JP2016124477A - Communication system and position determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system including an on-vehicle device and a portable machine, and capable of determining the position or the moving state of the portable machine within the transmission range of a request signal transmitted from the on-vehicle device.SOLUTION: A key 16 as a portable machine measures, when it receives a request signal transmitted from an on-vehicle device 2, the RSSI of the request signal, and transmits a responce signal including the RSSI to the on-vehicle device 2. The ECU 3 of the on-vehicle device 2 determines, when it obtains at least three RSSIs of request signals transmitted from different transmitters, the position of the key 16 within a position detectable area in which the transmission areas of at least three transmitters overlap based on the RSSIs. The ECU 3 determines whether the key 16 is moving or stopped within the position detectable area based on the presence of the time-depending change of the RSSI, and continues the periodic transmission of the request signal when moving, and stops the periodic transmission when stopped.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication system that performs communication between an in-vehicle device mounted on a vehicle and a portable device, and a position determination method for the portable device.

  2. Description of the Related Art Conventionally, a vehicle door includes an in-vehicle device mounted on a vehicle and a portable device carried by a user of the vehicle, and based on a response signal transmitted from the portable device in response to a request signal transmitted from the in-vehicle device. There is known an electronic key system that permits locking and unlocking and engine starting (see, for example, Patent Document 1). In this type of electronic key system, the in-vehicle device periodically transmits a request signal around the vehicle in order to detect the approach of the user (portable device) to the vehicle. Patent Document 1 describes changing the transmission cycle of a request signal according to a time zone or the like as a power saving measure for the vehicle battery with respect to the regular transmission of the request signal.

JP 2012-26141 A

  By the way, if the portable device does not move within the request signal transmission area during periodic transmission of the request signal, such as when the portable device is left in the garage where the vehicle is placed, the portable device transmits repeatedly. Will continue to respond to the request signal to be made, so the battery of the portable device will be consumed quickly. In order to prevent this, it is preferable to stop the periodic transmission of the request signal when the position of the portable device is stopped within the transmission area of the request signal. However, conventionally, when a portable device is located in the request signal transmission area, it has not been possible to determine whether the portable device is moving or stopped.

  Also, when the portable device is located in the transmission area of the request signal, determining where in the transmission area the portable device is located is when processing according to the position of the portable device is performed It is useful for such as. However, conventionally, it is possible to determine whether the portable device is located outside the vehicle or inside the vehicle, but it is possible to determine the position of the portable device more accurately than the position determination whether it is outside the vehicle or inside the vehicle. There wasn't.

  The present invention has been made in view of the above circumstances, and when a portable device is located in a transmission area of a request signal, an accurate position in the transmission area of the portable device can be determined, or the portable device It is an object of the present invention to provide a communication system and a position determination method that can determine whether the mobile station is moving or stopped in the transmission area.

In order to solve the above problems, a communication system of the present invention includes an in-vehicle device and a portable device mounted on a vehicle,
The portable device is
Portable device side receiving means for receiving a request signal transmitted from the in-vehicle device;
Obtaining means for obtaining information that changes with the position of the portable device in the transmission area of the request signal;
In response to the request signal received by the portable device side receiving means, comprising a response signal including the information to the in-vehicle device, the portable device side transmitting means,
The in-vehicle device is
Vehicle-side transmission means for transmitting the request signal around or in the vehicle;
Vehicle-side receiving means for receiving the response signal;
Based on the information included in the response signal received by the vehicle-side receiving means, determination of the position of the portable device in the transmission area, and whether or not the portable device is moving in the transmission area Determination means for performing at least one of determination of whether or not.

  According to the present invention, the portable device acquires information that changes with its own position change, and transmits it to the in-vehicle device by including it in the response signal. Thereby, the in-vehicle device (determination means) can determine the exact position of the portable device in the transmission area by obtaining this information included in the response signal, or is the portable device moving in the transmission area? You can determine whether it is stopped.

The position determination method of the present invention includes a transmission step of transmitting a request signal from the vehicle to the periphery of the vehicle or in the vehicle;
An acquisition step of receiving the request signal and acquiring information that changes with a change in position in the transmission area of the request signal of the portable device that transmits the response signal to the vehicle in response to the received request signal;
Based on the information acquired in the acquisition step, at least one of determination of the position of the portable device in the transmission area and determination of whether the portable device is moving or stopped in the transmission area is performed. A determination step;
It is characterized by providing.

  According to the present invention, since the acquisition step acquires information that changes with the change in the position of the portable device, the determination step can determine the exact position of the portable device within the transmission area based on the acquired information, or transmit the information. It can be determined whether the portable device is moving or stopped in the area.

