Abstract:
The method includes the steps of picking up a rear area image FI behind a motor vehicle, displaying the rear area image FI, sensing a steering angle of the vehicle, and sensing a position of the vehicle. A vehicle image VI is superposed on a desired parking position P of the vehicle in the rear area image FI, and a predicted vehicle route image TR 1  is generated within the predetermined area based on a steering angle and an initial position of the vehicle, while an actual vehicle route image TR 2  is generated based on actual steering angles and positions of the vehicle. The vehicle image V 1 , the predicted vehicle route image TR 1 , and the actual vehicle route image TR 2  are superposed on the rear area image FI. The method further has a step for obtaining a difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  and another step for noticing a steering angle correction message based on the difference.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a parking support unit and a parking support method for assisting a steering operation of a motor vehicle during parallel parking, garaging, etc. of the vehicle.  
           [0003]    2. Related Art  
           [0004]    A conventional one of such units is disclosed in Japanese Patent Application Laid-open No. 2000-79860. This unit displays a predicted vehicle route determined based on a steering angle during parking on a display screen positioned near a driver&#39;s seat. In connection with the predicted vehicle route, a window for finding white guide lines of a parking bay is prepared on the screen.  
           [0005]    The window is moved on the screen for finding positions and orientations of the white lines to determine a geometrical arrangement of the parking bay. The unit provides a phonic advice of vehicle steering for a driver in consideration of the parking operation.  
           [0006]    The conventional unit requires a complicated image processing for finding the white lines of the parking bay based on image information obtained by a camera. Thus, the unit needs a CPU having a higher process speed, disadvantageously increasing the cost of the unit.  
           [0007]    Furthermore, the unit can not be useful to guide the vehicle when there are no white lines in a parking bay and in a space between other stopped vehicles on a road, limiting the usage of the unit.  
         SUMMARY OF THE INVENTION  
         [0008]    In view of the foregoing disadvantage of the conventional unit, an object of the invention is to provide a parking support unit and a parking support method for assisting a steering operation of a motor vehicle to correctly guide the vehicle into a parking bay. The vehicle can be moved backward according to a predicted vehicle route indicated on a display screen during a parking operation of the vehicle.  
           [0009]    A parking support unit according to the present invention, as illustrated in a basic block diagram of FIG. 1, includes:  
           [0010]    an image pickup means  101  for picking up an image FI of a rear area behind a motor vehicle, the rear area located at a predetermined position relative to the vehicle,  
           [0011]    a display means  102  for displaying the rear area image FI,  
           [0012]    a steering angle sensing means  103 ,  
           [0013]    a vehicle position sensing means  104 ,  
           [0014]    an image storing means  105  for storing a vehicle image VI,  
           [0015]    a predicted vehicle route image TR 1 , and an actual vehicle route image TR 2  of the vehicle, and  
           [0016]    an image superposing means  106 ,  
           [0017]    wherein the vehicle image VI is superposed on a desired parking position P of the vehicle in the rear area image FI indicated by the display means  102 , and the predicted vehicle route image TR 1  is generated within the predetermined area based on a steering angle and an initial position of the vehicle, while the actual vehicle route image TR 2  is generated based on actual steering angles and positions of the vehicle, the image superposing means  106  indicating the vehicle image V 1 , the predicted vehicle route image TR 1 , and the actual vehicle route image TR 2  by the display means  102  to superpose them on the rear area image FI.  
           [0018]    Thus, the predicted vehicle route image TR 1  showing a predicted vehicle route from the present stopped position to a desired parking position is superposed on the rear area image FI indicated on the screen. Furthermore, the actual vehicle route image TR 2  is generated based on actual steering angles and positions of the vehicle while the vehicle moves backward from the present stopped position to the desired parking position, and the actual vehicle route image TR 2  is superposed on the predicted vehicle route image TR 1 . A difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  is used for an appropriate operation correction of a steering wheel by a driver. Accordingly, the driver can move backward the vehicle even to a parking space having no guide lines for parking the vehicle.  
           [0019]    The unit, an illustrated in FIG. 1, further has a computing means  107  for obtaining a difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  and a message informing means  108  for informing a steering angle correction message based on the difference.  
