Positioning with a radio-based locking system

Abstract

An access control device of a vehicle is configured to detect the spatial position of the access element of the vehicle safety unit relative to the vehicle via electromagnetically detecting the distances and angles between several low-frequency transmitting antennas of the vehicle safety unit and the low-frequency receiver of the access element. The access control device is also configured to detect the location position of an external induction charging unit relative to the vehicle via electromagnetically measuring the distance and angle between at least two transmitting antennas of several low-frequency transmitting antennas and at least one receiving antenna of the induction charging unit.

Claims

1. A system comprising: a vehicle-external induction charging unit comprising a primary coil and a low-frequency receiving antenna; and a vehicle comprising: a secondary coil configured for inductive charging of the vehicle at the induction charging unit via the primary coil, an automatic radio-based vehicle safety unit having at least two low-frequency transmitting antennas, and an access control device configured to: detect the spatial position of an access element relative to the vehicle based on the principle of electromagnetic distance and angle measuring between the transmitting antennas and a low-frequency receiver of the access element, and detect the location position of the induction charging unit relative to the vehicle based on the principle of electromagnetic distance and angle measuring between the transmitting antennas and the receiving antenna, wherein the access element is wirelessly coupled to the vehicle safety unit and is configured to permit user access to the vehicle when in the vicinity of the vehicle.

2. The system according to claim 1, wherein for the inductive charging, the secondary coil takes up a charging position, which is situated in a preferred spatial position area of the secondary coil with respect to the primary coil, and for establishing the charging position, the system detects a travel trajectory by means of the location position and the charging position, along which travel trajectory the charging position is taken up by the secondary coil.

3. The system according to claim 2, wherein the access control device drives the at least two transmitting antennas, the access control device comprises a first high-frequency communication unit, the induction charging unit has an induction control device, the induction control device comprises a second high-frequency communication unit, the induction control device is assigned to the at least one receiving antenna as a measuring unit of the electromagnetic distance and angle measuring, and measures the induction signals of the at least one receiving antenna, the induction signals are transmitted from the induction control device to the access control device, and the access control device as the arithmetic unit detects the location position by triangulation by means of the induction signals.

4. The system according to claim 3, wherein the access control device or a further control device of the vehicle detects the travel trajectory by means of the location position, and the vehicle automatically carries out a driving maneuver corresponding to the travel trajectory, or the vehicle outputs a driving maneuver corresponding to the travel trajectory to the driver of the vehicle by way of a suitable human-machine interface.

5. A method carried out by the system according to claim 3, wherein the method comprises the acts of: a) the first high-frequency communication unit sends out a coded search signal, b) the induction control device receives the search signal and the second high-frequency communication unit sends out a coded confirmation signal to the access control device, c) the access control device and the induction control device carry out an initialization routine between the at least two transmitting antennas and the at least two receiving antennas, d) the at least two transmitting antennas emit a coded electromagnetic positioning signal, with respect to the vehicle coordinate system, the magnetic fraction of the positioning signal having a specified field orientation and a specific field intensity, e) the at least one receiving antenna receives the at least two positioning signals of the at least two transmitting antennas, and the induction control device measures a magnetic field vector for each positioning signal, which magnetic field vector is unambiguously assigned to one of the at least two transmitting antennas by the coding of the positioning signal, f) the induction control device transmits the magnetic field vector to the access control device, g) according to the triangulation method, the access control device calculates the local position of the transmitting antennas with respect to the receiving antennas, which unambiguously describes the location position, h) the access control device or a further control device of the vehicle detects a travel trajectory, along which the charging position can be are taken up by the secondary coil.

6. A method carried out by the system according to claim 4, wherein the method comprises the acts of: a) the first high-frequency communication unit sends out a coded search signal, b) the induction control device receives the search signal and the second high-frequency communication unit sends out a coded confirmation signal to the access control device, c) the access control device and the induction control device carry out an initialization routine between the at least two transmitting antennas and the at least two receiving antennas, d) the at least two transmitting antennas emit a coded electromagnetic positioning signal, with respect to the vehicle coordinate system, the magnetic fraction of the positioning signal having a specified field orientation and a specific field intensity, e) the at least one receiving antenna receives the at least two positioning signals of the at least two transmitting antennas, and the induction control device measures a magnetic field vector for each positioning signal, which magnetic field vector is unambiguously assigned to one of the at least two transmitting antennas by the coding of the positioning signal, f) the induction control device transmits the magnetic field vector to the access control device, g) according to the triangulation method, the access control device calculates the local position of the transmitting antennas with respect to the receiving antennas, which unambiguously describes the location position, h) the access control device or a further control device of the vehicle detects a travel trajectory, along which the charging position can be are taken up by the secondary coil.

