METHOD FOR DETERMINING A RELATIVE POSITION P AND SYSTEM

Description

[0001] The invention relates to a method for determining a relative position P of a first object with respect to at least one reference object. Furthermore, the invention relates to a system comprising a first object, at least one reference object, and an evaluation device, wherein the system is configured to carry out the method according to the invention. State of the art

[0002] The precise positioning of objects, especially of autonomous systems such as drones or robots, is challenging. Key criteria include high precision in determining the location, usually in x, y, and z coordinates, and the orientation of the object. Furthermore, the cost, size, and power consumption of system components play an important role in the implementation of such systems. For example, robotic lawnmowers require accuracies of less than 5 cm within an area with a radius of 20 m to eliminate the need for a boundary wire as a means of positioning (see DE 102017214314 A1).

[0003] Cost-effective satellite-based navigation systems enable positioning accuracies of a few meters to less than 50 cm (ideally with reference signals of less than 2 cm), depending on the system's operating environment. However, their application is limited to outdoor areas. Radar-, video-, or lidar-based positioning systems, which allow position determination by evaluating information collected from the environment, require either expensive sensor systems and / or high computing power requirements within the system.

[0004] A comparatively simple alternative to such positioning systems are systems that use magnetic fields to determine the relative position, i.e., in particular, the orientation and / or orientation, of an object with respect to a magnetic field transmitter. Such systems are known, for example, from US 4,737,794 A1.

[0005] WO 2015 / 143500 A1 discloses a marking element for localization in a medium.

[0006] A movable, self-standing localization system for electromagnetic radiation is known from US 2011 / 006772 A1.

[0007] DE 10 2008 057705 A1 describes a system for collecting and providing information associated with football players. Disclosure of the invention

[0008] According to claim 1, a method for determining a relative position P of a first object with respect to at least one reference object is proposed. The method comprises: Generating at least three directed magnetic fields B1, B2, B3 with distinguishable modulation frequencies f1, f2, f3 by means of a magnetic field generating device assigned to the reference object, wherein the magnetic field generating device comprises at least three emitter coils Tx1, Tx2, Tx3 which alternately have a defined arrangement with respect to one another, detecting magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 by means of a magnetic field detecting device of the first object, determining the relative position P of the first object with respect to the at least one reference object by means of an evaluation device from the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| which can be assigned to the directed magnetic fields B1, B2, B3 via the detected modulation frequencies f1, f2, f3.

[0009] The recorded magnetic field strengths represent the magnetic field components |Bx 1,2,3< (P)|, |By 1,2,3< (P)|, |Bz 1,2,3< (P)| determined for each magnetic field B1, B2, B3 in detailed notation.

[0010] The relative position P of the first object with respect to the at least one reference object relates to its relative position, for example indicated by three coordinates x, y and z with respect to three, in particular, orthogonal coordinate axes X, Y, Z, and / or its relative orientation, for example indicated by three angles of rotation φ, θ, ρ, in particular about these three axes X, Y, Z.

[0011] The relative position is derived from the detection of magnetic fields B1, B2, and B3, which are generated and emitted by a magnetic field generating device. A magnetic field is understood to be, in particular, an alternating electromagnetic field; the alternating electric field component is not discussed in this document. The magnetic field generating device serves to generate at least three directed magnetic fields B1, B2, and B3, all of which act at any point in space. For this purpose, the magnetic field generating device comprises all components required for generating and emitting the magnetic fields, such as a control device, a signal generator, a power supply, etc.

[0012] The magnetic fields can overlap in direction and field strength, particularly when generated in parallel, so that a three-dimensional magnetic field composed of at least three magnetic fields B1, B2, B3 is generated at least in the vicinity of the magnetic field generating device. Alternatively, the magnetic fields can be generated sequentially, so that only one magnetic field B1, B2, or B3 is active at any given point in space at any given time. In this way, it is possible to achieve a greater range of a detectable position with a higher transmission power of each individually emitted magnetic field, while simultaneously keeping emission power limits low.

