Abstract:
The method for locating a certain object is a method for locating the object by means of a detected locating signal. With this method, locating of precisely this object is checked in such a way that an object with at least a temporally variable reflective property is used, and an influence of this reflective property on the detected locating signal is checked. The locating system has a locating sensor for locating an object by means of a locating signal detected by a locating sensor, as well as an evaluating device which is configured to check an influence of a temporally variable reflective property of the object on the locating signal detected by the locating sensor.

Description:
[0001]    This application is the National Stage of International Application No. PCT/EP2015/066290, filed Jul. 16, 2015, which claims the benefit of German Patent Application No. 10 2014 216 525.3, filed Aug. 20, 2014. The entire contents of these documents are hereby incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present embodiments relate to locating a specific object. 
         [0003]    For charging an electric vehicle at a charging station, the electric vehicle is regularly suitable for being positioned at the charging station. 
         [0004]    For positioning objects (e.g., containers or vehicles), it is known to use locating methods (e.g., in the form of laser locating or radar locating). 
         [0005]    Propagation time measurements and/or concepts based on frequency modulated continuous wave (FMCW) concepts are used in this case. With the use of such concepts, the form of the objects is to be regularly taken into account in order to be able to carry out reliable locating. Reflections often impair the reliability and accuracy of the locating. A particular challenge consists in reliably identifying the object to be located. 
       SUMMARY AND DESCRIPTION 
       [0006]    The scope of the present invention is defined solely by the appended claims and is not affected to any degree by the statements within this summary. 
         [0007]    The present embodiments may obviate one or more of the drawbacks or limitations in the related art. For example, an improved method for locating a specific object compared to the prior art is provided. As another example, an improved method for positioning an electric vehicle at a charging station compared to the prior art is provided. As other examples, an improved locating system for locating an object, an improved charging station, and an improved charging system compared to the prior art are provided. 
         [0008]    The method according to one or more of the present embodiments for locating a specific object is a method for locating the object using a detected locating signal. In the method, locating of precisely this object is checked such that the object used is one having at least one temporally variable reflection property. An influence of this reflection property on the detected locating signal is checked. According to one or more of the present embodiments, the object may thus be identified by the temporally variable reflection property and, having been identified in this way, may be unambiguously recognized during the locating. 
         [0009]    In one embodiment of the method, the locating is radio locating, laser locating, or acoustic locating. These known locating methods are sufficiently known and have been intensively tried and tested for the purpose of locating. The abovementioned methods are based on measurements of the signal propagation time. The measurement of the signal propagation time may be carried out according to methods known from the literature. The measurement of the signal propagation time is carried out in a suitable manner by taking into consideration the complex-valued phase of the spectrum of the received signal and/or based on FMCW. 
         [0010]    In one development of the method, the temporally variable reflection property is a temporally periodic reflection property. In this development, the temporally periodic reflection property is suitably expressed in such a modulation of the locating signal that may easily be recognized in a spectrum of the locating signal based on additional spectral components. This is recognizable in a particularly simple manner if the spectral components have one or more discrete accompanying frequencies or are at one or more, at least virtually, discrete frequencies. 
         [0011]    In one embodiment of the method, the temporally variable reflection property is formed by an oscillatorily deflected reflection surface. In this way, the temporally variable reflection property may be realized particularly easily in a mechanical manner (e.g., by an electrically drivable piezoelectric oscillator or a linear actuator). For example, the temporally variable reflection property may be realized by a modular supplementary part that, in cooperation with a further part, forms the object. For this purpose, the supplementary part may be arranged on the further part in a simple manner. 
         [0012]    In a suitable manner, in the method according to one or more of the present embodiments, the temporally variable reflection property is formed by at least one oscillatory or rotatory movement of at least one part (e.g., of a surface) of the object. A reflective rotor may be present on the surface of the object. 
         [0013]    In one embodiment of the method, the temporally variable reflection property is formed by a movement of a piezoelectric oscillator or of a linear actuator. 
