US 20120092129A1
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`a9y United States
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`a2y Patent Application Publication o) Pub. No.: US 2012/0092129 A1
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`Lickfelt 43) Pub. Date: Apr. 19,2012
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`(54) METHOD TO TRACK VEHICLE KEY NEAR (52) US.Cle .ot 340/5.72
`VEHICLE FOR SMART ENTRY (57) ABSTRACT
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`(75) TInventor: Brian K. Lickfelt. Powell. O An entry system for a vehicle includes a fob, a transmitter on
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`(US) ’ ’ the vehicle, a receiver on the vehicle, a control unit on the
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`vehicle, and a vehicle lock in communication with the control
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`unit. The fob is configured to transmit fob signals and to
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`(73) Assignee: Honda Motor Co., Ltd., Tokyo receive vehicle signals. The transmitter is for transmitting the
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`(IP) vehicle signals to the fob. The receiver is for receiving the fob
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`signals from the fob. The control unit is in communication
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`. with the transmitter and the receiver. The control unit is
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`(21) Appl. No: 12/507,198 configured to determine whether the fob is getting closer to or
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`farther from the vehicle based on the fob signals received by
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`(22) Filed: Oct. 19, 2010 the receiver. The vehicle lock locks or unlocks in response to
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`the control unit determining that the fob is getting closer to or
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`Publication Classification farther from the vehicle and that the fob is not located in a
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`hysteresis zone, which is disposed between a proximal zone,
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`(51) Int.Cl which is closer to the vehicle, and an outer zone, which is
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`G0O8B 29/00 (2006.01) farther from the vehicle.
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`100
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`FOB
`SIGNAL
`RECEIVED?
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`FOB SIGNAL
`AUTHENTIC?
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`YES
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`116
`\
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`STORE
`SIGNAL DATA
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`FOB GETTING
`CLOSER?
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`FOB
`IN PROXIMAL
`ZONE?
`
`UNLOCK
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`____________ -
`i 106
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`_____ : |
`12
`104 | i
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`| RECEIVE VEHICLE SIGNAL |
`@ 108
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`[ MEASURE SIGNAL STRENGTH !
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`L TRANSMIT FOB SIGNAL |
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`114
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`FOB GETTING
`FARTHER?
`
`FOB
`INOUTER
`ZONE?
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`Ford Ex. 1012 Page 1
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`Patent Application Publication Apr. 19,2012 Sheet 1 of 2 US 2012/0092129 A1
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`,/10
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`_—14
`—22
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`B~ 2B
`|PROC |
`> RSSI
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`FIG. 1
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`K38
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`Ford Ex. 1012 Page 2
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`Patent Application Publication Apr. 19,2012 Sheet 2 of 2 US 2012/0092129 A1
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`100
`/’
`— POLL |
`____________ _
`106
`102 { s
`\O RECEIVE VEHICLE SIGNAL
`RECEIVED? {18
`MEASURE SIGNAL STRENGTH
`_____ : .-
`112
`104 | 9 e
`' L—- TRANSMIT FOB SIGNAL
`FOB SIGNAL
`AUTHENTIC? e
`116\ YES - —— — —— —={ MEASURE SIGNAL STRENGTH
`STORE |, _ _ _ |
`SIGNAL DATA
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`FOB GETTING
`FARTHER?
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`FOB GETTING
`CLOSER?
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`132
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`FOB
`INOUTER
`ZONE?
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`YES
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`FOB
`IN PROXIMAL
`ZONE?
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`YES
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`134
`Ve
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`126
`)
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`UNLOCK LOCK
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`FIG. 2
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`METHOD TO TRACK VEHICLE KEY NEAR
`VEHICLE FOR SMART ENTRY
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`BACKGROUND
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`[0001] Smart entry and passive entry systems for vehicles
`currently use low frequency (“LF”) electromagnetic (“EM”)
`fields to search for a key fob for entry into the vehicle, starting
`of the vehicle, as well as locking and lockout protection for
`the vehicle. Many systems use an antenna to define a certain
`region for activity to take place. For example, a driver door
`area antenna generates a fob search for locking and unlock-
`ing, and an antenna inside the cabin searches for starting the
`vehicle and also preventing the driver from locking the fob in
`the car. Similar zones exist on the passenger side of the
`vehicle, in the trunk and also behind the vehicle for trunk
`access. This system requires many antennas to define each
`zone.