7. The method according to claim 5, wherein during a driving maneuver of the vehicle, acts d) to h) are repeated in real time in order to update the travel trajectory, when reaching the charging position, the updated travel trajectory will describe a stopping maneuver.

8. The method according to claim 6, wherein during a driving maneuver of the vehicle, acts d) to h) are repeated in real time in order to update the travel trajectory, when reaching the charging position, the updated travel trajectory will describe a stopping maneuver.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of a positioning with a locking system by means of triangulation having two transmitters at a vehicle and two receivers at a charging unit;

(2) FIG. 2 is a schematic view of an established charging position.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) In the figures, the same reference numbers describe identical technical characteristics. A vehicle with an electrified drive train can be wirelessly charged at an inductive charging station. In the embodiments, a vehicle 1 having an electrified drive train is schematically illustrated. This may be a hybrid or electric vehicle, possibly also a plug-in hybrid vehicle, if the latter, in addition to an interface for the wired charging, also has a charging interface for inductive charging. The vehicle comprises a vehicle-side charging structure for wireless inductive charging, in which case, the charging architecture as a central vehicle-side component, has a secondary coil 2.

(4) In addition, the vehicle has a radio-based locking system with an access control device 22. The radio-based locking system comprises at least two low-frequency antennas 5, 6 which can be operated by the access control device. Furthermore, a radio key 30, which may be situated inside or outside the vehicle, is part of the radio-based locking system. The radio key has a low-frequency receiver that is sensitive in all three spatial directions. This receiver is therefore called a 3d receiver. The radio-based locking system permits a “keyless” access to the vehicle and prevents a locking-out of vehicle users by preventing the locking of the vehicle when the key is situated in the vehicle. The access to the vehicle as well as the locking block take place by locating the key with respect to the spatial dimensions of the vehicle. The position determination takes place by a distance determination by way of the at least two low-frequency antennas of the vehicle and the 3d receiver of the key.

(5) A charging unit 3 for the inductive charging of a vehicle with an electrified drive train is situated outside the vehicle. The main component of the charging unit is a primary coil 4. The charging unit may be suitable for charging a plurality of vehicles, in which case, only a single vehicle can be charged at the primary coil at a certain point in time. The primary coil is mechanically fixedly integrated in the charging unit. The charging station is stationarily situated in or on the ground. In addition, the charging unit has an induction control device 22.

(6) A charging operation is any time period between an initialization operation of the charging connection and a termination operation of the charging connection. The charging operation comprises particularly those points in time at which electric power is transmitted or at least can be transmitted from the primary coil to the secondary coil.

(7) It is a prerequisite for a charging operation that the secondary coil is in the charging position, i.e. is situated within a defined spatial area relative to the primary coil. This spatial area is characterized such that a specified geometrical reference point of the secondary coil, which is a function of the configuration of the secondary coil, deviates from a specified geometrical reference point of the primary coil, which is a function of the configuration of the primary coil, with respect to the three spatial directions, which forms the vehicle-related coordinate system known to the person skilled in the art, only up to a specified tolerance dimension for each of the three spatial directions. By way of the transmission efficiency of electric power between the primary coil and the secondary coil, an optimal charging position is reached.

(8) When the reference point of the secondary coil relative to the reference point of the primary coil is situated such that the distance between these two reference points relative to each of the three spatial directions does not exceed the tolerance dimension specified for the respective axis, the secondary coil will be in the charging position. Because of the fact that the secondary coil is mechanically fixedly situated at the vehicle or is integrated in the vehicle, if the secondary coil is in the charging position, the vehicle is also in a vehicle charging position. Since, within the scope of this document, with respect to its technical effect, the vehicle charging position is synonymous with the charging position, in a simplifying manner, the term “charging position” also applies to the vehicle charging position.