[0013] The magnetic fields B1, B2, B3 are generated by means of at least three emitter coils Tx1, Tx2, Tx3, which alternately have a defined arrangement with respect to one another. RF coils, for example, are conceivable as emitter coils. In particular, the three emitter coils Tx1, Tx2, Tx3 are each mutually orthogonally aligned, so that the magnetic fields B1, B2, B3 generated by the emitter coils Tx1, Tx2, Tx3 are also mutually orthogonally aligned (i.e., they have a mutually orthogonal arrangement, for example, symmetry or shape). Alternatively, other angles between the emitter coils Tx1, Tx2, Tx3 can be selected. Due to the fixed relationship between the magnetic fields B1, B2, B3, the magnetic fields B1, B2, B3 can be understood as directional, i.e., there is no fundamentally random pattern of the magnetic fields B1, B2, B3 (apart from the influence of interference fields, see below).The magnetic fields B1, B2, and B3 can be described by magnetic field vectors with respective components in the x, y, and z directions, i.e., |B1 x,y,z< |, |B2 x,y,z< |, |B3 x,y,z< |. In the present method, the magnetic field vector is evaluated separately for the field of the Tx1, Tx2, and Tx3 emitter coils at a different point in space.

[0014] In one embodiment of the method for determining a relative position, a transmission level during the generation of the magnetic fields B1, B2, B3 is controlled, in particular regulated, depending on a magnetic field strength |Bx(P)|, |By(P)|, |Bz(P)| of each magnetic field B1, B2, and B3 detected by the magnetic field detection device at a point in space. In this way, a situational detection of the magnetic field strength can be used to adjust the transmission power of the magnetic fields B1, B2, B3. For this purpose, the first object can comprise, for example, a communication device for implementing a communication connection, in particular a wireless one, with a communication device of the reference object, wherein control is enabled via the communication connection. Furthermore, a rough distance measurement can already be carried out by evaluating a reception level of the communication connection.Furthermore, the transmission power can also be adjusted based on information acquired situationally by additional sensors. For example, radar and / or camera-based sensors can be used to acquire information about the environment, in particular about a distance, between the first object and the reference object, on the basis of which the transmission power is adjusted depending on the situation. This makes it possible, for example, to operate a transmission level as low as possible, for example, only 10 dB above the noise of the magnetic field detection device, thus minimizing energy consumption and interference potential.

[0015] The magnetic field generating device is configured to generate the magnetic fields B1, B2, B3 with distinguishable modulation frequencies f1, f2, f3, in particular by emitting them via the emitter coils Tx1, Tx2, Tx3. The modulation frequencies refer to frequencies of, in particular low-frequency, signals that are modulated onto the magnetic fields B1, B2, B3. In particular, the modulation causes a respective magnetic field to vary in its intensity (magnetic field strength), in particular to vary between "on" and "off." The modulation frequencies f1, f2, f3 differ in each case. If the magnetic field B1 is emitted, for example, over a period of one second, this magnetic field can be the carrier of a modulation signal f1, which is transmitted along with the emission of the magnetic field B1.Sufficient differentiation of the modulation frequencies f1, f2, f3 is determined by the resolution of a receiver, in this case the magnetic field detection device. In one embodiment of the method, the modulation frequencies f1, f2, f3 of the magnetic fields are greater than 30 kHz and / or less than 150 kHz. In particular, such limited modulation frequencies allow influences from the Earth's magnetic field and / or interference signals, for example, from the broadcast spectrum, to be avoided.

[0016] The magnetic field generating device is assigned to the reference object, i.e., it has a fixed spatial relationship to it. This allows for a relative position P determined with respect to the magnetic field generating device to be at least convertible into a relative position with respect to the reference object. In one embodiment, the magnetic field generating device is formed as a component of the reference object and is thus fixedly connected to it. In particular, the reference object can also be realized by the magnetic field generating device.

