Systems and methods for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer

Abstract

A system and method for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer. The invention relates to a system and method for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer, wherein a first relative pose is determined by at least a first radio direction finding system, wherein the first radio direction finding system comprises at least one transmitting device (8) and at least two receiving devices (5a, 5b) for receiving a position signal transmitted by the transmitting device (8), wherein the first relative pose is determined based on output values generated by the receiving devices (5a, 5b) when receiving the position signal, wherein at least one motion value of the vehicle (7) is determined, wherein the first relative pose is determined using a model-based determination, wherein input values of the model-based determination are provided by the output values of the receiving devices (5a, 5b) and the at least one motion value.

Description

TECHNICAL FIELD

[0001] The present invention relates to a system and method for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer. BACKGROUND

[0002] Document GB2542182A discloses a system for determining a relative position and orientation between a primary winding structure and a secondary winding structure of a system for inductive power transfer, in particular to a vehicle.

[0003] It is desirable to position a vehicle in a so-called charging pose (charging position and / or orientation) in which a required (e.g. maximum) amount of power can be transferred, in particular with a possible optimal efficiency. In order to position a vehicle in such a charging pose, it is necessary to provide information about the actual relative pose to the vehicle driver, for example by displaying such information on a vehicle-side display. In particular, in the last phase of approaching a charging unit by the vehicle, the driver usually cannot determine the above-mentioned relative pose by visual inspection.

[0004] Changing environmental influences can influence the determination of the relative pose in an undesirable manner, for example because of a reduced accuracy. Thus, although the actual relative pose does not change, the result of the above-mentioned determination of the relative pose changes due to changing environmental influences. For example, the method described in GB2542182A relies on an evaluation of transmitted signals, wherein these signals are dataless signals, i.e. do not encode data. In particular, a receiver receives the signals, wherein the receiver generates a voltage which depends on the received signals, wherein the voltage level is evaluated to determine the relative pose. These signals can be disturbed, for example, by environmental influences (e.g. metal objects or ferromagnetic materials such as reinforced concrete) and other types of influences. Furthermore, the above-mentioned influences can change during the use of the system for inductive power transfer.

[0005] It is further known that WO2019 / 072699 discloses a system and method for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer.

[0006] WO2014 / 095722A2 discloses an inductive sensing system having a plurality of detection windings.

[0007] WO 2012 / 047779 A1 discloses a safety system for a charger for providing protection for an object that can become hot during operation of the charger, wherein the safety system comprises a detection subsystem configured to detect whether an object is present and in close proximity to the charger and a notification subsystem operably coupled to the detection subsystem and configured to provide an indication of the object. The publication discloses that one or more inductive sensors can be integrated into a source device, a source housing, a vehicle, or a surrounding area to detect an obstruction, a foreign object, and / or a material between a source resonator and a device resonator. SUMMARY

[0008] There is the technical problem to provide an alternative system and an alternative method for determining a relative pose between a primary winding structure and a secondary winding structure of an inductive power transfer system, wherein inaccuracies in the determination of the relative pose due to environmental influences are minimized.

[0009] It is proposed a method for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer to a vehicle.

[0010] The system for inductive power transfer can comprise a primary unit having a primary winding structure and a secondary unit having a secondary winding structure. The vehicle can comprise a secondary unit having a secondary winding structure for receiving an alternating electromagnetic field generated by the primary winding structure of the primary unit. The primary winding structure generates the alternating electromagnetic field if the primary winding structure is energized or provided with an operating current. The primary unit can comprise all components or partial components that generate the alternating electromagnetic field for inductive power transfer. Correspondingly, the secondary unit can comprise all components or partial components that receive the alternating electromagnetic field for inductive power transfer and provide a corresponding output voltage.

[0011] The primary unit can be provided by an inductive power transfer pad. The inductive power transfer pad can be mounted on a surface of a road or a parking space or can be integrated within such a surface.

[0012] The invention can be particularly applied in the field of inductive energy transfer for any land vehicle, such as a rail vehicle, such as a tram, such as a tramcar. In particular, the invention relates to the field of inductive energy transfer to a road car, such as a personal (private) passenger car or a public transport vehicle, such as a bus.

[0013] In the following, reference can be made to a primary side coordinate system and a secondary side coordinate system. The primary side coordinate system can be a coordinate system of the primary winding structure and the secondary side coordinate system can be a coordinate system of the secondary winding structure.

[0014] The primary side coordinate system can comprise a first axis, which can also be referred to as a longitudinal axis, wherein the first axis can be a longitudinal axis of the primary winding structure or extend parallel to the longitudinal axis. A second axis, which can also be referred to as a transversal axis, can be a transversal axis of the primary winding structure or extend parallel to the transversal axis. A third axis, which can also be referred to as a vertical axis, can be oriented perpendicular to the first axis and the second axis. The third axis can be oriented parallel to a desired direction of power transfer, i.e. from the primary unit to the secondary unit. If pointing from the primary unit to the secondary unit, the vertical axis can be oriented from bottom to top.

[0015] The secondary side coordinate system can also comprise a first axis, which can be referred to as a longitudinal axis, wherein the first axis can be a longitudinal axis of the secondary winding structure or extend parallel to the longitudinal axis. A second axis of the secondary winding structure can be referred to as a transversal axis, wherein the second axis can be a transversal axis of the secondary winding structure or can extend parallel to the transversal axis. A third axis can be referred to as a vertical axis of the secondary winding structure and can be oriented perpendicular to the first axis and the second axis of the secondary winding structure. The third axis of the secondary winding structure can be oriented parallel to a desired direction of power transfer.

