Guided vehicle positioning for inductive charging using a vehicle camera

Abstract

Control unit (133) for a vehicle (100) comprising a secondary coil (102) for receiving electrical energy from a vehicle-external primary coil (111), wherein the vehicle comprises at least one camera (131) configured to detect the environment of the vehicle (100), wherein the control unit (133) is configured - To receive image data from at least one camera (131) of the vehicle (100); - to receive reference data from a control unit (110) of the primary coil (111); wherein the reference data includes information about at least one predefined reference object (701) in the detected environment of the vehicle (100) and about a position of the at least one predefined reference object (701) relative to the primary coil (111); wherein the reference data includes, - Information about optical features of the at least one reference object (701) that can be detected in the image data of the camera (131); and / or - Information about a spatial size of the at least one reference object (701); - to detect at least one predefined reference object (701) in the received image data based on the reference data; and - to determine, based on the detected at least one reference object (701), a position of the secondary coil (102) relative to the primary coil (111).

Description

[0001] The invention relates to the inductive charging of a rechargeable vehicle battery. In particular, the invention relates to a method and a corresponding device for positioning a vehicle over a primary coil for inductive charging of the vehicle's rechargeable battery.

[0002] Vehicles, especially electric vehicles, include rechargeable batteries for storing electrical energy. A vehicle's rechargeable battery can be charged, for example, by connecting it to an external power source (such as a public power grid). One approach to automatic, wireless, inductive charging of the vehicle's battery involves transferring electrical energy from the ground to the vehicle's underbody via magnetic induction using the underbody clearance. This is exemplified in... Fig. 1a is shown. In particular, it shows Fig. 1a A vehicle 100 with a storage device 103 for electrical energy (e.g., with a rechargeable battery 103). The vehicle 100 includes a so-called secondary coil 102 in the vehicle underbody, wherein the secondary coil 102 is connected to the storage device 103 via an impedance matching device (not shown) and a rectifier 101.

[0003] The secondary coil 102 can be positioned above a primary coil 111, which, for example, is mounted on the floor of a garage. The primary coil 111 is connected to a power supply 110. The power supply 110 can include a radio frequency generator that produces an AC (alternating current) current in the primary coil 111, thereby inducing a magnetic field. With sufficient magnetic coupling between the primary coil 111 and the secondary coil 102 via the ground clearance 120, the magnetic field induces a corresponding current in the secondary coil 102. The induced current in the secondary coil 102 is rectified by the rectifier 101 and stored in the energy storage device 103 (e.g., in the battery). In this way, electrical energy can be wirelessly transferred from the power supply 110 to the energy storage device 103 of the vehicle 100.

[0004] In order to achieve sufficient magnetic coupling between primary coil 111 and secondary coil 102, the secondary coil 102 of the vehicle 100 should be positioned with a certain precision (typically ±10cm) above the primary coil 111 (which is also referred to as the ground unit).

[0005] DE 10 2012 008 791 A1 describes a method for assisting a vehicle during a maneuvering operation. DE 10 2011 111 051 A1 describes a method for assisting a driver in controlling a vehicle. EP 1 930 203 A1 describes a parking assistance system. WO 2011 / 114 208 A2 describes a vehicle that can be charged inductively.

[0006] This document describes a method and a device that assists the driver of vehicle 100 in positioning the secondary coil 102 above the primary coil 111. Positioning assistance is particularly important because the driver cannot see the ground unit 111 during the final stage of positioning the vehicle 100, as the ground unit 111 is then located beneath the vehicle 100.

[0007] According to one aspect, a control unit for a vehicle is described. The vehicle can be, in particular, a two-track vehicle, such as a passenger car, a road vehicle, and / or an automobile. The vehicle includes a secondary coil for receiving electrical energy from a primary coil external to the vehicle. Typically, the secondary coil is mounted on the vehicle's underbody. The primary coil external to the vehicle is, for example, mounted on the ground of a parking space for the vehicle. The primary and secondary coils form a transformer if there is magnetic coupling between them. To ensure sufficient transfer of electrical energy from the primary to the secondary coil, the distance between the secondary and primary coils (especially the lateral distance) should reach or fall below a predefined threshold.The distance can be, for example, the geometric distance between one or more predefined points of the primary coil and one or more predefined points of the secondary coil.

[0008] The vehicle includes at least one camera configured to capture the vehicle's surroundings. This camera can be, for example, a front camera configured to capture the area in front of the vehicle and / or a rear camera configured to capture the area behind the vehicle. Specifically, the camera can capture the area in the direction of travel of the vehicle (e.g., a front camera when moving forward and / or a rear camera when reversing). Multiple cameras can also be used to capture the vehicle's surroundings. Furthermore, the vehicle can include additional environmental sensors, such as ultrasonic sensors, which can be used to determine the distance to specific objects (e.g., predefined reference objects) in the vehicle's environment.

[0009] The control unit is configured to receive image data from at least one camera on the vehicle. This image data can be, for example, an image of the vehicle's surroundings as captured by the camera at a specific point in time, and / or a sequence of images taken at a sequence of points in time.

[0010] Furthermore, the control unit is configured to access reference data. This reference data can include information about at least one predefined reference object in the vehicle's detected environment. For example, the reference data can include information about one or more optical features of the at least one reference object that can be detected in the camera's image data. In particular, the reference data can include a visual representation of the at least one reference object, which can be compared with the image data to detect the at least one reference object within the image data. Additionally, the reference data can include information about the spatial size of the at least one reference object.The spatial size in the reference data can be compared with the size of the at least one detected reference object in the image data to determine the distance of the camera (and the vehicle) from the at least one reference object.

