Patent Publication Number: US-2011068953-A1

Title: Vehicle Park Assist System and Method for Parking a Vehicle Using Such System

Description:
BACKGROUND 
     This invention relates in general to vehicle park assist systems and in particular to an improved park assist system and method for parking of such a vehicle. 
     Vehicle park assist systems are used to identify a feasible parking space, e.g., usually a parallel space, a rear perpendicular space, or a garage parking space, and then take over the steering of the vehicle to maneuver the vehicle into the identified space hands free. During operation, the driver still shifts the transmission and operates the gas and brake pedals. Thus, while the steering is done automatically, the driver is still responsible for safe parking of the vehicle. 
     One known vehicle park assist system is disclosed in U.S. Pat. No. 6,948,729 to Zalila el al. In U.S. Pat. No. 6,948,729, sensors 36 sense front obstacles 4, back obstacles 16 and an edge 5 of the possible parking space 2. Sensed data is processed and an output is provided which assists the driver in parking the vehicle. 
     SUMMARY 
     The present application describes various embodiments of a park assist system. One embodiment of the park assist system for parking a vehicle in a target parking space includes a first sensing system which determines whether there is a sufficient slot length in a target parking space in which to park the vehicle. A second sensing system determines whether an obstacle is located in a predetermined clearance zone on a side of the vehicle opposite the target parking space. A decision regarding whether to recommend parking the vehicle in the target parking space sensed by the first sensing system is dependent upon a determination that the clearance zone is free of obstacles. 
     According to another embodiment, a method for parking a vehicle in a target parking space includes a vehicle having a sensing system and a park assist system operatively connected thereto. Neighboring objects are scanned using a first sensor to determine if a target parking space is available for parking the vehicle. The neighboring objects include at least one object either in front of or behind the target parking space, and the first sensor provides an input signal to the park assist system. Neighboring objects on the side of the vehicle opposite the target parking space are scanned using a second sensor to determine if a clearance zone on the side of the vehicle opposite the target parking space is free of obstacles, and the second sensor provides an input signal to the park assist system. The park assist system is used to determine whether there is a sufficient slot length in which to park the vehicle and to determine whether there is sufficient clearance to an identified obstacle on the side of the vehicle opposite the target parking space. The vehicle is then parked in the target parking space using the park assist system if there is sufficient slot length in which to park the vehicle and sufficient clearance to an identified obstacle on the side of the vehicle opposite the target parking space. 
     According to yet another embodiment, a method for parking a vehicle in a target parking space includes a vehicle having a sensing system and a park assist system operatively connected thereto. A target parallel parking space is identified. Neighboring objects on the side of the vehicle opposite the target parking space are scanned using an ultrasonic sensor to determine if a clearance zone on the side of the vehicle opposite the target parking space is free of obstacles. The ultrasonic sensor provides an input signal to the park assist system. The park assist system is used to determine whether there is sufficient clearance to an identified obstacle on the side of the vehicle opposite the target parallel parking space. The vehicle is then parked in the target parking space using the park assist system if there is sufficient slot length in which to park the vehicle and sufficient clearance to an identified obstacle on the side of the vehicle opposite the target parking space. 
     Other advantages of the park assist system will become apparent to those skilled in the art from the following detailed description, when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a first embodiment of a path to a target parking space and a clearance zone using a park assist system according to the present invention. 
         FIG. 1A  is a schematic diagram of a portion of the park assist system illustrated in  FIG. 1 , showing the associated vehicle used therewith. 
         FIG. 2  is a flow chart of an embodiment of a method for parking a vehicle using the park assist system of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , there is illustrated a schematic diagram of a first embodiment of a path P for parking of a vehicle V to a target parking space or space  10  between two parked vehicles V 1  and V 2 , using a park assist system, which will be described in detail below, according to the present invention. In the illustrated embodiment, the vehicle V, schematically shown in  FIG. 1A , includes at least the following components or systems: a brake pedal  12 , a gas pedal  14 , a braking system  16 , a steering system  18 , a driveline system  20 , wheels  22 , an electric power assisted steering (EPAS) system  24  which is part of the steering system  18 , a sensing system  26 , a powertrain system  28 , and a park assist system  30 . Alternatively, an electro-hydraulic power assisted steering system may be used in lieu of EPAS. The park assist system  30  is also shown schematically in  FIG. 1 . However, it must be understood that the vehicle V to be parked may include any other suitable components or systems and that only those components or systems which are necessary for describing and explaining the function and operation of the present invention are illustrated herein. 
