Abstract:
A sensor for outputting a first measurement signal that is dependent on a measurement variable to be detected in a vehicle, including: a sensor circuit having a measuring sensor for generating the first measurement signal on the basis of the measurement variable, and a magnetic field probe for outputting a second measurement signal that is dependent on a magnetic field to be detected.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. National Phase Application of PCT International Application No. PCT/EP2015/070151 filed Sep. 3, 2015, which claims priority to German Patent Application No. 10 2014 219 384.2, filed Sep. 25, 2014, the contents of such applications being incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a distance sensor. 
       BACKGROUND OF THE INVENTION 
       [0003]    An electronic device in the form of a sensor for outputting an electric signal is known from WO 2010/037810A1, which is incorporated by reference which is dependent on a physical variable which is detected by means of a physical field on the basis of a measuring sensor. 
         [0004]    The printed publication WO 2014/023595, which is incorporated by reference discloses a vehicle having multiple receivers which are able to detect a magnetic field vector. In order to generate the magnetic field vectors, suitable antennas and/or transmitters are arranged on the primary coil of the charging unit, which generates a defined electromagnetic field. In this way, a precise positioning of the vehicle relative to the primary coil of the charging unit can be ascertained. 
       SUMMARY OF THE INVENTION 
       [0005]    Starting from this, an aspect of the invention is to improve the known sensor. 
         [0006]    According to one aspect of the invention, a sensor for outputting a first measurement signal that is dependent on a measurement variable to be detected in a vehicle comprises:
       a sensor circuit having a measuring sensor for generating the first measurement signal on the basis of the measurement variable, and   a magnetic field probe for outputting a second measurement signal that is dependent on a magnetic field to be detected.       
 
         [0009]    The indicated sensor is based on the consideration that electric vehicles could be charged with electric energy by means of transmission coils, which induce a charging voltage with a magnetic field in a receiving coil on the vehicle, with which charging voltage an electric energy storage device in the electric vehicle can in turn be charged up. To this end, the vehicle and in particular the receiving coil on the vehicle must be positioned exactly over the transmission coil, in order to achieve maximum efficiency during the inductive transfer of the electric energy. 
         [0010]    In order to position the vehicle exactly, localized magnetic field probes distributed across the vehicle, which detect the extent of the magnetic field of the transmission coil at the individual locations in the vehicle, can be used. On the basis of these extents of the magnetic field, the relative position of the transmission coil and that of the receiving coil with respect to one another can be determined, for example by means of triangulation, and the position of the vehicle can be regulated in a suitable manner by moving it such that the receiving coil is positioned exactly over the transmission coil. 
         [0011]    However, at least three magnetic field probes are required for a triangulation, in order to be able to determine the relative position between the transmission coil and the receiving coil in a meaningful manner, which is in turn associated with the installation space which is accordingly required. 
         [0012]    If the magnetic field of the transmission coil can also be detected directionally, two magnetic field probes could also suffice in order to localize the transmission coil relative to the vehicle. 
         [0013]    In this case, the use of the indicated sensor is based on the concept of integrating the magnetic field probe into an already existing sensor. In this way, a structure which already exists, such as a sensor circuit, signal processing circuit, data interface and a housing, can also be used, resulting in the amount of space required in the vehicle being considerably reduced. 
         [0014]    Any sensor which already exists in the vehicle can essentially be selected as an already existing sensor. However, already existing sensors should preferably be selected, which are already present a number of times in the vehicle in terms of their structure, because they have to detect the same measuring variable at various sensor locations in the vehicle, for example. For instance, distance sensors but also wheel speed sensors can be such already existing sensors. 
         [0015]    In a further development of the indicated sensor, the measuring sensor of the sensor circuit is set up to detect a distance from an obstacle which is located at a distance from the vehicle as a measurement variable. Already existing sensors in the vehicle having such measuring sensors are called distance sensors and have the advantage, compared with wheel speed sensors, that they can be effectively operated without a shielding plate. The disadvantage of the shielding plate, within the framework of the indicated sensor, is that it also shields the magnetic field of the transmission coil, thus making it unnecessarily difficult at the very least to determine the relative position between the transmission coil and the receiving coil. 
