Patent Publication Number: US-2020300025-A1

Title: Door opening restriction device, and opening operation control method for vehicle door

Description:
TECHNICAL FIELD 
     The present invention relates to a door opening restriction device and an opening operation control method for a vehicle door. 
     BACKGROUND ART 
     Some vehicle door units in related art include a door opening restriction device capable of restricting the opening operation angle of the vehicle door before the full open angle. For example, the door opening restriction device disclosed in Patent Document 1 restricts the opening operation angle of the vehicle door by the engagement between an engagement member on the door and an engagement member on the vehicle. Further, operation of the control switch allows arbitrary setting of the opening operation angle of the vehicle door where the engagement member on the door and the engagement member on the vehicle are engaged with each other. 
     The door opening restriction device disclosed in Patent Document 2 continuously measures the distance to an obstacle present in the opening operation direction of the vehicle door. After the vehicle has come to a stop, the door opening restriction device reads out the measurement record of the separation distance to the obstacle. Then, the door opening restriction device restricts the opening distance of the vehicle door, namely, the opening operation angle such that the opening distance of the vehicle door is smaller than the separation distance to the obstacle. 
     However, in the above-mentioned related art, in order to have an effective “separation distance to the obstacle” to be read out when the vehicle has come to a stop, at least the “opening operation direction of the vehicle door” at the vehicle location where the vehicle door will be opened has to match the “opening operation direction of the vehicle door” at the passing location in the past at which the separation distance to the obstacle was measured at the vehicle location. Thus, if the travel course is changed immediately before the vehicle stops in an attempt to avoid a detected obstacle, for example, door opening restriction control may not prevent contact between the vehicle door and the obstacle. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-327215 
     Patent Document 2: Japanese Patent No. 4062989 
     SUMMARY OF THE INVENTION 
     Problems that are to be Solved by the Invention 
     It is an objective of the present invention to provide a door opening restriction device and an opening operation control method for a vehicle door that more effectively prevent contact between the vehicle door and an obstacle even if the travel course is changed immediately before the vehicle stops. 
     Means for Solving the Problem 
     In order to achieve the above objective, an aspect of the present invention provides a door opening restriction device including a non-detection field calculation unit that calculates, based on a sensor output of a proximity sensor arranged in a vehicle, a non-detection field of an obstacle with reference to a location of the proximity sensor; a travel path calculation unit that calculates, based on traveling information on the vehicle, a travel path until the vehicle comes to a stopped state; a non-detection field movement path calculation unit that calculates a movement path of the non-detection field associated with the travel path of the vehicle; a door opening operation path calculation unit that calculates an opening operation path of a vehicle door when the vehicle is in the stopped state; and a door opening restriction unit that restricts an opening operation angle of the vehicle door in a case where the vehicle door may operate to open beyond the movement path of the non-detection field. 
     In order to achieve the above objective, another aspect of the present invention provides an opening operation control method for a vehicle door including calculating, based on a sensor output of a proximity sensor arranged in a vehicle, a non-detection field of an obstacle with reference to a location of the proximity sensor; calculating, based on traveling information on the vehicle, a travel path until the vehicle comes to a stopped state; calculating a movement path of the non-detection field associated with the travel path of the vehicle; calculating an opening operation path of a vehicle door when the vehicle is in the stopped state; and restricting an opening operation angle of the vehicle door in a case where the vehicle door may operate to open beyond the movement path of the non-detection field. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing a vehicle. 
         FIG. 2  is a schematic configuration diagram of a door opening restriction device. 
         FIG. 3  is a diagram showing an opening operation angle and an opening operation path of a vehicle door. 
         FIG. 4  is a diagram showing a detectable area of an obstacle formed by a corner sensor (proximity sensor) and obstacle detection fields, which are partitioned in accordance with the proximity distance of the obstacle. 
         FIG. 5  is a control block diagram of the door opening restriction device. 
         FIG. 6  is a flowchart showing a procedure of a door opening restriction operation. 
         FIG. 7  is a flowchart showing a procedure of door opening restriction control. 
         FIG. 8  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 9  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 10  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 11  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 12  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 13  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 14  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 15  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 16  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 17  is a diagram illustrating an operation of the door opening restriction device. 
         FIG. 18  is a diagram illustrating another example of a non-detection field calculation. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     In the following, a door opening restriction device according to one embodiment of the present invention will be described with reference to the drawings. 