(9) In order to initialize a charging operation, it is therefore necessary to bring the vehicle into the specified charging position. In the described embodiments, this takes place by a movement of the vehicle. In this case, it is essential to determine the position of the vehicle and thus the position of the secondary coil relative to the charging unit and therefore to the primary coil. In the embodiments, this takes place by distance and angle measuring by means of the triangulation method. The measuring is based on the acquisition of the magnetic field vector of a defined electromagnetic field generated by means of an antenna. If the antenna is further developed as a one-dimensional antenna, the received magnetic field vector is acquired at the location of the receiver as a one-dimensional vector, i.e. as a scalar.

(10) A first embodiment will be described by means of FIGS. 1 and 2. In this case, two transmitting antennas are used in the vehicle, and two receiving antennas are used in the charging unit. The two transmitting antennas are operated by the access control device, and the two receiving antennas are operated by the induction control device.

(11) According to the first embodiment, preferably the transmitting antennas, also called “transmitters”, are low-frequency antennas, and the receiving antennas, called “receivers”, preferably are low-frequency receivers. The transmitters and the receivers operate in a frequency range of below 150 kHz, a preferred frequency band being at approximately 125 kHz, with no limitation of generality.

(12) By means of FIG. 1, the first embodiment describes the location determination of the vehicle, the two transmitting antennas and the access control device being integrated in the vehicle as part of the radio-based locking system, and the two receivers as well as the induction control device being integrated in the charging unit. The antenna 5 is the first transmitting antenna; the antenna 6 is the second transmitting antenna. The receiver 7 is the first receiver; the receiver 8 is the second receiver.

(13) According to this embodiment, the access control device comprises a first communication unit, and the induction control unit comprises a second communication unit. Both communication units can exchange information signals in the high-frequency range in a preferred frequency band of the broadcast narrow-band radio communications at 433 MHz or 868 MHz. As an alternative, higher-frequency bands in the GHz range can be used, for example, according to WLAN or Bluetooth standards. These information signals are especially coded, so that a signal sent by a communication unit can clearly be assigned to the latter. Both communication units can send and receive information signals.

(14) In order to establish the charging position according to the first embodiment or according to the second embodiment, the basic communication is to be established first between the two communication units and thereby between the vehicle and the charging unit. For this purpose, at least one communication unit sends out, at regular intervals of fewer than 10 seconds, a coded high-frequency search signal with a searching range of up to 100 meters with respect to the sensitivity threshold of the receiving communication unit. As an alternative, the interval of the sending of the search signal is inversely proportionally linked with the speed of the vehicle. As soon as the receiving communication unit receives the search signal, the communication unit receiving the search signal sends out a coded confirmation signal with a range that corresponds to the searching range, to the communication unit sending the search signal. Provided that the confirmation signal is received by the communication unit sending the search signal, the basic communication between the communication units is established, and the vehicle is situated with respect to the charging unit at least within a distance that is not greater than the searching range. The communication unit of the charging station will send no signals if the charging station is not available for a charging operation, for example, when it is used by another vehicle. The vehicle will therefore at first be in a so-called rough position with respect to a charging unit currently usable for the charging.

(15) In the rough position, the basic communication connection exists between the vehicle and the charging unit by means of the two communication units. As a result of the coding of the search signal and the confirmation signal, it is guaranteed that the communication between the vehicle and the charging unit is unambiguous. This means that if, for example, there are several charging units of the same type for several vehicles having the same type of architecture, a communication exists between a specific vehicle of these several vehicles and a specific charging unit of these several charging units, and this specific vehicle is in a rough position with respect to the specific charging unit.

(16) When the basic communication is established in the rough position, additional information can be exchanged between the two communication units. In particular, the positioning of the vehicle can be initialized by means of triangulation. For the initialization, the access control device can direct an inquiry to the driver of the vehicle by way of a suitable human-machine interface (MMS) as to whether the establishment of the charging position with respect to the charging unit, with which there is basic communication, is to take place. If this is confirmed by the driver of the vehicle in a suitable manner, which is not the object of this document, the positioning of the vehicle will be initialized by triangulation.

(17) According to the first embodiment, the initialization is the triggering of the transmitters by the induction control device and the triggering of the receivers by the access control device as well as a connection establishment of the transmitters with the receivers in the low-frequency range. In this case, the signal emitted by the transmitters is coded in order to ensure an unambiguous assignment between the transmitters and receivers, i.e. between the vehicle and the charging unit. This can be made possible, for example, by an 8-bit coding.

