Patent Publication Number: US-2020291708-A1

Title: Opening and closing body control device for vehicle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2019-048208, filed on Mar. 15, 2019, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     This disclosure relates to an opening and closing body control device for a vehicle. 
     BACKGROUND DISCUSSION 
     JP 2009-108556A (Reference 1) discloses a vehicle including a back door that is operated by a motor, obstacle sensors provided on an outer surface of the back door, and a door control device that controls an operation of the back door. When the obstacle sensors detect that the back door is close to an obstacle during an opening operation of the back door, the door control device stops the back door. Thus, the door control device prevents the back door from coming into contact with the obstacle. 
     In the door control device as described above, when a timing to stop the back door is late, the back door may come into contact with the obstacle. On the other hand, when the timing to stop the back door is early, a convenience of a user may be reduced in that the back door stops at a position far away from the obstacle. For this reason, it is desired to improve a positional accuracy when the door control device as described above stops the back door. 
     Such a situation is not limited to the door control device that controls the operation of the back door, but is generally common to an opening and closing body control device for a vehicle that controls an operation of an opening and closing body such as a power slide door. Thus, a need exists for an opening and closing body control device for a vehicle which is not susceptible to the drawback mentioned above. 
     SUMMARY 
     Hereinafter, means for solving the above problems and effects thereof are described. 
     An opening and closing body control device for a vehicle includes a control unit configured to control an opening and closing body drive device driving an opening and closing body of a vehicle to open and close the opening and closing body based on an operation request; and a detection unit configured to detect an obstacle present around the opening and closing body based on a detection result of an obstacle sensor. The control unit is configured to set an operation speed of the opening and closing body to a first speed when the obstacle is not detected during an operation of the opening and closing body, and set the operation speed of the opening and closing body to a second speed or less, the second speed being lower than the first speed, and causes the opening and closing body to stop at a position where the opening and closing body is close to the obstacle, when the obstacle is detected during the operation of the opening and closing body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a rear portion of a vehicle; 
         FIG. 2  is a top view illustrating a detecting method implemented by obstacle sensors; 
         FIG. 3  is a side view illustrating the detecting method implemented by the obstacle sensors when an opening degree of a back door changes; 
         FIG. 4  is a map for setting an opening speed of the back door; 
         FIG. 5  is a flowchart showing a flow of processing executed by a door control device when starting an opening operation of the back door; 
         FIG. 6  is a flowchart showing a flow of processing executed by the door control device during the opening operation of the back door; 
         FIG. 7  is a timing chart illustrating an effect of the door control device; 
         FIG. 8  is a timing chart illustrating the effect of the door control device; and 
         FIG. 9  is a timing chart illustrating the effect of the door control device. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a vehicle including an opening and closing body control device for a vehicle is described with reference to the drawings. 
     As shown in  FIG. 1 , a vehicle  10  includes a vehicle body  12  in which a door opening  11  is formed in a rear portion, a back door  13  that opens and closes the door opening  11 , and a door lock device  14  that restrains the back door  13  on the vehicle body  12 . The vehicle  10  includes a door drive device  15  that drives the back door  13 , a door lock drive device  16  that drives the door lock device  14 , and a door control device  20  that controls the door drive device  15  and the door lock drive device  16 . 
     In this embodiment, the back door  13  corresponds to an example of an “opening and closing body”, the door drive device  15  corresponds to an example of an “opening and closing body drive device”, and the door control device  20  corresponds to an example of an “opening and closing body control device”. 
     The door opening  11  opens in a rear direction of the vehicle  10 . The door opening  11  has a substantially rectangular shape in which a width direction of the vehicle  10  is a longitudinal direction and an up and down direction of the vehicle  10  is a short-side direction. The door opening  11  is an opening for opening a luggage compartment of the vehicle  10  to an outside of the vehicle. A weather strip (not shown) is disposed along an opening edge of the door opening  11 . 
     The back door  13  is formed in a shape capable of closing the door opening  11 . The back door  13  is rotatably supported on an upper portion of the door opening  11 . A rotation axis of the back door  13  extends in the width direction of the vehicle  10 . Thus, the back door  13  rotates between a fully closed position where the door opening  11  is fully closed and a fully open position where the door opening  11  is fully opened. 
     A plurality of obstacle sensors SE is provided at a lower end of the back door  13 . In the embodiment, four obstacle sensors SE 1  to SE 4  are disposed side by side in the width direction of the vehicle  10 . The obstacle sensors SE detect reflected waves of ultrasonic waves transmitted in a direction intersecting with an outer surface of the back door  13 . When the back door  13  is disposed at the fully closed position, a detection range of the obstacle sensors SE is a region behind the back door  13 . The obstacle sensors SE preferably have a performance of being able to detect an obstacle  30  that is several centimeters to several meters away. Further, the obstacle  30  in the embodiment includes a vehicle different from a host vehicle, a wall and a fence of such as a building and a garage, and a person or an animal in a vicinity of the vehicle  10 . 
     The door drive device  15  is, for example, an actuator that expands and contracts by driving of a motor (not shown). A base end portion of the door drive device  15  is coupled to the vehicle body  12  rotatably about an axis extending in the width direction of the vehicle  10 , and a tip end portion of the door drive device  15  is coupled to the back door  13  rotatably about the axis extending in the width direction of the vehicle  10 . Thus, the door drive device  15  opens the back door  13  by expanding. On the other hand, the door drive device  15  closes the back door  13  by contracting. 