[0016] In the following, lengths can be measured along the first axis, widths can be measured along the second axis, and heights can be measured along the third axis. Directional terms referring to directions, such as "upper", "lower", "front", "side", etc., can be related to the above-mentioned longitudinal axis, transversal axis, and vertical axis of the corresponding coordinate system.

[0017] The origin of the primary side coordinate system can correspond to a geometrical center of the primary winding structure. Correspondingly, the origin of the secondary side coordinate system can correspond to a geometrical center of the secondary winding structure.

[0018] The primary winding structure and / or the secondary winding structure can comprise at least one sub-winding structure. The sub-winding structure can be provided by at least one portion of the winding structure. In particular, the sub-winding structure can provide a loop or a coil, wherein the loop or the coil is provided by one or more portions of the winding structure. The winding structure can extend along the longitudinal axis of the corresponding coordinate system. Preferably, the winding structure comprises a plurality of sub-winding structures extending along the longitudinal axis. In this case, consecutive sub-winding structures of the winding structure can be arranged adjacent to each other along the above-mentioned longitudinal axis. Adjacent to each other can mean that central axes, in particular symmetry axes, of the sub-windings are spaced apart from each other, e.g. at a predetermined distance from each other along the longitudinal axis. The loop or the coil can be circular, elliptical, or rectangular.

[0019] The winding structure can comprise at least one winding portion extending along a longitudinal axis of the corresponding coordinate system and at least one winding portion extending along a transversal axis. Thus, the winding structure (in particular each sub-winding structure) can be provided by portions extending substantially or completely parallel to the longitudinal axis and portions extending substantially or completely parallel to the transversal axis. In particular, each sub-winding can be provided by two portions extending substantially or completely parallel to the longitudinal axis and two portions extending substantially or completely parallel to the transversal axis.

[0020] determining a first relative pose from at least a first radio direction finding system, wherein the first radio direction finding system comprises at least one transmitting device and at least two receiving devices for receiving a position signal transmitted by the transmitting device. Preferably, the first radio direction finding system comprises exactly four receiving devices. However, the first radio direction finding system can also comprise less than four receiving devices or more than four receiving devices.

[0021] Preferably, the transmitting device is a vehicle-side transmitting device and the receiving devices are primary-side receiving devices. However, the transmitting device can also be a primary-side transmitting device and the receiving devices can also be vehicle-side receiving devices.

[0022] The first relative pose is determined based on output signals generated by the receiving devices upon reception of the position signal. In the context of the present invention, a radio direction finding system denotes a system which allows to determine a pose of a transmitting device in a desired coordinate system (in particular with respect to a coordinate system related to the receiving devices, e.g. in a coordinate system fixed with respect to the receiving devices). The pose determination is performed by evaluating output signals generated by the receiving devices upon reception of a position signal generated by the transmitting device. The transmitting device can be (or comprise) an antenna element. Further, the receiving devices can be (or comprise) antenna elements. In particular, in this case, the output signals can be output voltages and / or output currents of the receiving devices. Such voltages / currents can be induced within the antenna elements upon reception of the position signal, for example. For determining the relative pose, at least one feature of the output signals can be evaluated, e.g. an amplitude, a mean value, a frequency, or any other signal feature.

[0023] The relative pose denotes a relative position and / or orientation. The relative pose can be denoted by one or more parameters. For example, the relative pose can be determined as a position and / or orientation of the secondary winding structure in a common coordinate system. Preferably, the common coordinate system is provided by the secondary-side coordinate system. However, alternatively, the common coordinate system can be e.g. the primary-side coordinate system or a coordinate system fixed in position and fixed in orientation with respect to the primary-side coordinate system. However, another common reference coordinate system can also be used.

[0024] The above system may, for example, comprise at least one evaluation unit, in particular at least one primary-sided evaluation unit and / or at least one secondary-sided evaluation unit. The evaluation unit may, for example, comprise or be provided by a microcontroller or an integrated circuit. In the context of the present invention, the term “secondary-sided” can mean that the respective element is arranged in a position fixed with respect to a secondary-sided coordinate system. In particular, the position of the secondary-sided element in the secondary-sided coordinate system can be known. Furthermore, the term “secondary-sided” can mean that the respective element can be part of a secondary unit. Furthermore, the term “primary-sided” can mean that the respective element is arranged in a position fixed with respect to a primary-sided coordinate system. In particular, the position and orientation of the primary-sided element in the primary-sided coordinate system is known. Furthermore, the term “primary-sided” can mean that the respective element is part of a primary unit.

[0025] Furthermore, at least one motion value of the vehicle is determined. The motion value of the vehicle represents a feature of the motion or movement of the vehicle. Such a feature can be, for example, an acceleration, a speed, a distance, for example a traveled distance, of the vehicle. Furthermore, such a feature can be a yaw rate of the vehicle, a driving direction of the vehicle, a steering wheel angle, for example a steering angle or a rear axle steering angle, or any other dynamic feature of the vehicle. The above-mentioned features can be related to a longitudinal axis, a transverse axis, or a vertical axis of the vehicle.

[0026] The motion value can be measured, in particular by a measuring device, for example a sensor. However, the motion value can also be determined, for example by calculating an output signal from at least one measuring device which does not measure the above-mentioned motion value, but has an information content related to the above-mentioned motion value. Such a measuring device can measure, for example, a different motion value than the desired motion value.

[0027] For example, such a measuring device can be a position determination device or system. In this case, a position signal generated by the position determination device can be used to determine the motion value. For example, the measuring device can be a GNSS sensor for measuring the position of the vehicle. In this case, the above-mentioned position can provide the motion value. If the motion value is, for example, a speed value, this speed value can be determined from the positions of the vehicle at different points in time.

