Patent Publication Number: US-9852623-B2

Title: Controlling a parking lot sensor

Description:
CROSS REFERENCE 
     The present application claims the benefit under 35 U.S.C. §119 of German Patent Application No. DE 102015211053.2 filed on Jun. 16, 2015, which is expressly incorporated herein by reference in its entirety. 
     FIELD 
     The present invention relates to a parking lot sensor. The present invention in particular relates to controlling the parking lot sensor for scanning a measuring area in order to determine the presence of a vehicle. 
     BACKGROUND INFORMATION 
     A parking lot includes multiple parking spaces, in which respectively one vehicle may be parked. A management system for the parking lot includes a parking lot sensor at every one of the parking spaces, a central processing device and a communication network between the parking lot sensors and the processing device. Each parking lot sensor determines whether or not a vehicle is located in the parking space assigned to it. The parking lot sensor transmits the result of this determination to the management system, which thereupon is able for example to make arrangements so that free parking spaces become occupied or to charge for occupied parking spaces. 
     Each parking lot sensor includes a sensor for scanning the parking space. The sensor may implement one of several conventional measuring principles. The parking lot sensor may be operated by a battery that has a limited capacity. Additionally or alternatively, the parking lot sensor may also be designed to supply itself with energy, for example by energy harvesting. An average power consumption of the parking lot sensor may generally depend on how frequently determinations are made by the sensor. To save energy, it is therefore advantageous to perform scans as seldom as possible. On the other hand, this also increases a response time of the parking lot sensor such that it is possible that the parking lot sensor misses a change of a vehicle parked in the parking space. In practice, an attempt is therefore made to define a scanning frequency of the parking lot sensor in such a way that an acceptable compromise is achieved between a low power consumption and a short response time. 
     The present invention is based on the objective of indicating a technology for controlling a parking lot sensor that allows for the formation of an improved compromise. 
     SUMMARY 
     A method for controlling a parking lot sensor, which includes a sensor for scanning a predetermined measuring area, includes steps of determining an expected fluctuation of vehicles in the measuring area, of determining a scanning frequency on the basis of the expected fluctuation and of controlling, as a function of the scanning frequency, the sensor respectively for carrying out a scan. 
     The frequency with which the sensor scans as to whether or not a vehicle is located in the measuring area is preferably high when a high fluctuation of vehicles is to be expected and low when the fluctuation is to be assumed to be low. The fluctuation indicates how frequently an average change occurs in the determination value of the presence of a vehicle in the measuring area. 
     If a low fluctuation is expected, then the scanning frequency may be low such that the sensor is only seldom in operation and a power consumption of the parking lot sensor is therefore low. If by contrast a high fluctuation is expected, then the response time of the parking lot sensor may be shortened such that it is possible to detect an entry or exit of a vehicle into or out of the measuring area with a shortened response time. In this manner, the seemingly contradictory requirements of a low energy consumption and a short response time may be combined. 
     A parking lot sensor includes a sensor for scanning a parking space for a vehicle. A method for controlling the parking lot sensor includes steps of determining an activity of vehicles in the parking lot, of determining a scanning frequency on the basis of the activity, and of controlling, as a function of the scanning frequency, the sensor respectively for performing a scan. 
     In contrast to other technologies for controlling the scanning frequency of the parking lot sensor, real data ascertained in real time are used such that the determined scanning frequency is able to reflect the activity conditions prevailing in the area of the parking lot in a realistic and responsive manner. 
     The parking lot sensor may be operated both with quick response and in an energy-saving manner. Delayed or false determinations of vehicles in the area of the parking space may be avoided by a sufficiently high scanning frequency. A sufficiently low scanning frequency is simultaneously able to reduce servicing and maintenance costs for the parking lot sensor. By saving energy, an environmental load may be reduced. Moreover, this may result in a functional reserve in the event of a poor energy supply situation of the parking lot sensor. 
     The parking lot sensor preferably has a limited energy reserve, it being possible for the sensor to be switched to an energy-saving state between scans. In particular, the sensor may be switched off between scans. The sensor may have a significant share in the current consumption of the parking lot sensor such that much energy may be saved by switching it off periodically. 
     This is true especially if the sensor implements an active measuring principle, in which a signal is actively sent out and an object&#39;s influence on the signal in the measuring area is evaluated. The emitted signal may include for example a light or radar signal, the reflection or echo of which is detected. Other examples for active measuring principles include an electromagnetic determination, a magnetic determination or a determination by ultrasound. It is also possible for multiple sensors to be provided that preferably follow different measurement principles. 
     The activity may be determined on the basis of signals of an infrastructure device for scanning vehicles in a traffic area of the parking lot. This makes it possible for the determination to disregard vehicles that are parked in parking spaces and are not part of the traffic in the parking lot. 
     In another specific embodiment, however, it is also possible for a number of the vehicles parked in parking spaces to enter into the determination of the activity. 
     The infrastructure device may be designed to determine a speed of a vehicle in a traffic area and to determine the activity on the basis of the speed. A high speed may result in the determination of a low activity, and a low speed may result in the determination of a high activity. It is also possible to determine a distribution of speeds across vehicles, the activity being determined on the basis of the speed distribution, for example as a function of the average value or of the standard deviation. 