     The door lock device  14  is switched between a restraint state in which the back door  13  located at the fully closed position is restrained to the vehicle body  12  and a release state in which the restraint of the back door  13  located at the fully closed position with respect to the vehicle body  12  is released. In the following description, changing a state in which the door lock device  14  does not restrict the back door  13  to the vehicle body  12  to a state in which the back door  13  is restricted to the vehicle body  12  is also referred to as a “latch operation”, and changing a state in which the door lock device  14  restricts the back door  13  to the vehicle body  12  to a state in which the back door  13  is not restricted to the vehicle body  12  is also referred to as an “unlatch operation”. The door lock drive device  16  unlatches the door lock device  14  by driving the motor (not shown). 
     Next, the door control device  20  is described in detail. 
     The door control device  20  includes a detection unit  21  that detects the obstacle  30  present around the back door  13 , a calculation unit  22  that calculates a distance from the back door  13  to the obstacle  30 , a setting unit  23  that sets a range in which the back door  13  can be opened, and a control unit  24  that controls the door drive device  15  and the door lock drive device  16 . 
     The detection unit  21  detects the obstacle  30  based on detection results of the obstacle sensors SE. The detection unit  21  continuously acquires the detection results of the obstacle sensors SE in a predetermined control cycle. For example, the detection unit  21  repeatedly acquires the detection results of the obstacle sensors SE not only before an opening operation of the back door  13  is started but also during the opening operation of the back door  13 . 
     As shown in  FIG. 2 , the detection unit  21  causes one obstacle sensor SE among the plurality of obstacle sensors SE to function as a transmitter, and causes the other three obstacle sensors SE to function as receivers. Hereinafter, an obstacle detection method when a first obstacle sensor SE 1  is set as the transmitter and a second obstacle sensor SE 2 , a third obstacle sensor SE 3 , and a fourth obstacle sensor SE 4  are set as the receivers in a situation where the back door  13  is located at the fully closed position is to be described. 
     When the obstacle  30  is not present behind the back door  13 , ultrasonic waves transmitted from the first obstacle sensor SE 1  are not reflected. That is, the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4  do not receive the reflected waves of the ultrasonic waves transmitted from the first obstacle sensor SE 1 . In this case, based on the detection results of the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4 , the detection unit  21  can detect that the obstacle  30  is not present behind the back door  13 . 
     On the other hand, when the obstacle  30  is present behind the back door  13 , the ultrasonic waves transmitted from the first obstacle sensor SE 1  are reflected by the obstacle  30 . That is, the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4  receive the reflected waves of the ultrasonic waves transmitted from the first obstacle sensor SE 1 . In this case, based on the detection results of the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4 , the detection unit  21  can detect that the obstacle  30  is present behind the back door  13 . 
     As an example, when an intensity of the reflected waves received by the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4  is equal to or greater than a predetermined threshold, the detection unit  21  may determine that the obstacle  30  is present behind the back door  13 . 
     In the obstacle detection method described above, the first obstacle sensor SE 1  is set as the transmitter, the second obstacle sensor SE 2 , the third obstacle sensor SE 3 , and the fourth obstacle sensor SE 4  are set as the receivers, but an obstacle sensor SE different from the first obstacle sensor SE 1  may be set as the transmitter, and the other obstacle sensors SE may be set as the receivers. The detection unit  21  may perform the obstacle detection while changing a combination of the obstacle sensor SE serving as the transmitter and the obstacle sensors SE serving as the receivers. When the obstacle detection is performed by switching the obstacle sensors SE serving as the transmitter and the receivers, an accuracy of the obstacle detection is improved. 
     In the following description, among obstacles  30  to be detected by the detection unit  21 , the obstacle  30  detected before the opening operation of the back door  13  disposed in the fully closed position is started is also referred to as a “first obstacle”, and the obstacle  30  detected after the opening operation of the back door  13  is started is also referred to as a “second obstacle”. 
     When the obstacle  30  is detected behind the back door  13 , the calculation unit  22  calculates a distance from the back door  13  to the obstacle  30 . As shown in  FIG. 2 , when the second obstacle sensor SE 2  detects a reflected wave of an ultrasonic wave transmitted from the first obstacle sensor SE 1 , a distance from the back door  13  to the obstacle  30  is calculated according to time from when the first obstacle sensor SE 1  transmits the ultrasonic wave to when the second obstacle sensor SE 2  receives the reflected wave. In this embodiment, the “distance from the back door  13  to the obstacle  30 ” is a distance indicated by a dimension line in  FIG. 2 , and is a distance in a front-rear direction of the vehicle  10  from an installation location of the obstacle sensor SE in the back door  13  to the obstacle  30 . In the following description, the distance from the back door  13  to the obstacle  30  calculated by the calculation unit  22  is also referred to as a “measurement distance”. 
     When a first obstacle is detected behind the back door  13 , the setting unit  23  sets a “target stop position” which is a position for opening the back door  13  in a range in which the back door  13  does not contact the first obstacle. The target stop position is a position of the back door  13  when a distance from the back door  13  to the first obstacle is a “first determination distance Dth 1 ” indicating that the first obstacle is close. The target stop position may be geometrically determined based on the distance from the back door  13  to the first obstacle and a turning radius of the back door  13 . The setting unit  23  may manage the target stop position as an opening degree of the back door  13  based on the fully closed position. The first determination distance Dth 1  may be a variable value appropriately set by a user, or may be a preset fixed value. As an example, the first determination distance Dth 1  may be set to a distance of about 50 mm. 