[0028] The measuring device can also be an image capturing unit, for example a camera, more particularly a CMOS camera or a CCD camera. The image capturing unit can be attached to the vehicle. Based on an image analysis, in particular an analysis of images generated at different points in time, the motion value, for example a speed value, can be determined. Corresponding image processing algorithms are known to the person skilled in the art.

[0029] Of course, another position determination device or system independent of the GNSS position and / or the output of the image capturing unit can also be used to determine the position. Such another position determination device can for example provide a position determination based on Bluetooth RSSI values, a position determination based on LIDAR or a position determination of an indoor radar or a position determination according to another functionality.

[0030] The position can also be determined by fusing position values determined by at least two different position determination devices or systems. In this case, these different position determination devices or systems provide estimates according to different working principles, i.e. independently of each other, for example by evaluating the output signals of different sensors.

[0031] The motion values can be determined by a vehicle-side evaluation unit. In this case, the motion values can be determined using vehicle-side sensors. Furthermore, the motion values can be transmitted to the primary side, in particular to the primary-side evaluation unit, for example by means of appropriate signal or data transmission means.

[0032] The system can comprise a communication device for communication between the charging unit (primary unit) and the vehicle. The communication device can for example be configured to be able to establish a Bluetooth TM ) based communication. This communication device allows data communication and / or signal communication between the primary-side element and the secondary-side element, in particular the vehicle. Through this communication device, data encoded information about at least one motion value and all other types of information can be exchanged between the charging (primary) unit and the vehicle, for example information about the relative pose determined by the primary-side evaluation unit, and / or trajectory information, and / or information about at least one reference pose, and / or information about the detection of the charging pose, and / or information about the parameters of the coordinate transformation.

[0033] Alternatively, the motion values can be determined by the primary-side evaluation unit. In this case, the motion values can be determined using primary-side sensors. Alternatively, the output signals of the vehicle-side sensors can be transmitted to the primary side, wherein the primary-side evaluation unit determines the motion values on the basis of the transmitted output signals.

[0034] According to the application, a model-based determination is used to determine the first relative pose, wherein the input values of the model-based determination are provided by the output values of the receiving device of the first radio direction finding system and the at least one motion value. In this case, the above-mentioned relative pose can be determined as the first relative pose. For determining the first relative pose, the output values of the receiving device and the at least one motion value are taken into account synthetically. In other words, the output values of the receiving device and the at least one motion value are fused to determine the first relative pose.

[0035] The output value of the receiving device of the first radio direction finding system can be provided by an amplitude and / or a real part and / or an imaginary part of an AC voltage induced in the receiving device when receiving the position signal. Thus, the real part and / or the imaginary part and / or the amplitude can provide an input value for the model-based determination.

[0036] The first relative pose can be determined, for example, by a primary side evaluation unit. This evaluation unit can be connected to the receiving device, for example, by signal transmission means, such as wired or wireless signal transmission means.

[0037] The model-based determination can be based on a model representing a relationship between the output signal and the at least one motion value as input values and the first relative pose as output value. In this case, the model can describe a direct relationship between the input values and the relative pose. The model can be, for example, a mathematical description of a physical relationship between the input values / output values.

[0038] However, the model-based determination can also be based on a model representing a relationship between the output signal and the at least one motion value as input values and an output value different from the first relative pose. In other words, the model does not describe a direct relationship between the input values and the relative pose as described above.

[0039] The relative pose can be determined repeatedly, in particular at a predetermined frequency.

[0040] Advantageously, taking into account the output value of the receiving device of the first radio direction finding system and the at least one motion value allows a reliable and precise determination of the relative pose. Advantageously, the described consideration of the motion values allows to reduce inaccuracies of the pose determination by the first radio direction finding system, which can be caused, for example, by noise, environmental influences, such as temperature, and / or electromagnetic interference.

[0041] In other embodiments, the model-based determination comprises a step of determining a state variable based on the input values, wherein the first relative pose is determined as the at least one state variable. In this case, the model can represent a relationship, in particular a mathematical relationship, between the input values and one or more state variables. The state variables can be different from the input values, for example. The input values can also be referred to as observable values or measurable values. The state variables, in particular the state variables representing the first relative pose or encoding information about the first relative pose, are preferably unobservable state variables.

[0042] In particular, a state variable can be predicted based on previously determined state variables and a state transition model, and the predicted state variable is then updated based on an observation value. The observation value can be provided by the output signal of the receiving device and the at least one motion value. It is also possible to use output values provided by other sources than the receiving device or the source providing the motion values as observation values.

[0043] Further, the first relative pose is subsequently determined as a multiple of the above-mentioned updated (predicted) state variable. The updating can be performed by using an observation model. For the above-mentioned model-based determination, the output value and the at least one motion value generated by the receiving device can provide an observation or measurement value.

[0044] Advantageously, in particular when the first relative pose cannot be determined directly or accurately based on the input value, this allows to reliably and accurately determine the relative pose based on the output signal of the first radio direction finding system and the at least one motion value, i.e. to provide a so-called hidden or unobservable state variable.

[0045] In a preferred embodiment, a Kalman filter is used for determining the first relative pose. This can mean that a Kalman filter-based determination of the first relative pose is performed. Kalman filters are known to the person skilled in the art. The above-mentioned Kalman filter-based procedure uses a model (in particular a dynamic model of the system, e.g. based on physical laws of motion), known control inputs to the system (if applicable), and a plurality of sequential measurements / observations, e.g. from sensors, to determine an estimate of the system state variable. The above-mentioned estimate can be better than an estimate using only one measurement. It is thus a commonly used algorithm for sensor fusion and data fusion. In this case, the output value and the at least one motion value of the receiving device provide the measurements, wherein the first relative pose is the state variable.