[0011] Furthermore, the reference data can include information about the position of at least one predefined reference object relative to the primary coil. Specifically, the reference data can include information regarding the spatial coordinates of the at least one reference object within a predefined coordinate system. Additionally, the reference data can include information regarding the spatial coordinates of the primary coil within the predefined coordinate system. These respective coordinates then represent the relative position between the reference object and the primary coil.

[0012] The control unit can be further configured to detect at least one predefined reference object in the received image data based on the reference data. As explained above, the control unit can specifically be configured to detect a visual representation of the reference object in the image data. Furthermore, the control unit can be configured to determine the position of the secondary coil relative to the primary coil based on the detected reference object. The position of the detected reference object in the image data can provide information about the vehicle's position relative to the reference object. Additionally, the detected size of the reference object can provide information about the distance between the vehicle and the reference object.

[0013] In particular, the control unit can be configured to determine the camera angle of a beam between the at least one camera and the at least one reference object, based on the detected reference object. The camera angle indicates the angle at which the vehicle is oriented relative to the reference object. The control unit can also be configured to determine the distance between the secondary coil and the reference object, based on the determined camera angle. For this purpose, triangulation methods and / or other trigonometric methods (e.g., applying the triangle rule when simultaneously detecting at least two reference objects in the image data) can be used.

[0014] The control unit can be further configured to receive information regarding the vehicle's wheel angle and wheel speed. Based on this information, the vehicle's movement can be determined. This information can be synchronized with data obtained from the image (e.g., the determined camera angle). From this, the vehicle's movement (and / or position) relative to at least one reference object can be determined. Triangulation methods, for example, can be used for this purpose.

[0015] The reference data can include information about a multitude of predefined reference objects. These predefined reference objects can be arranged along the vehicle's approach trajectory to the primary coil. In this way, the entire vehicle positioning process can be supported by the multitude of predefined reference objects. The control unit can be configured to receive a temporal sequence of image data (in particular, a temporal sequence of images) from the vehicle's at least one camera along the approach trajectory. Furthermore, the control unit can be configured to detect the multitude of predefined reference objects within this temporal sequence of image data. The individual reference objects can be detectable on different image data (in particular, images or frames) within the sequence of image data. This allows, for example, the identification of different reference objects.It must be ensured that at least one predefined reference object can be detected by the vehicle's at least one camera at any given time during the positioning process. This allows for continuous support of the vehicle's positioning process. Furthermore, the control unit can be configured to bridge one or more points in the positioning process where no predefined reference object can be detected. For this purpose, vehicle-internal data (such as wheel angle and / or wheel rotation) can be used to determine the vehicle's movement.

[0016] The control unit can be configured to receive reference data from a control unit of the primary coil. This reference data can be transmitted, for example, via a wireless communication network (e.g., WLAN). This allows the vehicle to approach an unknown charging station and, at the start of the positioning process, receive the necessary reference data. The reference data can be stored in the vehicle's memory unit. The control unit can also be configured to use the stored reference data when the vehicle repeatedly approaches the same charging station. Furthermore, additional data (e.g., a previously determined target trajectory of the vehicle) can be used and updated as needed. This improves the positioning process when repeatedly approaching a charging station.

[0017] The control unit can be configured to send a control signal to the primary coil's control unit to illuminate at least one predefined reference object. This control signal can be transmitted via the aforementioned wireless communication network. Transmitting the control signal ensures that the vehicle's at least one camera can reliably detect the at least one predefined reference object.

[0018] The control unit can be configured to provide information regarding the position of the secondary coil relative to the primary coil for positioning purposes. For example, the information regarding the primary coil's position can be displayed on a screen in the vehicle, thus assisting the driver in positioning the vehicle. Alternatively or additionally, the information regarding the primary coil's position can be provided to the vehicle's parking assistance function. The control unit can then be configured to cause the vehicle's parking assistance function to move the vehicle in such a way that the distance between the secondary coil and the determined position of the primary coil reaches or falls below the predefined threshold (in order to achieve sufficiently strong magnetic coupling).

[0019] Overall, using at least one of the vehicle's cameras enables precise positioning of the vehicle above a primary coil. This camera is typically already installed in the vehicle for other driver assistance systems (e.g., parking assistance), making its use a cost-effective solution for vehicle positioning.

[0020] The control unit can be configured to generate a visual representation of the vehicle's surroundings, including the determined position of the primary coil. Preferably, the primary coil is graphically highlighted in the visual representation, making it clearly identifiable (e.g., by highlighted contours). Furthermore, the control unit can be configured to display this visual representation on a screen in the vehicle (e.g., a central display, such as on the center console).

[0021] The visual representation can include a "top view" of the vehicle and its surroundings with the primary coil highlighted. Furthermore, the visual representation can include a symbolic representation of the secondary coil within the vehicle. This allows the driver to simultaneously see the position of both the secondary and primary coils, thus assisting the driver in reducing the distance between them. Alternatively or additionally, the visual representation can include a "rear view" of the vehicle (from a rear camera) or a "front view" of the vehicle (from a front camera). In particular, images can be combined in an artificial aperture. This can incorporate images from different cameras with varying angles / positions and / or images from a single camera over time.This multitude of images can be synthesized into a new image, with the new image representing the vehicle's surroundings with the detected primary coil from a new perspective.

[0022] The control unit can be configured to highlight the symbolic representation of the secondary coil separately when the distance between the secondary and primary coils reaches or falls below a predefined threshold. This indicates to the driver that the vehicle is positioned in such a way that there is sufficient magnetic coupling between the primary and secondary coils.

[0023] The control unit can be configured to determine a target trajectory for the vehicle, enabling the distance between the secondary and primary coils to be reduced so that it reaches or falls below a predefined threshold. Furthermore, the control unit can be configured to determine an actual trajectory based on received information regarding the wheel angle. A graphical representation of the target and actual trajectories can be displayed on the vehicle's screen (e.g., along with a visual representation of the vehicle's surroundings). This shows the driver how to correctly position the vehicle over the primary coil.

