POSITIONING METHOD FOR A REMOTE KEYLESS ENTRY SYSTEM

REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States Provisional

Application No. 61/055,166, filed May 22, 2008.

1. Technical Field

[0002] This disclosure relates generally to a remote keyless entry system, and more particularly, to determining a position of the remote keyless entry system's fob device.

BACKGROUND

[0003] Bidirectional remote keyless entry systems typically include a fob or similar device having a transmitter. A user actuates buttons on the fob to send signals from the fob to a receiver on a vehicle. The received signals initiate various vehicle functions, such as locking vehicle doors, unlocking vehicle doors, chirping the vehicle horn, or sounding the vehicle's panic alarm. The fob is often secured to ignition keys for the vehicle. [0004] The user typically carries the fob with them when they leave a parked vehicle. When returning, the user may use the fob to initiate a chirp of the vehicle's horn if the user is having difficulty locating the parked vehicle. Hearing the chirp helps the user locate the parked vehicle. As can be appreciated, the user is only able to hear the chirp within a certain range of the vehicle. That is, if the user is too far away from the parked vehicle when they initiate the chirp, the user is unable to hear the chirp. Some remote keyless entry systems thus include fobs with vehicle finder functions that are able to direct the user to the parked vehicle through arrows, Global Positioning System coordinates, or voice commands.

SUMMARY

[0005] An example remote keyless entry locating method includes transmitting a signal from a fob to a first vehicle antenna and transmitting the signal from the fob to a second vehicle antenna. The example method further includes determining a position of the fob based on the signal.

[0006] Another example remote keyless entry locating method includes transmitting a first signal from a fob to a plurality of vehicle antennas, determining a first position of the fob relative to a vehicle, moving the fob to a second position different than the first position, and transmitting a second signal from the fob to the plurality of vehicle antennas when the fob is in the second position. The example method further includes determining a direction of movement of the fob from the first position to the second position.

[0007] An example remote keyless entry locator system includes a transmitter configured to transmit a signal to a first vehicle antenna and a second vehicle antenna spaced from the first vehicle antenna. The system also includes a controller configured to determine a location of a fob relative to a vehicle. The controller uses a first distance between the first vehicle antenna and the transmitter, and uses a second distance between the second vehicle antenna and the transmitter, to determine the location.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 schematically shows an example remote keyless entry locator system.

[0009] Figure 2 is a highly schematic view of the Figure 1 system showing a path of movement of a fob.

[0010] Figure 3 shows the flow of an example method of positioning the fob of the Figure 1 system.

DETAILED DESCRIPTION

[0011] As shown in Figure 1, an example remote keyless entry system includes a fob 10 having a display screen 12 and a transmitter 14 that is operative to transmit a signal 18 to a vehicle 20. The signal 18 is often configured to control various functions of the vehicle 20.

[0012] In this example, a first antenna 22 and a second antenna 26 on the vehicle 20 are each configured to receive a portion of the signal 18. The first antenna 22 and the second antenna 26, which are types of receivers, each communicate with a controller 34 in the vehicle 20. Spacing the first antenna 22 from the second antenna 26 on the vehicle 20 provides the vehicle with antenna diversity or spatial diversity between the first antenna 22 and the second antenna 26. Although only the first antenna 22 and the second antenna 26 are shown, other examples may include using additional antennas to facilitate receiving signals from, and positioning, the fob 10.

[0013] The example controller 34 includes a memory portion 46 and a processor 50. When the controller 34 is in operation, the processor 50 can be configured to execute software stored within the memory portion 46, to communicate data to and from the memory, and to generally control operations of the controller 34 pursuant to the software. Software in memory, in whole or in part, is read by the processor 50, perhaps buffered within the processor 50, and then executed. [0014] In this example, the first antenna 22 is located at a first end portion 38 of the vehicle. The second antenna 26 is spaced from the first antenna 22 and is located at an opposing, second end portion 42 of the vehicle 20. Notably, because the first antenna 22 is spaced from the second antenna 26, the distance between the fob 10 and the first antenna 22 is often different than the distance between the fob 10 and the second antenna 26.

[0015] Referring to the highly schematic view of Figure 2 with continuing reference to Figure 1, the fob 10 is shown in both a first position 52 relative to the vehicle 20 and a second position 56 relative to the vehicle 20. In one example, the fob 10 moves from the first position 52 to the second position 56 as a user carries the fob 10 while searching for the vehicle 20 in a parking lot.

