BAKCGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a parking support system that supports parking using a mobile terminal.

2. Description of the Related Art

[0002] Recently, various systems are known as a system that supports the driving operation at parking time. For example, one such system captures the surrounding of a vehicle and displays the captured image on a display and another system uses a distance measuring sensor, such as a sonar sensor, to detect that the vehicle is approaching an obstacle. However, even when such a system is mounted on a vehicle, the driver is required to have a relatively high driving skill to park the vehicle in a parking space smoothly.

[0003] On the other hand, a vehicle control system, which does not depend on the driver's driving skill, is also known. Such a system receives a remote control command from a remote control device carried by the user and performs an unmanned operation to move a vehicle to an automatic parking specification position (for example, Japanese Patent Application Publication No. 2006-335312 (JP2006-335312 A)).

[0004] The system described above is configured on the premise that a vehicle can be moved to an automatic parking specification position even when a vehicle is in a position the user cannot visually recognize. Therefore, the vehicle is required to have a vehicle surrounding detection sensor, which detects whether there is a person in the surrounding of the vehicle or in the vehicle moving direction, and an in-vehicle notification device that notifies the surrounding persons that the unmanned vehicle is moving. In addition, realizing the above-described system requires the vehicle to have sensors for detecting an obstacle other than a person. This system increases the number of parts and requires the system to perform more complicated operation processing to control those sensors. Therefore, as a system designed specifically for parking support, there is a need for an easy-to-operate parking support system that requires a fewer parts and does not depend on the user's driving skill.

SUMMARY OF THE INVENTION

[0005] The present invention provides a parking support system that depends less on a user's driving skill and allows for easier parking support.

[0006] A first aspect of the present invention relates to a parking support system that supports parking using a sound wave sending/receiving unit of a mobile terminal and a sound wave sending receiving unit of a vehicle. The parking support system includes: a distance measuring unit that measures a distance between the mobile terminal and the vehicle using the sound wave sending/receiving unit of the mobile terminal and the sound wave sending/receiving unit of the vehicle; an authentication unit, provided on the vehicle, that authenticates the mobile terminal; and a driving control unit, provided on the vehicle, that moves the vehicle based on a command sent from the authenticated mobile terminal. The driving control unit moves the vehicle based on the command sent from the mobile terminal if the measured distance is within a pre-set predetermined range, and stops the vehicle if the measured distance is outside the predetermined range and if the distance between the mobile terminal and the vehicle cannot be measured by the distance measuring unit.

[0007] According to this aspect, if the distance between the mobile terminal and the vehicle is within a predetermined range (for example, within a range equal to or smaller than several meters) in which the user can confirm the safety of the vehicle and the surrounding of the vehicle, the vehicle can be moved based on a command from the mobile terminal. Therefore, the user can easily confirm safety outside the vehicle and even a driver with a low driving skill can easily and smoothly move the vehicle to a target position. In addition, because the vehicle is stopped if the distance between the mobile terminal and the vehicle is outside the predetermined range described above, the operation via the mobile terminal from a remote position, where the user cannot sufficiently confirm safety, can be prohibited. In addition, because the vehicle is stopped when the distance between the mobile terminal and the vehicle cannot be measured, for example, due to a communication failure generated in the distance measuring unit, safety is maintained. The distance measuring unit, which is only required to measure a distance at least within the predetermined range described above, may be a radio wave sending/receiving unit for use in a short-range.

[0008] In the aspect described above, a plurality of sound wave sending receiving units may be provided on the vehicle, and the predetermined range may be a range that includes a whole distance range that is pre-set with each of the sound wave sending/receiving units as a center.

[0009] According to this aspect, the predetermined range described above is a range that includes a whole distance composed of the distance ranges each created with each of the sound wave sending/receiving units on the vehicle side as a center. This range defines the range in which the user can confirm safety. In addition, as compared with a case in which only one sound wave sending/receiving unit is provided, the range in which the operation of the vehicle via the mobile terminal is allowed can be extended.

[0010] In the aspect described above, the driving control unit may move the vehicle according to a moving direction or a turning direction of the vehicle commanded by the mobile terminal. In this configuration, because the user can give a moving direction instruction, such as forward or backward, and a turning direction instruction, such as right or left, via the mobile terminal, the user can move the vehicle to a target position and stop it there through the operation of the mobile information terminal without having to stop the vehicle in a particular direction with respect to the parking space.

[0011] A second aspect of the present invention relates to a parking support system that supports parking using a sound wave sending/receiving unit of a mobile terminal and a sound wave sending/receiving unit of a vehicle. The parking support system includes: a distance measuring unit that measures a distance between the mobile terminal and the vehicle using the sound wave sending/receiving unit of the mobile terminal and the sound wave sending/receiving unit of the vehicle; an authentication unit, mounted on the vehicle, that authenticates the mobile terminal; and a driving control unit that moves the vehicle so that, if a measured distance between the authenticated mobile terminal and the vehicle exceeds a reference distance to be reserved between the mobile terminal and the vehicle, the distance between the mobile terminal and the vehicle gets closer to the reference distance.