It is a block diagram of an electronic key system. It is the figure which showed the arrangement | positioning position of a transmitter, and the transmission area of a request signal. It is the table which showed the key position with respect to RSSI. It is a flowchart of the process which a key (control circuit) performs. It is the figure which showed the signal (data) transmitted / received between a vehicle-mounted apparatus and a key. It is a flowchart of the process which notifies a vehicle side that the key moved which the key (control circuit) moved. It is a flowchart of the process which a vehicle-mounted apparatus (ECU) performs. It is the flowchart which showed an example of the process according to the key position which an in-vehicle apparatus (ECU) performs.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of an electronic key system 1 to which a communication system and a position determination method of the present invention are applied. The electronic key system 1 includes an in-vehicle device 2 mounted on a vehicle 100 (see FIG. 2) and a key 16 as a portable device possessed by a user of the vehicle 100. The electronic key system 1 is based on a so-called smart entry system that controls locking / unlocking of the door of the vehicle 100 based on bidirectional communication between the in-vehicle device 2 and the key 16 and unidirectional communication from the key 16 to the in-vehicle device 2. The system is compatible with both RKE systems that control locking and unlocking of doors. First, the configuration of the in-vehicle device 2 will be described.

  The in-vehicle device 2 includes a transmitter 4, a receiver 12, a door lock switch 13, a door lock motor 14, a touch sensor 15, a trunk door drive motor 24, and an ECU 3 connected thereto. The transmitter 4 includes an antenna 4a, and is arranged at a plurality of locations of the vehicle 100 as shown in FIG. 2 and sends a request signal for requesting a reply from the antenna 4a to an area corresponding to the arrangement position in the LF band ( For example, it is a device that transmits as 125 kHz radio waves. The request signal is a signal for searching for and authenticating the key 16. The transmitter 4 transmits the request signal, for example, as an ASK modulated (ASK: Amplitude Shut Keying) radio wave. Transmitter 4 includes an in-vehicle transmitter 5 that transmits a request signal to a peripheral area of vehicle 100 outside the vehicle, and an in-vehicle transmitter 6 that transmits the request signal into the vehicle.

  As shown in FIG. 2, the outside transmitter 5 is arranged on the right side of the vehicle 100 and transmits a request signal to the right side of the vehicle 100 (for example, an area of about 1 m to 2 m from the right side). A left transmitter 5b that is arranged on the left side of the vehicle 100 and transmits a request signal to the left side of the vehicle 100 (for example, an area of about 1 m to 2 m from the left side), and is arranged near the trunk of the vehicle 100. And a trunk external transmitter 5c that transmits a request signal to a trunk peripheral area (an area of about 1 m to 2 m behind the rear surface of the vehicle 100). The right transmitter 5a and the left transmitter 5b are disposed at a position between the front seat and the rear seat on the side surface of the vehicle, for example. FIG. 2 shows an example in which three outside transmitters 5 are provided. However, any number of two or more outside transmitters 5 may be provided as long as there are two or more, for example, each door may be provided. In FIG. 2, the right transmitter 5a is illustrated as “ANT1”, the left transmitter 5b as “ANT2”, the non-trunk transmitter 5c as “ANT4”, and the in-vehicle transmitter 6 as “ANT3”.

  Each transmitter 4 also transmits a request signal to an area other than the transmission area intended by each transmitter 4 (for example, the right side area of the vehicle 100 in the case of the right transmitter 5a). ). FIG. 2 shows the transmission areas 7 to 10 for request signals of the transmitters 4. These transmission areas 7 to 10 are formed, for example, in a substantially elliptical shape centered on each transmitter 4. Therefore, the transmission areas 7 to 10 partially overlap each other. That is, the transmission area 7 of the right transmitter 5a partially overlaps with all the other transmission areas 8, 9, and 10. Similarly, the transmission area 8 of the left transmitter 5b partially overlaps with all other transmission areas 7, 9, and 10. A part of the transmission area 9 of the transmitter 5c outside the trunk overlaps with all the other transmission areas 7, 8, and 10. The transmission area 10 of the in-car transmitter 6 partially overlaps with all other transmission areas 7, 8, and 9. Thereby, the area 11 (hatching area of FIG. 2 including an in-vehicle area) where at least three of the transmission areas 7 to 10 overlap is formed. The transmitter 4 corresponds to the transmission unit of the present invention.

  The receiver 12 includes an antenna 12a that receives a response signal transmitted as an RF band radio wave (for example, 300 to 400 MHz radio wave) from the key 16, and performs a process such as demodulation on the response signal received by the antenna 12a. It is a device to perform. The receiver 12 corresponds to the vehicle side receiving means of the present invention.

  The door lock switch 13 is an operation unit (for example, a push switch) for instructing the in-vehicle device 2 to lock (lock) the door, for example, provided in the vicinity of a door handle provided on the outside of each door of the vehicle 100. . The door lock motor 14 is a motor that is provided for each door and operates the lock mechanism of each door to the lock side or to the unlock side. The touch sensor 15 is a sensor (for example, a capacitance sensor) that is provided at a door handle of each door, for example, and detects a user's touch (contact) on the door handle. The trunk door drive motor 24 is a motor that drives the trunk door provided on the rear surface of the vehicle 100 to the opening side.

  The ECU 3 is an electronic control device that includes a CPU, a ROM, a RAM, and the like and executes various processes related to the smart entry system and the RKE key system. Details of processing executed by the ECU 3 will be described later. Further, the ECU 3 is provided with a memory 3a that stores various information such as ROM and RAM. The memory 3 a stores a program for processing executed by the ECU 3 and a master ID code for authenticating the key 16.

