Vehicle control system

Abstract

The objective is to provide a vehicle control system that can reliably perform necessary vehicle control without causing communication disruptions at short range. [Solution] The vehicle control system comprises an on-board electronic control unit mounted in a vehicle and performing predetermined control over the vehicle, and a portable device carried by the vehicle user and communicating wirelessly with the on-board electronic control unit, wherein the on-board electronic control unit has a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device, the portable device has a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal, and the portable device determines the distance to the vehicle-side receiving unit and changes the transmission output strength of the answer signal according to the determined distance, thereby solving the problem.

Description

Technical Field

[0001] The present invention relates to a vehicle control system that executes authentication processing of a portable device by wirelessly communicating between an electronic control unit mounted on a vehicle and a portable device carried by a user.

Background Art

[0002] Conventionally, an electronic control unit mounted on a vehicle and a portable device carried by a user execute authentication processing by wireless communication, and based on the establishment of the authentication processing, the in-vehicle electronic control unit performs vehicle control such as unlocking and locking of vehicle doors and starting of the engine. A vehicle control system called smart key entry is known. A system centered on such an in-vehicle electronic control unit is described in, for example, Patent Document 1. Hereinafter, the in-vehicle electronic control unit may be abbreviated as in-vehicle ECU.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the vehicle control system described in Patent Document 1, when a user who owns a portable device operates a handle of a vehicle door or a touch sensor arranged at an appropriate position, the in-vehicle ECU and the portable device communicate with each other, and if it is authenticated that the user is a legitimate user, necessary processes such as unlocking the door and starting the engine are executed. Here, the intensity of the RF signal transmitted from the portable device is set large in order to improve noise resistance. On the other hand, in automotive ECUs, the receiving ICs that receive and process RF signals from mobile devices tend to use inexpensive components, which can result in a small dynamic range of received radio wave strength. Also, when smart key entry is introduced to motorcycles, depending on the positional relationship between the luggage containing the key and the antenna, the key and antenna may be in very close proximity. In these cases, the RF signal from the mobile device may exceed the dynamic range of the receiving IC, potentially causing communication problems.

[0005] The present invention aims to address these problems and provides a vehicle control system that can reliably perform necessary vehicle control without causing short-range communication interference. [Means for solving the problem]

[0006] To achieve this objective, the technical means according to the present invention is a vehicle control system comprising at least the following configurations.

[0007] A vehicle control system comprising an on-board electronic control unit mounted in a vehicle and performing predetermined control over the vehicle, and a portable device carried by the vehicle user and communicating wirelessly with the on-board electronic control unit, wherein the on-board electronic control unit has a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device, the portable device has a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal, and the portable device determines the distance to the vehicle-side receiving unit and changes the transmission output strength of the answer signal to a different level than normal according to the determined distance.

[0008] Furthermore, in order to achieve the above objective, the technical means according to the present invention is a vehicle control system comprising at least the following configurations.

[0009] A vehicle control system comprising: an on-board electronic control unit mounted in a vehicle and performing predetermined control over the vehicle; and a portable device carried by the vehicle user and communicating wirelessly with the on-board electronic control unit, wherein the on-board electronic control unit has a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device; the portable device has a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal; and the on-board electronic control unit measures the intensity of the answer signal, and if the RSSI is greater than a predetermined value, determines that the portable device is located nearby and retransmits the request signal to the portable device, including a request to reduce the transmission output intensity.

[0010] Furthermore, in order to achieve the above objective, the technical means according to the present invention is a vehicle control system comprising at least the following configurations.

[0011] A vehicle control system comprising: an on-board electronic control unit mounted in a vehicle and performing predetermined control over the vehicle; and a portable device carried by the vehicle user and communicating wirelessly with the on-board electronic control unit, wherein the on-board electronic control unit has a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device; the portable device has a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal; and the on-board electronic control unit measures the intensity of the answer signal, and if the RSSI is greater than a predetermined value, it determines that the portable device is located at close range and reduces the receiving sensitivity of the vehicle-side receiving unit to a lower level than when it is not determined that the device is located at close range. [Effects of the Invention]

[0012] Having these characteristics, the present invention provides the following effects. This system provides a vehicle control system that can reliably perform necessary vehicle control without causing communication disruptions at short range. [Brief explanation of the drawing]

[0013] [Figure 1] This is a functional block diagram of a vehicle control system according to the first embodiment of the present invention. [Figure 2] This is a flowchart showing the processing flow of a vehicle control system according to the first embodiment of the present invention. [Figure 3] This is a functional block diagram of a vehicle control system according to a second embodiment of the present invention. [Figure 4] This is a flowchart showing the processing flow of a vehicle control system according to a second embodiment of the present invention. [Figure 5] This is a functional block diagram of a vehicle control system according to a third embodiment of the present invention. [Figure 6] A flowchart illustrating the processing flow of a vehicle control system according to the third embodiment of the present invention. [Figure 7] This is a functional block diagram of a vehicle control system according to the fourth embodiment of the present invention. [Figure 8] This is a flowchart showing the processing flow of a vehicle control system according to the fourth embodiment of the present invention. [Modes for carrying out the invention]

[0014] The following describes an example of an embodiment of the vehicle control system according to the present invention, based on the drawings. The following drawings are created for illustrative purposes, and in order to make them easier to understand, some components that are not necessary for the explanation may be intentionally omitted. In the following description, the same reference numerals in different figures indicate parts with the same function, and redundant explanations in each figure will be omitted as appropriate.