[0024] According to another aspect, a vehicle (in particular a two-track vehicle, e.g., a passenger car) is described. The vehicle includes a secondary coil for receiving electrical energy from a primary coil external to the vehicle. Furthermore, the vehicle includes at least one camera configured to capture the vehicle's surroundings. The vehicle also includes the control unit described in this document, which is configured to support the positioning process of the secondary coil over the primary coil using image data and predefined reference data.

[0025] The vehicle may include a storage unit configured to store the reference data. Furthermore, the vehicle may include an on-board computer (e.g., as part of the vehicle's information and communication system) that allows a user to input the reference data. In particular, the on-board computer may include an application described in this document for defining reference data. This enables a vehicle user to flexibly define the reference data (especially the reference objects) for positioning the vehicle.

[0026] According to another aspect, a method for supporting the positioning of a vehicle's secondary coil relative to a vehicle-external primary coil is described. The method includes receiving image data from at least one camera of the vehicle, wherein the at least one camera is configured to capture the vehicle's surroundings. Furthermore, the method includes receiving or providing reference data. The reference data can include information about at least one predefined reference object in the captured vehicle environment. Additionally, the reference data can include information about the position of the at least one predefined reference object relative to the primary coil. Finally, the method includes detecting the at least one predefined reference object in the received image data, based on the reference data.The position of the secondary coil relative to the primary coil can be determined based on the detected at least one reference object.

[0027] As previously explained, the reference data can include information about a multitude of predefined reference objects. In particular, the reference data can include information about the relative position of a multitude of reference objects. The method can further include detecting the multitude of predefined reference objects in the received image data. Specifically, the actual relative position of the multitude of reference objects can be determined from the image data. The method can further include comparing the reference data with the detected multitude of predefined reference objects. In particular, the information about the relative position of a multitude of reference objects can be compared with the actual relative position of the multitude of reference objects. This allows the consistency and / or completeness of the information regarding the reference objects to be verified.In particular, this can be used to determine an indicator of the reliability of the vehicle's positioning above the primary coil, based on the predefined reference objects.

[0028] Another aspect described is a software (SW) program. The SW program can be configured to run on a processor and thereby execute the procedure described in this document.

[0029] Another aspect describes a storage medium. This storage medium can include a software program configured to run on a processor and thereby execute the procedure described in this document.

[0030] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspect of the methods, devices, and systems described in this document can be combined with one another in a variety of ways. In particular, the features of the claims can be combined with one another in a variety of ways.

[0031] The invention will now be described in more detail using exemplary embodiments. Fig. 1a an exemplary vehicle comprising a secondary coil for inductive charging of a vehicle battery; Fig. 1b an exemplary vehicle with additional environmental sensors; Fig. 2a an exemplary “top-view” representation of the vehicle’s surroundings generated using the vehicle’s environmental sensors; Fig. 2b a representation of the rear surroundings of the vehicle generated by a reversing camera of the vehicle; Fig. 3 an exemplary positioning process of the vehicle's secondary coil over a primary coil, supported by the vehicle's environmental sensors; Fig. 4a Exemplary features and reference points in the vicinity of the vehicle which can be used to position the vehicle; Fig. 4b the use of predefined markers when positioning the vehicle; Fig. 5a and Fig. 5b each an exemplary representation of a vehicle trajectory to assist the driver in positioning the vehicle; Fig. 6. The exemplary representation of the primary coil on a screen of the vehicle to assist the driver in positioning the vehicle; Fig. 7a Exemplary positions of predefined reference objects; Fig. 7b exemplary reference objects; Fig. 8a, Fig. 8b, Fig. 8c and Fig. 8d the exemplary use of predefined reference objects for positioning a vehicle; and Fig. 9. An exemplary user interface of an application for defining predefined reference objects.

[0032] As already explained at the outset, inductive charging of a vehicle battery 103 requires relatively precise positioning of the secondary coil 102 of the vehicle 100 above the primary coil 111. To assist the driver with positioning, additional vehicle-external units can be used, which must be installed separately in the vicinity of the parking space. These vehicle-external units can include, for example, cameras, optical positioning aids, mechanical thresholds, sensors, etc. Furthermore, additional sensors and / or transmitters can be integrated into existing components, such as the ground unit 111 and the vehicle 100, to assist the driver with positioning. However, the use of vehicle-external units and / or additional sensors / transmitters increases the cost of an inductive charging system.Furthermore, some systems only display positioning assistance in the immediate vicinity. This means that the driver has to perform a rough positioning of the vehicle largely without assistance.

[0033] This document describes a method and a corresponding device for assisting the driver in positioning the secondary coil 102 of a vehicle 100 over a primary coil 111. The described method and device enable continuous and cost-effective support of the positioning process.

[0034] In particular, it is proposed to use one or more of the environmental sensors installed in a vehicle (e.g. cameras and / or ultrasonic sensors) to support positioning. Fig. Figure 1b shows a vehicle 100 which, in addition to the secondary coil 102, includes environmental sensors 131, 132. Specifically, the vehicle 100 includes one or more cameras 131 configured to capture optical images of the vehicle 100's surroundings. In particular, the vehicle 100 may include one or more front cameras 131, one or more side cameras 131, and / or one or more rear cameras 131. Furthermore, the vehicle 100 may include ultrasonic sensors 132, which can be used, for example, to determine distances to objects in the vehicle's environment. Such environmental sensors 131, 132 are already used today for various driver assistance systems (e.g., for parking functions) and are therefore already present in many vehicles.