  Further, as shown in FIG. 3, the memory 3a has a request signal transmitted from each transmitter 4 (ANT1 to ANT4 in FIG. 2) when the key 16 receives the request signal field strength (RSSI: Received). The relationship between the Signal Strength Indicator) and the position of the key 16 is stored. In FIG. 3, a map (table) of key positions with respect to RSSI of request signals from ANT1 (right transmitter 5a), ANT2 (left transmitter 5b), ANT3 (in-car transmitter 6), and ANT4 (out-trunk transmitter 5c). Is shown. The RSSI of the request signal correlates with the position of the key 16 in the request signal transmission area, in other words, the distance between each of the ANT1 to ANT4 and the key 16. That is, as the key 16 receives a request signal at a position closer to each of the ANT1 to ANT4, the RSSI increases. Therefore, the greater the RSSI of ANT1, the closer the key 16 is to ANT1, the greater the RSSI of ANT2, the closer the key 16 is to ANT2, the greater the RSSI of ANT3, the closer the key 16 is to ANT3, and the greater the RSSI of ANT4. Key 16 is close to ANT4.

  Moreover, since RSSI correlates with the distance between ANT1 to ANT4 and the key 16, if at least three of RSSIs of ANT1 to ANT4 can be obtained, the position of the key 16 can be uniquely determined by the principle of triangulation. That is, since at least three RSSIs can be acquired when the key 16 is located in the area 11 of FIG. 2, the position of the key 16 can be uniquely determined. Hereinafter, the area 11 is referred to as a position detectable area. In addition, if all the RSSIs of ANT1 to ANT4 can be acquired, the position of the key 16 can be obtained more accurately. As described above, in the map of FIG. 3, the key position is determined only when at least three of RSSIs of ANT1 to ANT4 are prepared.

  Next, the configuration of the key 16 will be described. As shown in FIG. 1, the key 16 includes a reception unit 17, an RSSI determination unit 18, a control circuit 19, an output circuit 20, a transmission unit 21, an acceleration sensor 22, and a lock / unlock button 23. Each component of the key 16 operates by receiving electric power from a battery (not shown).

  The receiving unit 17 corresponds to the portable device side receiving means of the present invention, and is a part (receiving antenna) that receives the LF radio wave of the request signal transmitted from the in-vehicle device 2. The key 16 includes a demodulator (not shown) that demodulates the request signal (analog signal) received by the receiver 17 into the original digital signal (bit string). The digital signal demodulated by the demodulator is input to the control circuit 19.

  The RSSI determination unit 18 is a part that determines (measures) the RSSI of the analog signal when the request signal received by the reception unit 17 is input as an analog signal. The RSSI determined by the RSSI determination unit 18 is input to the control circuit 19.

  The output circuit 20 generates a bit string of a signal to be transmitted to the in-vehicle device 2 based on a command from the control circuit 19, modulates the bit string into an RF band signal (for example, ASK modulation), and then transmits the modulated signal to the transmission unit 21 is a circuit for outputting to the circuit 21. The transmission unit 21 is a part (transmission antenna) that transmits the signal output from the output circuit 20 to the periphery of the key 16 as an RF band radio wave. The signal transmission area (transmission distance) by the transmitter 21 is set to about 10 m to 100 m from the key 16, for example.

  The acceleration sensor 22 is a sensor that detects acceleration acting on the key 16. The acceleration detected by the acceleration sensor 22 is input to the control circuit 19. The lock / unlock button 23 is provided so as to be exposed from the casing of the key 16 and is an operation unit that instructs to lock or unlock the vehicle door. The lock / unlock button 23 may include two buttons, a lock button and an unlock button, or may be configured as a single button without distinguishing between lock and unlock buttons. Also good.

  The control circuit 19 includes a CPU, a ROM, a RAM, and the like, and is a part that executes various processes related to the smart entry system and the RKE system. Here, FIG. 4 shows a flowchart of processing relating to the smart entry system executed by the control circuit 19. Hereinafter, the process of FIG. 4 will be described. The control circuit 19 performs an intermittent operation while the process is not executed, and the process of FIG. 4 is started at the time of wake-up in the intermittent operation mode.

  When the processing of FIG. 4 is started, the control circuit 19 determines whether or not a request signal from the in-vehicle device 2 has been received (S31). If no request signal is received (S31: No), the process of FIG. 4 is terminated and the intermittent operation mode is continued. In this case, the key 16 is located outside the areas 7 to 10 of ANT1 to ANT4 in FIG. When the request signal is received (S31: Yes), that is, when the key 16 is located in the areas 7 to 10 in FIG. 2, the intermittent operation mode is shifted to the normal operation mode, and the RSSI determination unit 18 The RSSI (reception intensity) of the received request signal (strictly, RSSI measurement data in FIG. 5) is measured, and the control circuit 19 acquires the RSSI (S32).