         [0016]    According to another aspect of the invention, a method for positioning a vehicle, in which at least two, preferably at least three, of the indicated sensors are arranged at sensor locations which are located at a distance from one another, over a transmission coil in order to induce a charging voltage in a receiving coil of the vehicle in order to charge an electric energy storage device with a magnetic field, comprises the steps:
       detecting an extent of the magnetic field for each sensor location with the respective sensor arranged at the sensor location,   determining a relative position of the transmission coil with respect to the vehicle on the basis of the detected extents of the magnetic field at the sensor locations, and   moving the vehicle on the basis of the determined relative position until the vehicle is positioned with the transmission coil over the receiving coil.       
 
         [0020]    The vehicle can be aligned exactly over the transmission coil by using the indicated method, so that the energy storage device of the vehicle can be charged very efficiently. 
         [0021]    In a particular further development of the indicated method, the relative position of the transmission coil with respect to the vehicle is determined on the basis of a triangulation of the detected extents of the magnetic field at the sensor locations. 
         [0022]    In another further development of the indicated method, in order to move the vehicle over the transmission coil, the vehicle is moved on a path which is determined on the basis of the relative position, wherein the vehicle is monitored during the movement on this path with the first measurement signal from the sensor circuit with respect to a collision with obstacles in the surroundings. In this way, both measuring sensors of the aforementioned sensor can be meaningfully used during the implementation of the indicated method. 
         [0023]    In another further development, the indicated method comprises the step of positioning the vehicle in an area around the transmission coil until the magnetic field can be detected with the sensors on the basis of a global navigation satellite system which is called a GNSS. In this way, the vehicle can first be roughly positioned in the vicinity of the transmission coil, wherein the indicated method for precisely positioning the vehicle over the transmission coil by means of a handshake is used. The GNSS can, in this case, be used directly, but also as part of a fusion sensor. 
         [0024]    According to another aspect of the invention, the object is achieved by means of a pressure sensor device for ascertaining an impact of a person with a vehicle, having
       foam padding which is arranged in a bumper of a vehicle and which lies in contact with an internal wall of the bumper,   a pressure sensor for ascertaining a pressure acting from externally on the foam padding,       
 
         [0027]    wherein the pressure sensor device has a magnetic field probe for outputting a measurement signal that is dependent on a magnetic field to be detected. 
         [0028]    Advantageously, the pressure sensor device is further developed in that the magnetic probe is configured such that it is integrated in the pressure sensor. 
         [0029]    According to another aspect of the invention, a control device is set up to carry out one of the indicated methods. 
         [0030]    In a further development of the indicated control device, the indicated device has a storage unit and a processor. The indicated method is thereby stored in the storage device in the form of a computer program, and the processor is provided to execute the method when the computer program is loaded from the storage device into the processor. 
         [0031]    According to another aspect of the invention, a computer program comprises program code means, in order to perform all the steps of one of the indicated methods when the computer program is run on a computer or one of the indicated devices. 
         [0032]    According to another aspect of the invention, a computer program product contains a program code which is stored on a computer-readable disk and which, when it is run on a data processing device, carries out one of the indicated methods. 
         [0033]    According to another aspect of the invention, a vehicle comprises:
       a chassis supported on wheels,   at least three of the indicated sensors, whether these are distance sensors or pressure sensors, which are arranged at sensor locations which are located at a distance from one another, and   one of the indicated control devices for positioning the vehicle.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    The characteristics, features and advantages of this invention described above, as well as the way in which these are achieved, will become clearer and more readily comprehensible in connection with the following description of the embodiment examples which are explained in more detail in connection with the drawings, wherein: 
           [0038]      FIG. 1  shows a schematic diagram of a vehicle parking in a parking space having a transmission coil, 
           [0039]      FIG. 2  shows a schematic diagram of the vehicle from  FIG. 1 , 
           [0040]      FIG. 3  shows a schematic diagram of a sensor in the vehicle from  FIG. 2 , and 
           [0041]      FIG. 4  shows a schematic diagram of a sensor in the vehicle from  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    Identical technical elements in the figures are provided with the same reference numerals and are only described once. 
         [0043]    Reference is made to  FIG. 1  which shows a schematic diagram of a vehicle  2  intending to park in a parking space  6  between two other vehicles  8 ,  10  on a road  4 . In this case, the parking possibility is indicated by a suitable traffic sign  12 . 
         [0044]    The vehicle  2  is designed hereinafter as an electric vehicle and will therefore also be referred to as such. In this case, the electrical vehicle  2  is supplied by means of an electric energy storage device  14  in a way which still has to be described in order, amongst other things, to be driven with electric energy  15 . In addition, a receiving coil  16  is provided on the electrical vehicle  2 , by means of which the electrical vehicle  2  can receive a magnetic field  18  in order to charge the electric energy storage device  14  and transform it into electric energy  15  by induction. 