(18) It is also conceivable that the initialization is based on a simplified mutual recognition of the vehicle and the charging unit when a specific vehicle and a specific charging unit are fixedly coupled with one another, which a person skilled in the art knows as pairing.

(19) After the initialization, the actual location determination will take place by triangulation. For this purpose, the transmitters each send out an electromagnetic signal of defined field intensity, which is called a positioning signal. The range of the positioning signal exceeds the searching range. The positioning signal of the first transmitter 5 is called a first positioning signal. The positioning signal of the second transmitter 6 is called a second positioning signal.

(20) As a result of the installation position of the transmitters in the vehicle, the magnetic field vector of the positioning signals in each case oscillates along a specific spatial preferred axis, and the magnetic field has a preferred propagation direction. According to this embodiment, without any limitation of generality, the preferred axis is situated in a first approximation along the x-axis of the vehicle-related coordinate system known to the person skilled in the art of the vehicle situated in the rough position and the propagation direction in the z-axis of the vehicle situated in the rough position.

(21) The receivers in the charging unit have such an installation position that the receivers in the x-y plane of the vehicle-related coordinate system of the vehicle situated in the rough position have the highest reception sensitivity with respect to a magnetic field and therefore the highest measuring precision.

(22) As an alternative, three-dimensional receivers with a three-dimensional reception characteristic, which correspond to the 3d receiver of the radio key and which are characterized along all three spatial axes by a comparable measuring precision, can also be used as well as three-dimensional transmitters. This means that the transmitters have a three-dimensional emission characteristic. The following one-dimensional approach can analogously be applied to additional spatial dimensions in the case of a three-dimensional emission characteristic and a three-dimensional reception characteristic.

(23) Without limiting generality, in the following, one-dimensional transmitters and one-dimensional receivers are used as the basis. The field intensity of the first positioning signal and thus a first magnetic field vector H.sub.1 is unambiguously defined by a first transmitter current I.sub.1, by a first winding number N.sub.1 as well as by the radius r.sub.1 of the first transmitter. The field intensity of the second positioning signal and thus a second magnetic field vector H.sub.2 is unambiguously defined by a second transmitter current I.sub.2, by a first winding number N.sub.2 as well as by the radius r.sub.2 of the second transmitter.

(24) The two receivers are installed at a distance L in the vehicle, which distance is perpendicularly oriented on the longitudinal vehicle axis 10 and along a parallel 9 of the transverse vehicle axis.

(25) The first receiver detects the first magnetic field vector H.sub.1 at the location of the first receiver. The induction control device evaluates the receiver and detects a measuring signal H.sub.1,x1, which indicates the field intensity of the first magnetic field at the location of the first receiver with respect to the x-direction in the vehicle coordinate system.

(26) The second receiver detects the first magnetic field vector H.sub.1 at the location of the second receiver. The induction control device evaluates the second receiver and detects a measuring signal H.sub.1,x2, which indicates the field intensity of the first magnetic field at the location of the second receiver with respect to the x-direction in the vehicle coordinate system.

(27) The first receiver detects the second magnetic field vector H.sub.2 at the location of the first receiver. The induction control device evaluates the receiver and detects a measuring signal H.sub.2,x1, which indicates the field intensity of the second magnetic field at the location of the first receiver with respect to the x-direction in the vehicle coordinate system.

(28) The second receiver detects the second magnetic field vector H.sub.2 at the location of the second receiver. The induction control device evaluates the second receiver and detects a measuring signal H.sub.2,x2, which indicates the field intensity of the second magnetic field at the location of the second receiver with respect to the x-direction in the vehicle coordinate system.

(29) At a specified point in time t.sub.1, the time-dependent measuring signals are acquired as H.sub.1,x1(t.sub.1), H.sub.1,x2(t.sub.1), H.sub.2,x1(t.sub.1) and H.sub.2,x2(t.sub.1) and are processed by the induction control device or transmitted to the access control device and processed by the access control device. In the case of this signal processing, the position of the vehicle at the point in time t.sub.1 is detected by triangulation.