  Here, as shown in the upper part of FIG. 5, RSSI measurement data is transmitted from each of ANT1 to ANT4 in addition to a request signal (a bit string signal in which bits “1” and “0” are combined). . The RSSI measurement data is, for example, data having an amplitude of HIGH when ASK modulation is performed, that is, data including only “1” bits. Thereby, the RSSI determination unit 18 can easily measure the RSSI of the received signal (RSSI measurement data). When request signals from a plurality of different transmitters 4 (ANT1 to ANT4) are received, the RSSI determination unit 18 determines the RSSI for each request signal. In addition, the control circuit 19 which performs the process of RSSI determination part 18 and S32 corresponds to the acquisition means of this invention. The process of S32 corresponds to the acquisition step of the present invention.

  Next, the control circuit 19 causes the output circuit 20 and the transmission unit 21 to transmit a response signal in response to the request signal (S33). At this time, an ID code for authenticating the key 16 on the in-vehicle device 2 side is included in the response signal. For example, when the challenge and response method is adopted as the authentication method, the control circuit 19 performs a predetermined calculation process on the challenge code (random number) included in the request signal, and the value obtained by the calculation process is an ID code. Included in the response signal. Further, the control circuit 19 includes the RSSI acquired in S32 in the response signal. In this way, in S33, as shown in the lower part of FIG. 5, a response signal including RSSI is transmitted from the key 16.

  When request signals from a plurality of different transmitters 4 are received, a response signal is transmitted for each request signal in S33. At this time, the RSSI of the corresponding request signal is included in each response signal. That is, for example, when two request signals from ANT1 and ANT2 are received, a response signal responding to the request signal of ANT1 is transmitted including the RSSI of the request signal, and a response signal responding to the request signal of ANT2 is transmitted. It transmits including the RSSI of the request signal. After S33, the process of FIG. 4 is terminated and the process shifts to the intermittent operation mode. The output circuit 20, the transmission unit 21, and the control circuit 19 that executes the processing of S33 correspond to the portable device-side transmission means of the present invention.

  The control circuit 19 executes processing related to the RKE system in addition to the processing of FIG. Specifically, when the lock / unlock button 23 is operated by the user, the control circuit 19 causes the output circuit 20 and the transmission unit 21 to transmit a signal instructing to lock or unlock the vehicle door.

  Furthermore, when the position of the key 16 moves from the stop state, the control circuit 19 also executes a process of transmitting a notification signal for notifying the vehicle-mounted device 2 of that fact. FIG. 6 shows a flowchart of this process. The process of FIG. 6 starts at the time of wake-up in the intermittent operation mode and is executed in parallel with the process of FIG.

  When the processing of FIG. 6 is started, the control circuit 19 determines whether or not the position of the key 16 has moved from the stop state based on the acceleration detected by the acceleration sensor 22 (S41). Specifically, for example, it is determined whether or not the acceleration has reached a predetermined value greater than zero from a zero state for a certain time or more. Then, when the acceleration reaches a predetermined value or more from the zero state, it is determined that the position of the key 16 has moved from the stopped state. When the position of the key 16 is stopped, the acceleration is zero. When the key 16 is originally moving, the acceleration is originally equal to or higher than a predetermined value or zero (when the key 16 is moving at a constant speed). Therefore, in S41, when the acceleration detected by the acceleration sensor 22 is zero, it is determined that the key 16 is stopped or moving at a constant speed. If the acceleration is originally equal to or greater than a predetermined value, it is determined that the key 16 originally moved. The control circuit 19 that executes the processes of the acceleration sensor 22 and S41 corresponds to the detection means of the present invention.

  If the position of the key 16 remains stopped or has moved originally (S41: No), the processing of FIG. 6 is terminated. On the other hand, when the position of the key 16 has moved from the stopped state (S41: Yes), a notification signal for notifying the output circuit 20 and the transmission unit 21 that the key 16 has moved is displayed in the peripheral area of the key 16. Transmit (S42). The notification signal transmitted here is used as a trigger for returning communication stopped in the process of FIG. After S42, the process of FIG. 6 is terminated. The output circuit 20, the transmission unit 21, and the control circuit 19 that executes the processing of S42 correspond to the notification transmission unit of the present invention.

  Next, details of processing executed by the ECU 3 of the in-vehicle device 2 will be described. When the receiver 12 receives the RKE signal from the key 16, that is, the signal transmitted based on the operation of the lock / unlock button 23, as the process related to the RKE system, the ECU 3 performs the door lock motor 14 To lock or unlock the vehicle door. Further, as a process at the time of getting off in the smart entry system, when the door lock switch 13 is operated by the user getting off from the vehicle 100, the ECU 3 sends a request signal to each transmitter 4 so that the key 16 is outside the vehicle. Confirm that it was taken out. When it is confirmed that the key 16 has been taken out of the vehicle, that is, there is a response signal received in response to the request signal from the vehicle transmitter 5 and a response signal responding to the request signal from the vehicle transmitter 6. If the RSSI included in the response signal responding to the request signal from the in-vehicle transmitter 5 is greater than the RSSI included in the response signal responding to the request signal from the in-vehicle transmitter 6 Then, the door lock motor 14 is controlled to lock the vehicle door. Further, when the key 16 is left in the vehicle, that is, there is no reception of a response signal in response to the request signal from the outside transmitter 5 and no response signal is received in response to the request signal from the in-vehicle transmitter 6. If there is, or if the RSSI included in the response signal responding to the request signal from the in-vehicle transmitter 5 is smaller than the RSSI included in the response signal responding to the request signal from the in-vehicle transmitter 6, the door lock For example, giving a warning.