     The infrastructure device may also be designed to determine a waiting time of a vehicle in a traffic area and to determine the activity on the basis of the waiting time. A waiting time occurs when a vehicle is ready to drive in a traffic area, but is unable to drive for reasons of traffic volume. A long waiting time may result in the determination of a high activity, and a short waiting time may result in the determination of a low activity. It is also possible to determine a distribution of waiting times across vehicles, the activity being determined on the basis of the waiting time distribution, for example as a function of the average value or the standard deviation. 
     For example, in a parking lot, in an underground parking facility or in a multi-story parking garage, multiple parking spaces may be provided, which are each assigned one parking lot sensor. In different specific embodiments, it is then possible to determine scanning frequencies for an individual parking lot sensor, for a group of parking lot sensors or for all parking lot sensors of the parking lot. By combining several—or all—parking lot sensors into one group, which uses the same scanning frequencies, it is possible to reduce the expenditure of determination for individual scanning frequencies. It is preferred that the parking lot sensors of one group are similar in terms of traffic engineering, that is, that they may be reached via the same entrance for example. The parking lot sensors of one group should also be located as near to one another as possible. In a multi-story parking garage, for example, parking lot sensors of the same level may be grouped together. 
     A computer program product has program code for carrying out the method described above when it is run on a processing device or is stored on a computer-readable data carrier. 
     A parking lot sensor for a parking lot is designed to receive a scanning frequency and to determine the presence of a vehicle in the area of a parking space with the scanning frequency. 
     The parking lot sensor may in particular have a limited energy reserve and may be designed to switch a sensor for determining the presence of a vehicle in the area of the parking space into an energy-saving state between scans. 
     A parking system for a parking lot includes the above-described parking lot sensor, an infrastructure device for detecting vehicles in a traffic area of the parking lot and a processing device. The processing device is designed to scan the infrastructure device, to determine an activity of vehicles in the area of the parking lot on the basis of the scan, to determine a scanning frequency for a parking lot sensor on the basis of the activity, and to transmit the determined scanning frequency to the parking lot sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described below in greater detail with reference to the figures. 
         FIG. 1  shows an example system for managing a parking lot having multiple parking spaces. 
         FIG. 2  shows a flow chart of an example method for controlling a parking lot sensor of the system of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  shows a management system  100  for a parking lot  105  having multiple parking spaces  110 , which are designed respectively for a vehicle  115 , preferably a motor vehicle. At one or multiple parking spaces  110 , respectively one parking lot sensor  120  having a measuring area  125  is provided, which scans at least a portion of the space in which vehicle  115  may be parked in parking space  110 . In the illustrated specific embodiment, parking lot sensor  120  is disposed above parking space  110  or motor vehicle  115 , while in other specific embodiments parking lot sensor  120  may also be at another location, for example below vehicle  115  or at half height. 
     In the illustrated specific embodiment, parking lot sensor  120  is disposed above parking space  110  or motor vehicle  115 , while in other specific embodiments parking lot sensor  120  may also be at another location, for example below vehicle  115  of at half height. 
     In addition to parking lot sensors  120 , management system  100  also includes a central management unit  130 , which preferably includes a processing device  135  and optionally a memory  140 . Multiple management units  130  or processing devices  135  are also possible. A network  145  is provided for communication between central management unit  130  and parking lot sensors  120 , which in the present example is partly wireless and partly wired, although purely wireless or purely wired specific embodiments are likewise possible. For converting data traffic between a wired and a wireless part of network  145 , one or multiple gateways  150  are optionally provided. One part of network  145  may be implemented for example using WLAN, Bluetooth or mobile telephony. 
     Vehicle sensor  120  includes a control device  155 , a sensor  160 , and a communication device  165 . An energy supply  170  also may be provided, which in one specific embodiment is able to supply only limited energy. For example, energy supply  170  may be a battery, a local device for supplying electrical energy such as a solar cell for example, or a combination of these. A central wired energy supply is also possible. 
     Sensor  160  may implement any physical measuring principle. For this purpose, sensor  160  may be passive, in that it evaluates a physical signal present in measuring area  125 , or active, in that it provides a suitable physical signal in measuring area  125  and evaluates the influence of vehicle  115  on it. Examples of passive sensors include magnetometers and light sensors, while active sensors may include radar sensors, lidar sensors or ultrasonic sensors for example. 
     The present invention provides for a frequency, with which a vehicle sensor  120  by way of sensor  160  performs a determination about the presence of a vehicle  115  in the parking space  110 , to be set dynamically as a function of an activity of vehicles  115  in the area of parking lot  105 . For this purpose, a determination is preferably made as to whether a high activity or a low activity of vehicles  115  exists in the area of parking lot  105 , that is, whether many or few vehicles  115  are moving in the area of parking lot  105 . As a function of the activity, a scanning frequency is determined for one of parking lot sensors  120  and is transmitted to it, preferably via network  145 . If the activity is high, that is, if many vehicles  115  are moving, then a high scanning frequency is chosen, and a low scanning frequency is accordingly chosen in the event of low activity. 