         [0014]    In this development of the method, the temporally variable reflection property may be realized by a modular supplementary part that, in cooperation with a further part, forms the object. For this purpose, the supplementary part may be arranged on the further part in a simple manner. Piezoelectric ceramics of piezoelectric oscillators are robust to withstand weathering influences and may be of very flat design. Supplementary parts embodied in this way, for example, may therefore be embodied as not very susceptible to weathering influences or travel conditions such as occur in the case of electric vehicles, for example. 
         [0015]    In one embodiment of the method, the locating is radio locating (e.g., radar locating), and/or the locating signal is a radar signal, and/or the object is formed with (e.g., from) metal. Metal objects may easily be located by radar locating. For example, the locating of objects formed with metal (e.g., electric vehicles) is particularly significant economically. 
         [0016]    In one development of the method, the influence on the locating signal is checked spectrally. 
         [0017]    In a suitable development of the method, the influence of the variable reflection property in the range of a frequency or of frequencies of at least 300 Hz (e.g., at most 1 MHz) on the locating signal is checked. These frequencies are already comparatively high by comparison with frequencies that typically occur during movements as a commonplace occurrence (e.g., during electrical charging), such that the object may be reliably recognized by the abovementioned frequencies. For example, frequencies that may be generated by other moving objects may be reliably excluded. In one embodiment, the frequencies are kept stable over time. In this way, the influence of the variable reflection property may be determined particularly accurately. 
         [0018]    In one development of the method, the object used is an object that is formed with an electric vehicle or is an electric vehicle. 
         [0019]    In the method according to one or more of the present embodiments for positioning an electric vehicle at a charging station, a position of the electric vehicle is detected by a method for locating. The object includes at least one part of the electric vehicle, and/or the object is arranged at least partly on the vehicle. In this way, when carrying out the method according to one or more of the present embodiments, it is possible to check beforehand whether the electric vehicle is actually detected at all. If it is ascertained that the electric vehicle is not currently detected, then it is possible (e.g., via a user interface) to encourage a vehicle driver to occupy a predetermined setpoint position for carrying out the method for positioning the electric vehicle. Proceeding from this setpoint position, the method according to one or more of the present embodiments for locating may then support a more finely resolved positioning of the electric vehicle for charging the electric vehicle. 
         [0020]    The locating system according to one or more of the present embodiments has a locating sensor for locating an object using a locating signal detected by the locating sensor. The locating system also has an evaluation device. According to one or more of the present embodiments, the evaluation device is configured to check an influence of a temporally variable reflection property of the object on the locating signal detected by the locating sensor. 
         [0021]    In one development, in the locating system according to one or more of the present embodiments, the evaluation device is configured to check the influence of the variable reflection property such as is checked when carrying out a method for locating a specific object, as described above. 
         [0022]    The charging station according to one or more of the present embodiments for charging an electric vehicle includes a locating system, as described above, for positioning the electric vehicle. The charging station may be configured for inductively charging the electric vehicle. 
         [0023]    The charging system according to one or more of the present embodiments has a charging station, as described above, and an identification element. The identification element has parts that are movable (e.g., periodically) relative to one another. The parts that are movable relative to one another are movable, for example, rotationally (e.g., in the manner of a hub and a rotor rotating around said hub) or oscillatorily relative to one another. In one development, the parts are a clamped end and a free end of an oscillator (e.g., of a piezoelectric oscillator). 
         [0024]    In one embodiment of the charging system, the identification element includes an oscillator (e.g., a piezoelectric oscillator) that oscillates at an oscillation frequency (e.g., of at least 300 Hz). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  shows one embodiment of a charging system; and 
           [0026]      FIG. 2  shows an exemplary spectrum of a locating signal detected by a locating sensor of the charging station in accordance with  FIG. 1  when performing the method. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    A charging system  5  according to one or more of the present embodiments, as illustrated in  FIG. 1 , serves for charging an electric vehicle  10 . The charging system  5  includes a charging station  15  according to one or more of the present embodiments for charging an electric battery (not shown) of the electric vehicle  10 . 