  Moreover, ECU3 performs the process of FIG. 7 as one of the processes regarding a smart entry system. The process of FIG. 7 is a process that is assumed to be executed in a scene where the vehicle door is locked and the user is not in the vehicle. Therefore, the process of FIG. 7 is, for example, that the vehicle door is locked and the key 16 does not exist in the vehicle after the engine is stopped (no response signal is received in response to the request signal from the in-vehicle transmitter 6). Is started, and thereafter, it is repeatedly executed at a predetermined cycle.

  When the process of FIG. 7 is started, the ECU 3 periodically transmits a request signal for searching for the key 16 approaching the vehicle 100 (S1). Specifically, the ECU 3 causes each transmitter 4 to repeatedly transmit a request signal at a predetermined cycle (for example, about 100 msec). At this time, the request signal is transmitted not only to the vehicle transmitter 5 but also to the vehicle transmitter 6. Further, as shown in FIG. 2, the request signal is transmitted to the transmission areas 7 to 10 which are partially overlapped with each other. Further, in order to avoid interference of request signals from a plurality of different transmitters 4, the transmission times of request signals are shifted among the four transmitters 4 (ANT1 to ANT4). For example, when a challenge & response method is adopted as key authentication, a challenge code composed of random numbers is included in the request signal. Further, as described with reference to FIG. 5, in S1, the RSSI measurement data is transmitted in addition to the request signal. In addition, ECU3 which performs the process of transmitter 4 and S1 is equivalent to the vehicle side transmission means of this invention. Further, the process of S1 corresponds to the transmission step of the present invention.

  Next, it is determined whether or not a response signal responding to the request signal transmitted in S1 has been received (S2). If no response signal has been received (S2: No), the process returns to S1 and the periodic transmission of the request signal is continued. If the receiver 12 receives a response signal (S2: Yes), the key 16 is authenticated based on the ID code included in the response signal (S3). Specifically, when a challenge and response method is adopted as key authentication, for example, a predetermined calculation process is performed on the challenge code included in the request signal, and the value obtained by the calculation process is used as a master ID code in the memory 3a. Remember it. Note that the arithmetic processing applied to the challenge code is adjusted in advance so as to be the same processing between the ECU 3 and the key 16. Then, the master ID code stored in the memory 3a is collated with the ID code included in the response signal.

  Next, it is determined whether or not the authentication by S3 is successful (S4). If the authentication fails, that is, if the verification between the master ID code and the ID code fails (S4: No), the process returns to S1. On the other hand, if the authentication is successful, that is, if the verification of the master ID code and the ID code is successful (S4: Yes), the key 16 approaches the request signal transmission areas 7 to 10 (see FIG. 2). The touch sensor 15 is put into a standby state (S5). Thereafter, when the touch sensor 15 detects that the door handle is touched, the ECU 3 controls the door lock motor 14 to unlock the door touched by the door handle.

  Next, based on the number of response signals received in S2, in other words, the number of RSSIs obtained, it is determined whether or not the key 16 is located in the position detectable area 11 (see FIG. 2) (S6). . Specifically, when the number of received response signals (RSSI) is one or two, it is determined that the key 16 is located outside the position detectable area 11. In this case, the key 16 is located in an area other than the position detectable area 11 in the transmission areas 7 to 10. When the number of received response signals (RSSI) is three or four, it is determined that the key 16 is located in the position detectable area 11.

  If the key 16 is located outside the position detectable area 11 (S6: No), it is determined that there is no key 16 in the vicinity of the vehicle (position detectable area 11) (S15). Then, in order to detect the approach of the key 16 to the vicinity of the vehicle, the periodic transmission of the request signal is continued (S16). Then, the process of FIG. 7 is complete | finished.

  On the other hand, when the key 16 is located in the position detectable area 11 (S6: Yes), the position detectable area based on at least three RSSIs obtained by receiving the response signal and the map of FIG. 11 to determine the position of the key 16 (S7). In S7, the distance from each transmitter 4 to the key 16 is calculated from each obtained RSSI, and based on the obtained distance and the arrangement position of each transmitter 4 in the vehicle 100, triangulation This means that the position of the key 16 is determined based on the principle. Specifically, a circle with the radius of the distance to the key 16 determined based on each RSSI centered on the location of each transmitter 4 is obtained for each RSSI obtained, and a plurality of (at least three) obtained circles are obtained. Let the intersection be the position of the key 16. The location of each transmitter 4 may be stored in the memory 3a. In addition, ECU3 which performs the process of S6, S7 corresponds to the position determination means of this invention, and the process of S6, S7 corresponds to the position determination step of this invention.

  By determining the position of the key 16, processing corresponding to the position can be executed. For example, after determining the key position, the request signal is transmitted only to the transmitter located closest to the key 16 in the transmitter 4. Thereby, processing can be simplified and battery consumption of the vehicle 100 can be suppressed. Further, when the key 16 is in the vehicle, the user can stop the periodic transmission of the request signal, assuming that the user has boarded the vehicle 100. Moreover, ECU3 performs the process of FIG. 8 based on the key position obtained by S7. The process of FIG. 8 will be described later.