[0015] <First Embodiment of the Invention> FIG. 1 is a diagram showing a vehicle control system according to a first embodiment of the present invention. Since the hardware configuration of the vehicle control system is merely a system configuration generally provided in an information processing device such as a CPU, a memory such as a ROM and a RAM connected to the CPU by a bus, a storage device, a display means, a communication means, and an operation input means, the illustration is omitted and it is shown as a functional block diagram. Further, here, only the functional blocks related to the present invention are illustrated. The vehicle control system 100 according to the first embodiment of the present invention is composed of an in-vehicle ECU 10 and a portable device 20. The in-vehicle ECU 10 is an in-vehicle device mounted on a vehicle such as an automobile or an electric motorcycle, and performs predetermined control on each part of the vehicle. The portable device 20 is an electronic key that is operated when locking or unlocking the vehicle door, and is possessed by the user of the vehicle. The in-vehicle ECU 10 and the portable device 20 are configured to communicate with each other wirelessly.

[0016] The in-vehicle ECU 10 includes a transmission antenna 11 that transmits an LF signal to the portable device 20, a reception antenna 12 that receives an RF signal from the portable device 20, a control unit 13 composed of a CPU, a memory, etc., and an operation unit 14 that is operated to cause the vehicle to perform a predetermined operation. Although the transmission antenna 11, the reception antenna 12, and the operation unit 14 are connected to the control unit 13 of the in-vehicle ECU 10, actually, they are attached to the vehicle and are physically outside the in-vehicle ECU 10. However, in FIG. 1, the transmission antenna 11, the reception antenna 12, and the operation unit 14 are depicted as being suspended from the in-vehicle ECU 10 as functional blocks under its control.

[0017] The request signal for which the in-vehicle ECU 10 requests a response from the portable device 20 is an LF signal, and the answer signal returned from the portable device 20 is an RF signal. Further, when an operation is performed on the portable device 20 side, the operation signal transmitted from the portable device 20 to the in-vehicle ECU 10 is also an RF signal.

[0018] The control unit 13 includes a signal generation unit 131, an authentication unit 132, a control signal output unit 133, and a storage unit 134. The signal generation unit 131 generates a request signal transmitted from the transmission antenna 11 to the mobile device 20, and a continuous wave CW (continuous wave) as a measurement signal added to this request signal. When the answer signal transmitted from the mobile device 20 is received by the reception antenna 12, the authentication unit 132 collates the ID included in the answer signal to determine whether authentication is successful. The control signal output unit 133 outputs a control signal for controlling each part of the vehicle based on the operations of the operation unit 14 of the in-vehicle ECU 10 and the operation unit 24 of the mobile device 20. The storage unit 134 stores data necessary for control, the ID of the mobile device 20, and the like.

[0019] The operation unit 14 is provided with a lock switch 141 for locking the vehicle door, an unlock switch 142 for unlocking the vehicle door, and a start switch 143 for starting the engine. However, the physical structures and arrangements of the three switches are different. For example, the lock switch 141 may be a switch interlocked with the operation of the outer handle of the vehicle, the unlock switch 142 may be a touch sensor arranged near the outer handle of the vehicle, and the start switch 143 may be a push button switch arranged on the dashboard. Also, other switches may be provided as necessary.

[0020] The mobile device 20 includes a reception antenna 21 for receiving an LF signal from the in-vehicle ECU 10, a transmission antenna 22 for transmitting an RF signal to the in-vehicle ECU 10, a control unit 23 composed of a CPU, a memory, etc., and an operation unit 24 that is operated to cause the vehicle to perform a predetermined operation.

[0021] The control unit 23 includes a received signal strength measurement unit 231, a determination unit 232, a signal generation unit 233, and a transmitted signal strength setting unit 234. The received signal strength measurement unit 231 measures the received signal strength of the CW measurement signal, which is transmitted following the request signal received from the in-vehicle ECU 10. The determination unit 232 determines the distance between the receiving antenna 12 of the in-vehicle ECU 10 and the portable device 20 from the measured received signal strength. Specifically, it determines that the portable device 20 is at close range if the measured RSSI (Received Signal Strength Indicator) is greater than a predetermined value. The signal generation unit 233 generates an answer signal transmitted from the transmitting antenna 22 to the in-vehicle ECU 10, and an operation signal based on the operation of the operation unit 24. The transmitted signal strength setting unit 234 sets the transmission strength of the answer signal to be weaker as necessary based on the distance determined by the determination unit 232.

[0022] The control unit 24 is equipped with a lock switch 241 for locking the vehicle doors and an unlock switch 242 for unlocking the vehicle doors. These switches are arranged appropriately on the surface of the portable device 20. In addition, other switches, such as a trunk opener switch for opening the trunk, may be provided on the control unit 24 as needed.

[0023] Next, the operation of the vehicle control system 100 according to the first embodiment of the present invention, which has the above configuration, will be explained with reference to the flowchart in Figure 2.

[0024] In Figure 2, each process of the in-vehicle ECU 10 is executed by the control unit 13 of the in-vehicle ECU, and each process of the portable device 20 is executed by the control unit 23 of the portable device. The following example describes the operation when unlocking the vehicle doors.

[0025] The sequence of steps shown in the flowchart of Figure 2 begins when the unlock switch 142 for unlocking the doors is operated on the operating unit 14 of the in-vehicle ECU 10. In step S101 on the in-vehicle ECU 10 side, a request signal generated by the signal generation unit 131 is transmitted from the transmitting antenna 11. This request signal includes a data area. In step S102, a continuous wave CW signal is transmitted as a measurement signal. Meanwhile, in step S201 on the portable device 20 side, the request signal is received by the receiving antenna 21, and then in step S202, the received strength of the received continuous wave CW is measured by the received strength measurement unit 231. Specifically, the RSSI is measured as the strength of the radio waves. Here, the process is explained in two steps, such as steps S101 and S102, or steps S201 and S202. This is to clearly explain the correspondence between the processing on the in-vehicle ECU 10 side and the processing on the portable device 20 side. In reality, a continuous wave CW signal is transmitted as a measurement signal immediately following the request signal which includes the data area.