[0012] In this aspect, if the distance between the mobile terminal and the vehicle exceeds the reference distance to be reserved therebetween (for example, several tens of centimeters or smaller), the vehicle moves so that the distance between the mobile terminal and the vehicle gets closer to the reference distance. That is, the user is required only to guide the vehicle to a target parking space, meaning that the user can smoothly and easily part the vehicle independently of the user's driving skill. In addition, the distance measuring unit, which is only required to measure a distance at least within the predetermined range described above, may be a sound wave sending/receiving unit having directivity and available for use in a short range.

[0013] In the aspect described above, the driving control unit may stop the vehicle if the distance between the mobile terminal and the vehicle is equal to or smaller than a defined distance that is smaller than the reference distance. In this aspect, because the vehicle is stopped if the distance between the mobile terminal and the vehicle is equal to or smaller than the defined distance that is smaller than the reference distance, the vehicle can be stopped for safety when the user, who guides the vehicle, gets too close to the vehicle.

[0014] In the aspect described above, a plurality of sound wave sending/receiving units may be provided on the vehicle, the distance measuring unit may calculate a two-dimensional position of the mobile terminal with respect to the vehicle based on a transfer of a sound wave through the plurality of the sound wave sending/receiving units, and the driving control unit may control a steering device so that the vehicle follows the calculated two-dimensional position of the mobile terminal.

[0015] In this aspect, because the steering device is controlled so that the vehicle follows the calculated two-dimensional position of the mobile terminal, the user, who carries the mobile terminal, can guide the vehicle to a parking space more flexibly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is a block diagram showing a schematic configuration of a vehicle and a mobile information terminal that configure a parking support system in a first embodiment of the present invention;

FIG. 2 is a flowchart showing an operation of a parking support device in the first embodiment;

FIG. 3 is a diagram showing a range in which the mobile terminal in the first embodiment is allowed to operate the vehicle;

FIGS. 4A and 4B are diagrams showing a user operation on the mobile information terminal on a time-series basis;

FIG. 5 is a diagram showing the position of an in-vehicle sending/receiving unit and a method for calculating the steering angle of a vehicle in a parking support system in a second embodiment of the present invention;

FIG. 6 is a diagram showing a user operation on the mobile information terminal on a time-series basis in the embodiment; and

FIG. 7 is a flowchart showing an operation of a parking support device in the embodiment. DETAILED DESCRIPTION OF EMBODIMENTS

(First embodiment)

[0017] A first embodiment that implements a parking support system is described below. In this embodiment, a mobile terminal with the sound wave sending receiving unit is a mobile information terminal configured by a smartphone. In the description below, a vehicle that moves in response to a command from this mobile information terminal is a vehicle powered by an engine.

[0018] As shown in FIG. 1, the parking support system includes a parking support device 11 provided in a vehicle 10 and a mobile information terminal 12 carried by the user. The parking support device 11 includes a control unit 15 and an in-vehicle sending/receiving unit 16 that sends and receives an ultrasonic wave.

[0019] The control unit 15 stores authentication information on authentic users. When a signal including this authentication information is sent from the mobile information terminal 12, the parking support device 11 authenticates that the identification signal is authentic.

[0020] The control unit 15 is connected to an engine control unit 20 and an electric power steering computer 21 in such a way that the control unit 15 can communicates with them. The engine control unit 20 in this embodiment operates various types of actuators of the engine and, at the same time, controls the gear shifting of the automatic transmission. In addition, the engine control unit 20 starts and stops the engine based on a command from the parking support device 11 and, at the same time, performs the shift control. When the vehicle 10 travels, the electric power steering computer 21 calculates an assist current to be supplied to the motor, which configures the electric power steering device, to generate an assist torque that is required when the driver steers the vehicle. When the vehicle 10 is parked, the electric power steering computer 21 drives the above-described motor based on a command from the parking support device 11. [0021] The in-vehicle sending/receiving unit 16, which includes a piezo-electric device, has the function to send and receive an ultrasonic signal. The ultrasonic signal is a sound wave signal that has a frequency higher than that of the audible frequency range (equal or higher than 20 Hz and lower than 20 kHz). In this embodiment, two in-vehicle sending receiving units 16 are provided on the vehicle 10, one in the center of the front end of the vehicle 10 and the other in the center of the rear end of the vehicle 10. This in-vehicle sending/receiving unit 16 may be a sensor specifically designed for parking support or an existing clearance sonar sensor that detects that the vehicle 10 is approaching an obstacle.

[0022] The parking support device 11 receives the vehicle speed from a vehicle speed sensor 22 that detects the rotation speed of the wheel and, at the same time, receives the angular velocity of the vehicle 10 from a gyro 23. In addition, the parking support device 11 receives an outdoor tempera:ure from a temperature sensor 24 provided on the vehicle 10.