     When an operation request of the back door  13  is input, the control unit  24  causes the back door  13  to open and close. The operation request is a signal input to the door control device  20  when the user operates a switch provided in vicinity of a driver seat or on the back door  13 , or when the user operates a button provided on an electronic key. 
     Here, as shown in  FIG. 3 , when the detection unit  21  detects the obstacle  30  based on a detection result of the ultrasonic wave reflected by the obstacle  30 , the following problem arises. Specifically, as indicated by a solid line in  FIG. 3 , when the back door  13  is located at the fully closed position, the detection unit  21  can detect the first obstacle based on the detection result of the ultrasonic wave reflected normally. However, as indicated by a two-dot chain line in  FIG. 3 , when the opening degree of the back door  13  increases, the detection unit  21  may not be able to detect the first obstacle since a reflection direction of the ultrasonic wave does not face the obstacle sensors SE. In other words, the detection unit  21  may lose sight of the first obstacle, which can be detected when the opening degree of the back door  13  is small, since the opening degree of the back door  13  increases. 
     Therefore, in this embodiment, when the operation request for opening the back door  13  is input in a situation where the target stop position is set, the control unit  24  causes the back door  13  to open toward the target stop position. Therefore, even when the first obstacle is not detected, the control unit  24  can cause the back door  13  to open toward the target stop position which is a position in front of the first obstacle. 
     When a second obstacle closer to the back door  13  than the first obstacle is detected while the back door  13  is being opened toward the target stop position, the control unit  24  stops the back door  13  at a position in front of the second obstacle. Specifically, when a distance from the back door  13  to the second obstacle is the first determination distance Dth 1 , the control unit  24  stops the back door  13 . 
     On the other hand, when the operation request for opening the back door  13  is input in a situation where the target stop position is not set, the control unit  24  causes the back door  13  to open toward the fully open position. In this case, when the second obstacle is detected during the opening operation of the back door  13 , the control unit  24  also stops the back door  13  at the position in front of the second obstacle. 
     Further, the control unit  24  changes an opening speed as an operation speed of the back door  13  depending on whether or not the obstacle  30  is detected. In this embodiment, the opening speed of the back door  13  is a moving speed of a tip end portion of the back door  13 . When the obstacle  30  is not detected, the control unit  24  sets the opening speed of the back door  13  to a first speed V 1  that is a relatively high. On the other hand, when the obstacle  30  is detected, the control unit  24  sets the opening speed of the back door  13  to a second speed V 2  lower than the first speed V 1  or less. As an example, the first speed V 1  may be 300 to 400 mm/sec, and the second speed V 2  may be 100 to 200 mm/sec. 
       FIG. 4  is a map for setting the opening speed of the back door  13  when the obstacle  30  is detected. In the map shown in  FIG. 4 , a horizontal axis indicates the distance from the back door  13  to the obstacle  30 , and a vertical axis indicates the opening speed of the back door  13 . When the distance from the back door  13  to the obstacle  30  is equal to or greater than a second determination distance Dth 2 , the opening speed of the back door  13  is set to the second speed V 2  less than the first speed V 1 . When the distance from the back door  13  to the obstacle  30  is less than the second determination distance Dth 2 , the opening speed of the back door  13  is gradually reduced as the distance decreases. 
     In the map shown in  FIG. 4 , when the distance from the back door  13  to the obstacle  30  is the first determination distance Dth 1 , the opening speed of the back door  13  is “0”, but when the distance from the back door  13  to the obstacle  30  is the first determination distance Dth 1 , the opening speed of the back door  13  may be less than the second speed V 2  and greater than “0”. The obstacle  30  mentioned here includes both the first obstacle and the second obstacle. That is, when the first obstacle is detected, the control unit  24  sets the opening speed of the back door  13  to the second speed V 2  or less from a timing at which the opening operation of the back door  13  is started. On the other hand, when the second obstacle is detected during the opening operation of the back door  13 , the control unit  24  sets the opening speed of the back door  13  to the second speed V 2  or less from a timing at which the second obstacle is detected. 
     Next, with reference to a flowchart shown in  FIG. 5 , a flow of processing executed by the door control device  20 , when the operation request for opening the back door  13  is input in a situation where the back door  13  is disposed at the fully closed position, is to be described. 
     As shown in  FIG. 5 , when the operation request for opening the back door  13  is input, the door control device  20  acquires the detection results of the obstacle sensors SE (step S 11 ). Subsequently, based on the detection results of the obstacle sensors SE, the door control device  20  determines that whether or not the first obstacle is detected behind the back door  13  (step S 12 ). When the first obstacle is not detected (step S 12 : NO), the door control device  20  turns off a flag FLG (step S 13 ). The flag FLG is a flag indicating whether or not the first obstacle is detected behind the back door  13 . When the first obstacle is detected behind the back door  13 , the flag FLG is turned on, and when the first obstacle is not detected behind the back door  13 , the flag FLG is turned off. 