         [0028]    The electric vehicle  10  has a pantograph  20  for collecting current at a busbar  25 . The busbar  25  is part of the charging station  15  and provides the charging current for charging. For the purpose of charging, the electric vehicle  10  is positioned so that the pantograph  20  is arranged suitably with respect to the busbar  25  of the charging station  15 , such that the charging process may be initiated. 
         [0029]    For suitable positioning, the charging station  15  has a radio locating system  30  according to one or more of the present embodiments. The radio locating system  30  includes a radar sensor  35 . The radar sensor  35  is configured to emit a radar signal  40  having a frequency S 0  (see  FIG. 2 ) of 24 gigahertz in the exemplary embodiment illustrated. The radar sensor  35  is also configured to receive a reflected radar signal as locating signal  45 . The radio locating system  30  also includes an evaluation device  50  that is signal-connected to the radar sensor  35 . 
         [0030]    Using the radio locating system  30  according to one or more of the present embodiments, it is provided that the position of the electric vehicle  10  is actually checked, rather than, for example, the position of some other object. For this purpose, the charging system  5  includes an identification element  55  that is arranged on the electric vehicle  10 . The identification element  55  includes a metal plate (not specifically illustrated) and a piezoelectric oscillator, by which the metal plate is linked to the electric vehicle  10  in a deflectable manner. For this purpose, the piezoelectric oscillator is clamped rigidly on the electric vehicle  10 . The metal plate, by contrast, is linked to the free end of the piezoelectric oscillator. 
         [0031]    Using this arrangement, the metal plate is deflected in a direction toward the radar sensor  35  and away from the radar sensor  35  oscillatorily at an oscillation frequency of three kilohertz. The electric vehicle  10  together with the identification element  55  thus forms an object having a temporally variable reflection property. In the case illustrated, the oscillatorily deflected metal plate forms a reflection surface that leads to a temporal variation of the reflection phase. In the exemplary embodiment illustrated, the piezoelectric oscillator is configured for oscillation upon application of the metal plate at an oscillation frequency of 3 kilohertz. 
         [0032]    The method according to one or more of the present embodiments for locating a specific object is carried out with the charging system  5  such that the electric vehicle  10  is recognized by the radio locating system  30 . The method is carried out specifically as follows. The radar sensor  35  emits a radar signal  40  in the direction of the electric vehicle  10  to be located. The radar signal  40  impinges on the electric vehicle  10  and also, for example, on the oscillatorily deflected metal plate of the identification element  55 . In this case, the radar signal  40  is reflected as a locating signal  45  that is modulated, owing to the oscillating reflection phase with the oscillation frequency of the piezoelectric oscillator. Consequently, the locating signal  45  is modulated with an oscillation frequency of 3 kilohertz compared with the radar signal  40 . In this case, the oscillation frequency of the piezoelectric oscillator remains constant over time. In further exemplary embodiments, not specifically illustrated, the oscillation frequency is a different frequency (e.g., a frequency from the range of from 300 hertz to the ultrasonic range). 
         [0033]    The locating signal  45  is detected by the radar sensor  35  and communicated to the evaluation unit  50  for evaluation. A spectral analysis of the locating signal  45  is performed by the evaluation unit  50 . The spectrum illustrated in  FIG. 2  represents the contributions of the individual frequencies of the locating signal  45  as a function of the frequency f. The “contributions” are the respective squares of absolute values of the Fourier coefficients of the locating signal  45  (“contribution” hereinafter). The central peak Z corresponds to the dominant contribution B 0  of the frequency S 0  of the radar signal  40  at 24 gigahertz. Owing to the modulation of the locating signal  45  with the oscillation frequency of the piezoelectric oscillator with an oscillation frequency of 3 kilohertz, sidebands having sideband frequencies S 1 , S 2  occur in addition to the central peak Z in the spectrum. The sideband frequencies S 2  are equal to the summation frequency, and the sideband frequencies S 1  are equal to the difference frequency of the frequency S 0  of the radar signal  40  and the oscillation frequency of the piezoelectric oscillator (e.g., in the illustrated exemplary embodiment where S 0 =24 GHz, S 2 =24 GHz+3 kHz and S 1 =24 GHz−3 kHz). 