         [0045]    The magnetic field  18  is emitted within the framework of the present design by a transmission coil  20  which is provided as part of a charging station  22  in the parking space  6 . The charging station  22  additionally comprises a control terminal  24  at which a user can make inputs in order, for example, to pay for the electric energy supply. The control terminal  24  thereby applies the electric energy  15 , with which the electric energy storage device  14  is to be charged, to the transmission coil  20  which then excites the magnetic field  18  in the known way and thus transfers the electric energy by induction via the receiving coil  16  to the electric energy storage device  14  in the vehicle  2 . In this case, the electric energy  15  can, for example, be extracted from an electric energy supply network  26  to which the control terminal  24  can be connected. 
         [0046]    In order to transfer the electric energy  15  via the transmission coil  20  and the receiving coil  16  as efficiently as possible, the receiving coil  16  should be positioned as precisely as possible over the transmission coil  20 . 
         [0047]    To this end, magnetic field probes  30  are provided on the vehicle  2  within the framework of the present design at four different sensor locations  28  which are located at a distance from one another. The magnetic field probes  30  detect the magnetic field  18  of the transmission coil  20  and output a magnetic field measurement signal  32  which is indicated in  FIGS. 3 and 4 , the level of which magnetic field measurement signal is dependent on the extent of the magnetic field  18  at the respective sensor location  28 . Since the magnetic field  18  at the respective sensor locations  28  is dampened depending on the distance from the transmission coil  20 , the extent of the magnetic field  18  at the sensor location  28  and, therefore, also the level of the corresponding magnetic field measurement signal  32  are dependent on the distance of the sensor location  28  from the transmission coil  20 . If the magnetic field measurement signal  32  is therefore present at three different magnetic field probes  30  at least, the relative position  34  of the vehicle  2  with respect to the transmission coil  20  and, thus, the relative position  34  of the receiving coil  16  with respect to the transmission coil  20  can be determined. 
         [0048]    This relative position  34  can then, if possible, be reduced to zero and the receiving coil  16  therefore positioned exactly over the transmission coil  20 , by means of suitable control actions being taken on the vehicle such as, for example, driving and steering. 
         [0049]    In addition, there are provided on the vehicle  2  distance measuring sensors  36  which output, e.g. by means of radar beams  38 , distance measurement signals  40  that are dependent on the distance from obstacles such as, for example, the two other vehicles  8 ,  10  and that are indicated in  FIG. 4 . Alternatively, distance measuring sensors  36  which detect the distance by means of ultrasound are also conceivable. On the basis of the distance measurement signals  40  a collision with the obstacles  8 ,  10  can then be prevented, for example by means of braking interventions on the vehicle  2 . For the sake of clarity, not all of the distance measuring sensors  36  are provided with a reference numeral in  FIG. 1 . 
         [0050]    The magnetic field probes  30  have to be installed in the vehicle at the individual sensor locations  28  and take up installation space accordingly. In order to reduce the required amount of installation space, the magnetic field probes  30  should be integrated if at all possible into already existing sensors on the vehicle  2 . 
         [0051]    In order to explain this, the construction of the vehicle  2  will first of all be explained in greater detail with reference to  FIG. 2 . 
         [0052]    The vehicle  2  has a chassis  44  which is supported on four wheels  42 , wherein each wheel  42  can be individually driven by means of an electric motor  46 . An engine control system  48  is provided to drive the vehicle, which can supply the electric motors  46  with the electric energy  15  from the electric energy storage device  14  in order to propel the vehicle  2  on the basis of an acceleration request. 
         [0053]    In this case, each electric motor  46  can be individually supplied with electric energy  15  in order, for example, to regulate the driving dynamics of the vehicle  2  having known driving dynamics per se. 
         [0054]    The acceleration request  50  can come from various units in the vehicle  2  such as, for example, an accelerator pedal which is not illustrated in more detail. Within the framework of the present design, a parking assistant  52  outputs the acceleration request  50  in order to automatically park the vehicle  2  in the parking space  6 . In addition to the acceleration request  50 , the parking assistant  52  additionally outputs a steering angle  54 , in order to thus control a steering  56  of the vehicle  2 . In addition, the parking assistant  52  can additionally intervene in a brake of the vehicle  2 , which is not shown in greater detail, by providing brake control signals. 