     After setting the flag FLG, the door control device  20  sets the opening speed of the back door  13  to the first speed V 1  that is relatively high (step S 14 ). Then, the door control device  20  controls the door lock drive device  16  to unlatch the door lock device  14  (step S 15 ). Subsequently, the door control device  20  controls the door drive device  15  to start the opening operation of the back door  13  (step S 16 ). Thereafter, the door control device  20  ends the processing. 
     In step S 12 , when the first obstacle is detected behind the back door  13  (step S 12 : YES), the door control device  20  calculates a first measurement distance Dm 1  which is a measurement distance from the back door  13  to the first obstacle (step S 17 ). Subsequently, the door control device  20  determines whether or not the first measurement distance Dm 1  is less than a third determination distance Dth 3  (step S 18 ). The third determination distance Dth 3  is a distance for determining whether or not the distance from the back door  13  to the first obstacle is very short. As an example, the third determination distance Dth 3  is set to a length of about 400 mm. 
     When the first measurement distance Dm 1  is less than the third determination distance Dth 3  (step S 18 : YES), the door control device  20  controls the door lock drive device  16  to unlatch the door lock device  14  (step S 19 ). Thereafter, the door control device  20  ends the processing. Here, when the measurement distance is less than the third determination distance Dth 3 , even if the back door  13  is opened to the target stop position, the opening degree of the back door  13  can be only an opening degree at which a luggage cannot be loaded and unloaded. Therefore, when there is no point in opening the back door  13 , the door control device  20  restricts the opening operation of the back door  13 . On the other hand, for a purpose of notifying the user that an operation request from the user is input, the door control device  20  unlatches the door lock device  14 . 
     When the first measurement distance Dm 1  is equal to or greater than the third determination distance Dth 3  (step S 18 : NO), the door control device  20  sets the target stop position for stopping the back door  13  in front of the first obstacle (step S 20 ). Then, the door control device  20  turns on the flag FLG (step S 21 ), and sets the opening speed of the back door  13  to the second speed V 2  at a relatively low speed (step S 22 ). After setting the speed of the back door  13 , the door control device  20  proceeds the processing to step S 15 . 
     According to the flowchart shown in  FIG. 5 , whether when the first measurement distance Dm 1  is equal to or greater than the third determination distance Dth 3 , or when the first measurement distance Dm 1  is less than the third determination distance Dth 3 , the door control device  20  unlatches the door lock device  14  (steps S 15  and S 19 ). In this regard, it can be said that when there is an operation request, the door control device  20  releases the restraint of the back door  13  by the door lock device  14  regardless of the first measurement distance Dm 1  which is the measurement distance from the back door  13  to the first obstacle. 
     On the other hand, the door control device  20  restricts the opening operation of the back door  13  when the first measurement distance Dm 1  is less than the third determination distance Dth 3 , and permits the opening operation of the back door  13  when the first measurement distance Dm 1  is equal to or greater than the third determination distance Dth 3  (step S 16 ). In this regard, it can be said that the door control device  20  restricts the opening operation of the back door  13  when the first measurement distance Dm 1  is short, and permits the opening operation of the back door  13  when the first measurement distance Dm 1  is long. 
     Next, with reference to a flowchart shown in  FIG. 6 , a flow of a processing executed by the door control device  20  during the opening operation of the back door  13  is to be described. 
     As shown in  FIG. 6 , the door control device  20  acquires a current position of the back door  13  based on a movement amount of the back door  13  after the opening operation of the back door  13  is started (step S 31 ). Subsequently, the door control device  20  acquires the detection results of the obstacle sensors SE (step S 32 ), and determines that whether or not the second obstacle different from the first obstacle is detected behind the back door  13  based on the detection results of the obstacle sensors SE (step S 33 ). When the second obstacle is not detected (step S 33 : NO), the door control device  20  determines that whether or not the flag FLG is ON (step S 34 ). 
     When the flag FLG is OFF (step S 34 : NO), that is, when the first obstacle is not detected when the opening operation of the back door  13  is started, the door control device  20  determines that whether or not the back door  13  reaches the fully open position (step S 35 ). When the back door  13  does not reach the fully open position (step S 35 : NO), the door control device  20  proceeds to step S 31 . On the other hand, when the back door  13  reaches the fully open position (step S 35 : YES), the door control device  20  controls the door drive device  15  to stop the back door  13  (step S 36 ). Thereafter, the door control device  20  ends the processing. 
     In step S 34 , when the flag FLG is ON (step S 34 : YES), that is, when the first obstacle is detected when the opening operation of the back door  13  is started, the door control device  20  calculates a “first estimation distance Dc 1 ” which is the distance from the back door  13  to the first obstacle based on the current position of the back door  13  (step S 37 ). The first estimation distance Dc 1  is geometrically calculated based on the first measurement distance Dm 1  before the operation of the back door  13  is started and the current position of the back door  13 . 
     Then, the door control device  20  sets the opening speed of the back door  13  with reference to the map shown in  FIG. 4  (step S 38 ). The distance from the back door  13  to the first obstacle used in the setting of the opening speed of the back door  13  is not the first measurement distance Dm 1  calculated based on the detection results of the obstacle sensors SE but is the first estimation distance Dc 1  calculated in step S 37 . Thus, when the obstacle sensors SE cannot detect the first obstacle, the opening speed is prevented from being set in accordance with an erroneous first measurement distance Dm 1 . 