[0023] The mobile information terminal 12 includes a terminal-side sending/receiving unit 30 that acts as a sound wave sending/receiving unit, a phone line communication unit 31, a central processing unit (CPU) 32, a non-volatile memory 33, and a touch panel display 35. These components are connected via an input/output port 34 so that they can communicate with each other. The terminal-side sending/receiving unit 30 has the function to send and receive an ultrasonic signal. The microphone and the speaker provided on the smartphons can be used as the terminal-side sending/receiving unit 30.

[0024] The CPU 32 has the function :o execute various programs stored in the non- volatile memory 33. The non- volatile memory 33 is a rewritable memory that retains data even when not powered. In particular, an authentication program 36 and a parking operation program 37 are stored in the non-volatile memory 33 in this embodiment. The authentication program 36 is an application program that defines the processing to be executed on the mobile information terminal 12 side when electronic authentication is performed through communication between the mobile information terminal 12 and the vehicle 10. The parking operation program 37 is an application program that sends a command to the vehicle 10. The commands include a parking start command, a command indicating a movement direction and a turning direction at parking time, and a stop command.

[0025] The mobile information terminal 12 also includes the touch panel display 35. On the touch panel display 35, a screen is displayed to allow the user to perform the parking operation when the parking operation program 37 is started. The touch panel display 35 detects the touch position of the user's finger and outputs the detection result to the control unit 15 of the parking support device 11.

[0026] Next, with reference to FIG. 2, the operation of the parking support device 11 in this embodiment, as well as its processing procedure, is described below. The processing of the parking support device 11 is executed repeatedly at a predetermined periodic interval.

[0027] First, when the vehicle 10 is in an operable state, the control unit 15 determines whether the parking start command is received from the mobile information terminal 12 (step SI). The operable state refers to the vehicle state that corresponds to the preparatory stage for moving the vehicle 10 based on a command from the mobile information terminal 12. For example, in the operable state, the electric parking brake is applied or the gear shift lever is placed in a predetermined shift position.

[0028] If the parking start command is received when the vehicle 10 is in the operable state (step SI: YES), the control unit 15 uses the in-vehicle sending/receiving unit 16 to send the ultrasonic signal with a pre-set output intensity (step S2). This ultrasonic signal is composed of data containing the synchronization code, ID code, challenge code, and distance measuring code that are arranged sequentially. These codes are sent in the order in which they are arranged. The synchronization code is a preamble, and the ID code is data identifying the vehicle. The challenge code is data that requests the mobile information terminal 12 to send the identification information on the mobile information terminal 12. The challenge code is used also by the mobile information terminal 12 side to generate the identification signal that includes the identification information. The distance measuring code is a code used for measuring the distance between the in- vehicle sending/receiving unit 16 and the mobile information terminal 12.

[0029] In response to this ultrasonic signal, the mobile information terminal 12 sends the ultrasonic signal that responds to the in-vehicle sending/receiving unit 16 (hereinafter called a response signal). The response signal includes the response distance-measuring code and the response code arranged in this order. The response distance-measuring code is a code generated by logically inverting the bits of the distance measuring code sent from the in-vehicle sending/receiving unit 16 of the parking support device 11. The response code is generated by logically synthesizing the challenge code with a code (encryption key) having the identification information that identifies the mobile information terminal 12. This response code, which includes the information for identifying the mobile information terminal 12, is used as the input signal for authenticating that the mobile information terminal 12 is authentic.

[0030] The control unit 15 determines whether the response signal is received from the mobile information terminal 12 within a pre-set time (step S3). This time is set based on the average time from the moment the in-vehicle sending/receiving unit 16 sends the ultrasonic signal to the moment the response signal is received from the mobile information terminal 12 that can respond to the signal. If the response signal is not received within the pre-set time (step S3: NO), the processing proceeds to step S10 to perform the termination processing for terminating the control for the parking support. Therefore, the vehicle control based on the operation through the mobile information terminal 12 is terminated, for example, when a communication failure is caused by a noise, when there is a possibility that the processing time is prolonged due to a drop in the power of the mobile information terminal 12, or when the user leaves the place without performing a predetermined operation for terminating the mobile information terminal 12.

[0031] On the other hand, if the response signal is received from the mobile information terminal 12 within the pre-set time (step S3: YES), the control unit 15 calculates the distance L between the in-vehicle sending/receiving unit 16 and the mobile information terminal 12 (step S4). The distance L can be calculated based on the time difference T between the moment the distance measuring code is sent by the in-vehicle sending receiving unit 16 and the moment the response distance-measuring code is received from the mobile information terminal 12. In more detail, the distance L can be calculated using the expression "L = Vs-(T - ΔΤ)", where T is the time difference described above, ΔΤ is the processing time required from the moment the mobile information terminal 12 receives the distance measuring code to the moment the mobile information terminal 12 sends the response distance-measuring code, and Vs is the speed of sound. Note that the speed of sound Vs of the ultrasonic signal is affected by the temperature. Therefore, the speed of sound Vs is calculated using the expression "Vs = 331 + 0.6-Tm" where Tm is the outdoor temperature measured by the temperature sensor 24.