[0026] In step S203 on the portable device 20 side, the determination unit 232 determines whether the measured RSSI is greater than a predetermined value. If it is determined to be greater, in step S204, the transmission strength setting unit 234 sets the transmission strength of the signal transmitted by the portable device 20 to weak. On the other hand, in step S203, if it is determined that the measured RSSI is less than or equal to the predetermined value, the normal transmission strength, which is set high to improve noise immunity, is maintained.

[0027] In step S205, an answer signal is generated by the signal generation unit 233. Then, in step S206, the answer signal is transmitted from the transmitting antenna 22 at the set transmission strength. The answer signal includes the ID of the portable device 20.

[0028] In the in-vehicle ECU 10, an answer signal is received from the receiving antenna 12 in step S103. Next, in step S104, authentication is performed by the authentication unit 132 based on ID verification. Specifically, the ID of the portable device 20 included in the answer signal is compared with the ID stored in the storage unit 134. If the two match, authentication is deemed successful; otherwise, authentication is deemed unsuccessful. If authentication is successful, the determination in step S104 is YES, and the process proceeds to step S105. On the other hand, if authentication is unsuccessful, the determination in step S104 is NO, and the process ends without executing step S105.

[0029] In step S105, the control signal output unit 133 outputs an unlock signal as a control signal. This unlock signal activates the door unlocking mechanism, and the door is unlocked.

[0030] As described above, in the vehicle control system 100 of the first embodiment, the portable device 20 measures the intensity of the continuous wave included in the request signal, and when the RSSI is greater than a predetermined value, the portable device 20 determines that the distance to the vehicle-side transmitter is short, and reduces the transmission output intensity of the answer signal to less than when it is not determined to be short distance. As a result, the RF signal from the portable device does not become an input that exceeds the dynamic range of the receiving IC, and the necessary vehicle control can be reliably performed.

[0031] Several modifications are conceivable for the first embodiment. For example, in the first embodiment, the transmission strength of the answer signal, which is normally set high to improve noise immunity, may be set low under normal circumstances, the opposite of the first embodiment. When the RSSI is lower than a predetermined value, the system may determine that the distance to the vehicle-side transmitter is long, and the transmission output strength of the answer signal may be set higher than when it is not determined to be long. This modification also has the secondary effect of extending battery life. Whether to adopt the control mode of the first embodiment or the control mode of the modification should be determined according to the expected usage of the vehicle. Alternatively, the system may be configured to allow switching between the two control modes by a selection setting operation.

[0032] As another variation, the portable device may measure the intensity of the continuous wave included in the request signal, determine which of several ranges the RSSI belongs to, and then vary the transmission output intensity of the answer signal in multiple stages according to the distance to the vehicle-side transmitter. By setting the transmission output of the answer signal to a moderate radio wave strength under normal circumstances and controlling the radio wave strength to be stronger or weaker depending on the distance, it is possible to secure a wide response range for the portable device.

[0033] Furthermore, as another variation, the vehicle-side transmitter may have multiple antennas, and the portable device may be configured to determine the distance to the vehicle-side transmitter based on the strength of the request signals transmitted from the multiple antennas. When the transmission strength is determined using only one transmitting antenna, there is a possibility of making an incorrect judgment due to factors such as the antenna's directivity. However, by comprehensively determining the transmission strength of multiple antennas, it becomes possible to determine the distance more accurately.

[0034] <Second Embodiment of the Invention> Figure 3 is a functional block diagram showing a vehicle control system according to a second embodiment of the present invention. Here, only the functional blocks related to the present invention are shown. The vehicle control system 200 according to the second embodiment of the present invention consists of an on-board ECU 30 and a portable device 40. The on-board ECU 30 performs predetermined control over various parts of the vehicle. The portable device 40 consists of an electronic key that is operated when locking or unlocking the vehicle doors, and is carried by the vehicle user. The on-board ECU 30 and the portable device 40 are configured to communicate with each other wirelessly.

[0035] The in-vehicle ECU 30 includes a transmitting antenna 31 that transmits an LF signal to the portable device 40, a receiving antenna 32 that receives an RF signal from the portable device 40, a control unit 33 consisting of a CPU and memory, and an operating unit 34 that is operated to cause the vehicle to perform a predetermined operation. Although the transmitting antenna 31, receiving antenna 32, and operating unit 34 are connected to the control unit 33 of the in-vehicle ECU 30, they are actually mounted on the vehicle and are physically outside the in-vehicle ECU 30. However, in Figure 3, the transmitting antenna 31, receiving antenna 32, and operating unit 34 are depicted as functional blocks under its control, hanging from the in-vehicle ECU 30.

[0036] The control unit 33 includes a signal generation unit 331, an authentication unit 332, a control signal output unit 333, and a storage unit 334. The signal generation unit 331 generates request signals and the like that are transmitted from the transmitting antenna 31 to the portable device 40. When the answer signal transmitted from the portable device 40 is received by the receiving antenna 32, the authentication unit 332 verifies the ID contained in the answer signal and determines whether authentication is successful. The control signal output unit 333 outputs control signals to control various parts of the vehicle based on the operation of the operation unit 34 of the in-vehicle ECU 30 and the operation unit 44 of the portable device 40. The storage unit 334 stores data necessary for control, the ID of the portable device 40, and the like.

[0037] The control unit 34 is equipped with a lock switch 341 for locking the vehicle doors, an unlock switch 342 for unlocking the vehicle doors, and a start switch 343 for starting the engine.

[0038] The portable device 40 includes a receiving antenna 41 that receives an LF signal from the in-vehicle ECU 30, a transmitting antenna 42 that transmits an RF signal to the in-vehicle ECU 30, a control unit 43 consisting of a CPU and memory, and an operating unit 44 that is operated to cause the vehicle to perform a predetermined operation.