     Then, the door control device  20  determines that whether or not the back door  13  reaches the target stop position (step S 39 ). When the back door  13  does not reach the target stop position (step S 39 : NO), the door control device  20  proceeds to step S 31 . On the other hand, when the back door  13  reaches the target stop position (step S 39 : YES), the door control device  20  proceeds to step S 36 . 
     In step S 33 , when the second obstacle is detected (step S 33 : YES), the door control device  20  determines that whether or not the flag FLG is on (step S 40 ). When the flag FLG is off (step S 40 : NO), that is, when the first obstacle is not detected when the opening operation of the back door  13  is started, the door control device  20  calculates a second measurement distance Dm 2  which is a measurement distance from the back door  13  to the second obstacle (step S 41 ). Subsequently, the door control device  20  sets the opening speed of the back door  13  according to the second measurement distance Dm 2  with reference to the map shown in  FIG. 4  (step S 42 ). 
     Then, the door control device  20  determines that whether or not the second measurement distance Dm 2  is less than the first determination distance Dth 1  (step S 43 ). When the measurement distance from the back door  13  to the second obstacle is equal to or greater than the first determination distance Dth 1  (step S 43 : NO), that is, when the back door  13  is not close to the second obstacle, the door control device  20  proceeds to step S 31 . On the other hand, when the measurement distance from the back door  13  to the second obstacle is less than the first determination distance Dth 1  (step S 43 : YES), that is, when the back door  13  is close to the second obstacle, the door control device  20  proceeds to step S 36 . 
     In step S 40 , when the flag FLG is ON (step S 40 : YES), that is, when the first obstacle is detected when the opening operation of the back door  13  is started, the door control device  20  calculates the first estimation distance Dc 1  (step S 44 ) and calculates the second measurement distance Dm 2  (step S 45 ). Subsequently, the door control device  20  determines that whether or not the first estimation distance Dc 1  is less than the second measurement distance Dm 2  (step S 46 ). 
     When the first estimation distance Dc 1  is less than the second measurement distance Dm 2  (step S 46 : YES), that is, when the first obstacle is located closer than the second obstacle when viewed from the back door  13 , the door control device  20  proceeds to step S 38 . On the other hand, when the first estimation distance Dc 1  is equal to or greater than the second measurement distance Dm 2  (step S 46 : NO), that is, when the second obstacle is located closer than the first obstacle when viewed from the back door  13 , the door control device  20  proceeds to step S 42 . Thus, according to a determination in step S 46 , an opening speed is set according to a distance from the back door  13  to a closer obstacle of the first obstacle and the second obstacle. 
     Effects of this embodiment are to be described. 
     A transition of the opening speed of the back door  13  and a transition of the position of the back door  13  when the back door  13  is opened from the fully closed position are to be described with reference to  FIGS. 7 to 9 . In  FIGS. 7 to 9 , a first contact position indicates a position at which the back door  13  is in contact with the first obstacle, and in  FIGS. 8 and 9 , a second contact position indicates a position at which the back door  13  is in contact with the second obstacle. In other words, the first contact position indicates a position of the first obstacle, and the second contact position indicates a position of the second obstacle. 
     In  FIG. 7 , a case where the obstacle  30  is not detected before or during the opening operation is indicated by solid lines, and a case where the first obstacle is detected before the opening operation but the second obstacle is not detected during the opening operation is indicated by dash-dot lines. 
     As indicated by the solid lines in  FIG. 7 , when the first obstacle is not detected at a first timing t 11  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the first speed V 1 . Further, when the back door  13  starts to open at the first timing t 11 , the back door  13  reaches the fully open position at a second timing t 12 . Therefore, at the second timing t 12 , the back door  13  stops. 
     As indicated by the dash-dot lines in  FIG. 7 , when the first obstacle is detected at the first timing t 11  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the second speed V 2  lower than the first speed V 1 . Then, at the first timing t 11 , a position where the back door  13  is located in front of the first obstacle by the first determination distance Dth 1  is set as the target stop position. Further, when the back door  13  starts to open from the first timing t 11 , the first estimation distance Dc 1  is the second determination distance Dth 2  at a third timing t 13 . Therefore, after the third timing t 13 , the opening speed of the back door  13  gradually decreases as the first estimation distance Dc 1  decreases. When a fourth timing t 14  at which the back door  13  reaches the target stop position is reached, the back door  13  stops in front of the first obstacle. 
     In  FIG. 8 , a case where the first obstacle is not detected before the opening operation while the second obstacle is detected during the opening operation is indicated by solid lines, and a case where the first obstacle is detected before the opening operation and the second obstacle is detected during the opening operation is indicated by dash-dot lines. 
     As indicated by the solid lines in  FIG. 8 , when the first obstacle is not detected at a first timing t 21  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the first speed V 1 . Then, the back door  13  starts to open from the first timing t 21 . Further, when a second timing t 22  at which the second obstacle is detected is reached, the opening speed of the back door  13  is set to the second speed V 2 . Subsequently, after a third timing t 23  at which the second measurement distance Dm 2  is less than the second determination distance Dth 2 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. When a fourth timing t 24  at which the second measurement distance Dm 2  is the first determination distance Dth 1  is reached, the back door  13  stops at the position in front of the second obstacle. 