           [0020]    Thus, the driver can advantageously know a deviation of the vehicle from a predicted vehicle route image TR 1  at an earlier stage of the parking operation, so that the driver can correct the deviation to park the vehicle with ease.  
           [0021]    Preferably, the computing means  107  has a decision device  73  for determining a steering direction and a steering amount based on the difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  to correct the difference. The decision is noticed by the message informing means  108 .  
           [0022]    Preferably, the computing means  107  has a decision device  71  for determining whether the vehicle can be moved backward to a desired parking position from the present position of the vehicle within a maximum steering angle of the vehicle. The decision is noticed by a voice of the message informing means  108 . This allows the driver not to repeat a parking operation toward a parking bay.  
           [0023]    Preferably, the computing means  107  has a calculating device  72  for calculating a preliminary forwarding distance which is necessary for the vehicle to be moved to a desired parking position from the present position of the vehicle within a maximum steering angle of the vehicle. The result is noticed by a voice of the message informing means  108 . Thus, when it is determined that the vehicle can not be moved backward to a desired parking position, the message informing means  108  gives a preliminary forwarding distance of the vehicle to enable the parking at the desired parking position. Thus, the driver can know a correct start point for moving backward the vehicle with ease, enabling an efficient parking operation of the vehicle.  
           [0024]    A parking support method according to the present invention includes the steps of:  
           [0025]    picking up an image FI of a rear area behind a motor vehicle, the rear area located at a predetermined position relative to the vehicle,  
           [0026]    displaying the rear area image FI,  
           [0027]    sensing a steering angle of the vehicle,  
           [0028]    sensing a position of the vehicle,  
           [0029]    storing a vehicle image V 1 , a predicted vehicle route image TR 1 , and an actual vehicle route image TR 2  of the vehicle, and  
           [0030]    indicating the vehicle image V 1 , the predicted vehicle route image TR 1 , and the actual vehicle route image TR 2 ,  
           [0031]    wherein the vehicle image VI is superposed on a desired parking position P of the vehicle in the rear area image FI, and the predicted vehicle route image TR 1  is generated within the predetermined area based on a steering angle and an initial position of the vehicle, while the actual vehicle route image TR 2  is generated based on actual steering angles and positions of the vehicle, the indicating step indicating the vehicle image V 1 , the predicted vehicle route image TR 1 , and the actual vehicle route image TR 2  to superpose them on the rear area image FI.  
           [0032]    Thus, the predicted vehicle route image TR 1  showing a predicted vehicle route from the present stopped position to a desired parking position is superposed on the rear area image FI indicated on the screen. Furthermore, the actual vehicle route image TR 2  is generated based on actual steering angles and positions of the vehicle while the vehicle moves backward from the present stopped position to the desired parking position, and the actual vehicle route image TR 2  is superposed on the predicted vehicle route image TR 1 . A difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  is used for an appropriate correction of a steering wheel operation by a driver.  
           [0033]    The method further has a step for obtaining a difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  and another step for informing a steering-angle correction message based on the difference. Thus, the method can output a steering wheel turning direction based on the deference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2 .  
           [0034]    Preferably, the method further has a step for determining a steering direction and a steering amount based on the difference between the predicted vehicle route image TR 1  and the actual vehicle route image TR 2  to correct the difference. The decision is noticed by the message informing means  108 .  
           [0035]    Preferably, the method further has a step for determining whether the vehicle can be moved backward to a desired parking position from the present position of the vehicle within a maximum steering angle of the vehicle. The decision is noticed by the message informing means  108 .  
