Method and device for determining the absolute position of a vehicle

Abstract

Method for determining the absolute position of a vehicle (4) for short-range positioning of the same when parking the vehicle (4), in which an inductive positioning method is carried out, wherein a first transmitter in the infrastructure is excited to generate a positioning magnetic field and a second transmitter (7) in the infrastructure is excited to generate a further positioning magnetic field, wherein the two positioning magnetic fields are received by a receiving device in the vehicle (4) and the absolute position of the vehicle (4) is determined on the basis of the received positioning magnetic fields, wherein both transmitters (6, 7) in the infrastructure are located in a parking space for exactly one vehicle, wherein the first transmitter and the second transmitter (7) are excited sequentially.

Description

[0001] The present invention relates to a method for determining the absolute position of a vehicle for short-range positioning during parking. The invention further relates to a device for carrying out such a method.

[0002] "Parking" here refers to both automatic parking and manual parking, for example supported by an optical display.

[0003] Automated vehicle parking is a familiar concept. This can involve, for example, parking a vehicle in a marked parking space or in a garage. A special case concerns the inductive charging of electric vehicles, which must use a designated parking space equipped with such a charging option (for example, a transmitting coil embedded in the ground). In this case, precise vehicle positioning is crucial, as a strong magnetic field, dependent on the electrical power, is generated between the inductive charging unit (the ground coil) and the receiving unit (vehicle coil) located inside the vehicle. For safety, the magnetic field is generated beneath the vehicle, making it difficult for people to access.In addition, the vehicle itself provides a shielding effect, thus significantly minimizing the emission of fields into the surrounding area.

[0004] This advantage, however, comes with the disadvantage that the driver can hardly judge whether the two coils are positioned exactly between the vehicle. The less aligned the two coils are, i.e., the less precisely they are positioned on top of each other, the worse the energy transfer. The coupling factor decreases, and the efficiency drops, while the unwanted stray fields increase.

[0005] Depending on the coil design, for example, the efficiency decreases by 2% with an offset of just 8 cm. 2% of a transmission power of, for example, 4 kW corresponds to 80 W of additional power loss.

[0006] The driver must therefore park within a few centimeters without visual contact, which is difficult to guarantee without assistance. Besides the possibility of supporting the driver with a visual display, an automated parking process is of course also conceivable.

[0007] The present invention relates to a parking process, in particular an automated parking process, wherein parking for inductive charging of the vehicle represents a special case.

[0008] To implement automated parking, concepts have been developed that utilize camera image recognition systems, radio tracking, radar, ultrasound, or RFID. These concepts have also been combined. However, these approaches have drawbacks. For example, the environment of every parking space is different. If every parking space looks different, what should the tracking systems use as a reference point if no standardized identification mark is agreed upon? These systems without standardization therefore only function for specific applications and a single environmental situation. Furthermore, optical systems (cameras) have the disadvantage that the appearance of the parking space changes due to weather and season; contrasts and color saturation change with brightness and rain, and because leaves in autumn can at least partially obscure any colored parking space markings. This problem is always present in winter when there is snow.

[0009] From WO 2015 / 038 650 A1, a method for driving an electric vehicle is known, which includes determining the position of a charging point of a charging base in relation to a charging coupler of the electric vehicle. An indicator for the position of the charging point is displayed in a three-dimensional perspective view to assist the driver of the electric vehicle in positioning the charging coupler of the electric vehicle above the charging base within a tolerance range.

[0010] From DE 10 2013 016 880 A1, a method for positioning a vehicle at an inductive charging station is known. As the vehicle approaches the charging station, a first wireless communication connection for initial data transmission is established between the vehicle and at least one charging point of the charging station as soon as the vehicle is within communication range of that charging point. By evaluating the data transmission, the vehicle's position relative to the charging point is determined, and the vehicle is guided manually or automatically to that charging point, depending on the determined position.