(30) The length d.sub.1, which describes the distance between the first transmitter and the first receiver is obtained as:

(31) $d_1\left(t_1\right)=\sqrt{-r^2+{\left(\frac{2H_{1,x1}\left(t_1\right)}{N_1{I}_1{r}_1^2}\right)}^{\frac{2}{3}}}$

(32) The length e.sub.2, which describes the distance between the first transmitter and the second receiver, is obtained as:

(33) $e_2\left(t_1\right)=\sqrt{-r_1^2+{\left(\frac{2H_{1,x2}\left(t_1\right)}{N_1{I}_1{r}_1^2}\right)}^{\frac{2}{3}}}$

(34) The angle α1 between the length d.sub.1 and the length L, is obtained as:

(35) ${\alpha }_1\left(t_1\right)=\arccos \left(\frac{{e_2\left(t_1\right)}^2-{d_1\left(t_1\right)}^2-L^2}{-2d_1\left(t_1\right)L}\right)$

(36) As a result of the determination of d.sub.1, e.sub.2, and α.sub.1 at the point in time t.sub.1, the location position of the vehicle relative to the charging unit is unambiguously determined.

(37) Further variables can be detected by means of triangulation. The length d.sub.2, which describes the distance between the second transmitter and the first receiver, is obtained as:

(38) $d_2\left(t_1\right)=\sqrt{-r_2^2+{\left(\frac{2H_{2,x1}\left(t_1\right)}{N_2{I}_2{r}_2^2}\right)}^{\frac{2}{3}}}$

(39) The length e.sub.1, which describes the distance between the second transmitter and the first receiver, is obtained as:

(40) $e_1\left(t_1\right)=\sqrt{-r_2^2+{\left(\frac{2H_{2,x1}\left(t_1\right)}{N_2{I}_2{r}_2^2}\right)}^{\frac{2}{3}}}$

(41) The angle α.sub.2 between the length d.sub.2 and the length L is obtained as:

(42) ${\alpha }_2\left(t_1\right)=\arccos \left(\frac{{e_1\left(t_1\right)}^2-{d_2\left(t_1\right)}^2-L^2}{-2d_2\left(t_1\right)L}\right)$

(43) The signal processing further comprises the calculation of a travel trajectory of the vehicle, along which travel trajectory, starting from the location position of the vehicle, at the point in time t.sub.1, the vehicle can be moved into the charging position. The calculation of the travel trajectory will not be described here in detail.

(44) Starting from the point in time t.sub.1, at a repetition rate of at least 10 Hz, the position of the vehicle at later points in time t.sub.n is determined, and the travel trajectory is updated starting from the location position of the vehicle at the point in time tn.

(45) FIG. 2 illustrates the charging position for the first embodiment. The charging position will be established by the described arrangement of the transmitters in the vehicle and of the receivers in the charging unit respectively when the length d.sub.1 between the first transmitter and the first receiver describes the same distance as the length d.sub.2 between the second transmitter and the second receiver. This same distance corresponds to a specified desired distance d, which describes the setting of the charging position and which is filed in the access control device and/or induction control device. Furthermore, the two angles α.sub.1 and α.sub.2 correspond to a specified desired angle α, which also describes the setting of the charging position. As a result of the axially symmetrical arrangement of the transmitters and of the receivers when the charging position is established with respect to the longitudinal axis of the vehicle, the charging position is described by d=d.sub.1=d.sub.2 and α=α.sub.1=α.sub.2. In the case of a different type or geometrical arrangement of the transmitters and receivers, other desired angles will correspondingly occur for α.sub.1 and α.sub.2 as well as other desired distance for d.sub.1 and d.sub.2. When reaching the charging position, the travel trajectory describes a braking or stopping maneuver in order to bring the vehicle to a stop in the charging position.

(46) According to a variant of one of the embodiments, the desired distance d and the desired angle α are optimized by a learn algorithm with an increasing number of carried-out charging operations in the direction of an increasing transmission efficiency.

(47) According to a third embodiment, which represents a modification of the second embodiment, the primary coil itself acts as a receiver coil so that, in addition to the primary coil, the charging unit comprises no additional coil.

(48) In the case of several adjacent charging units, their receivers can also be operated in an interconnected manner. This means that, for increasing the range, the receiver of a charging unit is used for the location determination of the vehicle with respect to a third charging unit. This requires that the positions of the several charging units with respect to one another are known to the access control device or can be transmitted to the latter.

(49) The position determination by triangulation can also be used during a charging operation for checking whether the charging position is maintained.

(50) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.