     As indicated by the dash-dot lines in  FIG. 8 , when the first obstacle is detected at the first timing t 21  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the second speed V 2  lower than the first speed V 1 . Further, at the first timing t 21 , the position where the back door  13  is located in front of the first obstacle by the first determination distance Dth 1  is set to the target stop position. The back door  13  starts to open from the first timing t 21 . Further, even when the second timing t 22  at which the second obstacle is detected is reached, the opening speed of the back door  13  is maintained at the second speed V 2 . After the fourth timing t 24  at which the second measurement distance Dm 2  is less than the second determination distance Dth 2 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. When a fifth timing t 25  at which the second measurement distance Dm 2  is the first determination distance Dth 1  is reached, the back door  13  stops. That is, the back door  13  stops at the position in front of the second obstacle, instead of the target stop position in front of the first obstacle. 
     In  FIG. 9 , a case where the first obstacle is not detected before the opening operation while the second obstacle is temporarily detected during the opening operation is indicated by solid lines, and a case where the first obstacle is detected before the opening operation while the second obstacle is temporarily detected during the opening operation is indicated by dash-dot lines. 
     As indicated by the solid lines in  FIG. 9 , when the first obstacle is not detected at a first timing t 31  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the first speed V 1 . Then, the back door  13  starts to open from the first timing t 31 . Further, when a second timing t 32  at which the second obstacle is detected is reached, the opening speed of the back door  13  is set to the second speed V 2 . Subsequently, after a third timing t 33  at which the second measurement distance Dm 2  is less than the second determination distance Dth 2 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. When the second obstacle is no longer detected at a fourth timing t 34 , the opening speed of the back door  13  is increased to the second speed V 2  after the fourth timing t 34 . In a period from the second timing t 32  to the fourth timing t 34 , a case where the second obstacle is temporarily detected is, for example, a case where an object such as an animal or a ball temporarily passes through a detection area of the obstacle sensors SE. 
     After the fourth timing t 34  at which the opening speed of the back door  13  is the second speed V 2 , the opening speed of the back door  13  is maintained at the second speed V 2 . That is, even when the second obstacle is not detected, the opening speed of the back door  13  is not increased to the first speed V 1 . Although not shown in  FIG. 9 , when the back door  13  reaches the fully open position, the back door  13  stops. 
     As indicated by the dash-dot lines in  FIG. 9 , when the first obstacle is detected at the first timing t 31  at which the operation request of the back door  13  is input, the opening speed of the back door  13  is set to the second speed V 2  lower than the first speed V 1 . Further, at the first timing t 31 , the position where the back door  13  is located in front of the first obstacle by the first determination distance Dth 1  is set to the target stop position. Then, the back door  13  starts to open from the first timing t 31 . Further, even when the second timing t 32  at which the second obstacle is detected is reached, the opening speed of the back door  13  is maintained at the second speed V 2 . Subsequently, after a fifth timing t 35  at which the second measurement distance Dm 2  is less than the second determination distance Dth 2 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. When the second obstacle is no longer detected at a sixth timing t 36 , the opening speed of the back door  13  is increased to the second speed V 2  after the sixth timing t 36 . Further, the first estimation distance Dc 1  is the second determination distance Dth 2  at a seventh timing t 37 . Therefore, after the seventh timing t 37 , the opening speed of the back door  13  gradually decreases as the first estimation distance Dc 1  decreases. When an eighth timing t 38  at which the back door  13  reaches the target stop position is reached, the back door  13  stops at the position in front of the first obstacle. 
     At the fourth timing t 34  of a timing chart shown in  FIG. 9 , the second measurement distance Dm 2  from the back door  13  to the second obstacle is assumed to be longer than the first determination distance Dth 1 . Similarly, at the sixth timing t 36  of the timing chart shown in  FIG. 9 , the second measurement distance Dm 2  from the back door  13  to the second obstacle is assumed to be longer than the first determination distance Dth 1 . 
     Effects of this embodiment are to be described. 
     (1) As indicated by the solid lines in  FIG. 8 , when the second obstacle is detected during the opening operation of the back door  13  in a situation where the first obstacle is not detected when the operation request is input, the door control device  20  sets the opening speed of the back door  13  to the second speed V 2  lower than the first speed V 1 . Specifically, at the second timing t 22  in  FIG. 8 , the opening speed of the back door  13  is changed from the first speed V 1  to the second speed V 2 . Therefore, during the opening operation of the back door  13 , the door control device  20  can increase the number of times of detection of the obstacle sensors SE with respect to a unit movement amount of the back door  13 , and shorten a braking distance after trying to stop the back door  13  in operation. Therefore, the door control device  20  can improve a positional accuracy when stopping the back door  13  in operation in front of the second obstacle. 
     (2) As shown in  FIG. 8 , when the back door  13  is close to the second obstacle, the door control device  20  gradually decreases the opening speed of the back door  13  from the second speed V 2  as the distance from the back door  13  to the second obstacle decreases. Specifically, when indicated by the solid lines in  FIG. 8 , in a period from the third timing t 23  to the fourth timing t 24 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. Further, when indicated by the dash-dot lines in  FIG. 8 , in a period from the fourth timing t 24  to the fifth timing t 25 , the opening speed of the back door  13  gradually decreases as the second measurement distance Dm 2  decreases. Therefore, the door control device  20  can further improve the positional accuracy when stopping the back door  13  in operation in front of the obstacle  30 . 