     As shown in  FIGS. 1 and 2 , a vehicle  1  includes four vehicle doors  10  ( 10   a  to  10   d ) that each open and close a door opening  3  formed on a side of a vehicle body  2 . The vehicle  1  is a four-door sedan automobile. Each vehicle door  10  is a swing door arranged at a position corresponding to each of the right and left seats in the front and rear of the passenger compartment. 
     A front end  11  of each vehicle door  10  is supported by the vehicle body  2  via a hinge  12 . The door opening  3  of the vehicle  1  is opened or closed when each vehicle door  10  rotates on the hinge  12 . 
     As shown in  FIG. 2 , each vehicle door  10  includes a door check device  20 . The door check device  20  restricts an opening operation angle θ of each vehicle door  10 . In other words, the door check device  20  prevents each vehicle  10  from opening beyond a preset restricted angle. 
     Specifically, as shown in  FIGS. 2 and 3 , the vehicle  1  is designed such that the opening operation angle θ of each vehicle door  10  in a full open state is equal to a predetermined angle (full open angle θ 0 ). Further, the door check device  20  is configured to restrict the opening operation angle θ of the vehicle door  10  including the door check device  20  within a first restricted angle θ 1  smaller than the full open angle θ 0  or within a second restricted angle θ 2  smaller than the first restricted angle θ 1 . The actuation of each door check device  20  is controlled by a door ECU  21 . 
     More specifically, as shown in  FIG. 2 , the door ECU  21  obtains traveling information on the vehicle  1  via an in-vehicle network  22 . That is, the door ECU  21  obtains, as a traveling state of the vehicle  1 , a vehicle speed V (wheel speed Vw) detected by a vehicle speed sensor  23  and a steering angle As of the vehicle  1  detected by a steering angle sensor  24  included in the steering device (not shown). The door ECU  21  also obtains an ignition signal Sig and a shift position signal Ssp of the vehicle  1  via the in-vehicle network  22 . Further, the door ECU  21  detects the traveling state of the vehicle  1  based on the obtained traveling information (V, Vw, As) and control signals (Sig, Ssp). The door ECU  21  controls the actuation of each door check device  20  in accordance with the detected traveling state of the vehicle  1 . 
     As shown in  FIGS. 1 and 4 , the vehicle  1  includes corner sensors  30  ( 30   a  to  30   d ) for detecting proximity of an obstacle X to each corner  25  at respective corners  25  ( 25   a  to  25   d ) of the vehicle body  2 . 
     As shown in  FIG. 2 , each of the corner sensors  30  employs a radio-wave, electrostatic capacitance, or ultrasonic proximity sensor  40 , for example. A sensor output Sx of each corner sensor  30  is input to a body ECU  41 . The body ECU  41  detects a proximity distance r of the obstacle X to each corner  25  of the vehicle body  2  on the basis of the sensor output Sx of the corner sensor  30 . The body ECU  41  issues a warning indicative that the vehicle  1  is in proximity to the obstacle X on the basis of the proximity distance r of the detected obstacle X. 
     More specifically, as shown in  FIG. 4 , the body ECU  41  partitions the detectable area of the obstacle X formed by each corner sensor  30  into obstacle detection fields (α 1  to α 4 ) in accordance with the proximity distance r of the obstacle X to the corner  25 . That is, the body ECU  41  defines an area with reference to (starting from) each corner  25  of the vehicle body  2  up to a first proximity distance r 1  as a first obstacle detection field α 1 . Further, the body ECU  41  defines an area beyond the first proximity distance r 1  up to a second proximity distance r 2  as a second obstacle detection field α 2 . Further, the body ECU  41  defines an area beyond the second proximity distance r 2  up to a third proximity distance r 3  as a third obstacle detection field α 3 . Further, the body ECU  41  defines an area beyond the third proximity distance r 3  as a fourth obstacle detection field α 4 . 
     If the body ECU  41  detects the obstacle X in the obstacle detection fields (α 1  to α 3 ) in or inside the third obstacle detection field α 3 , a loudspeaker (not shown) in the passenger compartment issues an alarm sound at predetermined intervals. In other words, if the obstacle X is present in the fourth obstacle detection field α 4 , the body ECU  41  does not issue the warning. Further, in proportion as the obstacle detection field where the obstacle X is detected comes closer to the corner sensor  30 , namely, the corner  25  of the vehicle body  2 , the body ECU  41  shortens the intervals of the alarm sound to be output and increases the volume of the alarm sound. This will urge the driver to operate in an attempt to avoid the obstacle X. 