[0046] The Kalman filter determines an estimate of the state variable of the system as a weighted average of the predicted state variable of the system, the (new) output signal of the receiving device and the (new) motion value, and (if applicable) values from other sources. The purpose of the weighting is that values with better (i.e. smaller) estimated uncertainty are more “trusted”.

[0047] The above-mentioned weights are computed from covariances, which are measures of the estimated uncertainty of the prediction of the system state variable. The result of the weighted average is a new state variable estimate, which lies between the predicted state and the measured state, and has a better estimated uncertainty than either of the predicted or measured states. The procedure repeats at each time step, with the new estimate and its covariance influencing the prediction used in the next iteration. This means that the Kalman filter works recursively, and only needs the last “best guess” of the system state, not the entire history, to compute a new state.

[0048] The Kalman filter-based determination can comprise two steps.

[0049] In the prediction step, the predicted current state variable is determined based on a model, e.g. a model based on electromagnetic dipole theory and physical laws of motion. In this case, the model can also be denoted as a state variable transition model and describes the relationship between the predicted current state variable and the previous state variable, in particular the previously estimated state variable, and, if applicable, the control input value. Furthermore, the predicted current state variable is determined based on a process noise parameter, e.g. a noise parameter which can be predetermined or previously determined. The above-mentioned noise parameter can be provided, for example, by a process covariance, in particular a process covariance matrix. In addition to determining the predicted current state variable, an updated process noise parameter can also be determined in the prediction step.

[0050] In the update step, the observations are determined as output values of the signal reception device of the first radio direction finding system and at least one motion value. The observations can be assigned an observation noise parameter, wherein the observation noise parameter represents the degree of uncertainty in the determination of the above-mentioned values. The observation noise parameter can be provided, for example, by an observation covariance, in particular an observation covariance matrix. The above-mentioned covariance (with respect to the covariance of the prediction step) then determines to what extent a new measurement will influence the updated prediction.

[0051] Furthermore, the estimated current state variable is determined based on the above-mentioned observations, the predicted current state variable, and an observation model representing the relationship between the state variable and the observations. In addition to determining the estimated current state variable, an updated process noise parameter can also be determined in the prediction step.

[0052] The first relative pose can then be provided by one or more of the above-mentioned current estimated state variables or can be determined from these state variables.

[0053] In other embodiments, the motion value is a speed of the vehicle, a driving direction of the vehicle, or a steering wheel angle of the vehicle. Simulations have shown that such motion values can determine the relative pose very precisely.

[0054] In other embodiments, a further relative pose is determined by a further radio direction finding system, wherein the further radio direction finding system comprises at least one transmitting device and at least two receiving devices for receiving a position signal transmitted by the transmitting device. Furthermore, the further relative pose is determined based on output values generated by the receiving devices when receiving the position signal.

[0055] Aspects relating to the first radio direction finding system can also be applied to the above-mentioned further radio direction finding system. Thus, the above-mentioned further radio direction finding system refers to the corresponding aspects disclosed in the present application.

[0056] The receiving device of the first radio direction finding system and the other radio direction finding system can be designed as different or separate devices. Also, the transmitting device of the first radio direction finding system and the other radio direction finding system can be designed as different or separate devices. Preferably, however, the transmitting device of the first radio direction finding system provides the transmitting device of the other radio direction finding system and vice versa.

[0057] In this case, for example, the vehicle-side transmitting device can transmit a position signal, wherein the position signal is received by the receiving device of the first radio direction finding system as well as by the receiving device of the other radio direction finding system.

[0058] Further, the relative pose is determined by fusing the first relative pose and the other relative pose. Such a relative pose can be referred to as a fused relative pose. This can mean that the resulting pose is determined by combining the first relative pose and the other relative pose, wherein both the first relative pose and the other relative pose are determined by different methods and based at least partly on output signals from different sensors. This advantageously leads to a smaller uncertainty, i.e. an increased certainty, of the pose determination.

[0059] In other embodiments, the relative pose is determined as the first relative pose when the winding structures are at a first distance interval apart and as the fused relative pose when the winding structures are at a further distance interval apart. The minimum value of the first interval can be higher than the maximum value of the further interval. The minimum value of the first interval can be, for example, 0.5 m, 1.0 m, or 2.5 m. Correspondingly, the maximum value of the further interval can be less than 0.5 m, 1.0 m, or 2.5 m. The maximum value of the first interval can be, for example, 6.5 m. The minimum value of the further interval can be, for example, 0 m. Alternatively, the minimum value of the further interval can be higher than the maximum value of the first interval.

[0060] This advantageously allows for a more certain pose determination only for distances for which both radio direction finding systems provide a sufficiently accurate relative pose, in particular if one of the radio direction finding systems (more specifically, the other radio direction finding system) only provides accurate results at a predetermined distance interval.

[0061] In other embodiments, the distance of the further distance interval is smaller than the distance of the first distance interval. This advantageously allows for an increased certainty of the pose determination only for distances for which the other radio signal finding system provides a sufficiently accurate relative pose, if such accuracy is only achieved at small distances.

[0062] In other embodiments, at least one noise-related parameter of the output values generated by the receiving device of the first radio direction finding system and at least one noise-related parameter of the output values generated by the receiving device of the second radio direction finding system are determined, wherein the fused relative pose is determined depending on the noise-related parameters. The noise-related parameter may, for example, represent the amount of noise of the above-mentioned signal relative to the useful signal portion within this signal. In other words, the noise-related parameter can be the SNR. The noise-related parameter can be determined based on the amplitude of the output signal.

[0063] The determination of the noise-related parameter can be based on the output signal. Corresponding methods are known to the person skilled in the art. Alternatively or additionally, the noise-related parameter can be predetermined or can be determined based on predetermined characteristics of the receiving device.