[0039] The control unit 43 includes an operation content analysis unit 431, a determination unit 432, a signal generation unit 433, and a transmission strength setting unit 434. The operation content analysis unit 431 analyzes the content of the request signal received from the in-vehicle ECU 30. Specifically, it analyzes whether the operation performed on the in-vehicle ECU 30 was an unlock command or an engine start command, and what the order of operations was. The determination unit 432 determines the distance between the receiving antenna 32 of the in-vehicle ECU 30 and the portable device 40 from the analyzed operation content. For example, if the start switch 343 is operated, it determines that the portable device 40 is in close proximity. The signal generation unit 433 generates an answer signal to be transmitted from the transmitting antenna 42 to the in-vehicle ECU 30, and an operation signal based on the operation of the operation unit 44. The transmission strength setting unit 434 weakens the transmission strength of the answer signal as needed based on the distance determined by the determination unit 432.

[0040] The control unit 44 is equipped with a lock switch 441 for locking the vehicle doors and an unlock switch 442 for unlocking the vehicle doors. These switches are arranged appropriately on the surface of the portable device 40. In addition, other switches, such as a trunk opener switch for opening the trunk, may be provided on the control unit 44 as needed.

[0041] Next, the operation of the vehicle control system 200 according to the second embodiment of the present invention, which has the above configuration, will be explained with reference to the flowchart in Figure 4.

[0042] In Figure 4, each process of the in-vehicle ECU 30 is executed by the control unit 33 of the in-vehicle ECU, and each process of the portable device 40 is executed by the control unit 43 of the portable device. The following examples illustrate the operation when unlocking the vehicle doors or starting the engine.

[0043] The sequence of steps shown in the flowchart of Figure 4 is initiated when the unlock switch 342 for unlocking the doors or the start switch 343 is operated on the operation unit 34 of the in-vehicle ECU 30. In step S301 on the in-vehicle ECU 30 side, a request signal generated by the signal generation unit 331 is transmitted from the transmitting antenna 31. This request signal includes a data area. Although not shown in the illustration as it is not relevant to the processing of the second embodiment, in reality, a continuous wave CW is transmitted following the request signal. Meanwhile, in step S401 on the portable device 40 side, the request signal is received by the receiving antenna 41, and then in step S402, information regarding the operation content included in the data area of ​​the request signal is extracted and analyzed by the operation content analysis unit 431.

[0044] In step S403 on the portable device 40, if it is determined that the start switch has been operated based on the extracted operation information, then in step S404, the transmission strength setting unit 434 sets the transmission strength of the signal transmitted by the portable device 40 to low. On the other hand, if it is determined in step S403 that the unlock switch has been operated, the normal transmission strength, which is set high to improve noise immunity, is maintained.

[0045] In step S405, an answer signal is generated by the signal generation unit 433. Then, in step S406, the answer signal is transmitted from the transmitting antenna 42 at a set transmission strength. The answer signal includes the ID of the portable device 40.

[0046] In the in-vehicle ECU 30, an answer signal is received from the receiving antenna 32 in step S302. Next, in step S303, authentication is performed by the authentication unit 332 based on ID verification. Specifically, the ID of the portable device 40 included in the answer signal is compared with the ID stored in the storage unit 334. If the two match, authentication is deemed successful; otherwise, authentication is deemed unsuccessful. If authentication is successful, the determination in step S303 is YES, and the process proceeds to step S304. On the other hand, if authentication is unsuccessful, the determination in step S303 is NO, and the process ends without executing step S304.

[0047] In step S304, the control signal output unit 333 outputs either an unlock signal or an engine start signal as a control signal, depending on the operation performed initially. The unlock signal activates the door unlocking mechanism, unlocking the door, or the engine start signal starts the engine.

[0048] As described above, in the vehicle control system 200 of the second embodiment, the portable device 40 estimates the distance to the vehicle-side transmitter based on the operation performed by the vehicle user. If it is determined that the distance to the vehicle-side transmitter is short, the portable device 40 reduces the transmission output strength of the answer signal to a lower level than when it is not determined to be short. As a result, the RF signal from the portable device does not exceed the dynamic range of the receiving IC, and the necessary vehicle control can be reliably performed. Moreover, since it is no longer necessary to measure the strength of the continuous wave CW, the continuous wave CW can be used for other purposes.

[0049] In the examples described above, the decision was made based on a single operation, the start switch. However, the distance to the vehicle's transmitter could also be estimated by comprehensively evaluating multiple operations, such as monitoring a conditional history of multiple operations, for example, if the most recent operation was the unlock switch, followed by the start switch operation within a predetermined time. This would increase the likelihood of estimating the distance based on the user's actions.

[0050] <Third Embodiment of the Invention> Figure 5 is a functional block diagram showing a vehicle control system according to a third embodiment of the present invention. Here, only the functional blocks related to the present invention are shown. The vehicle control system 300 according to the third embodiment of the present invention consists of an on-board ECU 50 and a portable device 60. The on-board ECU 50 performs predetermined control over various parts of the vehicle. The portable device 60 consists of an electronic key that is operated when locking or unlocking the vehicle doors, and is carried by the vehicle user. The on-board ECU 50 and the portable device 60 are configured to communicate with each other wirelessly.

[0051] The in-vehicle ECU 50 includes a transmitting antenna 51 that transmits an LF signal to the portable device 60, a receiving antenna 52 that receives an RF signal from the portable device 60, a control unit 53 consisting of a CPU and memory, and an operating unit 54 that is operated to cause the vehicle to perform a predetermined operation. Although the transmitting antenna 51, receiving antenna 52, and operating unit 54 are connected to the control unit 53 of the in-vehicle ECU 50, they are actually mounted on the vehicle and are physically outside the in-vehicle ECU 50. However, in Figure 5, the transmitting antenna 51, receiving antenna 52, and operating unit 54 are depicted as functional blocks under its control, hanging from the in-vehicle ECU 50.