     As shown in  FIG. 2 , the door ECU  21  obtains a sensor output Sx of each corner sensor  30  in a similar manner. Specifically, the door ECU  21  obtains the sensor output Sx of each corner sensor  30  from the body ECU  41  via the in-vehicle network  22 . In particular, the door ECU  21  obtains a proximity distance r to the obstacle X indicated in the sensor output Sx. Further, the door ECU  21  controls the actuation of the door check device  20  of each vehicle door  10  based on the obtained sensor output Sx of each corner sensor  30 . With the above-mentioned structure, the vehicle  1  includes a door opening restriction device  50  configured to restrict the opening operation angle θ of the vehicle door  10  in order to prevent contact with the obstacle X in proximity to the vehicle  1 . 
     More specifically, as shown in  FIG. 5 , the door ECU  21  includes a non-detection field calculation unit  51  and a travel path calculation unit  52 . The non-detection field calculation unit  51  calculates, based on the proximity distance r of the obstacle X indicated in the obtained sensor output Sx, a non-detection field Rnd of the obstacle X with reference to the location of each corner sensor  30 , namely, the corner  25  of the vehicle body  2 . The travel path calculation unit  52  calculates a travel path Tvd until the vehicle  1  comes to a stopped state based on the vehicle speed V (wheel speed Vw) and the steering angle As obtained as traveling information on the vehicle  1 . The door ECU  21  also includes a non-detection field movement path calculation unit  53 , a door opening operation path calculation unit  54 , and a door opening restriction calculation unit  55 . The non-detection field movement path calculation unit  53  calculates a movement path Trnd of the non-detection field Rnd associated with the travel path Tvd of the vehicle  1 . The door opening operation path calculation unit  54  calculates an opening operation path Tdr of the vehicle door  10  when the vehicle  1  is in a stopped state. The door opening restriction calculation unit  55  generates, based on the calculation results of the non-detection field movement path calculation unit  53  and the door opening operation path calculation unit  54 , a control signal Sc of the door check device  20  in order to restrict the opening operation angle θ of the vehicle door  10  if the vehicle door  10  may operate to open beyond the movement path Trnd of the non-detection field Rnd. 
     Specifically, if the obstacle X is detected based on the sensor output Sx of the corner sensor  30 , the non-detection field calculation unit  51  sets the inside of the proximity distance r of the detected obstacle X as the non-detection field Rnd of the obstacle X, namely, an area where the obstacle X is not detected. In contrast, if the proximity of the obstacle X is not detected from the sensor output Sx of the corner sensor  30 , the non-detection field calculation unit  51  sets, as the non-detection field Rnd of the obstacle X, the inside of a predetermined distance (rx) in which detection accuracy of the corner sensor  30  is ensured. 
     Each of the control blocks ( 51  to  55 ) is implemented by a computer program executed by an information processing device (a microcomputer and a memory) constituting the door ECU  21 . In other words, the travel path calculation unit  52  establishes a vehicle model (such as a two-wheel vehicle model) based on the vehicle speed V (wheel speed Vw) and the steering angle As obtained as traveling information on the vehicle  1 . The travel path calculation unit  52  develops the travel path Tvd of the vehicle  1  obtained from the vehicle model on a virtual space  60  formed in a storage area  21   a  of the door ECU  21  (see  FIG. 2 ). Further, the non-detection field movement path calculation unit  53  associates the calculation result of the non-detection field calculation unit  51 , namely, the non-detection field Rnd with the travel path Tvd of the vehicle  1  and continuously develops them on the virtual space  60 . As a result, the movement path Trnd of the non-detection field Rnd extending along the travel path Tvd of the vehicle  1  is developed in the virtual space  60 . 
     Further, the door opening operation path calculation unit  54  holds, as opening operation information on each vehicle door  10 , the length and the full open angle θ 0  of the vehicle door  10  in the longitudinal direction of the vehicle and the first and second restricted angles θ 1  and θ 2  for the door check device  20 . Further, the door opening operation path calculation unit  54  associates the opening operation path Tdr (see  FIG. 3 , Tdr 0  to Tdr 2 ) having three stages calculated based on the opening operation information on each vehicle door  10  with the travel path Tvd of the vehicle  1  and develops them in the virtual space  60 . The door opening restriction calculation unit  55  determines whether the vehicle door  10  may operate to open beyond the movement path Trnd of the non-detection field Rnd by monitoring the overlapping between the movement path Trnd of the non-detection field Rnd and the opening operation path Tdr of the vehicle door  10  developed in the virtual space  60 . 