  Next, it is determined whether or not there is a change between a series of RSSIs included in the response signal continuously received with the periodic transmission of the request signal (S8). Specifically, for example, every time a response signal is received, a difference (difference) between the RSSI included in the currently received response signal and the RSSI included in the previously received response signal is obtained. It is determined whether or not the state where the obtained difference is less than a predetermined value continues for a predetermined time (for example, 1 minute). This predetermined value is set to such a small value that it can be considered that there is no change in RSSI in a smaller range.

  Note that the ECU 3 has acquired at least three RSSIs of request signals transmitted from different transmitters 4. Therefore, in S7, even if RSSI changes (time-dependent changes) are determined for each RSSI. It is good, and the change with time of RSSI may be judged only for any one RSSI. When judging the RSSI change over time for each RSSI, if there is no change over time in all RSSIs, it is determined that the position of the key 16 is stopped, and if there is even one RSSI change over time. The key 16 is determined to be moving.

  In S8, it is synonymous with determining whether or not the key position obtained in S7 has changed over time. That is, in S8, it means that the difference between the current key position and the previous key position is obtained and it is determined whether or not a state where the difference is less than a predetermined value has continued for a predetermined time.

  When the state in which the difference is less than the predetermined value does not continue for a predetermined time (when the difference exceeds the predetermined value even once during the predetermined time), that is, when there is a change in RSSI over time (S8: Yes). The key 16 is determined to be in a moving state in the vicinity of the vehicle (position detectable area 11) (S9). In this case, since the user is moving in the vicinity of the vehicle and is likely to get on the vehicle 100 after that, the periodic transmission of the request signal is continued (S10). Thus, it is possible to quickly grasp how the key 16 (user) moves thereafter. Then, the process of FIG. 7 is complete | finished.

  On the other hand, when the state in which the difference is less than the predetermined value continues for a predetermined time, that is, when there is no change in RSSI (key position) with time (S8: No), the key 16 is in the vicinity of the vehicle (position detectable area 11). Is determined to be left unattended (S11). Then, the periodic transmission of the request signal is stopped (S12). As a result, for example, even when the key 16 remains in the key yard in the home garage where the vehicle is placed, communication between the in-vehicle device 2 and the key 16 continues indefinitely even though the user does not get on. Can be avoided. Therefore, it is possible to suppress the battery consumption of the key 16 from being accelerated. Further, battery consumption of the vehicle 100 can be suppressed.

  Thereafter, it is determined whether or not a communication return trigger that is predetermined as a trigger for returning the stopped communication is input (S13). The communication return trigger is, for example, a notification signal transmitted in S42 of FIG. 6, an RKE signal transmitted from the key 16 when the lock / unlock button 23 is operated, or an operation on the vehicle 100. (For example, operation of the door lock switch 13).

  If there is no communication return trigger input (S13: No), the system waits for the input. If there is a communication return trigger input (S13: Yes), the periodic transmission of the request signal is returned (S14). Thus, the position of the key 16 can be determined, and processing (such as door locking / unlocking) corresponding to the position can be quickly executed. Then, the process of FIG. 7 is complete | finished.

  In addition, ECU3 which performs the process of S6-S9 and S11 corresponds to the determination means of this invention. The processing of S6 to S9 and S11 corresponds to the determination step of the present invention. Moreover, ECU3 which performs the process of S8, S9, S11 corresponds to the movement state determination means of this invention, and the process of S8, S9, S11 corresponds to the movement state determination step of this invention. Moreover, ECU3 which performs the process of S10, S12, S13, S14 is equivalent to the transmission control means of this invention.

  Next, the process of FIG. 8 will be described. The process of FIG. 8 starts when the key position is obtained in S7 of FIG. 7, for example, and is executed in parallel with the process of FIG. When the processing of FIG. 8 is started, the ECU 3 determines whether or not the key 16 is located in a trunk peripheral area outside the vehicle (for example, an area within a predetermined distance from the trunk door) based on the determination result of S7 of FIG. (S21). If the key 16 is located outside the trunk peripheral area (S21: No), the processing in FIG. 8 is terminated.

  If the key 16 is located in the trunk peripheral area (S21: Yes), it is determined whether or not the key 16 is stopped in the trunk peripheral area for a certain time (for example, several seconds) (S22). This determination is performed based on whether or not RSSI (key position) changes with time, as in S8 of FIG. When a state where a difference between a series of RSSIs (key positions) obtained with the passage of time is less than a predetermined value continues for a certain period of time, that is, when the key 16 is stopped for a certain period of time in the trunk peripheral area (S22: Yes), the door lock motor 14 is controlled to unlock the trunk door, and the trunk door drive motor 24 is controlled to drive the trunk door to the open side (S23). Thereby, the operation burden on the user can be reduced. Further, for example, even if the user's hand is covered with a luggage, the user can easily put the luggage into the trunk. If the key 16 is stopped in the trunk peripheral area for a certain period of time, the key 16 (user) is expected to move after taking in / out the luggage, etc., so the periodic transmission of the request signal is not stopped. . After S23, the process of FIG.