[0064] For example, the higher the signal noise represented by the above-mentioned noise-related parameter is when fusing the first relative pose and the further relative pose, the less the relative pose determined based on the above-mentioned signal can be considered.

[0065] This advantageously further improves the accuracy and certainty of the pose determination.

[0066] In other embodiments, at least the receiving device of the second radio direction finding system is provided by an element of a device for foreign object detection. Such a device for foreign object detection may, for example, comprise exactly one or more detection winding structures. The detection winding structure may, for example, be provided by a coil having exactly one or more turns. Such a device for foreign object detection is disclosed, for example, in WO 2014 / 095722 A2 or WO 2012 / 047779 A1. In addition to the above-mentioned detection winding structure, the device for foreign object detection can comprise at least one excitation winding structure.

[0067] The object detection device or system can comprise an inductive element and a capacitive element, wherein these elements can be different from the elements of the resonant circuit of the proposed system. Such elements advantageously allow for a detection of foreign objects depending on a change of the inductance or the capacitance of the aforementioned inductive element or capacitive element. The detection system is designed as an induction sensing system, wherein the induction sensing system can comprise one or more detection windings and, if applicable, one or more excitation windings. Using an induction detection system, an active detection or a passive detection can be realized. In the case of active detection, one or more excitation windings and one or more detection windings can be used. The active object detection can be performed by monitoring at least one characteristic of the excitation field generated by the excitation winding and received by the detection winding. In the case of passive detection, only one or more passive detection windings are used. The passive object detection is performed by monitoring at least one characteristic, in particular the inductance, of the one or more passive windings.

[0068] In particular, the at least one primary-side receiving unit can be provided at least partially by or comprise a detection winding structure. Alternatively, the at least one primary-side receiving unit can be provided at least partially by or comprise an excitation winding structure. Preferably, the detection winding structure can provide a receiving antenna structure of the primary-side receiving unit. Alternatively or additionally, the primary-side AD converter is provided by an AD converter of the inductive object detection system. In this case, the inductive object detection system can comprise an AD converter to digitize the output signal of the one or more detection windings.

[0069] The inductive object detection system can comprise a plurality of detection winding structures and / or excitation winding structures, wherein the winding structures can be preferably uniformly distributed over an active area assigned to the primary winding structure. The active area can represent an area covering the primary winding structure. The plurality of detection winding structures and / or excitation winding structures can be arranged, for example, as an array-like structure.

[0070] In this case, at least two selected detection winding structures or all detection winding structures of the device for foreign object detection can provide a receiving device of another radio direction finding system. This advantageously allows to reduce the construction space requirements for such a system, since already existing components can be used for the proposed pose determination.

[0071] In other embodiments, the motion value of the vehicle is determined based on GNSS signals and / or based on images and / or based on output values of vehicle sensors.

[0072] In other embodiments, the motion value information is transmitted from the vehicle to a way-sided primary unit.

[0073] It is also proposed a system for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transmission to a vehicle, wherein the system comprises at least a first radio direction finding system for determining a first relative pose, wherein the first radio direction finding system comprises at least one transmitting device and at least two receiving devices for receiving a position signal transmitted by the transmitting device, wherein the first relative pose is determined based on output values generated by the receiving devices when receiving the position signal, wherein at least one motion value of the vehicle is determined. Further, the first relative pose is determined using a model-based determination, wherein input values for the model-based determination are provided by the output values and the at least one motion value.

[0074] The system can further comprise at least one means for determining the at least one motion value.

[0075] The system advantageously allows to perform a method according to one of the embodiments disclosed herein. Thus, the system can be configured to perform such a method.

[0076] In other embodiments, the system comprises a further radio direction finding system for determining a further relative pose, wherein the further radio direction finding system comprises at least one transmitting device and at least two receiving devices for receiving a position signal transmitted by the transmitting device, wherein the further relative pose is determined based on output values generated by the receiving devices upon reception of the position signal, wherein the relative pose is determined by fusing the first relative pose and the further relative pose. This embodiment and its corresponding advantages have been set out in the foregoing.

[0077] In other embodiments, the system comprises a device for foreign object detection, wherein at least the receiving devices of the further radio direction finding system are provided by elements of the device for foreign object detection. This embodiment and its corresponding advantages have been set out in the foregoing.

[0078] In other embodiments, the system comprises means for transmitting motion value information from the vehicle to the road side primary unit. This embodiment and its corresponding advantages have been set out in the foregoing. BRIEF DESCRIPTION OF DRAWINGS

[0079] The application will be described with reference to the accompanying drawings. The drawings show:

[0080] Figure 1 : schematic block diagram of a system for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer,

[0081] Figure 2 : schematic block diagram of several parts of a system for determining a relative pose between a primary winding structure and a secondary winding structure of a system for inductive power transfer according to a further embodiment,

[0082] Figure 3 : schematic flow chart of a method for determining a relative pose between a primary winding structure and a secondary winding structure,

[0083] Figure 4 : schematic flow chart of a method for determining a relative pose between a primary winding structure and a secondary winding structure according to a further embodiment of the application,

[0084] Figure 5 : schematic flow chart of a method for determining a relative pose between a primary winding structure and a secondary winding structure according to a further embodiment of the application,

[0085] Figure 6 : schematic flow chart of a method for determining a relative pose between a primary winding structure and a secondary winding structure according to a further embodiment of the application. DETAILED DESCRIPTION

[0086] In the following, identical reference signs denote elements having identical or similar technical features.

[0087] Figure 1 A schematic block diagram of a system 1 for determining a relative pose between a primary winding structure 2 and a secondary winding structure 3 of a system for inductive power transfer is shown.