     Specifically, as shown in  FIG. 3  and the flowchart of  FIG. 6 , the door opening restriction calculation unit  55  first determines whether the opening operation path Tdr when the vehicle door  10  is operated to open up to the full open angle θ 0 , namely, the full open path Tdr 0  stays within the movement path Trnd of the non-detection field Rnd (Step  101 ). If the full open path Tdr 0  stays within the movement path Trnd of the non-detection field Rnd (YES in Step  101 ), the door opening restriction calculation unit  55  generates a control signal Sc indicative that the door check device  20  will not restrict the opening operation angle θ (Step  102 ). 
     If the full open path Tdr 0  of the vehicle door  10  exceeds the movement path Trnd of the non-detection field Rnd (NO in Step  101 ), the door ECU  21  determines whether a first restricted path Tdr 1  when the opening operation angle θ is restricted to the first restricted angle θ 1  stays within the movement path Trnd of the non-detection field Rnd (Step  103 ). If the first restricted path Tdr 1  stays within the movement path Trnd of the non-detection field Rnd (YES in Step  103 ), the door ECU  21  generates a control signal Sc to control the actuation of the door check device  20  such that the opening operation angle θ of the vehicle door  10  is restricted to the first restricted angle θ 1  (first restriction on the opening operation angle, Step  104 ). 
     If the first restricted path Tdr 1  of the vehicle door  10  exceeds the movement path Trnd of the non-detection field Rnd (NO in Step  103 ), the door ECU  21  determines whether a second restricted path Tdr 2  when the opening operation angle θ is restricted to the second restricted angle θ 2  stays within the movement path Trnd of the non-detection field Rnd (Step  105 ). If the second restricted path Tdr 2  stays within the movement path Trnd of the non-detection field Rnd (YES in Step  105 ), the door ECU  21  generates a control signal Sc to control the actuation of the door check device  20  such that the opening operation angle θ of the vehicle door  10  is restricted to the second restricted angle  82  (second restriction on the opening operation angle, Step  106 ). 
     Even if the second restricted path Tdr 2  of the vehicle door  10  exceeds the movement path Trnd of the non-detection field Rnd (NO in Step  105 ), the door ECU  21  generates the control signal Sc to control the actuation of the door check device  20  such that the opening operation angle θ of the vehicle door  10  is restricted to the second restricted angle θ 2 . In addition to the restriction control of door opening, the door ECU  21  issues a warning indicative that the vehicle door  10  may contact the obstacle X in proximity to the vehicle  1  upon opening operation of the vehicle door  10  (second restriction on the opening operation angle and issue of warning, Step  107 ). 
     The door ECU  21  activates a loudspeaker  65  (see  FIG. 2 ) arranged in the passenger compartment, for example, inside the vehicle door  10  to issue a warning such as an alarm sound or a voice. In this manner, the door opening restriction device  50  calls attention of the occupant who opens the vehicle door  10 . 
     More specifically, as shown in the flowchart of  FIG. 7 , the door ECU  21  in door opening restriction control first determines whether the vehicle speed V is equal to or less than a predetermined speed V 1  (Step  201 ). The predetermined speed V 1  is set to about 10 km/h, for example. If the vehicle speed V is equal to or less than the predetermined speed V 1  (V≤V 1 , YES in Step  201 ), the door ECU  21  performs non-detection field calculation, travel path calculation, and non-detection field movement path calculation based on a determination that the vehicle  1  is in a traveling state immediately before a stop (Steps  202  to  204 ). 