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`[0002] Some vehicles apply an LF polling strategy. Such a
`vehicle sends out periodic LF pulses from antennas mounted
`on the vehicle. If a fob is in the vicinity of the vehicle, a
`pre-authentication can take place, making the entry system
`response quicker for entry into the vehicle when an operator
`grabs the door handle. If the fob identification has already
`been authenticated as the driver approaches the vehicle, then
`the vehicle only has to send the unlock command when the
`vehicle detects the driver grabbing the door handle. Other
`entry systems send the LF field to authenticate the fob after
`the door handle is grabbed. If the operator is too fast, the
`authentication and unlock command may not take place in
`time for the door to be unlocked before the user pulls on the
`door handle. This requires the operator to pull a second time
`on the handle to open the door.
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`[0003] Some vehicles also apply a feature referred to as
`“walk away locking”. It is believed that in such a system when
`the door of the vehicle closes, an LF field search is performed
`inside the vehicle to ensure there are no fobs in the vehicle. A
`search can then be performed outside the vehicle to locate the
`fob outside the vehicle. If no fobs are in the car and the fob is
`outside the vehicle, the vehicle will automatically lock itself
`with no action by the operator or holder of the fob.
`
`[0004] Received signal strength indication (“RSSI”) has
`been used to locate fobs with respect to a vehicle. The vehicle
`can include an electronic control unit (“ECU”) that can cal-
`culate the position of the fob based on the signal strength of
`responses to each LF request. Problems still exist in known
`smart entry and passive entry systems, and even with systems
`that employ RSSI technology.
`
`SUMMARY
`
`[0005] An example of an entry system for a vehicle
`includes a fob, a transmitter on the vehicle, a receiver on the
`vehicle, a control unit on the vehicle, and a vehicle lock in
`communication with the control unit. The fob is configured to
`transmit fob signals and to receive vehicle signals. The trans-
`mitter is for transmitting the vehicle signals to the fob. The
`receiver is for receiving the fob signals from the fob. The
`control unit is in communication with the transmitter and the
`receiver. The control unit is configured to determine whether
`the fob is getting closer to or farther from the vehicle based on
`the fob signals received by the receiver. The vehicle lock
`locks or unlocks in response to the control unit determining
`that the fob is getting closer to or farther from the vehicle and
`that the fob is not located in a hysteresis zone, which is
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`Apr. 19,2012
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`disposed between a proximal zone, which is closer to the
`vehicle, and an outer zone, which is farther from the vehicle.
`[0006] A method for remotely controlling locks on a
`vehicle includes measuring signal strengths of signals
`received by or transmitted from a fob, determining whether
`the fob is getting closer to or farther from the vehicle based on
`the measured signal strengths, and determining in which zone
`among a plurality of zones the fob is located. The plurality of
`zones includes a proximal zone, a hysteresis zone, and an
`outer zone. The hysteresis zone is interposed between the
`proximal zone and the outer zone. The method for remotely
`controlling locks on the vehicle further includes operating a
`lock in response to receiving a respective fob signal from the
`fob by a receiver on the vehicle. Operating the lock includes
`at least one of unlocking the lock in response to receiving the
`respective fob signal after determining that the fob is getting
`closer to the vehicle and locking the lock in response to
`receiving the respective fob signal after determining that the
`fob is within the outer zone and that the fob is getting farther
`from the vehicle.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0007] FIG. 1 is a schematic depiction of a passive entry
`system for a vehicle.