[0088] The system for inductive power transfer comprises a primary unit 4 comprising the primary winding structure 2. Further, the primary unit 4 comprises a first receiving device 5a and a second receiving device 5b of a first radio direction finding system for determining a relative pose between the set primary winding structure 2 and the set secondary winding structure 3. Further, the system for inductive power transfer comprises a secondary unit 6 attached to a vehicle 7, in particular to an underbody side of the vehicle 7. The secondary unit 6 comprises the secondary winding structure 3. Further, the secondary unit 6 comprises a transmitting device 8 of the first radio direction finding system. The transmitting device 8 can comprise an antenna structure or be designed as an antenna structure. Further, each of the receiving devices 5a, 5b can also be designed as an antenna structure or comprise such an antenna structure. Figure 1 It is shown that the first radio direction finding system comprises two receiving devices 5a, 5b. However, the first radio direction finding system can comprise more receiving devices than shown, in particular exactly four receiving devices or more than four receiving devices. These receiving devices 5a, 5b can be arranged at different positions with respect to a primary side coordinate system.

[0089] In Figure 1 In the shown embodiment, the different receiving devices 5a, 5b are arranged along a longitudinal axis x of the primary side coordinate system at a predetermined distance. It is also shown a vertical axis z of the above-mentioned primary side coordinate system. A transversal axis (not shown) is oriented orthogonal to the longitudinal axis x and the vertical axis z. This transversal axis can be oriented perpendicular to the drawing plane. For example, at least two or all receiving devices 5a, 5b of the primary unit 4 can be offset with respect to each other along the longitudinal axis x by a non-zero distance. Alternatively or additionally, at least two or all receiving devices 5a, 5b of the primary unit 4 can be offset with respect to each other along the transversal axis by a non-zero distance.

[0090] In one embodiment, at least two receiving devices of a first group comprising at least two receiving devices of the primary unit 4 are offset with respect to each other along the longitudinal axis x by a non-zero distance, wherein at least two receiving devices of another group comprising at least two receiving devices of the primary unit 4 are offset with respect to each other along the transversal axis by a non-zero distance, wherein the above-mentioned first group comprises at least one receiving device not belonging to the above-mentioned another group.

[0091] Furthermore, the primary unit 4 can comprise an evaluation unit 9, wherein the evaluation unit 9 can be designed as (or comprise) a microcontroller or an integrated circuit. The evaluation unit 9 can be connected to the receiving devices 5a, 5b by appropriate signal transmission means, for example by a wired or wireless connection. By means of the evaluation unit 9, the first relative pose is determined from the output signals generated by the receiving devices 5a, 5b, in particular from at least one feature of the output signals. Such a procedure for determining a relative pose from output signals is known to the person skilled in the art.

[0092] Furthermore, the primary unit 4 comprises data reception means 10 for receiving data signals transmitted wirelessly, for example by means of Bluetooth-based communication, by a vehicle-side data transmission device 11. In particular, a communication link can be established between the vehicle-side data transmission device 11 and the primary-side data reception means 10. The transmission device and the reception means can each comprise at least one antenna structure.

[0093] A vehicle-side control unit 12 is also shown. By means of the vehicle-side control unit 12 and the data transmission device 11, at least one movement value of the vehicle 7 can be transmitted to the primary unit 4 by means of a corresponding data signal. Such a movement value can for example be the speed of the vehicle 7, which can for example be determined by a speed sensor (not shown), wherein the speed sensor can be connected to the control unit 12 shown. Alternatively or additionally, the at least one movement value described above can comprise information about the driving direction of the vehicle 7, in particular the direction in a world coordinate system. Alternatively or additionally, the at least one movement value can comprise or be provided by the steering wheel angle of the vehicle 7, which can for example be determined by a sensor (not shown).

[0094] Furthermore, the first relative pose is determined by the primary-side evaluation unit 9 using a model-based determination, wherein the input values for the model-based determination are provided by the output values of the receiving devices 5a, 5b and by the at least one movement value transmitted from the vehicle 7 to the primary unit 4, in particular from the vehicle-side control unit 12 to the primary-side evaluation unit 9. The primary-side evaluation unit 9 can be connected to the data reception means 10 by appropriate connection means, for example in a wired or wireless manner.

[0095] The movement values of the vehicle 7, for example the speed, can also be determined on the basis of GNSS signals provided for example by a GNSS sensor (not shown) of the vehicle 7. The movement values can be determined by the vehicle-side control unit 12 and transmitted to the primary side, in particular to the primary-side evaluation unit 9. Alternatively, the at least one movement value can be determined by the primary-side evaluation unit 9, wherein the signals for the determination described above are provided to the evaluation unit 9, for example by the vehicle 7, in particular by the vehicle-side control unit 12.

[0096] Figure 2A schematic block diagram showing several parts of a system for determining a relative pose between a primary winding structure 2 and a secondary winding structure 3 of a system for inductive power transfer is shown according to another embodiment.

[0097] In Figure 2 , only the primary unit 4 of the system for inductive power transfer is shown. The primary unit 4 is basically designed like the primary unit 4 shown in Figure 1 , thus, reference is made to the corresponding description above. In contrast to the embodiment shown in Figure 1 , the primary unit 4 comprises an array 13 of detection windings 14 of a foreign object detection device. For the sake of illustration, only one of the detection windings 14 is provided with a reference sign. Such a detection winding 14 can provide an antenna element for receiving a position signal, in particular a position signal generated and transmitted by the position signal transmitting device 8 (see Figure 1 ). In this case, the position signal transmitted by the transmitting device 8 is received by the receiving devices 5a, 5b of the first radio direction finding system as well as by the detection windings 14 of the foreign object detection device. Thus, these detection windings 14 and the transmitting device 8 provide a further radio direction finding system for determining a relative pose between the primary winding structure 2 and the secondary winding structure 3.