[0017] The magnetic fields B1, B2, B3 acting at a point in space are detected by the magnetic field detection device. The magnetic field detection device is assigned to the first object, in particular integrated therein or represents this first object. The magnetic field detection device serves to detect the at least three directed magnetic fields B1, B2, B3 at the location of the magnetic field detection device. The magnetic field detection device is configured to detect the acting magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|—or the acting magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and associated magnetic field directions (for example, using a vector magnetometer)—as well as the modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3. By means of the detected modulation frequency f1, f2 or f3, a detected magnetic field strength can be unambiguously assigned to a magnetic field B1, B2 or B3 emitted by the magnetic field generating device.In this way, the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| of each magnetic field B1, B2, and B3 acting at a point in space can be differentiated from one another and evaluated separately (also denoted as |B1 x,y,z< |, |B2 x,y,z< |, |B3 x,y,z< |). Based on the nine measured values ​​acquired in this way, the relative position P in the emitted magnetic field B1, B2, B3—i.e., relative to the magnetic field generating device and thus relative to the reference object—can be determined (via an overdetermined system of equations). For the precise derivation of the position from the recorded magnetic field strengths, reference is made to the prior art cited at the beginning.

[0018] The magnetic field detection device comprises all components required for signal-based detection of the acting magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and modulation frequencies f1, f2, f3, for example, a control device, an electrical receiving circuit, a power supply, etc. In one embodiment of the method for determining a relative position, the magnetic field detection device comprises at least one magnetic field sensor, in particular three magnetic field sensors, from a list of magnetic field sensors, wherein the list includes at least quantum sensors, TMR sensors, GMR sensors, receiving coils (e.g., pickup coils), fluxgate sensors, and Hall sensors. Such a magnetic field sensor is suitable for detecting acting magnetic field strengths—possibly also acting magnetic field strengths and associated magnetic field directions—as well as modulation frequencies of magnetic fields.The detection of a magnetic field strength conceptually also includes the detection of a magnetic flux density, i.e. the signal amplitude of a magnetic field sensor.

[0019] In one embodiment of the method for determining a relative position, the magnetic field detection device comprises at least one magnetic field sensor, which is implemented as a color-center-based magnetic field sensor, in particular as a quantum sensor based on color centers (nitrogen vacancies) in diamond. In particular, color-center-based magnetic field sensors, as known in principle from the prior art (e.g., from DE 102014219550 A1), enable a three-dimensional, direction-dependent measurement of the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| with only one magnetic field sensor.The sensitivity of such sensors can be significantly higher than conventional magnetic field sensors such as Hall sensors, TMR sensors, fluxgate sensors, pickup coils, or the like (for example, with a resolution of less than 1 pT / √(Hz) over a high measuring range of more than 1 Tesla), so that in principle a larger working range or functional range of the method for determining a relative position can be realized. Furthermore, requirements for the required installation space for accommodating the magnetic field sensor can be advantageously reduced (with up to a few cubic centimeters of installation space; for example, compared to receiver coils, which can easily have a diameter of approximately ten centimeters). Furthermore, a color center-based magnetic field sensor is also suitable in principle for vector magnetometry, i.e., the simultaneous determination of the direction of the detected magnetic fields.In one embodiment, the method is operated with modulation frequencies in the range between 10 Hz and 50 Hz to advantageously utilize the high sensor sensitivity of the color center-based magnetic field sensor. The modulation frequencies f1, f2, and f3 can differ by 3 Hz, for example.

[0020] In one embodiment of the method, the magnetic field detection device comprises three magnetic field sensors of the described type, which alternately have a defined, in particular orthogonal, arrangement and consequently a mutually defined, in particular orthogonal, sensitivity. Each magnetic field sensor detects the effective magnetic field strengths |Bx(P)| or |By(P)| or |Bz(P)| and the modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3.