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`[0008] FIG. 2 is a flow diagram depicting an example of a
`method for remotely controlling locks on a vehicle.
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`DETAILED DESCRIPTION
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`[0009] The descriptions and drawings herein are merely
`illustrative and various modifications and changes can be
`made in the components disclosed without departing from the
`scope of the appended claims. Moreover, various identified
`components of an entry system disclosed herein are merely
`terms of art that may vary from one manufacture to another
`and should not be deemed to limit the present disclosure.
`[0010] With reference to FIG. 1, a passive entry system 10
`for avehicle 12 includes a fob 14 that is configured to transmit
`and to receive signals. The entry system 10 further includes an
`ECU 16 on the vehicle 12. The ECU 16 is in communication
`with a transmitter 18 and a receiver 20. The transmitter 18 is
`also found on the vehicle and is for transmitting signals to the
`fob 14. For clarity purposes, signals transmitted from the fob
`14 will be referred to as “fob signals™ and signals transmitted
`from the transmitter 18 on the vehicle 12 will be referred to as
`“vehicle signals.” The receiver 20 is on the vehicle and is for
`receiving fob signals transmitted from the fob 20. Even
`though only three transmitters 18 and two receivers 20 are
`shown in FIG. 1, a fewer or a greater number of transmitters
`and/or receivers can be provided on the vehicle. Moreover, a
`plurality of transmitters and receivers can be beneficial when
`determining a location of the fob 14 with respect to the
`vehicle 12, which will be described in more detail below.
`[0011] The system 10 is also configured to measure signal
`strengths of signals received from or received by the fob 14.
`As such, the system 10 can include an RSSI circuit 22 to
`measure signal strength of signals. The RSSI circuit 22 can be
`associated with the ECU 16 on the vehicle and/or the RSSI
`circuit 22 can be located in the fob 14.
`
`[0012] In the illustrated embodiment, the fob 14 transmits
`radio frequency (“RF”) signals and receives LF EM signals.
`Accordingly, the fob 14 can include internal antennas 24, 26
`and a processor 28 to receive and to transmit these signals.
`Alternatively, the fob 14 could transmit and receive other
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`Ford Ex. 1012 Page 4
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`types of wireless signals, if desired. The fob 14, similar to
`known fobs, is typically small enough to be easily carried by
`an operator of the vehicle 12 and could be combined with or
`incorporated into other known devices such as a mobile
`phone or other small electronic device.
`
`[0013] The ECU 16 is configured to determine whether the
`fob 14 is getting closer to or farther from the vehicle 12 based
`on the measured signal strengths. For example, where the
`transmitters 18 on the vehicle transmit LF signals, one of the
`antennas on the fob 14 receives this LF signal and the received
`LF signal is processed by the RSSI circuit 22 on the fob 14.
`The fob 14 can then transmit a fob signal to the receiver 20 on
`the vehicle 12 that includes signal strength data for the
`received vehicle signal. The RSSI circuit 22 on the fob 14 can
`measure the signal strength of vehicle signals sent from each
`transmitter 20 on the vehicle, e.g. a transmitter located near
`the trunk of the vehicle and a transmitter located near a
`passenger door of the vehicle. The fob signal, which is sent to
`the receiver 20 on the vehicle from the fob 14, can also include
`transmitter identification data, which is associated with the
`transmitter from which the vehicle signal was received. The
`ECU 16 on the vehicle 12 can calculate the fob position based
`on the signal strength data and the transmitter identification
`data. The ECU 16 can determine whether the fob 14 is getting
`closer to or farther from the vehicle 12 by comparing signal
`strength and transmitter identification data from earlier
`received signals to signal strength and transmitter identifica-
`tion data from later received signals.