[0098] The evaluation unit 9 can be connected to the detection windings 14 by appropriate signal transmission means, for example by a wired or wireless connection. By means of the evaluation unit 9, a further relative pose as described above is determined from the output signals generated by the detection windings 14, in particular from at least one feature of the output signals. Such a procedure for determining a relative pose from output signals is known to the person skilled in the art.

[0099] Then, a final relative pose can also be determined by fusing the above-mentioned first relative pose determined from the output signals generated by the receiving devices 5a, 5b of the first radio direction finding system and the at least one motion value and the above-mentioned further relative pose determined from the output signals generated by the detection windings 14 of the receiving devices providing the further radio direction finding system. This means that both the above-mentioned first relative pose and the above-mentioned further relative pose are taken into account when determining the final relative pose.

[0100] Figure 3 A schematic flow chart showing a method for determining a relative pose between a primary winding structure and a secondary winding structure is shown.

[0101] A vehicle 7 is shown, wherein at least one motion value, in particular a speed value, a driving direction value, and / or a steering wheel angle value, is determined in a motion value determination step 14. Further, a receiving device 5a, 5b of a first radio direction finding system is shown, wherein an output value of the above-mentioned receiving device 5a, 5b is determined in an output value determination step 15. The values determined in steps 14, 15 are provided for a model-based determination of a relative pose between the primary winding structure 2 and the secondary winding structure 3, in particular as input values. In a determination step 16, the above-mentioned relative pose is determined.

[0102] Figure 4 A schematic flow chart of a method for determining a relative pose between a primary winding structure 2 and a secondary winding structure 3 according to another embodiment of the present application is shown. In a first step S1, a position signal is generated and transmitted, e.g. by a vehicle-side transmitting device 8 of a first radio direction finding system. In a second step S2, an output value of a receiving device 5a, 5b of the above-mentioned first radio direction finding system is determined. In a third step S3, at least one motion value of a vehicle 7 (cf. Fig. 1) is determined. In a fourth step S4, a first relative pose is determined using a model-based determination, wherein input values of the model-based determination are provided by the values determined in the second step S2 and the third step S3. Figure 1 ) of the vehicle 7. In a fourth step S4, a first relative pose is determined using a model-based determination, wherein input values of the model-based determination are provided by the values determined in the second step S2 and the third step S3.

[0103] For example, the first relative pose can be determined as an output of the model-based determination, wherein the model represents a relationship between the input values and the first relative pose. However, the model can also represent a relationship between the input values and an output different from the first relative pose. In this case, the model can be used to determine the first relative pose as a state variable, wherein the model describes a relationship between the input values and the state variable and a relationship between the state variable and an output of the model, in particular an observable or measurable output of the model. In particular, in this case, the first relative pose can be determined as an unobservable / unmeasurable state variable or depends on at least one such unobservable / unmeasurable state variable.

[0104] For example, the model can be a recursive model. In particular, the model can be provided such that a common feature based determination of the relative pose is enabled. In this case, the model can for example provide a so-called state variable transition model which describes or represents a relationship, in particular a mathematical relationship, between state variables at two different points in time. Further, the model can provide a so-called observation model which represents a relationship between a state variable and an observation value, i.e. at least one motion value and an output value of the receiving device 5a, 5b. In a first sub-step of the fourth step S4, a predicted state variable can be determined by using the state variable transition model with the previously determined estimated state variable, in particular the state variable estimated at the previous point in time, as input. In a second sub-step of the fourth step S4, an updated estimated state variable can be determined based on the predicted state variable determined in the first sub-step and the observation value, in particular using the observation model described above. These updated estimated state variables then provide the previously determined estimated state variables described above for the next round of steps S1 to S4.

[0105] The relative pose can be determined repeatedly, in particular at a predetermined frequency. This can be done by repeatedly performing steps S1 to S4.

[0106] Figure 5 A schematic flow chart of a method for determining a relative pose between a primary winding structure 2 and a secondary winding structure 3 according to another embodiment of the application is shown. The sequence of first step S1 to fourth step S4 corresponds to Figure 4 the sequence shown. Thus, reference is made to the corresponding description. In a fifth step S5, a further relative pose is determined based on output values generated by a receiving device of a further radio direction finding system, for example by a detection winding 14 of a foreign object detection system (see Figure 2 ). In a sixth step S6, a relative pose is determined by fusing the first relative pose determined in the fourth step S4 and the further relative pose determined in the fifth step S5, which relative pose can also be denoted as fused relative pose or final relative pose. For example, the fusion can be performed by determining an average, in particular a weighted average, of the first relative pose and the further relative pose described above. For example, noise related parameters can be determined which are provided by the receiving devices 5a, 5b of the first radio direction finding system and the receiving device of the further radio direction finding system, which noise related parameters are indicative of a noise portion, in particular related to a useful signal portion, of the output signals, and then the fused relative pose is determined in dependence on these noise related parameters. In particular, the weight of the first relative pose or the further relative pose described above can be increased with decreasing noise values when determining the weighted average.

[0107] Figure 6A schematic flow chart of a method for determining the relative posture between the primary winding structure 2 and the secondary winding structure 3 according to another embodiment of the present invention is shown. The first step S1 to the fourth step S4 correspond to Figure 4 Therefore, reference is made to the corresponding description. The fifth step S5 to the sixth step S6 correspond to Figure 5 Therefore, reference is made to the corresponding description. Figure 4 In contrast to the embodiment shown, the method comprises a decision step DS. In this decision step, the distance between the primary winding structure 2 and the secondary winding structure 3 is determined, in particular the distance between the primary winding structure 2 and the secondary winding structure 3 is determined based on the first relative posture determined in the fourth step S4. If the distance value is within the first distance interval, the relative posture is determined to be the first relative posture. If the distance value is within the other distance interval, the fifth step S5 and the sixth step S6 are performed, and the relative posture is determined to be the fused relative posture as described above. If the distance value is neither within the first distance interval nor within the other distance interval, the relative posture is not determined and out of range information is generated. The distance value of the first distance interval can be higher than the distance value of the other distance interval.