         [0055]    The parking assistant  52  is essentially one or multiple controllers which can output the acceleration request  50 , the steering angle  54  and the previously indicated brake control signals as control inputs on the basis of a comparison of nominal/actual values, as described, for example, in DE 198 09 416 A1 which is incorporated by reference. 
         [0056]    Sensor signals are required for this. The sensor signals can, for example, be distance sensor signals  58  from distance sensors  60  that generate the distance sensor signals  58  as a function of the distance measurement signals  40  from the distance measuring sensors  36 . In addition, the sensor signals can also be wheel speed signals  62  from wheel speed sensors  64 . As is shown in  FIG. 2 , it is advantageous to arrange the magnetic probe  30  at the corner areas of the vehicle  2 . Both the determined distance sensors  60  and the wheel speed sensors  64  are suitable in a particularly advantageous way as sensors for the magnetic probe  30 . 
         [0057]    The magnetic field probes  30  can be installed both in the distance sensors  60  and in the wheel speed sensors  64 . The advantage in both cases is that the resulting overall sensor can always be installed in the same way, because these types of sensors detect the same measurement variable at different sensor locations  28  in the vehicle  2 . 
         [0058]    According to  FIG. 3  the magnetic field probes  30  can be installed in the wheel speed sensors  64 , which is not preferred for the reasons explained below. 
         [0059]    Each wheel speed sensor  64  detects the speed of a wheel  42  on the basis of an encoder wheel  66  rotating at the speed of the wheel  42 , which encoder wheel is encoded in the circumferential direction of the rotation with magnetic north poles  68  and magnetic south poles  70  and thus excites a corresponding magnetic sensor field  72 . 
         [0060]    To this end, each wheel speed sensor  64  comprises a housing  73  in which a speed measuring sensor  74  which is sensitive to a magnetic field is housed, which detects the sensor field  72  and, on the basis thereof, outputs a speed sensor signal  76  dependent on the speed. The speed sensor signal  76  is evaluated in a signal processing circuit  34 , wherein the wheel speed signal  62  is generated and is output to an interface  80 . A shielding plate  82  in the housing  73  shields the electronic components of the wheel speed sensor  64  from external electromagnetic influences. 
         [0061]    The magnetic field probe  30  can be connected directly to the interface  80  or indirectly via the signal processing circuit  78 , wherein the interface  80  from the wheel speed signal  62  and the magnetic field measurement signal  32  generates a joint data transmission signal  84  and transfers this via a two-wire line  86  to the parking assistant  52 . 
         [0062]    However, the shielding plate  82  in this embodiment example not only shields against electromagnetic influences, but also the magnetic field  18 . Therefore, the use of the magnetic field probes  30  in the speed sensors  64  is not preferred, as already indicated. 
         [0063]    The design principle of the distance sensors  60  shown in  FIG. 4  is such that they do not have a shielding plate  82 , which is why it is not possible to shield the magnetic field here either. Therefore, the magnetic field probes  30  should be installed in the distance sensors  60  using the principle explained in  FIG. 3 . 
         [0064]    It is particularly advantageous to install the magnetic probes  30  in distance sensors. On the one hand, this removes the necessity for a separate sensor to sense the position of the charging station  22 . In this way, it is possible to make savings on installation space, additional electrical wiring and installation costs. In addition, a particularly major advantage of distance sensors is the fact that they are installed in the bumpers of the vehicle, which usually consist of plastic and therefore do not adversely affect the effectiveness of the magnetic probe  30 . However, it is just as conceivable that the magnetic probes  30  are incorporated or integrated into pressure sensors. Such pressure sensors are also located in the bumpers of a vehicle and are used to sense contact of the bumper with a person. The magnetic probes are expediently integrated into such pressure sensors. However, it is also conceivable for the magnetic probes  30  to be embedded separately in a foam, in which the pressure sensor is also embedded. Such a pressure sensor i  has been developed and sold by the applicant.  i http://www.continental-corporation.com/www/presseportal_com_de/themen/pressemitteilungen/3_automotive_group/chassis_safety/press_releases/pr_2010_10_05_fussagaengerschuts_sensoren_de.html 
         [0065]    In general, there should not be any metal in the surroundings of the magnetic field probes  30  so as not to disrupt the propagation of the magnetic field  18  in the area of the magnetic field probes  30 .