[0035] Based on the environmental sensors 131, 132 (in particular based on one or more cameras 131), a control unit 133 of the vehicle 100 can generate pictorial representations of the vehicle 100's surroundings, which can be displayed to the driver on a screen 134 of the vehicle 100 to assist the driver in positioning the vehicle 100. In particular, a 360° view of the vehicle 100 (e.g., a so-called "top view" representation of the vehicle 100) can be generated. An example of a "top view" representation is shown in Fig. 2a shown. The “Top View” display can be shown on a screen 134 of the vehicle 100 (e.g., in a so-called head unit). The “Top View” display can show the vehicle 100 itself. The position of the secondary coil 102 in the vehicle 100 can also be shown. Furthermore, a visual representation of the vehicle 100's surroundings (e.g., the area behind the vehicle 100) can be generated from the data of the environmental sensors 131, 132. In the Fig. In example 2a, the "Top View" representation shows, for example, the ground unit 111, as well as the boundary 201 of a parking bay and a column 202. The "Top View" representation typically displays a rectified image in Cartesian (xy) coordinates.

[0036] Alternatively or additionally to the synthetically generated "Top View" display, the image from a camera 131 of the vehicle (e.g., a rear-facing camera 131) can also be used directly. An example schematic image of a camera 131 is shown in Fig. 2b. The image from a camera 131 (especially a “surround camera”) is typically distorted, so that the surroundings of the vehicle 100 are represented in camera coordinates that do not correspond to the Cartesian (xy) coordinates of the surroundings of the vehicle 100. Nevertheless, the ground unit 111, the boundary 201 of the parking bay 201 and the column 202 can still be recognized in the camera image.

[0037] Fig. Figure 3 shows an example positioning process in which the vehicle 100 is reversed into a parking space containing a ground unit 111. During the positioning process, a "top view" generated from the environmental sensors 131, 132 can be displayed on a screen 134 of the vehicle 100. This assists the driver in positioning the vehicle 100. In particular, the control unit 133 can be configured to detect the ground unit 111 based on the data from the environmental sensors 131, 132 and to display the ground unit 111 in the screen, even if the ground unit 111 is already obscured by the vehicle 100. This provides continuous support to the driver during the positioning of the vehicle 100.

[0038] The control unit 133 can therefore be configured to detect the ground unit 111 based on data from the environmental sensors 131, 132 (in particular based on images from one or more cameras 131) (e.g., using image processing algorithms). To support the automatic detection of the ground unit 111, the ground unit 111 can include specific optical features and / or reference points that can be detected by the control unit. As described in Fig. As shown in Figure 4a, the corners 401 of the floor unit 111 can be determined as reference points. Furthermore, the edges of the floor unit 111 can be identified as reference points. From this, the dimensions of the floor unit 111 can be determined. Alternatively or additionally, other optical features or reference points (e.g., a [missing information]) can also be used. Fig. 4b (marking 411) can be used to identify the ground unit 111.

[0039] Furthermore, non-optical features (e.g., recognizing that the vehicle 100 is within the reception range of the WLAN communication of the ground unit 111) can be used to detect the position of the ground unit 111 in the vicinity of the vehicle 100.

[0040] Furthermore, the control unit 133 can be configured to detect additional reference points 402, 403 in the vicinity of the vehicle 100. Reference points 402, 403 can be located on the ground (i.e., in the ground plane z=0). Alternatively or additionally, reference points 402, 403 above or below the ground plane (z<>0) can also be used. In the Fig. In the example shown in Figure 4a, corner points 402 and / or edges of the boundary 201 of the parking bay in which the ground unit 111 is located are detected. Furthermore, a corner point of the column 202 can be detected, for example. The control unit 133 can be configured to determine the position of the ground unit 111 relative to the further reference points 402 and 403. Thus, the further reference points 402 and 403 can be used to position the secondary coil 102 of the vehicle 100 above the ground unit 111, even if the ground unit 111 is no longer detected by the environmental sensors 131 and 132 (e.g., because the ground unit 111 is already located under the vehicle 100).

[0041] The control unit 133 can be configured to determine the position of the vehicle 100 relative to the ground unit 111 using the determined reference points 401, 402, 403. Furthermore, the control unit 133 can be configured to determine the relative movement of the vehicle 100 (relative to the ground unit 111). The relative movement of the vehicle 100 can be determined from the movement of the objects 111, 201, 202 and reference points 401, 402, 403 detected in the images. In other words, the temporal development of the acquired data from the environmental sensors 131, 132 (e.g., a temporal sequence of images) can be used to determine the movement of specific objects 111, 201, 202 and / or specific reference points 401, 402, 403. Furthermore, the steering angle of vehicle 100 and / or the rotational movement of the wheels of vehicle 100 can be determined. The control unit 133 can be configured to determine the relative movement of vehicle 100 from this information.In particular, the control unit 133 can be configured to track the position of the vehicle 100 relative to the ground unit 111 (even if the ground unit 111 can no longer be detected by the environmental sensors 131, 132).

[0042] For example, the control unit 133 can be set up at the beginning of the positioning process (see, for example, the left image in [reference]). Fig. 3) To capture and save a visual representation (e.g., as a "top view") of the charging station (and especially the base unit 111). During the further course of the positioning process, the control unit 133 can be configured to update the position of the vehicle 100 relative to the charging station (especially relative to the base unit 111). Even if certain parts of the charging station (especially the base unit 111) can no longer be detected by the vehicle 100's environmental sensors 131, 132 (e.g., because they are obscured), these parts (especially the base unit 111) can still be displayed based on the saved visual representation of the charging station (as shown in the images from Fig. 3 shown). This makes it easier for the driver to position the secondary coil 102 of the vehicle 100 above the ground unit 111.