           [0036]    Preferably, the method has a step for calculating a preliminary forwarding distance which is necessary for the vehicle to be moved to a desired parking position from the present position of the vehicle within a maximum steering angle of the vehicle. The result is noticed by a voice of the message informing means  108 . Thus, when it is determined that the vehicle can not be moved backward to a desired parking position, the message informing means  108  informs the preliminary forwarding distance of the vehicle by a voice to enable the parking at the desired parking position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    [0037]FIG. 1 is a basic block diagram of a parking support unit according to the present invention;  
         [0038]    [0038]FIG. 2 is a block diagram of a parking support unit of an embodiment according to the present invention;  
         [0039]    [0039]FIG. 3 is a flowchart showing operations of the parking support unit of the embodiment;  
         [0040]    [0040]FIG. 4 is also a flowchart showing operations of the parking support unit of the embodiment;  
         [0041]    [0041]FIGS. 5A, 5B, and  5 C are illustrations showing vehicle routes during a parking operation of the vehicle; and  
         [0042]    [0042]FIG. 6 is an illustration showing a turning operation of the vehicle which is moved backward with a steering angle. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]    Referring to the accompanied drawings, a parking support unit of an embodiment according to the present invention will be discussed hereafter. FIG. 2 shows a parking support unit of the embodiment. The unit has a CCD camera  13  for taking a picture of a rear area of a vehicle (not shown) , a steering sensor  1  for sensing an angle of a steering wheel of the vehicle, a reverse position indicating switch  3  for indicating a reverse state of transmission shift lever (not shown) , a parking operation switch  4  for showing to perform a parking support operation (including a superposed displaying process) at the parking of the vehicle, a vehicle image positioning switch  13 A for moving a vehicle image to a desired parking position in a rear area image indicated on a display discussed later, a wheel speed sensor  5  for sensing a speed of each of left and right follower wheels, a steering angle sensor  6  for sensing a steering angle, a display  12 , and a voice synthesizing circuit  7 . On the rear area taken by the CCD camera  13 , the display  12  superposes a vehicle image VI which shows a desired parking position P of the vehicle. Furthermore, The display  12  superposes a predicted vehicle route image TR 1  generated within the predetermined area based on a steering angle and an initial position of the vehicle and an actual vehicle route image TR 2  generated based on actual steering angles and positions of the vehicle, when the vehicle moves backward toward the desired parking position P. The voice synthesizing circuit  7  serves to output synthesized voices via a speaker  8  to give a parking aiding message.  
         [0044]    The unit has a CPU 10 for controlling the whole unit, a graphic image generating circuit  11 , and an image superposing circuit  9 . The graphic image generating circuit  11  provides graphics which illustrate the predicted vehicle route image TR 1  generated based on outputs from the sensors  5 ,  6  and the switches, the actual vehicle route image TR 2 , and the vehicle image VI. The image superposing circuit  9  superposes graphic signals provided from the graphic image generating circuit  11  on image signals of a rear area image taken by the CCD camera  13 . Thus, the image superposing circuit  9  superposes the vehicle image VI, the predicted vehicle route image TR 1 , and the actual vehicle route image TR 2  to display them on the screen of the display  12 .  
         [0045]    CPU 10 has a memory (image storing means  105 ) for storing data of the predicted vehicle route image TR 1 , the actual vehicle route image TR 2 , and the vehicle image VI. The predicted vehicle route image TR 1  and the actual vehicle route image TR 2 , which are generated based on outputs of the wheel speed sensor  5  and the steering angle sensor  6 , are red out from the memory to be displayed on the display  12 .  
         [0046]    The CCD camera  13  for taking a picture of a rear area is mounted at a middle of a rear face above a number plate of the vehicle so as to orient diagonally downward. More specifically, the camera is directed backward at a 30° downward angle and has a wide angle lens allowing a 140° view. The camera can take a view extending 8 meters backward.  
         [0047]    The display  12  is arranged on a panel of a center console positioned in a cabin of the vehicle. In the console, there is provided a controller consisting of the image superposing circuit  9 , the graphic image generating circuit  11 , and the voice synthesizing circuit  7  above a glove box. Near the console, there may be arranged the parking operation switch  4  indicating the parking support operation and the vehicle image positioning switch  13 A for moving the vehicle image VI to the desired parking position P on the display  12 .  
         [0048]    A general configuration of the present invention will be discussed before referring to a parking support unit of an embodiment of the invention.  
         [0049]    In the present invention, the display  12  mounted in the vehicle displays the rear area for moving backward the vehicle from a road to a desired parking position P in a parking area. On an image of the rear area, the vehicle image VI at the desired parking area P is displayed in graphic image.  