[0032] To calculate the distance L more accurately, it is desirable that the processing time ΔΤ be a fixed value. This processing time ΔΤ is set based on the information, which is created by measuring the time between the moment the distance measuring code is received and the moment the response distance-measuring code is sent and is sent from the mobile information terminal 12 to the in-vehicle sending/receiving unit 16, or is set to a value calculated in advance. In this embodiment, to reduce a variation in the processing time ΔΤ, the mobile information terminal 12 sends the response distance-measuring code before generating the response code. This is because, if the response distance-measuring code is sent after waiting for the completion of response code generation that places a heavy calculation load on the CPU 32, the time required for the response code generation processing tends to vary; in addition, this variation, in turn, sometimes causes a variation in the processing time ΔΤ required until the response distance-measuring code is sent. In addition, to minimize the calculation load of the mobile information terminal 12 required for the response distance-measuring generation processing, the response distance-measuring code is generated simply by preforming the bit inversion processing for the received distance measuring code. The bit inversion processing makes the calculation load of the response distance-measuring code generation processing much smaller than that of the response code generation processing.

[0033] After calculating the distance L, the control unit 15 determines whether the distance L is equal to or smaller than the upper limit value Lmax (step S5). The upper limit value Lmax is set to the upper limit value of the distance range in which the user, who operates the mobile information terminal 12 outside the vehicle to move the vehicle at a low speed before parking, can visually confirm the safety of the vehicle and the surrounding of the vehicle. This upper limit value Lmax is set to a value ranging from several tens of centimeters to several meters.

[0034] As shown in FIG. 3, the distance range Zl, a predetermined range defined by the upper limit value Lmax, includes the following two ranges. One is a spherical distance range Z1A with the in- vehicle sending/receiving unit 16, provided on the front end of the vehicle 10, as the center, and the other is a spherical distance range ZIB with the in- vehicle sending/receiving unit 16, provided on the rear end of the vehicle 10, as the center. In this distance range Zl, the control of the vehicle 10 via the operation of the mobile information terminal 12 is allowed.

[0035] As shown in FIG. 2, if the calculated distance L is equal to or smaller than the upper limit value Lmax (step S5: YES), the control unit 15 determines whether the response code included in the response signal is authentic (step S6). If the control unit 15 determines that the response code is not authentic (step S6: NO), the processing proceeds to step S10 to perform the termination processing. If the response code is authentic (step S6: YES), the control unit 15 moves the vehicle 10 at a pre-set speed according to the command sent from the mobile information terminal 12 (step S7). [0036] When a user 100 performs an operation to reverse and turn the vehicle 10 in the right direction via the mobile information terminal 12 as shown in FIG. 4A, the moving direction command indicating the moving direction, either forward or backward, and the turning command indicating the turning direction and the steering angle are sent from the mobile information terminal 12. The control unit 15 calculates the steering angle and the moving direction based on the moving direction command the turning command, received from the in- vehicle sending/receiving unit 16, and outputs the commands to the engine control unit 20 and the electric power steering computer 21.

[0037] Next, the user 100 moves with the vehicle 10 as shown in FIG. 4B so that the position of the mobile information terminal 12 is included in the distance range Zl. In addition, considering the direction and the relative distance of the vehicle 10 with respect to the parking space, the user 100 performs the operation to change the turning direction and the moving direction as necessary.

[0038] If the control unit 15 determines that the measured distance L exceeds the upper limit value Lmax in step S5 as shown in FIG. 2 (step S5: NO), the control unit 15 stops the movement of the vehicle 10 regardless of the command received from the mobile information terminal 12 (step S8). That is, when the mobile information terminal 12 is outside the distance range Zl described above, the operation on the vehicle 10 via the mobile information terminal 12 is inhibited. After the vehicle 10 is stopped because the measured distance L exceeds the upper limit value Lmax, the control unit 15 proceeds to step S9.

[0039] Next, the control unit 15 determines whether the termination command is received from the mobile information terminal 12 (step S9). This termination command is sent from the mobile information terminal 12 when the user performs the operation for terminating the vehicle control that is based on the operation via the mobile information terminal 12. If the control unit 15 does not receive the termination command (step S9: NO), the processing returns to step S2 to repeat the processing described above. That is, the parking support device 11 repeatedly measures the distance to the mobile information terminal 12. If the distance L between the in-vehicle sending/receiving unit 16 and the mobile information terminal 12 is equal to or smaller than the upper limit value Lmax, the operation via the mobile information terminal 12 is allowed and the vehicle 10 moves according to the command received from the mobile information terminal 12.