[0052] The control unit 53 includes a signal generation unit 531, an authentication unit 532, a control signal output unit 533, a storage unit 534, a reception strength measurement unit 535, a determination unit 536, and a transmission data setting unit 537. The signal generation unit 531 generates request signals and the like that are transmitted from the transmitting antenna 51 to the portable device 60. When the answer signal transmitted from the portable device 60 is received by the receiving antenna 52, the authentication unit 532 verifies the ID included in the answer signal and determines whether authentication is successful. The control signal output unit 533 outputs control signals to control various parts of the vehicle based on the operation of the operation unit 54 of the in-vehicle ECU 50 and the operation unit 64 of the portable device 60. The storage unit 534 stores data necessary for control and the ID of the portable device 60. The reception strength measurement unit 535 measures the reception strength of the answer signal received from the portable device 60. The determination unit 536 determines the distance between the receiving antenna 52 of the in-vehicle ECU 50 and the portable device 60 from the measured reception strength. Specifically, if the measured RSSI is greater than a predetermined value, it is determined that the portable device 60 is at close range. Based on the distance determined by the determination unit 536, the transmission data setting unit 537 sets request data in the data area of ​​the request signal to be transmitted again, in order to weaken the transmission strength of the answer signal as needed.

[0053] The control unit 54 is equipped with a lock switch 541 for locking the vehicle doors, an unlock switch 542 for unlocking the vehicle doors, and a start switch 543 for starting the engine.

[0054] The portable device 60 includes a receiving antenna 61 that receives an LF signal from the in-vehicle ECU 50, a transmitting antenna 62 that transmits an RF signal to the in-vehicle ECU 50, a control unit 63 consisting of a CPU and memory, and an operating unit 64 that is operated to cause the vehicle to perform a predetermined operation.

[0055] The control unit 63 includes a transmission strength request determination unit 631, a signal generation unit 632, and a transmission strength setting unit 633. The transmission strength request determination unit 631 analyzes the content of the request signal received from the in-vehicle ECU 50 to check if there is a request to set the transmission strength low. The signal generation unit 632 generates an answer signal to be transmitted from the transmitting antenna 62 to the in-vehicle ECU 50, and an operation signal based on the operation of the operation unit 64. The transmission strength setting unit 633 sets the transmission strength of the answer signal low when the transmission strength request determination unit 631 determines that there is a request to set the transmission strength low.

[0056] The operating unit 64 is equipped with a lock switch 641 for locking the vehicle doors and an unlock switch 642 for unlocking the vehicle doors. These switches are arranged appropriately on the surface of the portable device 60. In addition, other switches, such as a trunk opener switch for opening the trunk, may be provided on the operating unit 64 as needed.

[0057] Next, the operation of the vehicle control system 300 according to the third embodiment of the present invention, which has the above configuration, will be explained with reference to the flowchart in Figure 6.

[0058] In Figure 6, each process of the in-vehicle ECU 50 is executed by the control unit 53 of the in-vehicle ECU, and each process of the portable device 60 is executed by the control unit 63 of the portable device. The following example describes the operation when unlocking the vehicle doors.

[0059] The sequence of steps shown in the flowchart of Figure 6 is initiated when the unlock switch 542 for unlocking the doors is operated on the operating unit 54 of the in-vehicle ECU 50. In step S501 on the in-vehicle ECU 50 side, a request signal generated by the signal generation unit 531 is transmitted from the transmitting antenna 51. This request signal includes a data area. Although not shown in the illustration as it is not relevant to the processing of the third embodiment, in reality, a continuous wave CW is transmitted following the request signal. Meanwhile, in step S601 on the portable device 60 side, the request signal is received by the receiving antenna 61, and then in step S602, an answer signal is created by the signal generation unit 632. Furthermore, in step S603, the answer signal is transmitted from the transmitting antenna 62. The answer signal includes the ID of the portable device 60.

[0060] In the in-vehicle ECU 50, in step S502, an answer signal is received from the receiving antenna 52, and at this time, the RSSI of the answer signal is measured by the reception strength measurement unit 535. Next, in step S503, authentication is performed by the authentication unit 532 based on ID verification. Specifically, the ID of the portable device 60 included in the answer signal is verified against the ID stored in the storage unit 534. If the two match, authentication is determined to be successful; otherwise, authentication is determined to be unsuccessful. If authentication is successful, the determination in step S503 is YES, and the process moves to step S504, where an unlock signal is output as a control signal from the control signal output unit 533. This unlock signal activates the door unlock mechanism, and the door is unlocked. On the other hand, if authentication is unsuccessful, the determination in step S503 is NO. However, even if authentication fails, there are two possible cases: one where the ID of the mobile device 60 is incorrect, and another where the RF signal from the mobile device exceeds the dynamic range of the receiving IC, resulting in authentication failure. Therefore, the process proceeds further to step S505.

[0061] In step S505, the determination unit 536 determines whether the measured RSSI of the answer signal is greater than a predetermined value. If it is determined to be greater, in step S506, the transmission data setting unit 537 sets request data in the data area of ​​the retransmitted request signal to weaken the transmission strength of the answer signal transmitted by the portable device 60. On the other hand, if it is determined in step S505 that the measured RSSI is less than or equal to the predetermined value, the above request data is not set.

[0062] In step S604 on the handheld device 60 side, the request signal is received again by the receiving antenna 61. Next, in step S605, the transmission strength request determination unit 631 determines whether or not there is a request to set the transmission strength to low in the request signal received from the in-vehicle ECU 50. If it is determined that such a request exists, in step S606, the transmission strength setting unit 633 sets the transmission strength of the signal transmitted by the handheld device 60 to low. On the other hand, if it is determined in step S605 that there is no request to set the transmission strength to low, the normal transmission strength is maintained.