     Next, the door ECU  21  determines whether the vehicle speed V is equal to or more than a predetermined speed V 2 , which is faster than the predetermined speed V 1  (Step  205 ). If the vehicle speed V is less than the predetermined speed V 2  (steV&lt;V 2 , NO in Step  205 ), the door ECU  21  determines whether the vehicle  1  is in a stopped state (Step  206 ). Specifically, of those signals obtained via the in-vehicle network  22  as described above, if the ignition signal Sig of the vehicle  1  indicates OFF and the shift position signal Ssp indicates the parking position, the door ECU  21  determines that the vehicle  1  is in the stopped state. In Step  206 , if the vehicle  1  is not determined to be in the stopped state (NO in Step  206 ), the door ECU  21  repeats processing in Steps  202  to  205  and  206 . If the door ECU  21  determines that the vehicle  1  is in the stopped state (YES in Step  206 ), the door ECU  21  performs the door opening operation path calculation (Step  207 ) and door opening restriction control calculation (Step  208 ). 
     In Step  205 , if the vehicle speed V is determined to be equal to or more than a predetermined speed V 2  (V V 2 , YES in Step  205 ), the door ECU  21  discards all the calculation results in Steps  202  to  204  that have been performed (Step  209 ). Then the door ECU  21  performs each process from Step  201  again. 
     In the following, the operation of the door opening restriction device  50  will be described. 
     As shown in  FIG. 8 , if there is no detectable obstacle X in the vicinity of the vehicle  1 , the non-detection field Rnd of the obstacle X is equal to an area within a predetermined distance rx with reference to the corner  25  ( 25   a ) of the vehicle body  2  where the corner sensor  30  ( 30   a ) is arranged. The movement path Trnd of the non-detection field Rnd extends along the travel path Tvd of the vehicle  1  in the travel direction of the vehicle  1 . 
     In the example shown in  FIG. 8  and the examples in  FIGS. 9 to 17  to be referenced below, the vehicle  1  is in a forward movement state immediately before a stop. In each of the drawings, the travel path Tvd of the vehicle  1  shown by a thick long dashed double-short dashed line corresponds to passing points of the center of the front end of the vehicle  1 . In each of the drawings, a thick long dashed short dashed line represents the outer edge of the movement path Trnd of the non-detection field Rnd. 
     For illustrative purposes, each of the drawings has the opening operation path Tdr of the vehicle door  10  ( 10   a ) when the vehicle  1  stops at a location shown in each drawing. As shown in  FIG. 8 , the door opening restriction device  50  is configured such that the opening operation path Tdr of the vehicle door  10  stays within the movement path Trnd of the non-detection field Rnd if the non-detection field Rnd defined by the predetermined distance rx is maintained, namely, if there is no detectable obstacle X in the vicinity of the vehicle  1 . 
     In the examples shown in  FIGS. 9 and 10 , with the forward movement of the vehicle  1 , the obstacle X approaches the corner  25  ( 25   a ) at the left end in the front of the vehicle where the corner sensor  30  ( 30   a ) is arranged. In this case, as the proximity distance r of the obstacle X detected based on a sensor output Sx of the corner sensor  30  becomes smaller, the non-detection field Rnd of the obstacle X is gradually reduced. Accordingly, the movement path Trnd of the non-detection field Rnd extends in the travel direction of the vehicle  1  to trace the contour of the obstacle X facing the vehicle  1 . 
     In the example shown in  FIG. 10 , the obstacle X is in proximity, up to the second obstacle detection field α 2 , to the corner  25  ( 25   a ) where the corner sensor  30  ( 30   a ) is arranged. In response to a warning using an alarm sound issued in this case, the driver changes the travel course of the vehicle  1  in an attempt to avoid the obstacle X as shown in  FIGS. 11 to 17 . 
     Specifically, as shown in  FIGS. 11 and 12 , the driver turns the vehicle  1  to the right (clockwise in each drawing) in the travel direction until the alarm sound ends, namely, until the obstacle X goes out of the third obstacle detection field α 3 . Further, as shown in  FIGS. 12 to 14 , the driver maintains the travel direction of the vehicle  1  for a while after the obstacle X goes out of the third obstacle detection field α 3  and the alarm sound ends. Then, as shown in  FIGS. 14 to 17 , the driver turns the vehicle  1  to the left in the travel direction (counterclockwise in each drawing). In this manner, the driver returns the travel course of the vehicle  1  to the travel direction (left in each drawing) maintained before the series of the above operations to avoid the obstacle. 