[0040] While the vehicle 10 is moved based on the command received from the mobile information terminal 12, the control unit 15 determines whether the termination command is received from the mobile information terminal 12 (step S9). If the termination command is not received from the mobile information terminal 12 (step S9: NO), the processing returns to step S2 and the ultrasonic signal is sent again. If the termination command is received from the mobile information terminal 12 (step S9: YES), the control unit 15 performs the termination processing (step S10).

[0041] Because the user can move the vehicle 10 through the operation via the mobile information terminal 12 as described above, even the user with a low driving skill can relatively easily stop the vehicle 10 in a parking space. In addition, because the user can operate the vehicle 10 outside the vehicle, there is no need to reserve space to open/close the door or space for occupants to get off even when the parking space is small. In addition, the operation of the vehicle 10 via the mobile information terminal 12 is allowed only when the mobile information terminal 12 is within the distance range Zl and the user can visually confirm the safety of the vehicle 10 and the surrounding of the vehicle 10. This means that the parking support system can support the user for parking basically by using only the in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30 as the sensors for parking support.

[0042] As described above, the parking support system in this embodiment gives the following effects. (1) If the distance L between the vehicle 10 and the mobile information terminal 12, which is measured based on the transfer of the ultrasonic wave between the in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30, is equal to or smaller than the upper limit value Lmax below which the user can confirm the safety of the vehicle 10 and the surrounding of the vehicle 10, the vehicle 10 can be moved based on a command sent from the mobile information terminal 12. Therefore, user can park the vehicle while visually confirming the safety outside the vehicle and even a driver with a low driving skill can easily and smoothly move the vehicle 10 to a target position. If the distance L between the mobile information terminal 12 and the vehicle 10 exceeds the upper limit value Lmax, the vehicle 10 is stopped. This inhibits the mobile information terminal 12 from performing the operation from a remote location where the user cannot sufficiently confirm the safety. In addition, when the distance between the mobile information terminal 12 and the vehicle 10 cannot be measured, for example, due to a communication failure between the in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30, the vehicle 10 is stopped for ensuring safety. The in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30, which are only required to measure at least the distance equal to or smaller than the upper limit value Lmax, may be an existing clearance sensor available for use in a short range. This eliminates the need for various types of sensors and for a special sensor, thus reducing the number of parts used by the parking support system and simplifying the system.

[0043] (2) The distance range Zl, which is defined by the upper limit value Lmax and in which the user is allowed to operate the vehicle 10 via the mobile information terminal 12, is a range that includes all distance ranges whose distance from each of the two in-vehicle sending/receiving units 16 is equal to or smaller than the upper limit value Lmax. This range defines a range in which the user can confirm safety. In addition, as compared with a case in which only one in-vehicle sending/receiving unit 16 is used to set the distance range, the range in which the user is allowed to operate the vehicle 10 via the mobile information terminal 12 can be increased.

[0044] (3) The parking support device 11 moves the vehicle 10 according to the moving direction and the turning direction of the vehicle 10 according to a command from the mobile information terminal 12. That is, the user can send a command indicating the moving direction, forward ar backward, and the turning direction, right turning or left, via the mobile information terminal 12. This allows the user to move the vehicle 10 to a parking space and stop it there through the operation of the mobile information terminal 12 without having to stop the vehicle 10 in a particular direction with respect to the parking space.

(Second embodiment)

[0045] Next, a parking support system and a parking support method in a second embodiment are described below with emphasis on the difference from the first embodiment. The basic configuration of the parking support system and the parking support method in this embodiment is the same as that in the first embodiment. In the figures, the same reference numeral is given to substantially the same element as that in the first embodiment, and the redundant description will be omitted.

[0046] In the parking support system in this embodiment, the vehicle 10 is made to follow the user, who moves with the mobile information terminal 12, to guide the vehicle 10 to a parking space. As shown in FIG. 5, the distance to the mobile information terminal 12 is measured in this embodiment using the in-vehicle sending/receiving units 16 provided in the separate two positions at the rear end of the vehicle. The in-vehicle sending/receiving units 16 alternately send the ultrasonic signal at different times. The control unit 15 identifies the detection signal received from each in-vehicle sending receiving unit 16 and calculates the distance L between the vehicle 10 and the mobile information terminal 12 in the same manner as in the first embodiment. That is, the control unit 15 calculates the distance LI based on the detection signal received from one in-vehicle sending receiving unit 16Aand the distance L2 based on the detection signal received from the other in-vehicle sending/receiving unit 16B.