[0043] As previously explained, in the immediate vicinity, when the vehicle 100 is located above the ground unit 111, typically only the additional reference points 402, 403 and the environmental sensors 131, 132 are available for measuring the distance between the ground unit 111 and the secondary coil 102. For this reason, the control unit 133 is typically configured to track the entire approach trajectory of the vehicle 100 to determine its position. In particular, the control unit 133 is typically configured to determine an initial position of the vehicle 100 relative to the ground unit 111 even while the ground unit 111 is still detectable by the environmental sensors 131, 132. Furthermore, the control unit 133 can be configured to continuously update the position of the vehicle 100 from this initial position.The update can be based on the determined movement of the further reference points 402, 403 and / or the further objects 201, 202, as well as on the basis of vehicle-internal information (such as steering angle and / or wheel rotation). This makes it possible to precisely position the vehicle 100 above the ground unit 111, even if the ground unit 111 can no longer be detected by the environmental sensors 131, 132.

[0044] Furthermore, a quality indicator of the magnetic coupling of the primary coil 111 and the secondary coil 102 can be used in the immediate vicinity of the ground unit 111 to check the final position.

[0045] The control unit 133 can be configured to determine a target trajectory 501 of the vehicle 100, starting from a current position of the vehicle 100 (see Fig. 5a and Fig. 5b). The target trajectory 501 can be displayed to the driver on screen 134 (in conjunction with the graphic representation of the vehicle's surroundings). The target trajectory 501 indicates the positioning procedure that will allow the vehicle 100 to be positioned as precisely as possible above the ground unit 111. Furthermore, the control unit 133 can be configured to determine an actual trajectory 502 of the vehicle 100 based on the current steering angle and display it on screen 134. This enables the driver to adjust the actual trajectory 502 (especially the steering angle) so that it approximates the target trajectory 501. Thus, the driver is assisted in positioning the vehicle 100.

[0046] Fig. Figure 6 shows another way in which the driver can be supported during a positioning process. As explained above, both the position of the vehicle's secondary coil 102 and the position of the ground unit 111 can be continuously displayed on the screen 134 by symbols 601 and 602, even when the ground unit 111 is no longer being detected by the environmental sensors 131 and 132. This allows the driver to align the displayed symbols 601 and 602 and thus precisely position the secondary coil 102 over the primary coil 111. The displayed symbols 601 and 602 can be changed depending on the positioning quality to inform the driver about the positioning progress. For example, the color of the symbols 601 and 602 can be changed (e.g., green, yellow, red) to indicate the positioning quality. In the Fig. In example 6, a green symbol 603 indicates a sufficiently precise overlap of primary coil 111 and secondary coil 102. Such a representation allows the driver to precisely position the vehicle 100 even without a target trajectory 501 being displayed. In other words, the Fig. The illustration shown in Figure 6 makes it possible to position the vehicle 100 even without the target trajectory 501. For this purpose, the "top-view" display continues below the vehicle 100, showing the images captured during the approach. The driver is shown the position of the secondary coil 102 in a transparent silhouette of the vehicle. The position of the secondary coil 102 can then be aligned with the image 602 of the primary coil 111.

[0047] Further variations of the positioning method described above are possible. For example, continuous monitoring of the vehicle's surroundings (using the environmental sensors 131, 132) during the charging process can be used to detect if an animal (e.g., a cat) runs under the vehicle 100. This can increase the safety of the charging process. In particular, the charging power could be reduced in such cases to minimize the risk to the animal from high field strengths.

[0048] The described positioning method can be combined with an automatic parking assistance function. In particular, an automatic parking function can be used based on the reference points 401, 402, 403 and / or the reference objects 111, 201, 202, as well as on the basis of the initial position of the vehicle 100, to position the vehicle 100 (e.g., according to the target trajectory 501) above the ground unit 111.

[0049] The control unit 133 can be configured to learn reference points 401, 402, and 403 when repeatedly approaching a charging station. This allows a primary coil 111 to be approached even if it is not visible, for example, if it is covered by snow. Furthermore, this allows for continuous improvement of positioning precision.

[0050] As explained above, additional reference points 402 and 403 can be used to support the positioning process. Reference points 402 and 403 can also be located above the ground plane (z>0). These reference points can be generated either by learning or by recognizing a pattern 411 typical for the charging station. Furthermore, alternative reference points can be used to approach even completely hidden primary coils 111 (e.g., those embedded in the ground).

[0051] As described above, the control unit 133 can be configured to detect reference objects 201, 202 and / or reference points 401, 402. These reference objects 201, 202 and / or reference points 401, 402 can be detected using image analysis methods. Furthermore, the geometric arrangement of the reference objects 201, 202 and / or reference points 401, 402 can be determined based on the data from the environmental sensors 131, 132.

[0052] To reduce the complexity of determining the reference objects 201, 202 and / or reference points 401, 402, as well as the geometric arrangement, and to increase the reliability of the determined information, it can be advantageous to use predefined markers or predefined reference objects. Information about such predefined reference objects can be provided to the control unit 133 as reference data. This improves the determination of the position of the secondary coil 102 relative to the ground unit 111.

[0053] Fig. Figure 7a shows various arrangements of predefined reference objects 701, 702 (e.g. predefined markers) and Fig. Figure 7b shows examples of predefined reference objects that can be detected by the control unit 133 of the vehicle 100 based on the image data acquired by a vehicle camera 131. The ground unit 111 can be positioned relative to the one or more reference objects 701, 702 in a predefined manner. Thus, the position of the ground unit 111 can be determined by determining the position of the one or more reference objects 701, 702. In particular, the position of the ground unit 111 relative to the vehicle 100 can be determined by determining the position of the one or more reference objects 701, 702 relative to the vehicle 100.