[0021] In one embodiment of the method for determining a relative position, the magnetic field detection device comprises at least one magnetic field sensor, which is implemented as a receiver coil, in particular an RF coil. The method can be implemented in a particularly simple manner using a magnetic field detection device comprising at least three receiver coils, in particular RF coils. The three receiver coils alternately have a defined arrangement relative to one another, in particular an alternately orthogonal arrangement relative to one another. Each of the three receiver coils—designated Rx, Ry, Rz—detects the effective magnetic field strengths of the magnetic fields B1, B2, B3 and their modulation frequencies f1, f2, f3.

[0022] In one embodiment of the method, particularly for use in a domestic interior, at least one coil of an induction hob and / or at least one coil of an inductive charging station is used as at least one emitter coil Tx1, Tx2, Tx3 of the magnetic field generating device. A coil—in the first case located below the cooking surface of the induction hob—is operated in such a way that a corresponding magnetic field is generated and emitted. In particular, it is conceivable that switching on and / or off and / or configuring an operation (for example, with regard to magnetic field strength or modulation frequency) of the coil takes place using a control device operating the coil. In particular, it is conceivable that for this purpose, the control device, particularly of the hob or the inductive charging station, communicates with the reference object via a communication interface.This embodiment is particularly suitable for robots used indoors in the home, such as robot vacuum cleaners or the like. This allows the use of existing components, allowing the process to be operated with fewer separate emitter coils.

[0023] In one embodiment of the method for determining a relative position, an energy storage device of the first object is inductively charged, at least temporarily, by means of at least one emitter coil Tx1, Tx2, Tx3 of the magnetic field generating device. In this way, further functionality can be provided based on at least one emitter coil of the system. In one embodiment, the reference object can be implemented as a type of docking station for the first object, wherein the first object is inductively charged by an emitter coil of the reference object as soon as it is located in the docking station.

[0024] The relative position P of the first object with respect to the at least one reference object is determined using an evaluation device from the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|, which can be assigned to the directed magnetic fields B1, B2, B3 via the detected modulation frequencies f1, f2, f3. The evaluation device is specially configured to carry out the corresponding method steps for determining the relative position. Corresponding method steps can be implemented, at least partially, in the form of software, in particular in the form of a computer-implemented method, or in a mixture of software and hardware. For example, the evaluation device can be implemented in the form of an electrical circuit and in particular comprise a bandpass filter and / or an amplifier. In particular, the evaluation device comprises a processor device for carrying out corresponding method steps.It is conceivable to implement the evaluation device associated with the first object, associated with the reference object, or also separately from them, for example in a cloud, a separate computer, or the like. The evaluation device may comprise control electronics, which in particular also include means for communicating with other components, for example the magnetic field detection device, the magnetic field generation device, etc. Furthermore, the processor device may access at least one memory device in which algorithms are stored, at least in part, as a machine-readable computer program. The computer program contains instructions which, when executed by the processor device of the evaluation device, cause the processor device to determine the relative position P of the first object with respect to the at least one reference object from the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|.

[0025] In one embodiment of the method for determining a relative position, in a further method step, the modulation frequencies f1, f2, f3 are transmitted from the magnetic field generating device to the magnetic field detecting device and / or to the evaluation device, wherein the transmitted modulation frequencies f1, f2, f3 are used to improve a signal-to-noise ratio when determining the relative position P. For example, the transmitted modulation frequencies can be used for more precise detection of the modulation frequencies, in particular for determining the modulation frequencies from a time profile of the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|. In particular, knowledge of the phase relationship between the magnetic field generating device (ieThe modulation frequencies f1, f2, f3 are transmitted via a radio connection (e.g., the emitter coils Tx1, Tx2, Tx3) and the magnetic field detection device to improve the accuracy of the method, in particular when determining the relative position. In one embodiment of the method for determining a relative position, the modulation frequencies f1, f2, f3 are transmitted via a radio connection. For example, a LoRa, WLAN, Bluetooth radio connection, or the like are suitable for the radio connection. In one embodiment, the modulation frequencies can be in the range of 30 kHz, while the modulation frequencies f1, f2, f3 are transmitted, in particular synchronization with the modulation frequencies f1, f2, f3, via a radio connection - in particular as a carrier signal - which has a 30 MHz signal. Alternatively or additionally, a synchronization pulse and / or a multiple of the frequencies f1, f2, f3 can be transmitted via the radio connection.