[0011] From DE 10 2014 217 056 A1, a method for assisting in the positioning of a motor vehicle for the inductive charging of the motor vehicle's battery is known. The method comprises the following steps: reading a license plate associated with the motor vehicle; using the license plate information to determine the location of a vehicle-mounted inductive coupling point (VICP) in the vehicle with respect to at least one reference point in the motor vehicle; comparing a predicted current position of the VICP with a fixed inductive coupling point (ICP) located in or on a road surface over which the motor vehicle is to be positioned; and providing feedback to the driver or the motor vehicle indicating the action required to align the VICP with the ICP.

[0012] From DE 10 2012 214 199 A1, a system is known that comprises a vehicle and an inductive charging unit, wherein the inductive charging unit includes a primary coil and the vehicle includes a secondary coil, and electrical power can be inductively transferred from the primary coil to the secondary coil during a charging process in a charging position. In the charging position, the secondary coil is located in a preferred spatial position range with respect to the primary coil. To set the charging position, a time-dependent position of the secondary coil with respect to the primary coil is determined by electromagnetic distance and angle measurement using triangulation, and based on this position and the charging position, at least a partial driving trajectory is determined along which the position of the charging position can be approximated.

[0013] An inductive positioning system is known from US Patent 2012 / 0262002A1. In this method, the ground coil of a charging station is subjected to a weak magnetic field, which serves as a positioning field. Based on the strength and / or direction of this magnetic field, the system can calculate the position of the charging coil. Consequently, a vehicle equipped with such an inductive positioning system is able to locate the ground coil in virtually any parking space under any weather conditions.

[0014] However, if such a vehicle is now allowed to park itself automatically, the problem arises that indistinguishable parking positions exist. This is further explained below. Fig. Reference is made to Figure 1. This figure schematically shows a parking lot from above. Using the magnetic method described above, the vehicle can determine the x and y offset of the ground coil relative to the vehicle itself. However, positions 1-3 shown in the figure all yield the same result. Of course, the position of the parking lot can also be determined using a camera system, but this method would again be dependent on weather conditions, such as snow and leaves.

[0015] The present invention is therefore based on the objective of providing a method of the described type that enables particularly precise parking of the vehicle.

[0016] This problem is solved according to the invention by a method of the type described at the outset, in which an inductive positioning method is carried out, wherein a first transmitter in the infrastructure is excited to generate a positioning magnetic field and a second transmitter in the infrastructure is excited to generate a further positioning magnetic field, the two positioning magnetic fields are received by a receiving device in the vehicle and The absolute position of the vehicle is determined based on the received positioning magnetic fields, with both transmitters located in the infrastructure in a parking lot for charging exactly one vehicle, and the first transmitter and the second transmitter being excited sequentially.

[0017] The following description assumes that the receiving device is located in the vehicle and the transmitters are in the infrastructure, i.e., in the vicinity of the vehicle. When a parking bay or parking space is mentioned below, these terms are intended to cover all possible parking spaces, including covered parking spaces or garages, as well as those equipped with charging facilities.

[0018] To determine the orientation of the parking space in addition to the position of the first transmitter, the vehicle requires a further reference point located within the infrastructure. In the method described here, where a positioning field is measured from the first transmitter, this point is a second transmitter on the infrastructure side. This allows not only the x- and y-offset of the vehicle relative to the first transmitter to be determined, but also the x- and y-offset of the second transmitter relative to the vehicle's coordinate system.

[0019] The inventive method thus employs a second transmitter or auxiliary transmitter. While, as described above, positions 1-3 cannot be distinguished from one another without the second transmitter, the second transmitter enables a clear differentiation between the individual positions. This is because two points of the infrastructure are now known, and thus the relative coordinate system of the vehicle can be transformed into the absolute coordinate system of the infrastructure. Besides the advantage of knowing precisely where the vehicle is located within the infrastructure, the complexity of the system also increases, since both a positioning magnetic field and a positioning signal must be emitted and evaluated.

[0020] According to the invention, a second transmitter is used, which also generates a positioning magnetic field. Thus, two positioning magnetic fields are used. The two fields can superimpose, resulting in a field with a more complex shape than the individual fields. The influence of the second transmitter on the positioning field varies depending on its distance from and direction relative to the first transmitter.