[0054] As shown in picture a) in Fig. As shown in Figure 7a, reference objects 701 and 702 can be assigned coordinates in a coordinate system (e.g., a Cartesian coordinate system). In the example shown, the ground unit 111 is located at the center of the coordinate system. The position of a reference object 701 can thus be described by coordinates (x, y) in this coordinate system. Similarly, the position of the vehicle 100, e.g., the position of a camera 131 on the vehicle, can be described by coordinates (x, y) of the coordinate system. By knowing the position of the ground coil 111 and the position of the vehicle 100 in a predefined coordinate system, the control unit 133 is able to assist the driver of the vehicle 100 in positioning the secondary coil 102 above the ground unit 111.

[0055] Image b) in Fig. Figure 7a indicates that the orientation of the vehicle 100 relative to the ground unit 111 can also be determined based on the predefined reference objects 701, 702. In particular, the camera angles φ can be determined. m1 and φ m2 between the longitudinal axis of the vehicle 100 and the beam between camera 131 and reference object 701, 702.

[0056] Image c) of Fig. Figure 7a shows an example in which the reference objects 701 and 702 cannot be simultaneously detected by the camera 131 of the vehicle 100. For example, the first reference object 701 may be positioned at a garage entrance, and the second reference object 702 may be located at the primary electronics 110 (i.e., the power supply 110) of the charging station. As discussed in the context of Fig. As shown in Figure 8d, such widely separated reference objects 701, 702 can be used to support the entire positioning process of the vehicle 100 (even in the remote range).

[0057] Fig. Figure 7b shows exemplary reference objects 711, 712, and 713. The reference objects should be located in an illuminated area, or they should be self-illuminating, or they should be located in an area that can be illuminated by the vehicle's headlights. In other words, it should be ensured that the reference objects can be reliably detected by the vehicle's camera 131 100. For example, the reference object could be an illuminated marker 711 on the electronics 110 for controlling the primary coil 111 (e.g., integrated into a wallbox for wired charging). The illumination can be controlled and switched on via an existing radio connection between the charging station and the vehicle during the positioning process. The illumination could, for example, also indicate that the correct end position has been reached by switching off. Alternatively or additionally, the marker 711 could be a sticker on the primary electronics 110.

[0058] Alternatively or additionally, existing fixed markings 712, 713 in the vicinity of the parking space where the charging station is located can be used as reference objects (e.g. a parking sign 712 or a pillar 713), provided that these markings 712, 713 have sufficient contrast.

[0059] The dimensions 721, 722 of the predefined reference objects 711, 712, 713 can be used to determine the distance between camera 131 and reference objects 711, 712, 713. The actual dimensions 721, 722 (e.g., height, width) of the reference objects 711, 712, 713 are known to the control unit 133, so that the distance between reference objects 711, 712, 713 and vehicle camera 131 can be determined from the dimensions of the reference objects 711, 712, 713 as determined based on the image data of the vehicle camera 131. Alternatively or additionally, data from the vehicle 100's distance sensors 132 can also be used to determine the distance.

[0060] By using a predefined reference object 701 with predefined dimensions 721, 722, the control unit 133 is able to determine the distance of the vehicle 100 to the reference object and the orientation of the vehicle 100 relative to the reference object. Since the one or more reference objects 701, 702 are arranged in a predefined manner relative to the ground unit 111, this enables the positioning of the secondary coil 102 of the vehicle 100 above the ground unit 111 based on the data from the vehicle camera 131.

[0061] Triangulation methods can be used to determine the distance between a reference object 701 and the camera 131 of the vehicle 100. This is exemplified in the Fig. 8a and Fig. 8b is shown. It holds that the sum of the angles is 804 (φ m1_2 ) and 805 (φ m1_b2 ) 180°, and that the sum of the angles is 803 (φ m1_12 ), 805 (φ m1_b2 ) and 806 (φ m1_1) 180° results. From the Law of Sines s12sin(φm1_12)=sm1_2sin(φm1_1) (where s 12 The movement path 807 of vehicle 100 is, and where s m1_2 the current distance 802 of vehicle 100 to reference object 701) results sm1_2=s12sin(φm1_1)sin(φm1_12)=s12sin(φm1_1)sin(φm1_2−φm1_1).

[0062] Thus, if the camera angles 806, 804 are known at two consecutive times and if the distance traveled between these two times 807 is known, the current distance 802 of the vehicle 100 to the reference object 701 can be determined.

[0063] For the special case where φ m1_2 - φ m1_1If the distance is small or zero (i.e., if vehicle 100 is moving directly towards reference object 701), the distance 802 cannot be calculated using the triangulation formula above. However, the vehicle's path 807 directly reveals how the distance between vehicle 100 and reference object 701 changes. Specifically, the change in distance between 801 at the first time and 802 at the second time corresponds to the distance 807.

[0064] Even when the steering wheel is turned, the distance 802 between reference object 701 and vehicle 100 can be determined by triangulation by measuring the camera angles 804, 806 and by measuring the movement distance 807 of vehicle 100 (e.g., based on the wheel rotation). As in Fig. As shown in Figure 8b, the measured quantities—camera angle 816 at the first time, steering angle or rotation, and movement distance 819—can be used to determine values ​​for the corrected movement distance 807 and the corrected angle 806. The current distance 802 (at the second time) is then calculated using the triangulation formula described above.

[0065] The absolute position of the vehicle can be determined by detecting at least two reference objects 701 and 702, as shown in Fig. Figure 8c shows that all necessary coordinates and angles can be calculated from the distances 822 and 821 to the two reference objects 701 and 702. The distances 822 and 821 can be determined using the methods described above. For example, the angle φ m1m2k_i based on the formula φm1m2k_i=arccos(sm1_i2+dm1_m22−sm2_i22sm1_idm1_m2) to be determined, whereby d m1_m2The predefined distance 823 between the two reference objects 701, 702 is given. Therefore, the coordinates and orientation of vehicle 100 (i.e., the position and orientation of the secondary coil 102 of vehicle 100) can be determined. The coordinates of reference objects 701, 702 and the primary coil 111 are known, so all the necessary information for positioning vehicle 100 is available.