     In other words, as shown in  FIG. 17 , in this example, the travel path Tvd of the vehicle  1  meanders to the right in the travel direction of the vehicle  1  (right in  FIG. 17 ) in a section in which the corner  25  ( 25   a ), where the corner sensor ( 30   a ) is arranged, goes through the vicinity of the obstacle X. However, in this case, as shown in  FIGS. 12 to 17 , as the proximity distance r of the obstacle X detected based on the sensor output Sx of the corner sensor  30  is changed, the non-detection field Rnd is gradually increased or reduced. The door opening restriction device  50  restricts the opening operation angle θ of the vehicle door  10  such that the vehicle door  10  ( 10   a ) upon opening operation does not touch the obstacle X by extending the movement path Trnd of the non-detection field Rnd in the travel direction of the vehicle  1  to trace the contour of the obstacle X even if the travel course of the vehicle  1  is changed as mentioned above. 
     Specifically, if the vehicle  1  stops at the location shown in  FIG. 14 , the opening operation angle θ of the vehicle door  10  ( 10   a ) located in the vicinity of the obstacle X is restricted to the first restricted angle  81  (see  FIG. 3 ). If the vehicle  1  stops at the location shown in  FIG. 15 , the opening operation angle θ of the vehicle door  10  ( 10   a ) is restricted to the second restricted angle θ 2  (see  FIG. 3 ). 
     If the vehicle  1  stops at the location shown in  FIG. 16 , the opening operation angle θ of the vehicle door  10  ( 10   a ) is restricted to the second restricted angle θ 2  and a warning indicative that the vehicle door  10  ( 10   a ) upon opening operation may contact the obstacle X is issued. As shown in  FIG. 17 , if the vehicle  1  stops at the location where the vehicle door  10  ( 10   a ) has run past the vicinity of the obstacle X, the restriction on the opening operation angle of the vehicle door  10  is cancelled. 
     As described above, the present embodiment provides the following advantages. 
     (1) The door ECU  21  includes the non-detection field calculation unit  51  that calculates the non-detection field Rnd of the obstacle X with reference to the location of the proximity sensor  40  (corner sensor  30 ) arranged in the vehicle  1 , and the travel path calculation unit  52  that calculates the travel path Tvd until the vehicle  1  comes to the stopped state. Further, the door ECU  21  includes the non-detection field movement path calculation unit  53  that calculates the movement path Trnd of the non-detection field Rnd associated with the travel path Tvd of the vehicle  1 , and the door opening operation path calculation unit  54  that calculates the opening operation path Tdr of the vehicle door  10  when the vehicle  1  is in the stopped state. Further, the door ECU  21  includes the door opening restriction calculation unit  55  that generates the control signal Sc of the door check device  20  in order to restrict the opening operation angle θ of the vehicle door  10  if the vehicle door  10  may operate to open beyond the movement path Trnd of the non-detection field Rnd. 
     With the above-mentioned structure, even if the travel course of the vehicle  1  is changed immediately before the vehicle  1  stops, whether the vehicle door  10  upon opening operation may contact the obstacle X in proximity to the vehicle  1  is determined with improved accuracy. Further, the contact between the vehicle door  10  and the obstacle X is prevented more effectively based on this determination result by restricting the opening operation angle θ of the vehicle door  10 . 
     (2) The door opening restriction calculation unit  55  generates the control signal Sc, which indicates that the opening operation angle θ of the vehicle door  10  should be restricted such that the opening operation path Tdr of the vehicle door  10  stays within the movement path Trnd of the non-detection field Rnd. This effectively prevents the contact between the vehicle door  10  and the obstacle X. 
     (3) If the opening operation path Tdr of the vehicle door  10  cannot stay within the movement path Trnd of the non-detection field Rnd by the restriction on the opening operation angle θ, the door opening restriction calculation unit  55  issues a warning indicative that the vehicle door  10  upon opening operation may contact the obstacle X. In this manner, the door opening restriction calculation unit  55  calls attention of the occupant who opens the vehicle door  10  and more effectively prevents the contact between the vehicle door  10  and the obstacle X. 
     The above embodiment may be modified as follows. 
     In the above embodiment, the door opening restriction device is embodied by the door opening restriction device  50 , which restricts the opening operation angle θ of the swing vehicle door  10 , which opens and closes the door opening  3  formed on a side of the vehicle body  2 . However, the embodiment is not limited to this. The type and arrangement of the vehicle door  10  may be changed arbitrarily. For example, the door opening restriction device may be applied to a hatchback rear door arranged in a rear opening of the vehicle. In other words, the non-detection field Rnd of the obstacle X and its movement path Trnd, and the opening operation path Tdr of the vehicle door  10  may be calculated in a three-dimensional space. Further, the door opening restriction device may be applied to a rear-hinged door, a slide door, or a gull-wing door as a vehicle door. 