  On the other hand, when there is a change in RSSI (key position) with time, that is, when the key 16 is moving in the trunk peripheral area, it is assumed that the user has only passed around the trunk and there is no user's work on the trunk. The process of 8 is finished.

  As described above, according to the present embodiment, since the position of the key is determined based on at least three RSSIs, compared to the conventional method that can only determine whether the key is in the vehicle or outside the vehicle, The exact position of the key can be obtained. In addition, since it is determined whether or not there is a key in an area where at least three transmission areas overlap (position detectable area), an area where the transmission areas do not overlap or an area where only two transmission areas overlap In comparison, it is possible to determine the key position and the moving state of the key in an area closer to the vehicle.

  Further, since it is determined whether or not the RSSI changes with time, it can be quickly and accurately determined whether the key is moving or stopped in the position detectable area. As a result, when the key position is stopped, the periodic transmission of the request signal can be stopped quickly, and battery consumption can be suppressed.

  On the other hand, when the communication between the vehicle and the key continues for a certain period of time, the request signal transmission area is configured to stop the periodic transmission of the request signal, assuming that the key is stopped in the transmission area of the request signal. In this case, sufficient time is required for reliably determining that the key is stopped, and it takes time to stop the periodic transmission. In this embodiment, since it can be determined whether the key is moving or stopped, it is not necessary to determine the duration of communication between the vehicle and the key, and when the key is stopped, the request signal is periodically transmitted immediately. Can be stopped.

  In this embodiment, since the key position and the moving state of the key are determined based on the RSSI of the LF signal (request signal) having a short transmission distance, the RF signal (response signal) transmitted from the key and having a long transmission distance is transmitted. The change (sensitivity) of the RSSI with respect to the change of the key position in the transmission area can be made larger than the RSSI of As a result, it is possible to accurately determine the key position and the moving state of the key.

  In this embodiment, when the key moves after stopping the periodic transmission of the request signal, the periodic transmission automatically returns based on the notification signal from the key, so that the user returns the periodic transmission. You don't have to do any special operations. Therefore, the operation burden on the user can be reduced.

  In addition, this invention is not limited to the said embodiment, A various change is possible to the limit which does not deviate from description of a claim. For example, in the above embodiment, the key position and the moving state of the key are determined based on the RSSI, but the determination is performed based on information other than RSSI that changes with the key position change, specifically, for example, based on the GPS signal. May be. In this case, the key is provided with a receiver that receives GPS signals. Then, the key includes the GPS signal received by the receiver in the response signal as the key position information. Thereby, the in-vehicle device can determine the position of the key based on the GPS signal included in the response signal, and can determine whether the key is moving or stopped based on whether or not the GPS signal changes with time.

  Further, as information other than RSSI that changes with a change in key position, information on acceleration and speed acting on the key may be used. That is, an acceleration sensor or a speed sensor is provided on the key. The key includes acceleration or speed information in the response signal. The in-vehicle device determines whether the key is moving or stopped based on the presence or absence of a change with time in the acceleration or speed included in the response signal.

  Moreover, in the said embodiment, although the key position and the movement state of the key were determined by the vehicle-mounted apparatus side, you may make it a key perform the determination and transmit the determination result to a vehicle-mounted apparatus. Specifically, when the key receives the request signal, the key measures the RSSI of the request signal, and executes processing corresponding to S6 to S9, S11, and S15 of FIG. 7 based on the RSSI, The key position and the moving state of the key are determined. The key includes the determination result in the response signal. The in-vehicle device determines to continue or stop the periodic transmission of the request signal based on the determination result (key position and key movement state) included in the response signal.

  In the above embodiment, an area where at least three transmission areas overlap is set as a position detectable area, and it is determined whether the key is moving or stopped in the position detectable area. However, the present invention is not limited to this, and it may be determined whether the key is moving or stopped even in a transmission area that does not overlap with another transmission area or an area in which only two transmission areas overlap. That is, it may be determined whether the key is moving or stopped in an area outside the position detectable area 11 in the transmission areas 7 to 10 in FIG. Even in this case, since one or two RSSIs are obtained, it is possible to determine whether the key is moving or stopped by observing a change with time of the RSSI. As a result, when the key is stopped, the periodic transmission of the request signal can be stopped without waiting for a certain period of time.

  In addition, when only one or two RSSIs are obtained, that is, when the key is located in an area outside the position detectable area 11 in the transmission areas 7 to 10, the determination of the key position is attempted. Also good. For example, if the key is located in only one of the transmission areas 7 to 10 in FIG. 2, that is, if the key is located in an area that does not overlap between the transmission areas 7 to 10, one RSSI Based on this, it can be determined at which distance the key is located from the transmitter. In addition, when the key is located in an area where only two of the transmission areas 7 to 10 are overlapped, two RSSIs are obtained, so the principle of triangulation from the two RSSIs (distance information) Can determine the key position. Thus, even when only one or two RSSIs can be obtained, accurate position determination is possible as compared with the conventional method that can only determine the key position outside or inside the vehicle.

  Further, the key position determination of the present embodiment may be applied to a process of determining whether the key is taken out of the vehicle or left in the vehicle when getting off the vehicle. In the above embodiment, an example in which both the key position determination (S6, S7 in FIG. 7) and the key movement state determination (S8, S9, S11 in FIG. 7) are performed has been described. May be implemented.