     In the illustrated embodiment, the sensing system  26  is operatively connected to the park assist system  30  to provide input signal(s) thereto and preferably includes ultrasonic sensors, GPS and/or odometric sensors, and an absolute steering wheel angle sensor. Alternatively, the park assist system  30  may include a relative steering wheel angle sensor in lieu of an absolute steering wheel angle sensor, and radar, lidar, lasers, or thermal sensors may be used in lieu of the ultrasonic sensors. The ultrasonic sensors may be located on a side(s) of a front and/or rear bumpers of the vehicle V. In the illustrated embodiment of  FIG. 1 , ultrasonic sensors, indicated generally at S 1  and S 2  are illustrated schematically. The sensor S 1  is shown as being located on a front passenger or right side bumper of the vehicle V. The sensor S 2  is shown as being located on a front driver or left side bumper of the vehicle V. 
     Alternatively, the number and or the location of the ultrasonic sensors may be other than illustrated if so desired. For example, one or more ultrasonic sensors may be located on one or both of the rear bumpers of the vehicle (as shown as S 3  and S 4  in  FIG. 1 ), or in any suitable combinations of or desired locations thereof on the vehicle V. The sensor or sensors S 1  and/or S 3  mounted on the passenger side of the vehicle V define a first sensing system. Similarly, the sensor or sensors S 2  and/or S 4  mounted on the driver side of the vehicle V define a second sensing system. 
     In the illustrated embodiment, the odometric sensors may be located on one or more of the wheels  22  of the vehicle V and/or in the driveline system  20  of the vehicle. The steering wheel angle sensor is located on the steering system  18  of the vehicle and preferably is located on a steering wheel of the steering system  18 . Alternatively, the construction and/or the components of the sensing system  26  of the vehicle V may be other than illustrated and described if so desired. 
     In the illustrated embodiment, the vehicle V is parked into the target parking space  10  using the park assist system  30  of the present invention. To accomplish this, at least one of the ultrasonic sensors S 1 , S 3  is used in conjunction with the odometric sensors and the steering wheel angle sensor to scan neighboring objects and their location relative to the position of the vehicle V as a driver of the vehicle drives by the objects. In the illustrated embodiment of  FIG. 1 , the neighboring objects are illustrated as being the two parked vehicles V 1  and V 2  and an object  32 , such as for example, a curb or a wall. However, one or more of the neighboring objects may be other kinds or types than that which are illustrated and described. It will be understood that the park assist system  30  of the present invention may successfully identify a target parking space  10  relative to only one object or vehicle, such as either the vehicle V 1  or the vehicle V 2 , is present and sensed. 
     The information from the sensors is processed by a computer of the park assist system  30  to determine if a valid path trajectory T can be performed to park the vehicle V into the target parking space  10 . The calculation by the computer of the park assist system  30  includes a determination of a slot length  34  depending upon a length  36  of the vehicle V. 
     Additionally, the calculation by the computer of the park assist system  30  includes a determination of whether there is sufficient space to maneuver the vehicle V into the target parking space  10  by determining whether a neighboring object or potential obstacle is present on the side of the vehicle opposite the target parking space  10 . To accomplish this, at least one of the ultrasonic sensors S 2 , S 4  is used in conjunction with the odometric sensors and the steering wheel angle sensor to scan neighboring objects or potential obstacle(s) on the side of the vehicle V opposite the target parking space  10 , and their position(s) relative to the vehicle V as a driver of the vehicle drives by the potential obstacle(s). 
     In the illustrated embodiment, the potential obstacle is illustrated as a vehicle V 3  in the roadway R. In order for the vehicle V to successfully maneuver into the target parking space  10 , a clearance zone CZ must be free of obstacles. A line L 1  is parallel to the path P and runs through the closest point that the vehicle V 3  may be to the vehicle V without encroaching into the path the vehicle V must travel to successfully maneuver into the target parking space  10 . The clearance zone CZ is therefore defined as the space between the driver side of the vehicle V and the line L 1 . It will be understood that the potential obstacle may be more than one object, such as the vehicle V 3  and another vehicle V 4  in the roadway R in front of and/or behind the vehicle V. 
