detection method according to claim 10, further comprising:

transmitting in a direction toward each of the wheel positions an instruction signal that requests the transmitter to transmit the wheel condition data; and

receiving the instruction signal by a wheel-mounted receiver installed at each of the wheels,

wherein, if the wheel-mounted receiver receives the instruction signal, each of the transmitters transmits the wheel condition data representing a condition of a corresponding wheel in response to the instruction signal.

18. The wheel position detection method according to claim 10, wherein the antenna directivity of the receiver is changed if the time interval between the previous turn-off and the current turn-on of the ignition switch is greater than the predetermined time that is required to exchange the wheels.