     (3) As shown in  FIG. 9 , when the second obstacle is no longer detected during the operation of the back door  13 , the door control device  20  increases the opening speed of the back door  13  which is set to the second speed V 2  or less since the back door  13  is close to the second obstacle. Specifically, when indicated by the solid lines in  FIG. 9 , the opening speed of the back door  13  which is set to the second speed V 2  or less in a period from the third timing t 33  to the fourth timing t 34  is increased at the fourth timing t 34 . In addition, when indicated by the dash-dot lines in  FIG. 9 , the opening speed of the back door  13  which is set to the second speed V 2  or less in a period from the fifth timing t 35  to the sixth timing t 36  is increased at the sixth timing t 36 . Therefore, when the second obstacle is no longer present, the door control device  20  can promptly operate the back door  13  to a target position. 
     (4) As indicated by the solid lines in  FIG. 9 , after the fourth timing t 34 , the door control device  20  sets an upper limit of the opening speed of the back door  13  to the second speed V 2 . Therefore, the door control device  20  can prepare for a situation in which the second obstacle is detected again. 
     (5) As indicated by the dash-dot lines in  FIG. 7 , when the first obstacle is present around the back door  13 , the door control device  20  sets the target stop position, which is a position close to the first obstacle, before the operation of the back door  13  is started. Therefore, even when the door control device  20  cannot detect the first obstacle during the operation of the back door  13 , the back door  13  operates to the target stop position. Therefore, even when the first obstacle cannot be detected during the operation of the back door  13 , the door control device  20  can stop the back door  13  in front of the first obstacle. 
     (6) When a distance from a position where the operation of the back door  13  is started to the obstacle  30  is short, the back door  13  moves only slightly even when the back door  13  is opened to close to the obstacle  30 . That is, in this case, even when the back door  13  is opened, the user cannot load or unload the luggage with respect to the luggage compartment of the vehicle  10 . In this regard, the door control device  20  restricts the opening operation of the back door  13  when the distance from the position where the opening operation of the back door  13  is started to the obstacle  30  is short. Specifically, the door control device  20  restricts the opening operation of the back door  13  when the first measurement distance Dm 1  is less than the third determination distance Dth 3 . Therefore, the door control device  20  can restrict a meaningless opening operation of the back door  13 . 
     (7) When the back door  13  does not operate regardless the user makes the operation request to the door control device  20 , the user may feel uncomfortable that the back door  13  does not operate normally. In this regard, even when the distance from the back door  13  to the obstacle  30  is short, the door control device  20  releases the restraint of the back door  13  by the door lock device  14 . Therefore, the door control device  20  can respond to the operation request of the user by releasing the restraint of the back door  13 , and can notify the user that the back door  13  cannot be opened. Thus, the door control device  20  can prevent the user from feeling uncomfortable. Further, depending on an elastic modulus of a weather strip disposed between the door opening  11  and the back door  13 , the back door  13  can be slightly moved while the restraint of the back door  13  is released by a restoring force of the weather strip. 
     (8) As indicated by the dash-dot lines in  FIG. 8 , even in a situation where the back door  13  is operated toward the target stop position, the door control device  20  stops the back door  13  in front of the second obstacle when the second obstacle is detected at a position in front of the target stop position. Therefore, the door control device  20  can prevent the back door  13  from coming into contact with the second obstacle even when the second obstacle appears during the operation of the back door  13 . 
     This embodiment may be modified and implemented as follows. This embodiment and the following modifications can be implemented in combination with each other within a technically consistent range. 
     The back door  13  may be another opening and closing body driven by another opening and closing body drive device. For example, another opening and closing body may be a slide door or a swing door that opens and closes the door opening  11  formed on a side portion of the vehicle  10 , or a sunroof movable panel that opens and closes a roof opening formed in a roof of the vehicle  10 . In a case where another opening and closing body is the slide door, the door control device  20  may perform the above control in relation to the obstacle  30  that can come into contact with the slide door that is operated to close. 
     The door control device  20  may perform the above control when the back door  13  is not located at the fully closed position. For example, the door control device  20  may perform the above control when the operation request for opening the back door  13  is input in a situation where the back door  13  is disposed at a slightly open position from the fully closed position. 
     The door drive device  15  may not be the actuator that expands and contracts as long as the door drive device  15  can open and close the back door  13 . For example, the door drive device  15  may be the actuator that applies a torque to a rotation shaft of the back door  13 . 
     The obstacle sensors SE may use light or radio waves instead of the ultrasonic waves. 
     The obstacle sensors SE may be cameras. In this case, the cameras may be provided on the back door  13  or may be provided on the vehicle body  12 . Even when the obstacle sensors SE are implemented by the cameras, the detection results of the obstacle sensors SE may not be normal during the opening operation of the back door  13 . For example, images of the cameras may be disturbed due to that raindrops adheres to a surface of a camera lens or an amount of light incident on the cameras changes significantly during the opening operation of the back door  13 . Therefore, even when the obstacle sensors SE are set as the cameras, an effect (5) of the above embodiment can be obtained. 
     The back door  13  may be provided with only one obstacle sensor SE. In this case, reflected waves of ultrasonic waves transmitted from one obstacle sensor SE may be received by the one obstacle sensor SE. The same may be applied to a case where the back door  13  is provided with a plurality of obstacle sensors SE. 
     The obstacle sensors SE may be disposed on the back door  13  so as to be arranged in a grid shape in both the width direction of the vehicle  10  and the up and down direction of the vehicle  10 . 