[0021] In one embodiment of the method according to the invention, the position of the second transmitter is standardized relative to the first transmitter. Standardizing the position of the second transmitter relative to the first transmitter avoids the disadvantages described above; however, the algorithm for calculating the position would become significantly more complex. The solution algorithm would therefore have to be adapted to this complex form.

[0022] Further options for implementing the procedure described above are outlined below. First, the position of the second transmitter relative to the first transmitter is determined. Once this position is known, the vehicle's position within the infrastructure can be calculated from the calculated distances between the vehicle and the transmitters. For example, the position of the second transmitter can be determined via a different channel, particularly Wi-Fi. This approach has the advantage that the second transmitter can be adapted to local conditions.

[0023] According to the invention, the first and second transmitters are excited sequentially. This allows the x and y offsets of the individual transmitters to be detected separately. The algorithm used to calculate the position can then be significantly simpler and faster due to the simpler and more symmetrical geometry of the individual fields. To distinguish which transmitter is emitting the currently transmitted field, an additional communication channel, such as WLAN, can be used between the transmitter and the vehicle.

[0024] To distinguish between the two transmitters, an identifier can also be modulated onto a position signal, for example a coil identifier.

[0025] In addition to sequential transmission, different frequencies can of course be used for the two transmitters. This allows the receiving device to distinguish between the two transmitters. With suitable filtering (e.g., resonant circuits) of the individual fields, simple localization of the vehicle within the infrastructure is thus possible.

[0026] The method according to the invention is preferably used for the short-range positioning of an electrically powered vehicle for inductive charging. Such a method has already been sufficiently explained above. In this variant of the method, a positioning magnetic field is generated by the unit for inductively charging the vehicle, which is used here as the first transmitter, in addition to the magnetic field emitted during the charging process. The positioning magnetic field is therefore used to precisely position the vehicle in order to align the inductive charging unit, which is preferably embedded as a ground coil in the ground of the parking space, exactly with the receiving device arranged in the vehicle.

[0027] Such a method is described in the aforementioned US 2012 / 0262002 A1. According to the invention, such a method is extended in this particular embodiment by the arrangement of a second transmitter, as explained above.

[0028] While the preceding discussion focused on individual parking spaces, the method according to the invention also applies to a case where several parking spaces are arranged side by side. In this case, each parking space is equipped with a first transmitter for emitting a positioning magnetic field and has a second transmitter, which can have the embodiments described above and can emit a corresponding positioning signal, which can also be a positioning magnetic field or other signals. In this embodiment as well, the first transmitters can be inductive charging units, preferably operated by a central charging station.

[0029] Specifically, this setup involves, for example, several inductive charging stations arranged side by side. To coordinate the charging of individual vehicles and assign the appropriate parking spaces to newly arriving vehicles, the corresponding charging units (ground coils) are best operated by a central charging station. If a vehicle wants to occupy a completely empty inductive charging station, it sends a request to the charging station, for example, via Wi-Fi. Since no vehicle is currently occupying a charging station, the first ground coil is assigned to the vehicle. Because there is another ground coil in the adjacent space, this additional ground coil (the neighboring inductive charging unit) can be used as a second transmitter. Therefore, a separate auxiliary transmitter is not required.

[0030] However, if the adjacent inductive charging points are already occupied, their charging units (ground coils) can no longer be used as auxiliary transmitters. In this case, a different system must be used, such as an optical system that acts as a second transmitter. For example, if a vehicle approaches a middle parking space with a vehicle already parked to its right and left, these two vehicles can serve as optical recognition features, allowing the vehicle to park automatically even if the parking space boundaries are not visible.

[0031] As already mentioned, it is not absolutely necessary to use an inductive charging unit, specifically a ground coil, as the first transmitter (positioning transmitter). The essential feature of the method according to the invention is that an inductive positioning method is carried out using a first transmitter, regardless of whether the first transmitter is a charging unit or not. The second transmitter can be any transmitter that emits a positioning signal, for example, an optical transmitter, although here too an inductive transmitter is preferred.

[0032] It is understood that other transmitters can also be used in the method according to the invention.