[0016] When the fob 10 is in the first position 52, the example controller 34 is configured to determine a first distance X ₁ between the first antenna 22 and the fob 10, and a second distance X ₂ between the second antenna 26 and the fob 10. Because the first antenna 22 and the second antenna 26 are mounted directly to the vehicle 20, a third distance X ₃ between the first antenna 22 and the second antenna 26 stays the same regardless the position of the fob 10 relative to the vehicle 20.

[0017] The example controller 34 determines the first distance X ₁ and the second distance X ₂ using triangulation methods. The controller 34 uses inputs such as the strengths of the signal 18 received by the first antenna 22 and the second antenna 26, and the angles B ₁ and θ ₂ of the received signals relative to the vehicle 20.

[0018] After determining the first distance X ₁ and the second distance X ₂ , the controller 34 determines the first position 52 of the fob 10 relative to the vehicle 20. Determining the first position 52 may include determining a distance Z between the first position 52 and a midpoint 54 of the vehicle 20 or another distance different than the first distance X ₁ and the second distance X ₂ . In one example, the positioning also uses the angles B ₁ and θ ₂ to ensure that the fob 10 is positioning on the correct side of the vehicle 20. A person skilled in this art and having the benefit of this disclosure would be able to suitably program the processor 50 to determine the first position 52 of the fob 10 relative the vehicle 20 given these inputs. [0019] Once the fob 10 moves to the second position 56, the controller 34 determines the first distance Y ₁ and the second distance Y ₂ of the fob 10 in the second position. A third distance Y ₃ between the first antenna 22 and the second antenna 26 again stays the same regardless the position of the fob 10 relative to the vehicle 20. The controller 34 then determines the second position 56 of the fob 10 relative to the vehicle 20.

[0020] Using the first position 52 and the second position 56, the controller 34 determines a path of movement 60 from the first position 52 to the second position 56. In one example, the path of movement 60 is displayed on the display screen 12 of the fob 10 to indicate to a user carrying the fob 10 their path of movement relative to the vehicle 20. In such an example, the vehicle 20 includes a vehicle transmitter (not

shown) linked to the controller 34. The vehicle transmitter sends the path of movement 60 to the fob 10. The path of movement is displayed as an arrow on the display screen 12 in one example. In another example, the path of movement is a pre-recorded voice that audibly indicates the path of movement, and the path of movement necessary to move the fob 10 closer to the vehicle 20.

[0021] In some examples, the signal 18 from the fob 10 to the first antenna 22 or the second antenna 26 is blocked or shadowed. For example, the path of the signal 18 to the first antenna 22 could be blocked by another vehicle or another object. In such an example, the controller 34 may prompt the user (through the fob 10) to continue to move the fob 10 relative to the vehicle 20 until the path of the signal 18 to the first antenna 22 is clear. In such an example, the second antenna 26 continues to receive the signal 18 from the fob 10. Thus control over the functions of the vehicle 20 is not entirely lost due to the blocked signal path to the first antenna 22.

[0022] Referring to Figure 3 with continuing reference to Figures 1-2, an example method 100 of positioning the fob 10 relative to the vehicle 20 includes transmitting the signal 18 from the fob 10 to both the first antenna 22 and the second antenna 26 at step 104. The method then determines the first position 52 of the fob 10 relative to the vehicle 10 at a step 108. Triangulating using the first distance X ₁ , the second distance X ₂ and the third distance X ₃ is one example technique used to determine the first position 52 of the fob 10.

[0023] The method 100 next moves the fob 10 away from the first position

52 to the second position 56 at 112. The method 100 then transmits a second signal from the fob 10 to the first antenna 22 and the second antenna 26. The second signal is transmitted after the fob 10 has moved. The method then determines the second position 56 of the fob 10 at step 116.

[0024] At step 120, the direction of fob 10 movement is determined by comparing the first position to the second position using the controller 34.

[0025] Features of this invention include determining the position of a fob relative to a vehicle, and a direction of movement of the fob relative to the vehicle. Another feature includes displaying the positional information on the fob. Another

feature of this invention includes limiting the effect of shadowing or blocking a signal from a fob to a vehicle by providing more antennas to receive signals from the fob, the antenna's being positioned at various locations on the vehicle.