     As shown in  FIG. 1 , a predetermined lateral distance A is defined as the minimum lateral distance between the left or driver side of the vehicle V and the line L 1 , and defines a width of the clearance zone CZ. 
     A lateral distance B is the measured lateral distance between the right or passenger side of the vehicle V and a left-most edge, illustrated by the line L 2 , of the target parking space  10 . A predetermined lateral distance C represents the minimum total lateral distance between the left-most edge L 2  of the target parking space  10  and the left-most edge L 1  of the clearance zone CZ required to successfully maneuver the vehicle V into the target parking space  10 . 
     If the computer of the park assist system  30  determines that a measured lateral distance A 1  to a potential obstacle, such as the vehicle V 3 , as measured by the sensor S 2  and/or S 4  is larger than the predetermined lateral distance A, then the clearance zone CZ will be considered free of obstacles. 
     Referring now to  FIG. 2 , there is illustrated a flow chart of an embodiment of a method for parking a vehicle using the park assist system  30  of the present invention. As shown in  FIG. 2 , the method of the present invention includes a first step  50  in which the park assist system  30  determines if there is a feasible target parking space  10  available for parking of the vehicle V. To accomplish this, the park assist system  30  uses the sensor S 1  of the sensing system  26 . As discussed above, the sensor S 1  determines whether there is a sufficient slot length  34  in which to park the vehicle V. 
     In a second step  51 , the sensor S 2  determines whether there is sufficient clearance to an obstacle, such as a vehicle V 3 , on the side of the vehicle V opposite the target parking space  10 . If such an obstacle is in a predetermined clearance zone CZ, i.e., is less than the predetermined lateral distance A from the vehicle V, the obstacle is thus considered in a position to interfere with the successful maneuver of the vehicle V into the target parking space  10 . It will be understood that the steps  50  and  51  may occur sequentially or simultaneously. 
     Once it is determined that a feasible target parking space  10  has been identified by the park assist system  30 , and that there are no obstacles in the clearance zone CZ, the park assist system  30  in step  52  prompts the driver via a visual and/or audible interface that a feasible target parking space  10  is available. The park assist system  30  then recommends the parking space  10 . One example of a visual interface is a text message displayed in a message center in the vehicle instrument panel. Alternatively, the visual interface may be a graphic image, icon, or other non-text representation. It will be understood that such a visual interface may be located at any other desired location in the vehicle, such as an overhead console. 
     Next, in step  54 , the driver is instructed by the park assist system  30 , either visually and/or audibly, to stop in order to accept the system assistance to park. Once the driver has stopped the park assist system  30  in step  56  will prompt the driver to remove his or her hands from a steering wheel of the steering system  18  and engage or shift the transmission of the powertrain system  28  into reverse gear. Once the driver has removed his or her hands from the steering wheel and engaged reverse gear, the park assist system  30  in step  58  will take over the steering wheel movement and control the EPAS system  24  to execute the calculated steering trajectory T based on the relative vehicle position to the neighboring objects, i.e., in  FIG. 1  the vehicles V 1  and V 2  and the object  32 . The park assist system  30  will prompt the driver when to stop, drive backward, and pull forward to park the vehicle V in the target parking space  10 . 
     Although the target parking space  10  has been described as a parallel parking space between a forward first object and a rearward second object, the target parking space may alternatively be a rear perpendicular parking space, such as found in typical multi-vehicle parking lots and garages. Additionally, the target parking space  10  has been described as being on the right side of the vehicle V and the obstacle or vehicle V 3  has been described as being on the left side of the vehicle V. Alternatively, the park assist system  30  may be used to identify a target parking space on the left side of the vehicle V and identify an obstacle or vehicle V 3  on the right side of the vehicle V. 
     One advantage of the embodiments of the present invention is that the park assist system  30  and method of the operation thereof is capable of identifying obstacles on the side of the vehicle opposite the target parking space  10 . As a result of this, the park assist system  30  can bypass or not recommend a target parking space  10  that otherwise may have sufficient slot length in which to park the vehicle, but for which an obstacle has been identified in the clearance zone CZ. As a result of this, the park assist system  30  and method of operation thereof minimizes the risk of collision with an object on the side of the vehicle opposite the target parking space  10 . 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.