     To determine the activity, preferably signals of an infrastructure device  175  are evaluated. Preferably, multiple infrastructure devices  175  are scanned, and the scanned signals are preferably processed as a function of the type of infrastructure device  175  and its place of installation. 
     A first exemplary infrastructure device  175  includes an induction loop, which is able to determine the presence of a vehicle  115  in an area  180  such as a traffic area, an entrance or an exit of parking lot  105 . In the process, it is also possible to determine a driving speed or a dwell time of vehicle  115 . In this manner, it is possible for example to detect a traffic jam situation in the entrance or exit area  180  and to take it into account in a suitable manner. A second exemplary infrastructure device  175  includes a barrier, which is preferably installed in the area  180  of an entrance or an exit. The barrier or a comparable access control system is able to signal how many vehicles  115  per unit of time enter or exit parking lot  105 . A third exemplary infrastructure device  175  is provided by a camera, which is mounted in the area  180  of parking lot  105  in order to monitor vehicles  115 . The camera may be connected to a detection system for license plates (Automatic Number Plate Recognition, ANPR) so as to make it possible to reconstruct the movement of a vehicle  115  in the area  180  of parking lot  105  by analyzing the signals of multiple cameras. Other or additional infrastructure devices  175  may also be provided, for example a photoelectric barrier, a radar sensor, a lidar sensor or an ultrasonic sensor. Particularly in a parking lot  105  that is designed to be traveled by an autonomously controllable vehicle  115 , such infrastructure devices  175  may already exist. 
     Processing device  135  or a dedicated separate processing device evaluates the signals of infrastructure devices  175  and determines the activity of vehicles  115 , that is, effectively a traffic volume or a congestion in the area of parking lot  105 . On the basis of the activity, a scanning frequency is then determined for at least one of parking lot sensors  120  and is transmitted to the latter. In a preferred specific embodiment, scanning frequencies for individual parking lot sensors  120  or groups of parking lot sensors  120  are determined and transmitted. The parking lot sensors  120  of a group may be mounted in proximity to one another or may be accessible by a vehicle  115  via a common access path. Although it is preferred that the specific scanning frequencies are transmitted individually to each parking lot sensor  120 , a scanning frequency for a group of parking lot sensors  120  may also be transmitted by a multipoint connection (multicast), or a parking lot sensor  120  may transmit a received scanning frequency to another parking lot sensor  120  of the same group. 
       FIG. 2  shows a flowchart of a method  200  for controlling the parking lot sensor  120  of system  100  of  FIG. 1 . In a first step  205 , vehicle sensor  120  waits as a function of a predetermined scanning frequency until a scan is required. If this is the case, then sensor  160  is activated in a step  210 , and the measuring area  125  is scanned in a step  215 , and sensor  160  is deactivated in a step  220 . The activation may include switching sensor  160  on and the deactivation may include switching sensor  160  off. Depending on the construction or measuring principle of sensor  160 , another procedure may be required, it being possible in particular for steps  210  and  220  to be omitted in the case of a passive sensor. 
     In a subsequent step  225 , a determination is made on the basis of the scanning result as to whether or not a vehicle  115  is located in measuring area  125 . 
     This determination is preferably made on the part of sensor  160  or on the part of control unit  155 . In a step  230 , the result of the determination is preferably transmitted via communication device  165  to central management unit  130 . Under certain circumstances, for example if an occupancy state of parking space  110  has not changed, the transmission of the result of the determination may also be omitted. In a subsequent step  235 , the scanning frequency is received for a new run through steps  205  through  235 . This step may also occur at any other point in time when carrying out method  200 . Subsequently, method  200  may return to step  205  and run through anew. 
     The scanning frequency received in step  235  is provided on the part of processing device  135 . For this purpose, a separate portion of method  200  having steps  240  through  255  may be executed, which is described in the following. The two sub-methods of steps  205  through  235  and  240  through  255  may generally be executed concurrently or in parallel, it being possible for a synchronization to be performed or for an asynchronous operation to be implemented. 
     In a step  240 , one or more infrastructure devices  240  are scanned. The data accumulating in the process are processed together in a step  245 , if applicable with the aid of statistical data such as installation locations of the individual infrastructure devices  240 , in order to determine the activity of vehicles  115  in parking lot  105 . The activity depends on a number of vehicles  115  that are traveling in parking lot  105 . This also includes vehicles  115  that must wait in a traffic area before they are able to proceed. In one specific embodiment, the activity additionally depends on the driving speed of a vehicle  115 , a higher driving speed generally indicating a lower activity and a lower driving speed or even a standstill indicating a high activity. The longer the standstill, the higher the activity may be determined. For the speeds and standstill times, it is possible to form and evaluate average values or distributions across the individual vehicles  115 . 
     Based on the determined activity, a scanning frequency is determined in a step  250 . In a simple specific embodiment, only one scanning frequency is determined for multiple or all parking lot sensors  120 , while in a more complex specific embodiment, scanning frequencies may be determined for groups of parking lot sensors  120  or for individual parking lot sensors  120 . In a step  255 , the determined scanning frequencies are transmitted to the parking lot sensors  120 .