`
`[0014] LF RSSI analysis is typically more reliable than RF
`RSSI analysis, however, where the vehicle 12 includes the
`RSSI circuit 22, the RSSI circuit 22 can be used to measure
`signal strengths of fob signals received from the fob 14 by the
`receiver 20. The ECU 16 can determine whether the fob 14 is
`getting closer to or farther from the vehicle 12 by comparing
`signal strengths from earlier received fob signals to signal
`strengths from later fob received signals. Which receiver 20
`that receives each respective fob signal can also be used to
`determine whether the fob 14 is getting closer to or farther
`from the vehicle 12.
`
`[0015] The entry system 10 also includes a lock 24 that is in
`communication with the ECU 16. Only one vehicle door lock
`24 is depicted in FIG. 1; however, a plurality of door locks, as
`well as a trunk lock or other closure lock, can be provided.
`The door lock 24 is an electronic door lock and can be similar
`to known door locks; however, the door lock operates in a
`manner that will be described in more detail below.
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`[0016] The entry system 10 is configured to define a plu-
`rality of zones with respect to the vehicle 12. These zones can
`include an internal zone 30, a proximal zone 32, a hysteresis
`zone 34, and an outer zone 36. The internal zone 30 is defined
`by the external boundary 40 of the vehicle 12, which is typi-
`cally the outer surface of the vehicle body. If it is determined
`that the fob 14 is located in the internal zone 30, then it is
`assumed the fob 14 is located within the vehicle, e.g. within
`the cabin or the trunk of the vehicle. The proximal zone 32 is
`the zone closest to the vehicle 12, but located outside of or
`external to the vehicle. The outer zone 36 is defined at its outer
`limit 38 by the range of the signals sent from the transmitter
`18 that can be detected by the fob 14 or by an outer limit in
`which the fob 14 can send detectible signals to the receiver 20.
`The hysteresis zone 34 is interposed between the proximal
`zone 32 and the outer zone 36. The proximal zone 32 and the
`hysteresis zone 34 share a common proximal/hysteresis
`boundary 42, which can be located about 1 meter from an
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`Apr. 19,2012
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`external boundary 40 of the vehicle 12. The outer zone 36 and
`the hysteresis zone 34 share a common outer/hysteresis
`boundary 46. The size and shape of the zones depicted in F1G.
`1 is merely illustrative and is not drawn to scale.
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`[0017] The ECU 16, as mentioned above, is configured to
`determine whether the fob 14 is getting closer to or farther
`from the vehicle 12 based on signals received from the fob. As
`mentioned above, more than one transmitter 18 and receiver
`20 canbe located on the vehicle 12. Where the RSSI circuit 22
`is on the vehicle 12, each receiver 20 can receive a respective
`fob signal and the RSSI circuit 22 can determine the signal
`strength of the respective fob signal received from the fob to
`determine a location of the fob by, for example, triangulation.
`Where the RSSI circuit 22 is on the fob, each transmitter 18
`can transmit a respective vehicle signal and the RSSI circuit
`22 can determine the signal strength of the respective vehicle
`signals. This data, e.g. signal strength and transmitter identity,
`can be sent back to the ECU 16 to determine a location of the
`fob 14 by, for example, triangulation
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`[0018] The vehicle door lock 24 locks or unlocks in
`response to the ECU 16 determining that the fob 14 is getting
`closer to or farther from the vehicle 12 and that the fob is not
`located in the hysteresis zone 34. The hysteresis zone 34 is
`disposed between the proximal zone 32, which is closer to the
`vehicle 12, and the outer zone 36, which is farther from the
`vehicle. The ECU 16 is also configured to store distance data
`for each signal received from the fob 14. The distance data is
`associated with a distance that the fob 14 is spaced from the
`vehicle 12. The distance data can be associated with when a
`respective fob signal was sent from the fob or when a respec-
`tive vehicle signal was received by the fob. Since the signals
`travel so quickly and the data is processed so quickly, basing
`the location of the fob 14 on a signal received by the fob ora
`signal sent from the fob should not lead to a large discrepancy
`between the determined position of the fob and the actual
`position of the fob. The ECU 16 is also configured to deter-
`mine a location of the fob 14 within one of the plurality of
`zones, for example, as within the external zone 36, the hys-
`teresis zone 34, the proximal zone 32, or the internal zone 30
`based on the distance data. The ECU 16 is further configured
`to store zone data, which is associated with the zone in which
`the fob 14 is located.