         [0050]    Next, it is determined whether the vehicle can reach the desired parking position P from the present position. When the decision is affirmative, the display  12  displays a graphic image of a predicted vehicle route image TR 1  along which the vehicle moves from the present position to the desired parking position P with a steering angle.  
         [0051]    Furthermore, present positions of the vehicle are determined based on outputs of the steering sensor and the wheel speed sensor. This can generate an actual vehicle route image TR 2  along which the vehicle moves from the initial position to the desired parking position P. The actual vehicle route image TR 2  is superposed on the predicted vehicle route image TR 1  on the display  12 .  
         [0052]    When the actual vehicle route image TR 2  is deviated from the predicted vehicle route image TR 1 , a phonic warning is given to a driver of the vehicle or the driver can see the deviation on the display  12 . Thereby, the driver operates a steering wheel to coincide the actual vehicle route image TR 2  with the predicted vehicle route image TR 1 . Accordingly, the driver requires a minimum wheel operation to move backward the vehicle to the desired parking position P.  
         [0053]    Next, referring to flowcharts shown in FIGS. 3 and 4, the embodiment will be discussed in detail.  
         [0054]    The controller starts processing when a power source switch is turned on. Step S 1  sets various initial values necessary for desired processes. Then, step S 3  checks a state of the reverse position indicating switch  3 . When the switch  3  does not indicate a reverse lever state, step S 3   a  stops a related indication and the execution returns to step  3 .  
         [0055]    On the other hand, when the reverse position indicating switch  3  is turned on (in a reverse lever state) , the execution goes to step S 5 . Step S 5  changes the display  12  in a camera image displaying mode so that the rear area image F is indicated on the display. That is, the display  12  shows a correct rear view to recognize persons standing therein, goods lying thereon, etc.  
         [0056]    Next, step S 7  checks the parking operation switch  4  for showing whether the vehicle will be parked or not. When the parking operation switch  4  is off, step S 7   a  clears a related graphic image on the display  12  and shows only a rear area image FI. Then the execution returns to step S 3 .  
         [0057]    In step S 7 , when the parking operation switch  4  is on, the desired parking area P is confirmed in a rear area image FI. Then, step S 39  moves the vehicle image positioning switch  13 A upward, downward, left, or right, so that step S 41  moves a vehicle image VI to the desired parking position P.  
         [0058]    Next, step S 43  develops ordinates of the vehicle image VI, e.g. relative to the present position of the vehicle. Step S 45  recognizes a maximum steering angle of a steering wheel and the execution goes to step S 47 . Step S 47  determines whether the vehicle can be moved backward from the present position to the desired parking position P with the maximum steering angle.  
         [0059]    For example, the parking possibility is determined by whether the vehicle route of the vehicle with the maximum steering angle crosses a vehicle route of the vehicle image VI positioned at the desired parking position P.  
         [0060]    Note that the steering angle is not only set at the maximum angle but a more practical steering angle may be selected.  
         [0061]    Step S 49  determines whether the vehicle can be moved backward to the desired parking position P within the maximum steering angle. When the decision is negative, step S 9  gives phonic information indicating the negative state to the driver by a speaker  8  via the voice synthesizing circuit  7 . Then, a forwarding distance of the vehicle is obtained to enable the vehicle to be moved backward to the desired parking position P with an appropriate steering angle.  
         [0062]    On the contrary, when the vehicle will be able to be moved backward to the desired parking position P within the maximum steering angle, a predicted vehicle route image TR 1  corresponding to a present steering angle is superposed on a rear area image FI on the screen of the display  12  (see FIG. 5A). The driver can move backward the vehicle such that the vehicle image VI traces the predicted vehicle route image TR 1 .  
         [0063]    The rear area image FI moves on the screen with the movement of the vehicle. However, the vehicle image VI located at the desired parking position P keeps the predetermined position within the rear area image FI.  