[0026] In one embodiment of the method for determining a relative position, the transmitted modulation frequencies are used as a reference signal of a lock-in amplifier of the magnetic field detection device and / or the evaluation device. In this way, even with large distances between the magnetic field generation device and the magnetic field detection device, which result in a poor signal-to-noise ratio, a respective detected magnetic field B1, B2, B3 can be identified or assigned via its modulation frequency in a particularly simple manner by specifying the frequencies. In a temporal progression of the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|, the synchronized lock-in amplifier can filter out the corresponding modulation frequencies and thus detect them.

[0027] In one embodiment of the method for determining a relative position, the relative position P of the first object is determined, in particular selectively, with respect to a plurality of reference objects, wherein each reference object comprises an associated magnetic field generating device. In this way, it is possible to switch, in particular, between directed magnetic fields B1, B2, B3, which are generated by different magnetic field generating devices with distinguishable frequencies. A determination of a relative position is possible with respect to different reference objects. All statements made with respect to the magnetic field generating device of the at least one reference object apply to the magnetic field generating devices of the reference objects. In particular, it is conceivable to determine relative positions P in parallel or successively, or even as an average value with respect to several references.It is conceivable to determine the relative position with respect to two, three, or more reference objects. For example, in the case of a drone intended for delivering packages, provision can be made, in particular selectively, to determine a relative position with respect to the ground (e.g., with respect to a landing position) and with respect to the package, in particular the top side of the package.

[0028] In particular, the determined relative positions of the first object with respect to the plurality of reference objects can also be used to determine the mutual relative positions of the plurality of reference objects among each other (determination P1 between reference object 1 and first object, determination P2 between reference object 2 and first object, from this P3 (= P1 + P2) between reference object 1 and reference object 2 can be determined).

[0029] In an alternative, particularly analog, embodiment of the method for determining a relative position, the relative position P of a reference object is determined, particularly selectively, with respect to a plurality of first objects, wherein each reference object comprises an associated magnetic field generating device and each first object comprises an associated magnetic field detecting device. In this embodiment, the relative position P of a plurality of first objects is determined, particularly selectively, with respect to at least one reference object. Since this merely involves an exchange of magnetic field generating device and magnetic field detecting device, this embodiment is considered analog.

[0030] In one embodiment of the method for determining a relative position, each modulation frequency f1, f2, f3 of the magnetic fields B1, B2, B3 encodes a piece of system information and / or all modulation frequencies f1, f2, f3 together encode a piece of system information. In particular, it is conceivable to use the modulation frequencies to provide the first object and / or the evaluation device with further information about the reference object and / or about other properties relating to the system (e.g. location, identification number or the like). In this way, in addition to the relative position, at least one further piece of information can be transmitted to the first object and / or the evaluation device and made available in this way. For example, an assignment orDistinguishability of relative positions determined for different reference objects is achieved through coding (coding, for example, via an ID assigned to each reference object).

[0031] In one embodiment of the method for determining a relative position, the influence of an interference field is detected, and a detected magnetic field strength |Bx(P)|, |By(P)|, |Bz(P)| is corrected for the influence of the interference field by means of the evaluation device, and / or the influence of the interference field is compensated by controlling and / or regulating an electromagnetic superposition field emitted by at least one compensation coil when detecting the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|. In this way, it is possible to determine a relative position more precisely. Alternatively or additionally, the sensitivity requirement of the magnetic field detection device can be advantageously reduced. In particular, magnetic interference fields located at the location of the first object can be advantageously compensated. In particular, such interference fields can be detected and compensated using an electrical compensation circuit.In this case, the compensation circuit can comprise at least one compensation coil as well as receiving coils, amplifiers, etc. The receiving coil(s) and / or compensation coil(s) are located as close as possible to the magnetic field detection device. Furthermore, it is conceivable to minimize, in particular prevent, and / or compensate for, and / or measure an influence acting at least during a period in which the magnetic fields B1, B2, B3 are detected, and to later compensate for this influence during an evaluation. A control device and / or evaluation device implementing the method can be configured to compensate for this influence. The method can be implemented, at least partially, in the form of software or in a mixture of software and hardware.In particular, it is conceivable that the influence is determined using a reference measurement carried out essentially in parallel with the detection of the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|. In particular, it is conceivable that the influence is actively compensated for during the detection of the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| depending on the determined influence, for example by controlling and / or regulating and / or adapting an electromagnetic superposition field that is generated using the at least one compensation coil. Alternatively or additionally, it is conceivable that the influence is avoided and / or compensated for by using the data recorded on the influence of an interference field to determine a point in time at which the influence is relatively small, in particular negligible, wherein the detection of the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| is carried out at this point in time.