     In the above embodiment, the corner sensor  30  ( 30   a  to  30   d ) arranged at each corner  25  ( 25   a  to  25   d ) of the vehicle body  2  is used as the proximity sensor  40  for detecting the obstacle X. However, the embodiment is not limited to this. The arrangement of the proximity sensor  40  in the vehicle  1  may be changed arbitrarily. 
     In the above embodiment, if the vehicle  1  is in a traveling state immediately before a stop, the door ECU  21  performs non-detection field calculation, travel path calculation, and non-detection field movement path calculation while the vehicle  1  is traveling (see  FIG. 7 ). However the embodiment is not limited to this. The CU  21  may continuously store the sensor output Sx to be used for the non-detection field calculation and the traveling information (As, Vm) on the vehicle  1  to be used for the travel path calculation. After the vehicle  1  is stopped, the door ECU  21  may perform the non-detection field calculation, the travel path calculation, and the non-detection field movement path calculation based on the stored sensor output Sx and traveling information. 
     In the above embodiment, if the obstacle X is detected based on the sensor output Sx of the corner sensor (proximity sensor  40 ), the non-detection field calculation unit  51  sets the inside of the detected proximity distance r as the non-detection field Rnd of the obstacle X. However, the embodiment is not limited to this. As shown in  FIG. 18 , the non-detection field calculation unit  51  may set the non-detection field Rnd of the obstacle X on the basis of in which of the obstacle detection fields (α 1  to α 3 ) formed by partitioning a detectable area Rd of the obstacle X formed by the proximity sensor  40 , the obstacle X is detected. 
       FIG. 18  shows an example in which the obstacle X is detected in the third obstacle detection field α 3 . In this case, the second obstacle detection field α 2 , which is the outermost obstacle detection field where the obstacle X is not detected, and the inside thereof, namely, the first and second obstacle detection fields α 1  and α 2  are set as the non-detection field Rnd. If the obstacle X is detected in the second obstacle detection field α 2 , the first obstacle detection field α 1  may be set as the non-detection field Rnd. In this case, the body ECU  41  outputting the sensor output Sx to the door ECU  21  constitutes a field partitioning unit, which partitions the detectable area Rd of the obstacle X in accordance with the proximity distance r. 
     With this configuration, even if detection accuracy of the proximity distance r by the proximity sensor is low, the non-detection field Rnd is appropriately set. Even in a case where only limited detection information on the sensor output Sx of the proximity sensor  40 , for example, “in which of the obstacle detection fields (α 1  to α 3 ) the obstacle X is detected” may be obtained, the non-detection field Rnd is appropriately set. 
     Further, in the above-mentioned embodiment, the door ECU  21  obtains the sensor output Sx of each corner sensor  30 , specifically, the proximity distance r of the obstacle X indicated in the sensor output Sx, from the body ECU  41  via the in-vehicle network  22 . However, the embodiment is not limited to this. The door ECU  21  may directly obtain the sensor output Sx of the proximity sensor  40 . 
     In the above-mentioned embodiment, if the ignition signal Sig indicates OFF and the shift position signal Ssp indicates the parking position, the vehicle  1  is determined to be in the stopped state. However, the embodiment is not limited to this. The manner in which the vehicle  1  is determined to be in a stopped state may be changed arbitrarily, for example, by determining based on the vehicle speed V. 
     In the above-mentioned embodiment, the opening operation angle θ of the vehicle door  10  is restricted in three stages ( 80 ,  81 , and  82 ) by the actuation of the door check device  20  controlled by the door ECU  21 . However, the embodiment is not limited to this. The mechanical structure for restricting the opening operation angle θ of the vehicle door  10  may be changed arbitrarily. For example, the opening operation angle θ may be restricted in two stages or multiple stages equal to or more than four. The opening operation angle θ may be restricted without stages to have an arbitrary opening operation angle θ. 
     The door opening restriction device may be embodied by the door opening restriction device  50  that restricts the opening operation angle θ, which may be applied not only to a vehicle door being opened manually but also to a vehicle door operating to open automatically with a driving source. In this case, the opening operation angle θ of the vehicle door may be restricted through control of an actuator that opens and closes the vehicle door, for example.