         [0034]    Using the evaluation unit  50 , the locating signal  45  is spectrally decomposed into the contributions B 0  of the frequency S 0  of the radar signal  40  and also the contributions B 1 , B 2  of the locating signal  45  at the sideband frequencies S 1 , S 2 . The contributions B 1 , B 2  at the sideband frequencies S 1 , S 2  are averaged arithmetically and then put into a ratio with the contribution B 0  of the frequency S 0  of the radar signal  40 . If this ratio exceeds a predetermined threshold value, then the evaluation unit  50  ascertains a detection of a locating signal  45  emitted by the electric vehicle  10 . If an appreciable ratio (e.g., ratio at least reaching the threshold value, of contributions B 1 , B 2  at the sideband frequencies S 1 , S 2 ) is not present, then the evaluation unit  50  ascertains that the locating signal  45  has not been reflected by the electric vehicle  10 . In this case, the propagation time measurement may be carried out according to the methods known from the literature (e.g., by taking into consideration the complex-valued phase of the spectrum of the received signal and/or based on FMCW). 
         [0035]    Using the method according to one or more of the present embodiments for locating the electric vehicle  10 , the method according to one or more of the present embodiments for positioning the electric vehicle  10  is carried out (e.g., a position check is additionally carried out in this method). The radar sensor  35  emits the radar signal  40  in a direction in which ideally the electric vehicle  10  is situated in the ideal case (e.g., if the electric vehicle  10  is positioned suitably for charging). In this case, the locating signal  45  is monitored for the oscillation frequency of the piezoelectric oscillator by the evaluation device  50 . If, as explained above, it is ascertained hat the locating signal  45  has not been reflected by the electric vehicle  10 , then the evaluation device  50  communicates a signal to a control device (not illustrated) of the charging station  15 . The control device thereupon drives a user interface (not illustrated) of the charging station  15  such that the user interface requests a driver of the electric vehicle  10  to drive to a position of the electric vehicle  10  that is suitable for charging. If this request is complied with, then the locating signal  45  is subsequently actually reflected by the electric vehicle  10 , which is ascertained by the evaluation device  50 , as described. 
         [0036]    Once it has been ascertained that the locating signal  45  is actually reflected by the electric vehicle  10 , continuous locating of the electric vehicle  10  is performed by the locating signal  45 . Using the locating signal  45 , it is possible to emit detailed navigation signals via the user interface, such that the position of the electric vehicle  10  for collecting current at the busbars  25  of the charging station  15  may be optimized based on the locating signal  45 . 
         [0037]    The exemplary embodiment explained above may be adapted to the effect that the charging station  15  is not necessarily configured for busbar-based charging of the electric vehicle  10 . 
         [0038]    In one exemplary embodiment, not specifically illustrated, instead of busbars  25  and a pantograph  20 , for example, a primary charging coil may be provided on the charging station  15 , and a secondary charging coil may be provided on the electric vehicle  10 . In the last-mentioned exemplary embodiment, the electric vehicle  10  is then positioned at a position of the electric vehicle  10  such that the relative positioning of primary charging coil and secondary charging coil is effected suitably for charging. 
         [0039]    In principle, instead of a radar sensor, a laser sensor with a correspondingly higher laser frequency may be used instead of the radar frequency. 
         [0040]    In one exemplary embodiment, not specifically illustrated, an acoustic sensor is used instead of a radar sensor. The acoustic sensor is configured to perform locating by signal propagation time measurements analogously to a radar sensor. 
         [0041]    The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification. 
         [0042]    While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.