[0066] By using a series of reference objects 701, 702, the entire approach trajectory of the vehicle 100 can be tracked and supported. For this purpose, predefined reference objects 701, 702 can be positioned along the approach trajectory so that, whenever possible, at least one reference object 701, 702 is always detectable by the vehicle's camera 131. This is exemplified in Fig. Figure 8d shows that during the approach of vehicle 100, a position calculation (e.g., using the methods described above) is performed at different times i (i = 1 ... n, where n corresponds to the time at which the target position is reached). For this purpose, at least one reference object 701, 702 can always be detected by camera 131, if possible.

[0067] In the Fig. In the example shown in Figure 8d, the vehicle 100 moves directly towards the first reference object 701 in trajectory segment 831. The distance between the vehicle and the first reference object can be estimated, for example, from the size of the first reference object 701 as detected by camera 131 (see Figure 8d). Fig. 8a) In trajectory section 832, the distance to reference object 701 can be determined via triangulation. In trajectory section 833, the camera 131 of vehicle 100 does not detect reference objects 701 or 702. The distance and angle to reference object 701 can be tracked via vehicle sensors (wheel rotation and / or steering angle). In trajectory section 833, the camera 131 of vehicle 100 detects the second reference object 702. The distance and relative position of vehicle 100 to the primary coil 111 can be continuously updated until the target position is reached. Thus, the control unit 133 can be configured to assist the driver of vehicle 100 with positioning along the entire trajectory.

[0068] The geometry of a charging station (i.e., in particular the coordinates of the reference objects 701, 702; the dimensions 721, 722 of the reference objects 701, 702; the description of the reference objects 701, 702 (for automatic recognition); and / or the relative position of the ground unit) can be stored on a memory unit in the vehicle 100. The control unit 133 can access this memory unit as needed. For example, the geometry of a charging station can be transmitted from the charging station (e.g., from the primary electronics 110) to the vehicle 100 via a wireless communication link (e.g., when the vehicle 100 approaches).

[0069] An application can be provided that assists a user in determining the geometry of a charging station. The interface 900 of an example application (e.g., an application for a smartphone or for the vehicle's on-board computer 100) is in Fig. Figure 9 shows how images 901 of the charging station can be displayed, on which one or more reference objects or reference points 401 can be selected. The images 901 can be taken, for example, with the camera 131 of the vehicle 100 or with a smartphone camera. The description of a reference object (size, shape, color, etc.) can be determined and recorded. The reference objects from the image can be included as reference objects 701 in a sketch 902 of the charging station and linked to the description of the corresponding reference objects. The dimensions 721, 722 and positions of the reference objects 701 and the primary coil 111 can be inserted into the sketch 902. Information about the vehicle type used can also be added. This determines the position of the camera 131 and the secondary coil 111 in the vehicle 100. The input can be done manually or by data transfer from the vehicle 100 to the application.Furthermore, instructions 903 and 904 regarding the setup of the charging station (such as the quality of the setup and / or further steps to be carried out) can be determined and displayed.

[0070] In an exemplary procedure, the primary unit 110, 111 and the reference objects (e.g., markers) can be attached in a first step. The reference objects can then be photographed using the vehicle camera 131 or a tablet PC camera. The data of the vehicle (geometry and, if applicable, images) for which the charging station is to be used can be transferred to the tablet PC. With this information, the following can then be done (as in Fig.(described in section 9) a configuration of the charging station is performed. The data relating to the charging station can then be stored in the off-board electronics 110 (also called primary electronics or control unit) of the charging station and transmitted to the vehicle 100. Knowing the data relating to the charging station enables the control unit 133 of the vehicle 100 to determine the relative position of the vehicle 100 to the ground unit 111. Optionally, the control unit 133 can be configured to cause the primary electronics 110 to illuminate the reference objects from the beginning of the positioning process so that they can be sufficiently well detected by the camera 131 of the vehicle 100. Furthermore, an illuminated reference object can be used to acknowledge a successful positioning process by means of appropriate control signals.

[0071] To position a different vehicle type, the data regarding the reference objects can be transferred from the off-board electronics 110 of the charging station, or from a network database, to the storage unit of the vehicle 100 (e.g., when the vehicle 100 approaches). The vehicle 100 then calculates the complete data using its known vehicle geometry and can thus support the positioning process.

[0072] The use of a charging station with predefined reference objects 701 and 702 requires that the position of the ground unit 111 remains constant relative to these reference objects. However, the ground unit 111 could, for example, be a flat object on a non-slip mat that is not securely bolted to the ground. This could result in the ground unit 111 shifting unnoticed, preventing the secondary coil 102 from being effectively positioned over it. The charging station (and the vehicle) should be configured to detect any movement of the ground unit 111. This movement detection should function even when no vehicle is charging or positioned over the primary coil. Furthermore, detection should be possible even during a power outage.To solve this problem, the ground unit 111 can be positioned on a mechanical sensor sphere, with the sensor sphere registering any movement of the ground unit 111. Alternatively or additionally, the ground unit 111 can be mounted along a marker on the ground. An optical sensor on the ground unit 111 can then detect whether the ground unit 111 remains aligned with the marker or whether it has been moved.

[0073] This means that, to prevent the vehicle from moving to the wrong position if the floor unit 111 has shifted, a sensor can be installed in the floor unit 111 to detect any movement (slipping, lifting, etc.). The driver can then be notified after the floor unit 111 has shifted and, if necessary, asked to check its position.