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`[0019] For example, when an operator approaches the
`vehicle 12 carrying the fob 14, the ECU 16 polls for the fob by
`transmitting LF signals. An RF fob signal is transmitted from
`the fob 14 to the receiver 20 in reply to the polling signal when
`the fob enters within a range to receive the polling signal.
`When an operator of the vehicle 12 is approaching the vehicle
`12, the initial FOB signal received by the receiver 20 is
`typically from the fob 14 located within the outer zone 36.
`The location of the fob 14 can be determined by measuring
`the strength of the polling signal received by the fob in the
`RSSI circuit 22 on the fob or by measuring the strength of the
`fob signal sent in reply to the polling signal in the RSSI circuit
`22 on the vehicle 12. The ECU 16 stores data associated with
`the signals in a memory 50 associated with the ECU 16. The
`ECU 16 continues to poll for the fob 14 after receiving the
`initial fob signal and a subsequent fob signal is transmitted
`from the fob 14 to the receiver 20 in response to the subse-
`quent polling signal from the transmitter 18. The strength of
`the subsequent fob signal or the strength of the subsequent
`polling signal is then measured in the RSSI circuit 22, either
`in the fob 14 or on the vehicle 12, and the data for the
`subsequent signal is also stored in the database 50.
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`Ford Ex. 1012 Page 5
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`[0020] The ECU 16 can now determine whether the fob 14
`is getting closer to or farther from the vehicle 12 based on
`comparing the data associated with the initial signal (fob or
`polling signal) compared to the data associated with the sub-
`sequent signal (fob or polling). The zone in which the fob 14
`is located can be determined based on the signal strength of
`the respective signals and triangulation by knowing the
`respective transmitter that initiated the polling signal or the
`respective receiver that received the fob signal. This zone data
`can also be stored in the memory 50. If the signal strength of
`the subsequent signal (fob or polling signal) is greater than the
`signal strength of the initial signal, then it can be deduced that
`the fob 14 is getting closer to the vehicle 12.
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`[0021] The lock 24 unlocks upon receiving a fob signal by
`the receiver 20 after determining that the fob 14 is getting
`closer to the vehicle 12 and the fob is within the proximal zone
`32. The lock 24 remains unlocked after receiving a subse-
`quent fob signal and determining that the fob 14 is within the
`hysteresis zone 34 when a fob signal immediately preceding
`the subsequent fob signal was received from the fob 14 when
`the fob 14 was within the proximal zone 32. As an example, if
`an operator carrying a fob approached a vehicle having only
`aproximal zone and an outer zone, i.e. no hysteresis zone, and
`the operator were to stop adjacent the proximal/outer bound-
`ary, the locks on such a vehicle could cycle between locking
`and unlocking where the operator carrying the fob moves
`back and forth between the proximal zone and the outer zone.
`By having the lock 24 remain unlocked after receiving a
`subsequent fob signal from within the hysteresis zone 34
`when a signal immediately preceding the subsequent fob
`signal was received from the fob when the fob was in the
`proximal zone 32, the cycling between lock and unlock does
`not occur.
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`[0022] The passive entry system 10 can also automatically
`lock the door locks 24 upon receiving a subsequent fob signal
`and determining that the fob 14 is within the external zone 36
`when a fob signal immediately preceding the subsequent fob
`signal was received from the fob 14 when the fob was within
`the vehicle, i.e. within the internal zone 30, or when the fob
`was in the proximal zone 32 or the hysteresis zone 34.
`Accordingly, the lock 24 can automatically lock when an
`operator of the vehicle walks away from the vehicle 12. The
`lock 24 can lock upon receiving a respective fob signal by the
`receiver after determining the fob is getting further from the
`vehicle 12 and the fob 14 is located within the external zone
`36. By providing the hysteresis zone 34 cycling between
`locking and unlocking of the door lock 24 is mitigated.