[0063] In step S607, an answer signal is generated by the signal generation unit 632. Then, in step S608, the answer signal is transmitted from the transmitting antenna 62 at a set transmission strength. The answer signal includes the ID of the portable device 60.

[0064] In the in-vehicle ECU 50, an answer signal is received from the receiving antenna 52 in step S508. Next, in step S509, authentication is performed by the authentication unit 532 based on ID verification. Specifically, the ID of the portable device 60 included in the answer signal is compared with the ID stored in the storage unit 534. If the two match, authentication is deemed successful; otherwise, authentication is deemed unsuccessful. If authentication is successful, the determination in step S509 is YES, and the process proceeds to step S510. On the other hand, if authentication is unsuccessful, the determination in step S509 is NO, and the process ends without executing step S510.

[0065] In step S510, the control signal output unit 533 outputs an unlock signal as a control signal. This unlock signal activates the door's unlocking mechanism, and the door is unlocked.

[0066] As described above, in the vehicle control system 300 of the third embodiment, the onboard ECU 50 measures the strength of the answer signal from the portable device 60, and if the RSSI is greater than a predetermined value, it determines that the portable device 60 is located at close range, and the onboard ECU 50 retransmits the request signal to the portable device 60, including a request to reduce the transmission output strength. As a result, the transmission output strength of the answer signal from the portable device 60 is reduced to that of when it is not determined to be at close range, so that the RF signal from the portable device does not exceed the dynamic range of the receiving IC, and the necessary vehicle control can be reliably executed. While the portable device's functions are concentrated in a small housing such as an electronic key, the onboard ECU has no placement constraints, which is advantageous as it allows the onboard ECU to handle advanced processing.

[0067] In the example described above, if the RSSI of the answer signal is determined to be below a predetermined value after the initial authentication process fails, the control mechanism is such that the request signal is retransmitted while maintaining the normal transmission strength. However, if the RSSI of the answer signal is determined to be below a predetermined value, the system may be configured to terminate the process without retransmitting the request signal. This is because in this case, there is a high probability that the ID of the mobile device 60 is incorrect. However, since authentication may fail even if the key is correct due to some unforeseen circumstances, it can be said that the reliability of the system is improved by performing a re-request.

[0068] <Fourth Embodiment of the Invention> Figure 7 is a functional block diagram showing a vehicle control system according to the fourth embodiment of the present invention. Here, only the functional blocks related to the present invention are shown. The vehicle control system 400 according to the fourth embodiment of the present invention consists of an on-board ECU 70 and a portable device 80. The on-board ECU 70 performs predetermined control over various parts of the vehicle. The portable device 80 consists of an electronic key that is operated when locking or unlocking the vehicle doors, and is carried by the vehicle user. The on-board ECU 70 and the portable device 80 are configured to communicate with each other wirelessly.

[0069] The in-vehicle ECU 70 includes a transmitting antenna 71 that transmits an LF signal to the portable device 80, a receiving antenna 72 that receives an RF signal from the portable device 80, a control unit 73 consisting of a CPU and memory, and an operating unit 74 that is operated to cause the vehicle to perform a predetermined operation. Although the transmitting antenna 71, receiving antenna 72, and operating unit 74 are connected to the control unit 73 of the in-vehicle ECU 70, they are actually mounted on the vehicle and are physically outside the in-vehicle ECU 70. However, in Figure 7, the transmitting antenna 71, receiving antenna 72, and operating unit 74 are depicted as functional blocks under its control, hanging from the in-vehicle ECU 70.

[0070] The control unit 73 includes a signal generation unit 731, an authentication unit 732, a control signal output unit 733, a storage unit 734, a reception strength measurement unit 735, a determination unit 736, and a reception sensitivity setting unit 737. The signal generation unit 731 generates request signals and the like that are transmitted from the transmitting antenna 71 to the portable device 80. When the answer signal transmitted from the portable device 80 is received by the receiving antenna 72, the authentication unit 732 verifies the ID contained in the answer signal and determines whether authentication is successful. The control signal output unit 733 outputs control signals to control various parts of the vehicle based on the operation of the operation unit 74 of the in-vehicle ECU 70 and the operation unit 84 of the portable device 80. The storage unit 734 stores data necessary for control and the ID of the portable device 80. The reception strength measurement unit 735 measures the reception strength of the answer signal received from the portable device 80. The determination unit 736 determines the distance between the receiving antenna 72 of the in-vehicle ECU 70 and the portable device 80 from the measured reception strength. Specifically, if the measured RSSI is greater than a predetermined value, it is determined that the portable device 80 is at close range. Based on the distance determined by the determination unit 736, the receiving sensitivity setting unit 737 sets the receiving sensitivity of the vehicle-side receiver to be lower than normal as necessary. Specifically, the received signal strength at the vehicle-side receiver is reduced by shifting the carrier wave center frequency of the answer signal from the portable device, but other methods may also be used, for example, to attenuate the received signal.

[0071] The control unit 74 is equipped with a lock switch 741 for locking the vehicle doors, an unlock switch 742 for unlocking the vehicle doors, and a start switch 743 for starting the engine.

[0072] The portable device 80 includes a receiving antenna 81 that receives an LF signal from the in-vehicle ECU 70, a transmitting antenna 82 that transmits an RF signal to the in-vehicle ECU 70, a control unit 83 consisting of a CPU and memory, and an operating unit 84 that is operated to cause the vehicle to perform a predetermined operation.

[0073] The control unit 83 includes a signal generation unit 831. The signal generation unit 831 generates an answer signal transmitted from the transmitting antenna 82 to the on-board ECU 70, and an operation signal based on the operation of the operation unit 84.

[0074] The operating unit 84 is equipped with a lock switch 841 for locking the vehicle doors and an unlock switch 842 for unlocking the vehicle doors. These switches are arranged appropriately on the surface of the portable device 80. In addition, other switches, such as a trunk opener switch for opening the trunk, may be provided on the operating unit 84 as needed.