[0108] Figures 4 to 6 The illustrated sequence of steps S1, ..., S6 does not necessarily define a temporal ordering of steps S1, ..., S6. In particular, the at least one motion value determined in the third step S3 and the output value of the receiving devices 5a, 5b determined in the second step S2 may be determined simultaneously. Furthermore, the determination of the output value of the receiving device of the further wireless direction finding system in the fifth step S5 may be performed simultaneously with the determination performed in the second step S2 and / or the determination performed in the third step S3. Furthermore, the determination of the first relative position in the fourth step S4 and the determination of the further relative position in the sixth step S6 may also be performed simultaneously.

Claims

1. A method for determining the relative position between a primary winding structure (2) and a secondary winding structure (3) of a system for inductive power transmission to a vehicle (7), wherein: A first relative pose is determined by at least a first radio direction finding system, wherein the first radio direction finding system comprises at least one transmitting device (8) and at least two receiving devices (5a, 5b) for receiving position signals sent by the transmitting device (8), wherein the first relative pose is determined based on output values ​​generated by the receiving devices (5a, 5b) when receiving the position signals, wherein at least one movement value of the vehicle (7) is determined, It is characterized by The relative pose is determined as the first relative pose, wherein the first relative pose is determined using a model-based determination, wherein input values ​​of the model-based determination are provided by at least the output value of the receiving device (5a, 5b) and the at least one motion value.

2. The method according to claim 1, characterized in that The model-based determination comprises the step of determining state variables based on the input values, wherein the first relative pose is determined as at least one state variable.

3. The method according to claim 1 or 2, characterized in that The first relative pose is determined using a Kalman filter.

4. The method according to claim 1 or 2, characterized in that The motion value is the speed of the vehicle (7), the driving direction of the vehicle (7), or the steering wheel angle of the vehicle (7).

5. The method according to claim 1 or 2, characterized in that Another relative pose is determined by another radio direction-finding system, wherein the another radio direction-finding system includes at least one transmitting device and at least two receiving devices for receiving a position signal sent by the transmitting device, wherein the another relative pose is determined based on an output value generated by the receiving device when the position signal is received, wherein the relative pose is determined as a fused relative pose by fusing the first relative pose and the another relative pose.

6. The method according to claim 5, characterized in that When the winding structures (2, 3) are spaced at a first distance, the relative posture is determined as the first relative posture; when the winding structures (2, 3) are spaced at another distance, the relative posture is determined as the fused relative posture.

7. The method according to claim 6, characterized in that The distance of the another distance interval is smaller than the distance of the first distance interval.

8. The method according to claim 5, characterized in that At least one noise-related parameter of the output values ​​generated by the receiving device (5a, 5b) of the first radio direction finding system and at least one noise-related parameter of the output values ​​generated by the receiving device of the further radio direction finding system are determined, wherein the fused relative pose is determined based on the noise-related parameters.

9. The method according to claim 5, characterized in that At least the receiving device of the further radio direction finding system is provided by an element (14) of the device for foreign object detection.

10. The method according to claim 1 or 2, characterized in that A movement value of the vehicle is determined based on GNSS signals and / or based on images and / or based on output values ​​of vehicle sensors.

11. The method according to claim 1 or 2, characterized in that Movement value information is sent from the vehicle (7) to a roadside primary unit (4).

12. The method according to claim 1 or 2, characterized in that The output value of the receiving device (5a, 5b) and the at least one motion value are fused to determine the first relative pose.

13. The method according to claim 1 or 2, characterized in that The model-based determination describes a direct relationship between the input values ​​and the relative pose.

14. The method according to claim 1 or 2, characterized in that The model-based determination is used to determine the first relative pose as a state variable, wherein the model-based determination describes a relationship between the input value and the state variable and a relationship between the state variable and an output of the model.

15. A system for determining a relative position between a primary winding structure (2) and a secondary winding structure (3) of a system for inductive power transmission to a vehicle (7), wherein the system (1) comprises at least a first radio direction finding system for determining a first relative position, wherein: The first radio direction finding system comprises at least one transmitting device (8) and at least two receiving devices (5a, 5b) for receiving a position signal transmitted by the transmitting device (8), wherein the first relative pose is determined based on output values ​​generated by the receiving devices (5a, 5b) when receiving the position signal, wherein at least one movement value of the vehicle (7) is determined, It is characterized by The relative pose is determined as the first relative pose, wherein the first relative pose is determined using a model-based determination, wherein input values ​​of the model-based determination are provided by at least the output values ​​of the at least two receiving devices (5a, 5b) and the at least one motion value.

16. The system according to claim 15, wherein: The system (1) includes another radio direction-finding system for determining another relative pose, wherein the another radio direction-finding system includes at least one transmitting device and at least two receiving devices for receiving a position signal sent by the transmitting device, wherein the another relative pose is determined based on an output value generated by the receiving device when the position signal is received, and wherein the relative pose is determined as a fused relative pose by fusing the first relative pose and the another relative pose.

17. The system according to claim 16, wherein: The system (1) comprises a device for foreign object detection, wherein at least the receiving device of the further radio direction finding system is provided by an element (14) of the device for foreign object detection.

18. System according to one of claims 15 to 16, characterized in that The system (1) comprises means for sending motion value information from the vehicle (7) to a roadside primary unit (4).

Images