[0032] In one embodiment of the method for determining a relative position, additional position data, in particular additional position data from another internal and / or external sensor device, are included when determining the relative position P to increase precision and / or to determine an absolute position. "Including" is also understood to mean, in particular, fusing or correlating. The additional position data can, for example, represent relative or absolute position data. Relative position data can, for example, be position data from acceleration sensors, yaw rate sensors, odometry data, or the like. Absolute position data can, for example, be GPS or GNSS data. Radar, lidar, or video sensors can also be used to determine a position.In one embodiment of the method, the additional position data are acquired as absolute position data, wherein the relative position P is determined relative to this absolute position data. Using absolute position data, an absolute position can thus be determined from the determined relative position. Furthermore, such a sensor fusion can be used, in particular, to perform a plausibility check and / or correction of the relative position, thus making the obtained relative positions more robust. Furthermore, it is conceivable to dynamically detect distortions in the acquired magnetic fields that affect errors in the determined relative position using sensor fusion with other sensor data.In particular, such a fusion of position data allows for the detection of magnetic field distortions (e.g., induced by interference fields) in the magnetic fields B1, B2, B3. Using this knowledge, position-dependent correction data can be derived and stored, for example, in a magnetic field map, which can then be taken into account during a repeated or further determination of the relative position. Furthermore, such errors can be used, for example, via a machine learning algorithm to improve positioning accuracy. This allows the occurrence of magnetic objects and associated interference fields (magnetic field distortions) to be detected during operation of the process, and the process for determining a relative position can be dynamically corrected.In particular, correction data can be continuously updated so that even temporary magnetic field distortions can be quickly detected and corresponding correction data can be determined, which are then available for subsequent determinations of a relative position.

[0033] According to the invention, in order to determine a relative position, a relative position P' of the at least one reference object with respect to at least one further reference object is determined, comprising: Generating at least three directed magnetic fields B1', B2', B3' of distinguishable modulation frequencies f1', f2', f3' by means of a further magnetic field generating device assigned to the further reference object, wherein the further magnetic field generating device comprises at least three emitter coils Tx1', Tx2', Tx3', which alternately have a defined arrangement with respect to one another, detecting magnetic field strengths |Bx'(P')|, |By'(P')|, |Bz'(P')| and modulation frequencies f1', f2', f3' of the magnetic fields B1', B2', B3' by means of a magnetic field detection device of the reference object, determining the relative position P' of the reference object with respect to the at least one further reference object by means of an evaluation device from the detected magnetic field strengths |Bx'(P')], |By'(P')|, |Bz'(P')| which can be assigned to the directed magnetic fields B1', B2', B3' via the detected modulation frequencies f1', f2', f3'.

[0034] In particular, it is also conceivable to operate several reference objects in a staggered manner, one after the other, with each "intermediate" reference object having at least one magnetic field generating device and one magnetic field detecting device, so that this reference object can both detect magnetic fields to determine its own relative position and generate magnetic fields to determine the relative position of a subsequent first object and / or reference object. In particular, entire chains of staggered reference objects are conceivable (reference object 1 - reference object 2 - reference object 3 - first object). In this way, each "intermediate" reference object serves as a first object whose relative position P with respect to the preceding reference object is determined.It should be noted that the magnetic field detection device and the magnetic field generation device can also be realized as a single component that is used both as a magnetic field detection device and as a magnetic field generation device (for example, as a coil system that is operated in a receiving mode and in a transmitting mode).