[0075] Next, the operation of the vehicle control system 400 according to the fourth embodiment of the present invention, which has the above configuration, will be explained with reference to the flowchart in Figure 8.

[0076] In Figure 8, each process of the in-vehicle ECU 70 is executed by the control unit 73 of the in-vehicle ECU, and each process of the portable device 80 is executed by the control unit 83 of the portable device. The following example describes the operation when unlocking the vehicle doors.

[0077] The sequence of steps shown in the flowchart of Figure 8 is initiated when the unlock switch 742 for unlocking the doors is operated on the operating unit 74 of the in-vehicle ECU 70. In step S701 on the in-vehicle ECU 70 side, a request signal generated by the signal generation unit 731 is transmitted from the transmitting antenna 71. This request signal includes a data area. Although not shown in the figure as it is not relevant to the processing of the fourth embodiment, in reality, a continuous wave CW is transmitted following the request signal. Meanwhile, in step S801 on the portable device 80 side, the request signal is received by the receiving antenna 81, and then in step S802, an answer signal is created by the signal generation unit 831. Furthermore, in step S803, the answer signal is transmitted from the transmitting antenna 82. The answer signal includes the ID of the portable device 80.

[0078] In the in-vehicle ECU 70, in step S702, an answer signal is received from the receiving antenna 72, and at this time, the RSSI of the answer signal is measured by the reception strength measurement unit 735. Next, in step S703, authentication is performed by the authentication unit 732 based on ID verification. Specifically, the ID of the portable device 80 included in the answer signal is verified against the ID stored in the storage unit 734. If the two match, authentication is determined to be successful; otherwise, authentication is determined to be unsuccessful. If authentication is successful, the determination in step S703 is YES, and the process moves to step S704, where an unlock signal is output as a control signal from the control signal output unit 733. This unlock signal activates the door unlock mechanism, and the door is unlocked. On the other hand, if authentication is unsuccessful, the determination in step S703 is NO. However, even if authentication fails, there are two possible cases: one where the ID of the portable device 80 is incorrect, and another where the RF signal from the portable device exceeds the dynamic range of the receiving IC, resulting in authentication failure. Therefore, the process proceeds to step S705.

[0079] In step S705, the determination unit 736 determines whether the measured RSSI of the answer signal is greater than a predetermined value. If it is determined to be greater, in step S706, the receiving sensitivity when receiving the answer signal is reduced. On the other hand, if it is determined in step S705 that the measured RSSI is less than or equal to the predetermined value, the normal receiving sensitivity is maintained.

[0080] In step S804 on the handheld device 80, the request signal is received again by the receiving antenna 81. In step S805, the answer signal is generated by the signal generation unit 831. Then, in step S806, the answer signal is transmitted from the transmitting antenna 82. The answer signal includes the ID of the handheld device 80.

[0081] In the in-vehicle ECU 70, in step S708, an answer signal is received from the receiving antenna 72 at the receiving sensitivity set in step S706. Next, in step S709, authentication is performed by the authentication unit 732 based on ID verification. Specifically, the ID of the portable device 80 included in the answer signal is compared with the ID stored in the storage unit 734. If the two match, authentication is deemed successful; otherwise, authentication is deemed unsuccessful. If authentication is successful, the determination in step S709 is YES, and the process proceeds to step S710. On the other hand, if authentication is unsuccessful, the determination in step S709 is NO, and the process ends without executing step S710.

[0082] In step S710, the control signal output unit 733 outputs an unlock signal as a control signal. This unlock signal activates the door's unlocking mechanism, and the door is unlocked.

[0083] As described above, in the vehicle control system 400 of the fourth embodiment, the on-board ECU 70 measures the strength of the answer signal from the portable device 80, and if the RSSI is greater than a predetermined value, it determines that the portable device 80 is located at close range, and the on-board ECU 70 sets the receiving sensitivity to low. As a result, the answer signal from the portable device 80 does not exceed the dynamic range of the receiving IC, and the necessary vehicle control can be reliably executed. As can be clearly seen from Figure 7, the fourth embodiment requires fewer components in the control unit on the portable device side compared to the first to third embodiments. This is advantageous in situations where the functions of the portable device are concentrated in a small housing such as an electronic key.

[0084] In the example described above, the system was configured to reduce the receiving sensitivity, retransmit the request signal, and receive the second answer signal with reduced sensitivity. However, it is also possible to include a redundant signal at the beginning of the answer signal, measure the RSSI at the start of reception, and then reduce the receiving sensitivity during the reception.

[0085] Although the vehicle control systems according to each embodiment of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the spirit of the present invention are also included. For example, if, during a retry, the answer signal whose transmission strength has been reduced by a request from the in-vehicle ECU still exceeds the dynamic range of the receiving IC, the present invention also includes a configuration in which the receiving ECU further reduces the receiving sensitivity. The smart key entry system, which allows operation simply by possessing the key, has created diverse situations where some users try to operate it while holding the key, while others try to operate it while the key is in a bag or other container. This has completely changed the situation of mutual communication compared to before, and now requires a wide dynamic range of response. Furthermore, with the introduction of smart key entry in electric motorcycles, situations have arisen where the antenna and key are in very close proximity. In these circumstances, the advantages of the present invention should be properly understood. [Explanation of symbols]