[0047] As shown in FIG. 6, to guide the vehicle 10 to a parking space, the user 100 at a position 100A, somewhat away from a parking space 101, performs the operation to start parking via the mobile information terminal 12 and slowly moves toward the parking space 101 while carrying the mobile information terminal 12. In the example shown in FIG. 6, the user 100 moves from the position 100A, where parking is started, to a position lOOC, where parking is finished, via a position 100B. The vehicle

10 moves in the direction, in which the user 100 walks, while maintaining a distance, equal to the reference distance Lrf, to the mobile information terminal 12 carried by the user 100. The reference distance Lrf, a distance to be reserved between the user and the vehicle 10 for safety, is set to a distance from several tens of centimeters to several meters. For example, when the user 100 reaches the position lOOC, the user operates the mobile information terminal 12 to perform the operation to terminate parking and stops the vehicle 10. That is, the user performs the operation to start parking and terminate parking but not the operation to send a turning command or a reversing command via the mobile information terminal 12.

[0048] Next, with reference to FIG. 7, the operation of the parking support device

11 in this embodiment, as well as its processing procedure, is described below. The processing of the parking support device 11 is executed repeatedly at a predetermined periodic interval.

[0049] When the vehicle 10 is in the operable state described above, the control unit 15 determines whether the parking start command is received from the mobile information terminal 12 (step SI). If the parking start command is received when the vehicle 10 is in the operable state (step SI: YES), the control unit 15 uses the in-vehicle sending/receiving unit 16 to send the ultrasonic signal (step S2).

[0050] The control unit 15 determines whether the response signal is received from the mobile information terminal 12 within a pre-set time (step S3). If the response signal is not received from the mobile information terminal 12 within the pre-set time (step S3: NO), the processing proceeds to step S10 to perform the termination processing. If the response signal is received from the mobile information terminal 12 within the pre-set time (step S3: YES), the control unit 15 calculates the distance (LI, L2) between the in-vehicle sending/receiving unit 16 and the mobile information terminal 12 for each in-vehicle sending/receiving unit 16 (step S20).

[0051] After calculating the distances LI and L2 based on each in-vehicle sending/receiving unit 16, the control unit 15 determines whether at least one of the calculated distances LI and L2 (distance L) exceeds the reference distance Lrf (step S21).

[0052] If the calculated distance LI exceeds the reference distance Lrf or the calculated distance L2 exceeds the reference distance Lrf or if both distances LI and L2 exceed the reference distance Lrf (step S21: YES), the control unit 15 determines whether the response code is authentic (step S6). If the response code is not authentic (step S6: NO), the processing proceeds to step S10 to perform the termination processing.

[0053] On the other hand, if the response code is authentic (step S6: YES), the control unit 15 calculates the steering angle for the vehicle 10 to follow the user, based on the position of the mobile information terminal 12 (step S22). In other words, the control unit 15 calculates the steering angle required for the center of the rear end of the vehicle 10 to approach the position of the mobile information terminal 12.

[0054] That is, as shown in FIG. 5, the control unit 15 calculates the intersection P between a circle CI with a radius of the distance LI and a circle C2 with a radius of the distance L2, considering that the distance LI and the distance L2 are two-dimensional distances. After that, the control unit 15 identifies the intersection P as the position of the mobile information terminal 12. Then, the control unit 15 calculates the steering angle of the vehicle from the relative direction D determined by the identified position and the center of the rear end of the vehicle.

[0055] After that, the control unit 15 moves the vehicle 10 according to the calculated steering angle (step S23). That is, the control unit 15 outputs a command to the engine control unit 20 to reverse the vehicle 10 and, if the vehicle 10 is to be turned, outputs a command for driving the electric power steering computer 21 and a steering angle command to turn the vehicle 10.

[0056] While the vehicle 10 is moving, the control unit 15 determines whether at least one of the distances LI and L2 (distance L) becomes smaller than the movement stop distance Lst (step S24). The movement stop distance Lst is set to a minimum distance to be reserved between the vehicle 10 and the user when the user's walking speed becomes higher than the speed of the vehicle 10 or when the user approaches the vehicle 10 while parking.

[0057] If at least one of the distances LI and L2 is smaller than the movement stop distance Lst (step S24: YES), the control unit 15 stops the movement of the vehicle 10 (step S25). On the other hand, if both the distances LI and L2 are equal to or larger than the movement stop distance Lst (step S24: NO), the processing proceeds to step S9.

[0058] The control unit 15 determines whether the termination command is received from the mobile information terminal 12 (step S9). If the termination command is received (YES in step S9), the control unit 15 performs the termination processing (step S10).

[0059] Because the vehicle 10 can be moved to a user's desired position through the guidance by the user as described above, the user need not issue a control instruction to the vehicle 10 via the terminal. Therefore, even the user with a low driving skill can relatively easily stop the vehicle 10 in a parking space. In addition, even when the parking space is small, there is no need to reserve space to open/close the door or space for occupants to get off.