     The map shown in  FIG. 4  may be changed as appropriate. For example, when the distance from the back door  13  to the obstacle  30  is less than the second determination distance Dth 2 , the opening speed of the back door  13  may be changed stepwise according to the distance from the back door  13  to the obstacle  30 , or the opening speed of the back door  13  may be changed nonlinearly according to the distance from the back door  13  to the obstacle  30 . The same applies to the case where the distance from the back door  13  to the obstacle  30  is equal to or greater than the second determination distance Dth 2 . 
     The door control device  20  may keep the opening speed of the back door  13  constant regardless of the distance from the back door  13  to the obstacle  30 . For example, the door control device  20  may set the opening speed of the back door  13  to the first speed V 1  when the obstacle  30  is not detected, and may set the opening speed of the back door  13  to the second speed V 2  when the obstacle  30  is detected. 
     When the second obstacle is no longer detected, the door control device  20  may not suddenly change the opening speed of the back door  13  to the second speed V 2 , but gradually increases the opening speed to the second speed V 2  as time elapses. 
     When the second obstacle is no longer detected, the door control device  20  may increase the opening speed of the back door  13  to a speed higher than the second speed V 2 . For example, as indicated by the solid lines in  FIG. 9 , after the fourth timing t 34 , the opening speed of the back door  13  may be increased with the first speed V 1  as an upper limit. 
     When the first measurement distance Dm 1  is less than the third determination distance Dth 3  (step S 18 : YES), the door control device  20  may issue an alarm sound together with the unlatch operation. The alarm sound in this case is an alarm sound intended to notify that the back door  13  cannot be opened since the distance from the back door  13  to the first obstacle is short. 
     When the first measurement distance Dm 1  is less than the third determination distance Dth 3  (step S 18 : YES), the door control device  20  may issue the alarm sound instead of the unlatch operation. 
     The fully open position of the back door  13  may not be a position of the back door  13  when the opening degree of the back door  13  is maximized. For example, the fully open position of the back door  13  may be a memory location set in advance by the user. 
     The opening speed of the back door  13  may be a rotation speed of the back door  13 . 
     The door control device  20  includes one or more processors that operate according to a computer program (software), and one or more dedicated hardware circuits such as dedicated hardware (Application-Specific Integrated Circuit: ASIC) that executes at least a part of various processing, or a circuit including a combination thereof. The processor includes a CPU and a memory such as RAM and ROM, and the memory stores program codes or instructions configured to cause the CPU to execute the processing. The memory, that is a storage medium, includes any available medium that can be accessed by a general-purpose computer or a dedicated computer. 
     An opening and closing body control device for a vehicle includes a control unit configured to control an opening and closing body drive device driving an opening and closing body of a vehicle to open and close the opening and closing body based on an operation request; and a detection unit configured to detect an obstacle present around the opening and closing body based on a detection result of an obstacle sensor. The control unit is configured to set an operation speed of the opening and closing body to a first speed when the obstacle is not detected during an operation of the opening and closing body, and set the operation speed of the opening and closing body to a second speed or less, the second speed being lower than the first speed, and causes the opening and closing body to stop at a position where the opening and closing body is close to the obstacle, when the obstacle is detected during the operation of the opening and closing body. 
     The opening and closing body control device for a vehicle configured as described above sets the operation speed of the opening and closing body to the second speed, which is lower than the first speed, or less when the obstacle is detected during the operation of the opening and closing body. Therefore, the opening and closing body control device for a vehicle can increase the number of times of detection of the obstacle sensor with respect to a unit movement amount of the opening and closing body, and shorten a braking distance which is a distance the opening and closing body moves when the opening and closing body in operation is stopped until the opening and closing body is actually stopped. Therefore, the opening and closing body control device for a vehicle can improve the positional accuracy when stopping the opening and closing body in operation in front of the obstacle. 
     In the opening and closing body control device for a vehicle, it is preferable that, when a distance from the opening and closing body to the obstacle when the control unit stops the opening and closing body is set as a first determination distance, the control unit is configured to, in a situation where the obstacle is detected during the operation of the opening and closing body, set the operation speed of the opening and closing body to the second speed when the distance from the opening and closing body to the obstacle is equal to or greater than a second determination distance which is longer than the first determination distance, and decrease the operation speed of the opening and closing body as the distance decreases when the distance from the opening and closing body to the obstacle is less than the second determination distance. 
     When the opening and closing body is getting close to the obstacle, the opening and closing body control device for a vehicle configured as described above gradually decreases the operation speed of the opening and closing body from the second speed as a distance from the opening and closing body to the obstacle decreases. Therefore, the opening and closing body control device for a vehicle can further improve the positional accuracy when stopping the opening and closing body in operation in front of the obstacle. 
     In the opening and closing body control device for a vehicle, it is preferable that the control unit is configured to, in the situation where the obstacle is detected during the operation of the opening and closing body, increase the operation speed of the opening and closing body when the obstacle is no longer present, when the distance from the opening and closing body to the obstacle is less than the second determination distance. 
     The opening and closing body control device for a vehicle configured as described above increases the operation speed of the opening and closing body which is set to the second speed or less since the opening and closing body is close to the obstacle when the obstacle is not detected during the operation of the opening and closing body. Therefore, the opening and closing body control device for a vehicle can promptly operate the opening and closing body to a target position. 
     The opening and closing body control device for a vehicle can improve the positional accuracy when stopping the opening and closing body in operation in front of the obstacle. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.