[0074] It should be noted that in addition to one or more vehicle cameras 131, further external cameras can also be used. The external cameras can be used to record the movement of the vehicle 100. The data from the one or more external cameras can be used with the data from the one or more vehicle cameras 131 for optimized position determination.

[0075] This document describes a method and a device (control unit) that assist the driver of a vehicle 100 in positioning the vehicle 100 above a ground unit 111. The method and device allow the use of components 131, 132 already present in the vehicle 100 for positioning. This enables the method and device to be implemented cost-effectively (e.g., using software). In particular, the cameras 131 for all-around vision are already optimally integrated into vehicles 100 (e.g., in low-contamination positions), so these features can be utilized. The target position can be displayed in a known format, e.g., a top-view or rear-view display.Therefore, no new form of representation is required to provide the described positioning function, and the described positioning function can be implemented within a consistent interface with other driver assistance functions. Furthermore, potential errors in the optical system (e.g., contamination of camera 131) are clearly recognizable to the driver in the displayed image and therefore do not lead to incorrect vehicle positioning. The method described in this document thus enables reliable vehicle positioning.

[0076] Furthermore, by selecting appropriate predefined reference objects, positioning independent of dirt and weather conditions (e.g., snow) can be achieved. The charging station can be installed and its geometry data captured even without a vehicle (e.g., using a tablet PC). Reference object capture can be optimized by using original images from the vehicle's camera and supported by offline processing. This increases the system's reliability. Additionally, the use of the vehicle's camera and the ability to control the system directly from the vehicle allow for easy access to information about the vehicle's movement from the chassis (steering angle, wheel rotation).

[0077] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and the figures are intended only to illustrate the principle of the proposed methods, devices, and systems.

Claims

[1] Control unit (133) for a vehicle (100), which comprises a secondary coil (102) for receiving electrical energy from a vehicle-external primary coil (111), wherein the vehicle comprises at least one camera (131) which is configured to capture an environment of the vehicle (100), wherein the control unit (133) is configured, - to receive image data from the at least one camera (131) of the vehicle (100); - to receive reference data from a control unit (110) of the primary coil (111); wherein the reference data comprises information about at least one predefined reference object (701) in the detected environment of the vehicle (100) and about a position of the at least one predefined reference object (701) relative to the primary coil (111); wherein the reference data comprises, - information about optical features of the at least one reference object (701) that can be detected in the image data of the camera (131); and / or - information about a spatial size of the at least one reference object (701); - to detect the at least one predefined reference object (701) in the received image data on the basis of the reference data; and - to determine a position of the secondary coil (102) relative to the primary coil (111) on the basis of the detected at least one reference object (701). [2] Control unit (133) according to claim 1, wherein the reference data comprises one or more of: - information regarding spatial coordinates of the at least one reference object (701) in a predefined coordinate system; and - Information regarding spatial coordinates of the primary coil (111) in the predefined coordinate system. [3] Control unit (133) according to any one of the preceding claims, wherein the control unit (133) is arranged - to receive information regarding a wheel angle and a wheel speed of the vehicle (100); and - on the basis of the received information regarding the wheel angle and the wheel speed, to determine a movement (807, 819) of the vehicle (100) relative to the at least one reference object (701). [4] Control unit (133) according to any one of the preceding claims, wherein the control unit (133) is arranged - on the basis of the detected at least one reference object (701), to determine a camera angle (804, 806) of a beam between the at least one camera (131) and the at least one reference object (701); and - to determine a distance of the secondary coil (102) to the at least one reference object (701) on the basis of the determined camera angle (804, 806). [5] Control unit (133) according to any one of the preceding claims, wherein - the reference data comprises information about a plurality of predefined reference objects (701, 702) along an approach trajectory of the vehicle (100) to the primary coil (111); - the control unit (133) is configured to receive a temporal sequence of image data from the at least one camera (131) of the vehicle (100) along the approach trajectory; and - the control unit (133) is configured to detect the plurality of predefined reference objects (701, 702) in the temporal sequence of image data. [6] Control unit (133) according to any one of the preceding claims, wherein the control unit (133) is arranged to cause a control signal to be sent to a control unit (110) of the primary coil (111) in order to illuminate the at least one predefined reference object (701). [7] Vehicle (100), wherein the vehicle (100) comprises - a secondary coil (102) for receiving electrical energy from a vehicle-external primary coil (111); - at least one camera (131) configured to capture an environment of the vehicle (100); - a control unit (133) according to any one of claims 1 to 6; and - a storage unit configured to store the reference data. [8] A method for assisting the positioning of a secondary coil (102) of a vehicle (100) relative to a vehicle-external primary coil (111), the method comprising - receiving image data from at least one camera (131) of the vehicle (100), wherein the at least one camera (131) is configured to capture an environment of the vehicle (100); - Receiving reference data from a control unit (110) of the primary coil (111); wherein the reference data comprises information about at least one predefined reference object (701) in the detected environment of the vehicle (100) and about a position of the at least one predefined reference object (701) relative to the primary coil (111); wherein the reference data comprises, - information about optical features of the at least one reference object (701) that can be detected in the image data of the camera (131); and / or - information about a spatial size of the at least one reference object (701); - detecting the at least one predefined reference object (701) in the received image data, based on the reference data; and - Determining a position of the secondary coil (102) relative to the primary coil (111) on the basis of the detected at least one reference object (701). [9] Method according to claim 8, wherein - the reference data comprises information about a plurality of predefined reference objects (701, 702); - the method further comprises detecting the plurality of predefined reference objects (701, 702) in the received image data; and - the method further comprises comparing the reference data with the detected plurality of predefined reference objects (701, 702).

Images