1 Electronic key system (communication system)
2 In-vehicle device 3 ECU
4 transmitter 16 key (portable)
17 receiving unit 18 RSSI determining unit 19 control circuit 21 transmitting unit 100 vehicle

Claims (12)

An in-vehicle device (2) mounted on a vehicle (100) and a portable device (16);
The portable device is
Portable device side receiving means (17) for receiving a request signal transmitted from the in-vehicle device;
Acquisition means (18, 19, S32) for acquiring information that changes with a change in the position of the portable device in the transmission area (7-10, 11) of the request signal;
Portable device side transmission means (19, 20, 21, S33) for transmitting a response signal including the information to the in-vehicle device in response to the request signal received by the portable device side reception means;
The in-vehicle device is
Vehicle-side transmission means (3, 4, S1) for transmitting the request signal around or in the vehicle;
Vehicle-side receiving means (12) for receiving the response signal;
Based on the information included in the response signal received by the vehicle-side receiving means, determination of the position of the portable device in the transmission area, and whether or not the portable device is moving in the transmission area A communication system (1) comprising: determination means (3, S6 to S9, S11) for performing at least one of determination of whether or not.   The communication system according to claim 1, wherein the acquisition unit acquires the reception intensity of the request signal received by the portable device side reception unit as the information. The vehicle-side transmission means periodically transmits the request signal repeatedly,
The determination unit is configured to move the portable device within the transmission area based on a difference between the information included for each response signal repeatedly transmitted from the portable device in response to the periodic transmission of the request signal. The communication system according to claim 1 or 2, further comprising movement state determination means (S8, S9, S11) for determining whether the vehicle is stopped or stopped. The vehicle-side transmission means periodically transmits the request signal repeatedly,
The in-vehicle device stops the periodic transmission of the request signal when the portable device is stopped in the transmission area, and the periodic transmission of the request signal when the portable device is moving in the transmission area. The communication system according to any one of claims 1 to 3, further comprising transmission control means (3, S10, S12) for continuing the transmission. The portable device is
Detection means (22, 19, S41) for detecting that the position of the portable device has moved from the stop;
Notification transmission means (19, S42, 20, 21) for transmitting a notification signal to the in-vehicle device when the detection means detects that the portable device has moved,
The vehicle side receiving means also receives the notification signal,
The transmission control means (S13, S14) returns the periodic transmission of the request signal when the notification signal is received while the periodic transmission of the request signal is stopped. Communication system. The vehicle-side transmission means includes a plurality of transmission units (4) that are arranged at different positions of the vehicle and transmit the request signal to an area according to the arrangement position, and the transmission area of each transmission unit includes: It partially overlaps with the transmission area of the other transmission unit,
The acquisition unit acquires the reception intensity of the request signal received by the portable device side reception unit as the information,
The determination means is based on the reception strengths of the plurality of request signals transmitted from different transmission units included in the response signal from the portable device located in an overlapping area of the plurality of transmission areas. The communication system according to any one of claims 1 to 5, further comprising position determination means (S6, S7) for determining a position of the portable device in the overlapping area.   The position determination means includes at least three transmission units included in the response signal from the portable device located in the position detectable area (11) that is the overlapping area where at least three transmission areas overlap. The communication system according to claim 6, wherein the position of the portable device in the position detectable area is determined based on the reception strengths of the transmitted at least three request signals. A transmission step (S1) for transmitting a request signal from the vehicle (100) to the vicinity of the vehicle or in the vehicle;
The portable device (16) that receives the request signal and transmits a response signal in response to the received request signal to the vehicle changes with a change in position in the request signal transmission area (7 to 10, 11). An acquisition step (S32) for acquiring information to be performed;
Based on the information acquired in the acquisition step, at least one of determination of the position of the portable device in the transmission area and determination of whether the portable device is moving or stopped in the transmission area is performed. Determination steps (S6 to S9, S11);
A position determination method comprising:   The position determination method according to claim 8, wherein in the obtaining step, the reception intensity of the request signal received by the portable device is obtained as the information. In the transmission step, the request signal is transmitted periodically and repeatedly,
The determination step determines whether the portable device is moving in the transmission area or stopped based on a difference between the information for each request signal repeatedly received by the portable device. The position determination method according to claim 8 or 9, comprising S8, S9, S11). In the transmission step, the request signal is transmitted from a plurality of transmission units (4) arranged at different positions of the vehicle, and the transmission area of each transmission unit is identical to the transmission areas of the other transmission units. Duplicated,
The determination step is based on the reception strengths of the plurality of request signals transmitted from the different transmission units received by the portable device located in the overlapping area of the plurality of transmission areas, and in the overlapping area. The position determination method according to claim 9, further comprising a position determination step (S6, S7) for determining a position of the portable device.   In the position determination step, at least three transmitted from the at least three transmitters received by the portable device located in the position detectable area (11) which is the overlapping area where at least three of the transmission areas overlap. The position determination method according to claim 11, wherein the position of the portable device in the position detectable area is determined based on the reception intensity of the request signal.

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