[0060] As described above, the parking support system in this embodiment gives the following effects. (4) If the distance L between the vehicle 10 and the mobile information terminal 12, which is measured based on the transfer of the sound wave between the in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30, exceeds the reference distance Lrf to be reserved therebetween, the vehicle 10 is moved so that the distance L gets close to the reference distance Lrf. That is, because the user is required only to guide the vehicle 10 to a target parking space, the user can smoothly and easily park the vehicle independently of the user's driving skill. In addition, the in-vehicle sending receiving unit 16 and the terminal-side sending/receiving unit 30, which are only required to measure at least a distance close to the reference value Lrf, may be an existing short-distance, directional clearance sonar sensor. This eliminates the need for various types of sensors and for a special sensor, thus reducing the number of parts used by the parking support system and simplifying the system.

[0061] (5) The vehicle is stopped when the distance L between the vehicle 10 and the mobile information terminal 12 becomes equal to or smaller than the movement stop distance Lst that is smaller than the reference distance Lrf. This capability allows the vehicle to stop for safety when the user, who guides the vehicle, gets too close to the vehicle 10.

[0062] (6) The two-dimensional position of the mobile information terminal 12 is calculated based on the transfer of the ultrasonic wave between each of the two in-vehicle sending/receiving units 16 provided at the rear end of the vehicle 10 and the mobile information terminal 12. Then, the electric steering system is controlled in such a manner that the vehicle follows the two-dimensional position of the mobile information terminal 12. Therefore, the user can guide the vehicle 10 to a parking space through the mobile information terminal 12 without having to stop the vehicle 10 in a particular direction with respect to the parking space.

(Other embodiments)

[0063] The above embodiments may also be implemented in the following modes. The distance to the mobile information terminal 12, though measured using two in-vehicle sending receiving units 16 in the first embodiment, may be measured by one in-vehicle sending/receiving unit 16. In that case, the spherical range with the in-vehicle sending/receiving unit 16 as the center may be defined as a distance range where the user can perform the operation via the mobile information terminal 12. In addition, three or more in-vehicle sending/receiving units 16 may be used to measure the distance to the mobile information terminal 12 in the first embodiment.

[0064] In the second embodiment, the two in-vehicle sending/receiving units 16 are used to detect the distances LI and L2 and the intersection P of the two circles, one with a radius of the distance LI and the other with a radius of the distance L2, is identified as the position of the mobile information terminal 12. Instead of this method or configuration, the position of the mobile information terminal 12 may be identified by another method or in another configuration. For example, a three-dimensional position of the mobile information terminal 12 may be identified based on the three distances detected using the three in-vehicle sending/receiving units 16 and, then, the three-dimensional position may be projected onto the two-dimensional plane to find the two-dimensional position.

[0065] In the second embodiment, the steering angle is determined based on the relative direction between the position of the identified mobile information terminal 12 and the center of the rear end of the vehicle 10. Instead, the steering angle may be determined using other methods. For example, it is possible to divide the area behind the vehicle 10 into three or more, to determine in which of these areas the mobile information terminal 12 is included, and then to cause the vehicle to turn at a constant angle (for example, at an angle of 30 degrees) with respect to the determined area.

[0066] In the second embodiment, the two in-vehicle sending/receiving units 16 are used to identify the position of the mobile information terminal 12. Instead of this, one in-vehicle sending/receiving unit 16 may also be used on the premise that the user guides the vehicle in the center of the width direction of the vehicle.

[0067] The in-vehicle sending/receiving units 16, though mounted on the rear end of the vehicle 10 in the second embodiment, may also be mounted on the front end. When the in-vehicle sending/receiving units 16 are mounted on the front end of the vehicle 10, the vehicle 10 moves in such a way that the distance L between at least one of the in-vehicle sending/receiving units 16 on the front end of the vehicle 10 and the mobile information terminal 12 is maintained at the reference distance Lrf. This means that the user can stop the vehicle 10 in a parking space without having to enter the parking space. In addition, a plurality of in-vehicle sending/receiving units 16 may be provided on each of the front end and the rear end of the vehicle 10. In this case, it is possible to determine whether the mobile information terminal 12 is present in front of or behind the vehicle 10 based on the detection result of the in-vehicle sending/receiving units 16 and, according to the position of the mobile information terminal 12, to determine the in-vehicle sending/receiving unit 16 against which the reference distance Lrf is to be maintained. For example, when the mobile information terminal 12 is present in front of the vehicle 10, the vehicle 10 is moved so that the reference distance Lrf should be maintained between the in-vehicle sending/receiving unit 16 provided on the front end and the mobile information terminal 12.

[0068] In the above embodiments, the control unit 15 calculates the distance L between the vehicle 10 and the mobile information terminal 12, compares the calculated distance L and the threshold (upper limit value Lmax, reference distance Lrf), and then determines whether the response code is authentic. These steps may be executed in any order. That is, the control unit 15 may determine whether the response code is authentic either before the step of calculation of the distance L and the step of comparison between the distance L and the threshold (upper limit value Lmax, reference distance Lrf) or between these two steps. In this case, the control unit 15 retains the reception time of the response distance-measuring code included in the response signal and, if it is determined that the response code is authentic, calculates the distance L based on the reception time of the response distance-measuring code and the sending time of the distance measuring code.