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`[0023] For example, when an operator gets out of the
`vehicle 12 and walks away from the vehicle, the ECU 16 polls
`for the fob 14. The door lock 24 remains unlocked in response
`to reply signals received from the fob 14 when the fob is
`within the proximal zone 32 and the hysteresis zone 34. If it is
`determined that the fob 14 is getting farther from the vehicle
`and the latest reply signal received from fob is where the fob
`is within the outer zone 36, then the lock 24 locks. After the
`lock 24 locks, the lock will not unlock until it is determined
`that the fob 14 is getting closer to the vehicle and the reply
`signal triggering the unlock event is received from the fob 14
`where the fob is located within the proximal zone 32. Accord-
`ingly, if an operator of the vehicle 12 is standing adjacent the
`outer/hysteresis boundary 46, the door locks 24 do not cycle
`between locking and unlocking. Such a configuration reduces
`the likelihood of the door lock 24 cycling between lock and
`unlock in an undesirable manner.
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`Apr. 19,2012
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`[0024] A method for remotely controlling locks on a
`vehicle will be described with reference to FIGS. 1 and 2.
`Even though the method will be described with reference to
`components shown in FIG. 1, the method described with
`reference to FIG. 2 could be used with other passive entry
`systems.
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`[0025] At 100, the ECU 16 (FIG. 1) polls for fobs, such as
`the fob 14. At 102, a determination is made as to whether a
`reply signal is received from a fob. If no reply signal is
`received, at 102, the algorithm reverts to 100 and continues to
`poll for fobs. If a reply signal is received at 102, then at 104,
`a determination is made as to whether the reply signal is
`authentic. More than one fob may transmit reply signals in
`response to the polling signal transmitted from the receiver
`20. Only fobs associated with the vehicle 12 can unlock the
`door lock 24 (and perform other vehicle operations). Accord-
`ingly, if the reply signal received by the receiver 20 is deter-
`mined to be not authentic, at 104, then the ECU 16 continues
`to poll for fobs that are associated with the vehicle 12.
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`[0026] Steps 100,102 and 104 are performed on the vehicle
`12. The fob 14 can receive the polling signal, at 106. The
`polling signal is transmitted from one of the transmitters 18
`onthe vehicle 12, and therefore, can be referred to as a vehicle
`signal. After receiving the polling signal, the fob 14 can
`measure the signal strength of the polling signal at 108. As
`discussed above, the fob 14 can include the RSSI circuit 22
`for measuring the strength of the polling signal. At 112, the
`fob 14 can transmit the fob signal to the receiver 20 and the
`fob signal can include signal strength data associated with the
`polling signal that was received by the fob and the fob signal
`can further include transmitter identification data identifying
`the transmitter 18 on the vehicle 12 that transmitted the
`respective polling signal.
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`[0027] With reference back to the vehicle 12, if the fob
`signal is determined to be authentic, at 104, then at 114, the
`strength of the fob signal can be measured in the RSSI circuit
`22 on the vehicle 12. At 116, signal data, such as the signal
`strength data and the zone data (each described above), are
`stored in the database 50. The ECU 16 is configured to deter-
`mine whether the fob 14 is getting closer to or farther from the
`vehicle 12 and, therefore, at 118, a determination is made as
`to whether the reply signal that was sent from the fob 14 to the
`receiver 20 is an initial signal. If it is determined that the
`signal received from the fob 14 is an initial signal, at 118, then
`the ECU is unable to determine whether the fob is getting
`closer to or farther from the vehicle, and therefore, the algo-
`rithm reverts back to polling for the fob at 100. If, however,
`the respective reply signal received from the fob 14 by the
`receiver 20 is not an initial signal, then a determination is
`made, at 122, as to whether the fob 14 is getting closer to the
`vehicle 12. As discussed above, the ECU 16 can determine
`whether the fob 14 is getting closer to the vehicle, at 122, by
`comparing the strength of a subsequent vehicle or fob signal
`to the strength of a preceding vehicle or fob signal. At 124, a
`determination is made as to whether the fob 14 is located
`within the proximal zone 32. If it is determined that both the
`fob 14 is getting closer to the vehicle, at 122, and that the last
`signal sent from the fob 14 to the receiver 20 was sent with the
`fob located within the proximal zone 34, at 124, then the lock
`24 unlocks at 126. If, however, the last signal sent from the fob
`14 was with the fob not located within the proximal zone 34,
`i.e. the fob 14 was located in the hysteresis zone 34 or the
`outer zone 36, then the algorithm reverts back to polling for
`the fob at 100.