[0086] 10. In-vehicle ECU (In-vehicle Electronic Control Unit) 11. Transmitting antenna (vehicle-side transmitting unit) 12. Receiving antenna (vehicle-side receiving unit) 13 Control Unit 131 Signal Generation Unit 132 Authentication Department 133 Control signal output section 134 Storage section 14 Control section 141 Lock switch 142 Unlock Switch 143 Start switch 20 Handheld devices 21 Receiving antenna (handheld device receiver) 22. Transmitting antenna (portable device transmitter) 23 Control Unit 231 Received signal strength measurement unit 232 Judgment section 233 Signal generation unit 234 Transmission strength setting section 24 Control section 241 Lock switch 242 Unlock Switch 100 Vehicle control systems 30. Automotive ECU (Automotive Electronic Control Unit) 31. Transmitting antenna (vehicle-side transmitting unit) 32 Receiving antenna (vehicle-side receiving unit) 33 Control Unit 331 Signal generation unit 332 Authentication Department 333 Control signal output section 334 Storage section 34 Control section 341 Lock switch 342 Unlock Switch 343 Start switch 40 Handheld devices 41 Receiving antenna (handheld device receiver) 42. Transmitting antenna (portable device transmitter) 43 Control Unit 431 Operation content analysis section 432 Judgment section 433 Signal Generation Unit 434 Transmission strength setting section 44 Control section 441 Lock switch 442 Unlock Switch 200 Vehicle control systems 50. Automotive ECU (Automotive Electronic Control Unit) 51 Transmitting antenna (vehicle-side transmitting unit) 52 Receiving antenna (vehicle-side receiving unit) 53 Control Unit 531 Signal Generation Unit 532 Certification Department 533 Control signal output section 534 Storage section 535 Received signal strength measurement unit 536 Judgment section 537 Transmission Data Setting Section 54 Operation section 541 Lock switch 542 Unlock Switch 543 Start switch 60 handheld devices 61 Receiving antenna (handheld device receiver) 62. Transmitting antenna (portable device transmitter) 63 Control Unit 631 Transmission strength request determination unit 632 Signal Generation Unit 633 Transmission strength setting section 64 Operation section 641 Lock switch 642 Unlock Switch 300 Vehicle Control Systems 70. Automotive ECU (Automotive Electronic Control Unit) 71. Transmitting antenna (vehicle-side transmitting unit) 72 Receiving antenna (vehicle-side receiving unit) 73 Control Unit 731 Signal Generation Unit 732 Certification Department 733 Control signal output section 734 Storage section 735 Received signal strength measurement unit 736 Judgment section 737 Reception Sensitivity Setting Section 74 Control section 741 Lock switch 742 Unlock Switch 743 Start switch 80 Handheld devices 81 Receiving antenna (handheld device receiver) 82. Transmitting antenna (portable device transmitter) 83 Control Unit 831 Signal Generation Unit 84 Control section 841 Lock switch 842 Unlock Switch 400 Vehicle Control System

Claims

1. An on-board electronic control unit installed in a vehicle and performing predetermined control over the vehicle, A vehicle control system comprising a portable device, which is carried by the vehicle user and communicates wirelessly with the on-board electronic control unit, The in-vehicle electronic control unit includes a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device. The aforementioned portable device includes a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal. The portable device determines the distance to the vehicle-side receiving unit and adjusts the transmission output strength of the answer signal according to the determined distance. A vehicle control system characterized by the following features.

2. The portable device measures the intensity of the continuous wave included in the request signal, and if the RSSI is greater than a predetermined value, it determines that the distance to the vehicle-side receiver is short, and reduces the transmission output intensity of the answer signal to less than when it is not determined to be short distance. The vehicle control system according to feature 1.

3. The portable device measures the intensity of the continuous wave included in the request signal, and if the RSSI is less than a predetermined value, it determines that the distance to the vehicle-side receiver is long, and increases the transmission output intensity of the answer signal to a level greater than when it is not determined to be a long distance. The vehicle control system according to feature 1.

4. The portable device measures the intensity of the continuous wave included in the request signal, determines which of the multiple ranges the RSSI belongs to, and adjusts the transmission output intensity of the answer signal in multiple stages according to the distance to the vehicle-side receiver. The vehicle control system according to feature 1.

5. The portable device estimates the distance to the vehicle-side receiver based on the operation performed by the vehicle user, and if it determines that the distance to the vehicle-side receiver is short, it reduces the transmission output strength of the answer signal to a lower level than when it is not determined to be short distance. The vehicle control system according to feature 1.

6. The vehicle-side transmitting unit has multiple antennas, The portable device determines the distance to the vehicle-side receiving unit based on the strength of the request signals transmitted from the multiple antennas. The vehicle control system according to feature 1.

7. An on-board electronic control unit installed in a vehicle and performing predetermined control over the vehicle, A vehicle control system comprising a portable device, which is carried by the vehicle user and communicates wirelessly with the on-board electronic control unit, The in-vehicle electronic control unit includes a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device. The aforementioned portable device includes a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal. The in-vehicle electronic control unit measures the strength of the answer signal, and if RSSI is greater than a predetermined value, it determines that the portable device is located nearby, and retransmits the request signal to the portable device, including a request to reduce the transmission output strength. A vehicle control system characterized by the following features.

8. An on-board electronic control unit installed in a vehicle and performing predetermined control over the vehicle, A vehicle control system comprising a portable device, which is carried by the vehicle user and communicates wirelessly with the on-board electronic control unit, The in-vehicle electronic control unit includes a vehicle-side transmitting unit that transmits a request signal to the portable device and a vehicle-side receiving unit that receives an answer signal from the portable device. The aforementioned portable device includes a portable device receiving unit that receives the request signal and a portable device transmitting unit that transmits the answer signal. The in-vehicle electronic control unit measures the strength of the answer signal, and if the RSSI is greater than a predetermined value, it determines that the portable device is located at close range and reduces the reception sensitivity of the vehicle-side receiver to a level lower than when it is not determined that the device is located at close range. A vehicle control system characterized by the following features.

9. The in-vehicle electronic control unit reduces the reception strength at the vehicle-side receiver by shifting the carrier wave center frequency of the answer signal from the portable device. The vehicle control system according to claim 1 or 8.

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