[0069] In the above embodiments, to measure the distance L, the parking support device 11 sequentially sends the synchronization code, ID code, challenge code, and distance measuring code and, in response to these codes, the mobile information terminal 12 sends back the response distance-measuring code. The present invention is not limited to this method. For example, it is possible that the parking support device 11 sends the synchronization code, ID code, and distance measuring code and, in response to these codes, the mobile information terminal 12 sends back the response distance-measuring code, and after that, the parking support device 11 sends the challenge code. Furthermore, the distance may also be measured without using the codes described above. It is also possible that the mobile information terminal 12 sends the distance measuring code to the parking support device 11, the parking support device 11 receives this distance measuring code and sends back the distance measuring code to the mobile information terminal 12, and then the mobile information terminal 12 receives this distance measuring code. In this case, the mobile information terminal 12 is only required to feed back the information on the time difference between the sending time and the receiving time of the distance measuring code to the parking support device 11.

[0070] In the first embodiment, the vehicle 10 is stopped when the distance L between the vehicle 10 and the mobile information terminal 12 exceeds the upper limit value Lmax. In the second embodiment, the vehicle 10 is moved so that it approaches the mobile information terminal 12 when the distance L between the vehicle 10 and the mobile information terminal 12 exceeds the reference distance Lrf. In addition, the vehicle 10 is stopped when the distance L becomes smaller than the movement stop distance Lst during movement. Another mode is also possible; for example, in a mode in which the vehicle 10 follows the user, the vehicle 10 may be stopped when the distance L exceeds the upper limit value Lmax and, in addition, the vehicle 10 may be moved so that it approaches the mobile information terminal 12 when the distance L exceeds the reference distance Lrf that is smaller than the upper limit value Lmax. In that case, when the distance L becomes smaller than the movement stop distance Lst during movement, the vehicle 10 may be stopped. In addition, in a mode in which the vehicle 10 is moved based on the operation via the mobile information terminal 12, the vehicle 10 may be stopped when the distance L exceeds the upper limit value Lmax and when the distance L becomes smaller than the movement stop distance Lst.

[0071] In the embodiments described above, the in-vehicle sending/receiving unit 16 first sends the ultrasonic signal and, in response to this ultrasonic signal, the terminal-side sending/receiving unit 30 sends back the response signal to allow the vehicle side to measure the distance. Instead of this method, any other procedure may also be used to measure the distance. For example, the terminal-side sending/receiving unit 30 may first send the ultrasonic signal and, in response to this ultrasonic signal, the in-vehicle sending receiving unit 16 sends back the response signal to allow the mobile information terminal 12 side to measure the distance. In that case, the mobile information terminal 12 may also calculate the distance L and compare the calculated distance L and the threshold values (upper limit value Lmax, reference distance Lrf, movement stop distance Lst). Based on the comparison result, the mobile information terminal 12 may output a command to move the vehicle 10 or a command to stop the vehicle 10.

[0072] The mobile terminal of the present invention may be a mobile phone other than a smartphone. In this case, the user operates, not the touch panel display 35, but the operation buttons provided on the mobile phone, to perform the parking operation. In addition, the mobile terminal is not limited to a smartphone or a mobile information terminal such as a mobile phone. For example, a device specifically designed for vehicle parking support may be used. This device includes a module, corresponding to the terminal-side sending receiving unit 30, CPU 32, and non-volatile memory 33, and the touch panel display 35 or another operation unit. This type of device, if used, reduces a variation in the ultrasonic communication function such as a variation in the sensitivity for the ultrasonic signal.

[0073] The in- vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30 in the above embodiments, which have the function to send an ultrasonic wave, may also have the radio wave communication function for a long wave, a short wave, a microwave, and a millimetsr wave. Another configuration is also possible in which the vehicle 10 includes a sending/receiving unit, which has the radio wave communication function for these waves, separately from the in-vehicle sending/receiving unit 16 and in which the mobile information terminal 12 includes a sending/receiving unit, which has the radio wave communication function for these waves, separately from the terminal-side sending/receiving unit 30. In this case, the ultrasonic signal may be used between the vehicle 10 and the mobile information terminal 12 to measure the distance and. on the other hand, the radio wave communication function may be used to send a command, such as a parking start command, a parking termination command, or an advance/reverse/turning command, from the mobile information terminal 12 to the vehicle 10.

[0074] The in-vehicle sending/receiving unit 16 and the terminal-side sending/receiving unit 30 may send and receive not only the ultrasonic wave but also a sound wave signal in the audible frequency range. In this case, because the diffraction phenomena occurs more readily than with the ultrasonic signal, it becomes easier to communicate with the mobile information terminal 12 by bypassing an obstacle around the in-vehicle sending receiving unit 16 and the terminal-side sending/receiving unit 30.