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`Ford Ex. 1012 Page 6
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`[0028] Ifitisdetermined that the fob 14 is not getting closer
`to the vehicle 12, at 122, then a determination is made as to
`whether the fob is getting farther from the vehicle, at 128. As
`discussed above, the ECU 16 can determine whether the fob
`14 is getting farther from the vehicle 12 by comparing the
`signal strength of a subsequent vehicle or fob signal to the
`signal strength of a preceding vehicle or fob signal. If the
`signal strength of a subsequent signal is less than the signal
`strength of a preceding signal, then it can be deduced that the
`fob 14 is getting farther from the vehicle 12. Ifit is determined
`that the fob 14 is not getting farther from the vehicle, at 128,
`then the algorithm reverts back to polling for the fob at 100. If
`it is determined that the fob 14 is getting farther from the
`vehicle 12, at 128, then a determination is made as to whether
`the last signal sent from the fob 14 was when the fob was
`within the outer zone 36, at 132. If the last signal sent from the
`fob 14 was determined, at 132, to be from when the fob was
`located within the outer zone 36, then the door locks at 134. If
`it is determined that the last signal sent from the fob 14 was
`when the fob was not within the outer zone 36, i.e., the fob
`was within the hysteresis zone 34, the proximal zone 32 or
`within the internal zone 30, then the algorithm reverts back to
`polling for the fob at 100.
`
`[0029] Accordingly, the method for remotely controlling
`locks on a vehicle 12 can include measuring signal strengths
`of'signals received by or from the fob 14. This is shown at 108
`and 144, respectively, in FIG. 2. The method for remotely
`controlling door locks can further include determining
`whether the fob is getting closer to (step 122) or farther from
`(step 128) the vehicle 12 based on the measured signal
`strengths. The method can further include determining in
`which zone, among a plurality of zones, the fob is located
`when the fob is transmitting each signal, which is shown at
`124 and 132. As mentioned above, the plurality of zones
`includes the outer zone 36, the hysteresis zone 34, the proxi-
`mal zone 32, and the internal zone 30.
`
`[0030] The method for remotely controlling locks can fur-
`ther include operating the door lock 24 in response to a
`respective reply signal received from the fob 14. Operating
`the door lock 24 caninclude at least one of unlocking the door
`lock 24 in response to receiving the respective reply signal
`from the fob 14 from within the internal zone 32 after deter-
`mining that the fob is getting closer to the vehicle 12 and
`locking the door lock 24 in response to receiving the respec-
`tive reply signal from the fob 14 from within the external zone
`36 after determining the fob is getting farther from the
`vehicle.
`
`[0031] The method for remotely controlling door locks 24
`on the vehicle 12 can further include storing distance data for
`each signal received from the fob 14. This is shown at 116 in
`FIG. 2, and the distance data can be stored in the database 50
`(FIG. 1). The method for remotely controlling door locks 24
`on the vehicle 12 can further include storing zone data for
`each signal received from the fob 14. The zone data can be
`stored in the database 50 and is associated with the zone in
`which the fob 14 was located when the respective signal was
`sent from the fob. The zone data can be determined based on
`the measured signal strength and the boundaries of the zones,
`which can be defined by predetermined distances from the
`vehicle and coordinates defining zones with respect to the
`vehicle. For example, the proximal/hysteresis boundary 42,
`which is the outer boundary of the proximal zone 32, can be
`about 1 meter from the external boundary 40 ofthe vehicle 12.