[0033] In the specific embodiments described above, it was assumed that the transmitters are located in the infrastructure and that a corresponding receiving device is provided in the vehicle. Preferably, at least three transmitters are used as receiving devices to determine the x and y offsets. This allows the positions of the transmitters to be triangulated.

[0034] According to the invention, it is of course equally possible to arrange corresponding transmitters, preferably three or more, in the vehicle and to replace the second transmitter in the infrastructure (one or more auxiliary transmitters) with auxiliary receivers. For example, it is possible to generate several search fields with the transmitting coils of a Pase system, for instance, sequentially. The receivers in the infrastructure can then triangulate the x and y offset of the vehicle relative to the transmitter and, for example, transmit this information back to the vehicle via another channel (e.g., radio, WLAN). If the values ​​from at least two receivers in the infrastructure are known, the vehicle's position within the infrastructure can be calculated.

[0035] The method according to the invention can also be combined with other methods. For example, existing cameras or top-view systems can be integrated, as well as fully automatic parking aids and / or wheel speed sensors, GPS / Galileo, etc., Google Street View, known WLAN nodes, etc.

[0036] Another option is to map the geographical location of the ground coil and the corresponding parking space. As a vehicle approaches, it orients itself using the magnetic fields, but also receives the parking space's geographical orientation via coding or Wi-Fi information. For example, if the parking space is oriented north-south, the vehicle can use its GPS and compass to precisely locate the parking space.

[0037] According to the invention, a positioning system is therefore created that enables the vehicle to be located in relation to the infrastructure. This makes automatic parking possible during inductive charging processes or other parking maneuvers, without limitations to conventional sensor functions (snow, leaves, etc.).

[0038] The invention further relates to a device for carrying out the method described above.

[0039] The invention is explained in detail below with reference to an exemplary embodiment in conjunction with the drawing. The drawing shows: Fig. 1. A top-down representation of a parking lot using a prior art method with indistinguishable parking positions; Fig. 2 a schematic view of how Fig. 1 in one embodiment of the method according to the invention; Fig. 3 a schematic view of a parking lot from above with three parking bays in another embodiment of the method according to the invention; Fig. 4 a schematic view of a parking lot from above with three parking bays in yet another embodiment of the method according to the invention; and Fig. 5 A schematic view of parking lots from above, showing various embodiments of the invention.

[0040] In the state of the art procedure according to Fig. 1. The absolute position of a vehicle is determined for short-range positioning during automatic parking. An inductive positioning method is used, whereby a ground coil 6 (first transmitter) embedded in the ground of a parking space 5 is excited to generate a positioning magnetic field. This magnetic field is received by a receiver located in a vehicle 4. The vehicle's position is determined based on the received positioning magnetic field.

[0041] The magnetic method described above allows vehicle 4 to determine the x and y offset of the ground coil 6 relative to vehicle 4 itself. However, the following are not provided: Fig. Positions 1-3 of the vehicle shown in Figure 1 all yield the same result. Therefore, the correct position of vehicle 4 exactly above the ground coil 6 cannot be determined.

[0042] Fig. 2 shows the same parking situation as in Fig. 1, however, an embodiment of the method according to the invention is carried out here. In this inductive positioning method, in addition to the ground coil 6 embedded in the ground of the parking space 5, a second transmitter (auxiliary transmitter) 7 is used, which is arranged, for example, at the edge of the parking space 5. Here, too, the ground coil 6 used for charging the vehicle 4 is used as an inductive positioning transmitter before charging, which generates a positioning magnetic field. The second transmitter 7 also generates a positioning magnetic field. Both positioning magnetic fields are received by a receiver in the vehicle 4, and the absolute position of the vehicle is determined on the basis of the received positioning magnetic fields.

[0043] While positions 1-3 cannot be distinguished from each other without the second transmitter 7 (auxiliary transmitter), a clear differentiation between the individual positions is possible with the second transmitter 7. This is because two points of the infrastructure are now known, and thus the relative coordinate system of vehicle 4 can be converted into the absolute coordinate system of the infrastructure.

[0044] Fig. Figure 3 shows a top view of a parking area with three parking bays or parking spaces 5. A ground coil 6 is embedded in the ground of each parking space 5. All three ground coils 6 are supplied by a common charging station 8.