         [0064]    It may be possible that phonic messages are given to the driver to assist the parking operation at an initial stage of the operation. For example, the messages are predetermined such as “please move your vehicle backward along a predicted vehicle route image TR 1  displayed on a screen with being careful about surroundings” or “please start a parking operation and please turn a steering wheel such that a leading end of a predicted vehicle route image TR 1  (e.g. colored green) directs to a parking bay”.  
         [0065]    For knowing a deviation of the actual vehicle route image TR 2  from the predicted vehicle route image TR 1 , an envelop of the predicted vehicle route image TR 1  is preliminarily provided. For the purpose, step S 11  receives a steering angle from the steering sensor  1  to obtain a turning radius R for the parking operation. Furthermore, step S 13  receives signals from the wheel speed sensor  5  to obtain a present position of the vehicle.  
         [0066]    Based on the signals from the sensors, step S 15  develops parameters defining a predicted vehicle route image TR 1 . Then, step S 17  generates coordinates based on the parameters of the predicted vehicle route image TR 1 .  
         [0067]    As illustrated in FIG. 6, the parameters of the predicted vehicle route image TR 1  are obtained from the turning radius R which is determined from a steering angle θ and a wheel base L. The predicted vehicle route image TR 1  may have a width of 2.0 m to 2.2 m in a radial direction of the turning radius R while the parking bay has a width of about 2.2 m to 2.4 m.  
         [0068]    Next, as illustrated in FIG. 5A, step S 19  superposes an actual vehicle route image TR 2  on the predicted vehicle route image TR 1 .  
         [0069]    For obtaining a latest one of the actual vehicle route image TR 2 , step S 21  receives signals from steering sensor  1 , and step S 23  receives signals from the wheel speed sensor  5 . Based on the signals, step S 25  develops parameters of the actual vehicle route image TR 2 . These parameters show positions relative to a center of a camera mounted on the vehicle.  
         [0070]    Step S 27  develops coordinates of the actual vehicle route image TR 2 . The coordinates of the actual vehicle route image TR 2  are defined relative to a turning center  0  shown in FIG. 6 as well as the coordinates of the predicted vehicle route image TR 1 .  
         [0071]    Thus obtained coordinates of the predicted vehicle route image TR 1  and the actual vehicle route image actual vehicle route image TR 2  are updated according to signals from the steering sensor  1  and the wheel speed sensor  5 .  
         [0072]    Step S 29  determines whether the actual vehicle route image TR 2  traces the predicted vehicle route image TR 1  based on a deviation value between the coordinates of the predicted vehicle route image TR 1  and the actual vehicle route image TR 2 . When the actual vehicle route image TR 2  is not within the predicted vehicle route image TR 1  as illustrated in FIG. 5B, step S 31  gives a phonic message such as “please turn the steering wheel a little rightward”.  
         [0073]    When the actual vehicle route image TR 2  is much deviated from the predicted vehicle route image TR 1 , step  33  carries out again a graphic process in which another predicted vehicle route image TR 1  is superposed on a rear area image FI in the display screen to try another parking operation.  
         [0074]    When the trial is successful so that the actual vehicle route image TR 2  is within the predicted vehicle route image TR 1 , the parking is possible with a present steering angle. In that case, the speaker outputs a phonic message such as “please move the vehicle backward with a present steering angle and please be careful for surroundings”.  
         [0075]    Next, step S 35  determines whether the parking operation switch  4  is on or not. When the parking operation switch  4  is not on, the execution returns to step S 7 .  
         [0076]    On the contrary, when the parking operation switch  4  is on, step S 37  checks whether the reverse position indicating switch  3  is in a reverse state. When the switch is not in a reverse state, the execution returns to step S 3 . When the switch is in a reverse state, processes of steps  1  to  35  are repeated.  
         [0077]    Accordingly, when the shift lever is in a reverse state and a parking support is requested, a predicted vehicle route image TR 1  is superposed on a rear area image FI in the display screen. A driver can turn the steering wheel based on an image of the display  12  to move the vehicle backward appropriately.  
         [0078]    As illustrated in FIG. 5C, when the vehicle has correctly moved into the parking bay, the steering wheel is returned in a straight forward position and the vehicle is further moved backward to reach an end of the parking bay. This operation can be safely carried out with watching a rearward view.