`The outer boundary of the hysteresis zone 34, i.e. the outer/
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`Apr. 19,2012
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`hysteresis boundary 46, can be located about 3-5 meters from
`the vehicle 12. The outer boundary 38 of the outer zone 36 can
`be about 5-7 meters from the vehicle.
`
`[0032] Asdiscussed above, determining whether the fob 14
`is getting closer to or farther from the vehicle 12 is based on
`the measured signal strengths as determined in the RSSI
`circuit 22, which can be associated with the ECU 16 in the
`vehicle 12 or found in the fob 14. The method could further
`include keeping the door lock 24 in whichever state, locked or
`unlocked, that the door lock is currently in in response to
`signals received from the fob when the fob is in the hysteresis
`zone 34. Accordingly, any signals received from the fob 14
`when the fob is within the hysteresis zone 34 do not change
`the state of the locks. This reduces the likelihood of the lock
`24 cycling between lock and unlock, which can be undesir-
`able.
`
`[0033] A passive entry system and a method for remotely
`controlling door locks on a vehicle has been described with
`particularity. Modifications and alterations will occur to those
`upon reading and understanding the preceding detailed
`description. The appended claims are not limited to only the
`embodiments described above. Instead, the invention is
`broadly defined by the appended claims and the equivalents
`thereof.
`
`[0034] It will be appreciated that various of the above-
`disclosed and other features and functions, or alternatives or
`varieties thereof, may be desirably combined into many other
`different systems or applications. Also that various presently
`unforeseen or unanticipated alternatives, modifications,
`variations or improvements therein may be subsequently
`made by those skilled in the art which are also intended to be
`encompassed by the following claims.
`
`1. An entry system for a vehicle comprising:
`
`a fob configured to transmit fob signals and to receive
`vehicle signals;
`
`a transmitter on the vehicle for transmitting the vehicle
`signals to the fob;
`
`a receiver on the vehicle for receiving the fob signals from
`the fob;
`
`a control unit on the vehicle and in communication with the
`transmitter and the receiver, the control unit being con-
`figured to determine whether the fob is getting closer to
`or farther from the vehicle based on the fob signals
`received by the receiver; and
`
`a vehicle lock in communication with the control unit,
`wherein the vehicle lock locks or unlocks in response to
`the control unit determining that the fob is getting closer
`to or farther from the vehicle and that the fob is not
`located in a hysteresis zone, which is disposed between
`a proximal zone, which is closer to the vehicle, and an
`outer zone, which is farther from the vehicle.
`
`2. The system of claim 1, further comprising an RSSI
`circuit in the fob for measuring signal strength of the vehicle
`signals received by the fob, wherein respective fob signals
`include signal strength data associated with a respective
`vehicle signal received by the fob, wherein the control unit
`calculates a fob position based on the signal strength data.
`
`3. The system of claim 2, wherein the transmitter includes
`a plurality of transmitters and the RSSI circuit measures the
`signal strength of vehicle signals sent from respective trans-
`mitters, wherein respective fob signals include signal strength
`data for respective vehicle signals and transmitter identifica-
`tion data associated with the respective transmitter transmit-
`ting the respective vehicle signal, wherein the control unit
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`Ford Ex. 1012 Page 7
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`calculates the fob position based on the signal strength data
`and the transmitter identification data.
`
`4. The system of claim 1, wherein the control unit is con-
`figured to store distance data for each fob signal, wherein the
`distance data is associated with a distance that the fob was
`spaced from the vehicle when a respective fob signal was sent
`from the fob or the distance that the fob was spaced from the
`vehicle when the fob received a respective vehicle signal.
`
`5. The system of claim 4, wherein the control unit is con-
`figured to determine a l