[0035] In this way, staggered relative positions can be advantageously determined. Examples of applications for this could be robots navigating in a swarm of robots, where the position of each robot is determined relative to the other robots, i.e. the robots are localized among themselves. If relative positions of the robots are also exchanged, joint path planning (swarm intelligence) is possible. This could, for example, be used specifically to extend a range or the like. Furthermore, the method can also be transferred to the control of robot arms, etc. where, for example, a relative position of each individually movable part of the robot arm can be determined relative to every other movable part of the robot arm.All features set out in this document also apply to the at least one further reference object, for example that in a further method step the modulation frequencies f1', f2', f3' are transmitted from the further magnetic field generating device assigned to the further reference object to the magnetic field detection device of the reference object and / or to the evaluation device, wherein the transmitted modulation frequencies f1', f2', f3' are also used to improve a signal-to-noise ratio when determining the relative position P'.

[0036] In one embodiment of the method for determining a relative position P, magnetic field strengths |Bx i (P)|, |By i (P)|, |Bz i (P)| and modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 are detected by means of at least one further magnetic field detection device i of the first object, which has a defined arrangement to the magnetic field detection device of the first object, wherein a relationship of the magnetic field strengths |Bx i (P)| and |Bx(P)| to one another and / or |By i (P)| and |By(P)| to one another and / or |Bz i (P)| and |Bz(P)| to one another is determined by means of an evaluation device. A defined arrangement is to be understood in particular as a defined distance and a defined alignment of the magnetic field detection devices i to one another.In particular, the relation is determined as a component-wise relation of the magnetic field strengths |Bx i (P)| and |Bx(P)| to one another and / or |By i (P)| and |By(P)| to one another and / or |Bz i (P)| and |Bz(P)| to one another. A relation is understood to be any mathematical relationship in which the magnetic field strengths can be compared or related to one another, in particular component-wise. In particular, a difference, a quotient, a greater-to-smaller ratio or the like is conceivable. In one embodiment of the method for determining a relative position P, the relation, in particular in the form of a magnetic field gradient, is determined as the difference |Bx i (P)| - |Bx(P)|, |By i (P)| - |By(P)| or |Bz i (P)| - |Bz(P)|. In this way, a particularly simple relation can be specified, whereby the magnetic field gradient is determined as a pairwise difference.Alternatively or additionally, a relative position P could also be determined as the quotient |Bx i (P)| / |Bx(P)|, |By i (P)| / |By(P)|, or |Bz i (P)| / |Bz(P)|. Furthermore, using the relation can also increase the accuracy in determining the relative position P.