[0045] In the situation depicted here, where a vehicle 4 moves into the upper parking bay shown in the figure, the two lower parking bays are empty. The ground coil 6 of the middle parking bay serves as a second transmitter or auxiliary transmitter.

[0046] If vehicle 4 wants to charge at the completely empty low-loader bay, it sends a request, for example via Wi-Fi, to charging station 8. Since there is currently no vehicle at any charging station, the vehicle is assigned ground coil 6 of the uppermost parking bay. Ground coil 6 in the middle parking bay acts as a second transmitter or auxiliary transmitter.

[0047] At the in Fig. In the schematically depicted parking situation 4, there are also three parking bays 5, each parking bay 5 having a ground coil 6. All ground coils 6 are supplied by a common charging station 8. The situation shown here differs from that of the Fig. 3. This is because the upper and lower parking spaces in the figure are already occupied. The corresponding ground coils 6 of these parking spaces can therefore no longer be used as auxiliary transmitters. Vehicle 4 can therefore only be parked in the middle parking space. Since there is already a vehicle on both sides of the middle parking space, serving as an optical recognition feature, vehicle 4 can still be parked automatically in this case using an optical system.

[0048] Fig. Figure 5 shows a schematic view of various parking lots from above, illustrating different embodiments of the invention. In the embodiment of Fig. 5 A) A first transmitter in the form of a ground coil 6 and a second transmitter 7 are provided in the infrastructure (in the parking area). The associated vehicle has a receiving device which includes three receivers 11.

[0049] At the in Fig. In the embodiment shown in 5 B), a first transmitter 6 and a second transmitter 7 are provided on the vehicle, while three receivers 11 are located in the parking area (in the infrastructure).

[0050] The embodiment of the Fig. Figure 5C) shows a first transmitter 6 and two second transmitters 7 on the vehicle and two receivers 11 in the parking area (infrastructure).

[0051] Finally, the embodiment of Fig. 5 D) a first transmitter as a ground coil 6 and two second transmitters 7, which are arranged in the parking area, as well as two receivers 11 arranged on the vehicle.

[0052] If the receivers are located outside the vehicle, they must send their data back to the vehicle so that the vehicle knows its position.

Claims

[1] Method for determining the absolute position of a vehicle (4) for short-range positioning of the same when parking the vehicle (4), in which an inductive positioning method is carried out, wherein a first transmitter in the infrastructure is excited to generate a positioning magnetic field and a second transmitter (7) in the infrastructure is excited to generate a further positioning magnetic field, wherein the two positioning magnetic fields are received by a receiving device in the vehicle (4) and the absolute position of the vehicle (4) is determined on the basis of the received positioning magnetic fields, wherein both transmitters (6, 7) in the infrastructure are located in a parking space for exactly one vehicle, wherein the first transmitter and the second transmitter (7) are excited sequentially. [2] Method according to claim 1, characterized by , that the position of the second transmitter (7) is standardized in relation to the first transmitter. [3] Method according to claim 1, characterized by , that the position of the second transmitter (7) is determined in relation to the first transmitter. [4] Method according to claim 3, characterized by , that the position of the second transmitter (7) is transmitted via another channel, in particular WLAN. [5] Method according to any of the preceding claims, characterized by , that an identifier is modulated onto a positioning signal to distinguish between the two transmitters. [6] Method according to any of the preceding claims, characterized by , that different transmission frequencies are used for the first and second transmitters (7). [7] Method according to any of the preceding claims, characterized by , that it is used for inductive charging in the short-range positioning of an electrically powered vehicle (4). [8] Method according to claim 7, characterized by, that the first transmitter will be a unit for inductively charging the vehicle. [9] Method according to claim 8, characterized by , that a ground coil (6) is used as a unit for inductive charging. [10] Method according to claim 8 or 9, characterized by , that several adjacent units for inductive charging, in particular floor coils (6), are provided, which are operated in particular by a central charging station (8). [11] Equipment for carrying out the procedure according to any of the preceding claims.

Images