[0037] In one embodiment of the method for determining a relative position P, in which the relation is determined as a difference, a clear identification of the relative position P, in particular one which may otherwise be ambiguous (in particular multifaceted), is carried out on the basis of a sign of the relation. In an alternative embodiment of the method, in which the relation is determined as a quotient, a clear identification of the relative position P, in particular one which may otherwise be ambiguous (in particular multifaceted), is carried out on the basis of a comparison of the relation with the value 1. A relative position can initially be ambiguity, in particular due to a symmetrical course of the magnetic fields B1, B2, B3 generated by the magnetic field generating device. A magnetic field generated by an emitter coil has regions of the magnetic field in the direction perpendicular to the winding plane where the magnetic field strength is minimal (possibly0 T). On both sides of this mirror symmetry axis (which corresponds to the normal to the winding plane of the emitter coil) and mirror-symmetrical to the winding plane of the emitter coil are regions of identical magnetic field strength, so that an (ideal, undisturbed) magnetic field basically comprises four regions of equal magnetic field strength (located in four quadrants, with the emitter coil at the center). According to the invention, using the relation, a suitable measure can be specified to assign the relative position to a quadrant despite these ambiguities. In particular, a transition between any two adjacent quadrants can be detected using the method according to the invention. For this purpose, the relations of the detected magnetic field strengths are continuously evaluated and magnetic field gradients are thus continuously determined.In a method implementation in which the relation is determined as a difference, the sign of the relation (the difference) is reversed as soon as a transition between two quadrants has occurred. In a method implementation in which the relation is determined as a quotient, the quotient changes from a value greater than one to a value less than one as soon as a transition between two quadrants has occurred. In this way, transitions of the first object between different quadrants can be determined. Consequently, an unambiguous assignment of the otherwise possibly ambiguous (in particular, multifaceted) relative position P of the first object to one of the four quadrants can be carried out in this way, in particular under the assumption that at the beginning of a movement of the first object, the starting position can be assigned to one of the quadrants (e.g., because the base station is located there).For example, if a first object, conceivable as a robot, is moving, relations can be continuously determined. If this relation then changes sign (or from a value greater than one to a value less than one (or vice versa)), a transition between two adjacent quadrants can be derived.

[0038] In one embodiment of the method for determining a relative position P, a change in the direction of movement of the first object, in particular a reversal of the direction of movement by 180°, is detected by means of a rotation-sensitive sensor device. In the case of a change in the direction of movement of the first object, in particular by more than 90°, a reversal of the sign of the relation or an inversion of the relation (change of value from less than one to greater than one (or vice versa) by forming the reciprocal value) is taken into account, in particular carried out. In this way, it can also be ruled out that a change in the direction of movement, in particular a change in the direction of movement by 180°, leads to an (unnoticed or unexpected) change in the relation, which would otherwise be generated by a quadrant transition. "Taking into account" is to be understood in particular as meaning that such a change in value is mathematically corrected or compensated for in an evaluation.A rotation-sensitive sensor device is understood, in particular, to be a sensor device that is sensitive to a spatial rotation and / or change in direction of the first object (for example, implemented by acceleration sensors, cameras, or the like). In principle, any sensor that can be used to derive information about a direction of movement of the first object is suitable for this purpose. For example, Magnetic field-sensitive sensors such as compasses, magnetic field sensors, fluxgate magnetometers, and Hall sensors; capacitive sensors; position-sensitive and / or attitude-sensitive sensors such as GPS, position sensors, odometry sensors, and steering wheel angle sensors; speed-sensitive and / or acceleration-sensitive sensors such as gyroscopes, inertial sensors, and acceleration sensors; distance-sensitive sensors such as laser rangefinders, ultrasonic sensors, and radar; pressure-sensitive sensors, optical sensors, voltage-sensitive and / or current-sensitive sensors or a combination of these.

[0039] It should be noted that the orientation (and thus the direction of movement of the first object) can, in principle, also be determined using the existing magnetic field detection device by evaluating a DC component in the measurement signals of the detected magnetic field. This has the advantage that no additional yaw rate sensor or compass is required.

[0040] Alternatively or additionally, it is conceivable to measure a phase position of the magnetic fields B1, B2, B3 by means of a sensor in order to determine therefrom a clear identification of the relative position P of the first object with respect to the reference object, in particular a position which may otherwise be ambiguous (in particular ambiguous).

[0041] Furthermore, interference fields, such as those generated by metallic objects such as vehicles or buried objects, can be detected particularly efficiently in this way. In one embodiment of the method for determining a relative position P, deviations in the relationship from the target relationships expected according to the defined arrangement of the magnetic field detection device and the at least one further magnetic field detection device i are evaluated, in particular identified, in order to detect magnetic field distortions. In other words, since the distance and angle of the magnetic field sensors to one another are known, the values ​​of the detected magnetic fields of the individual magnetic field detection devices can be used to compare them with values ​​expected on the basis of the arrangement. This can be evaluated in particular during a movement of the first object and unexpected interference fields, i.e. magnetic field distortions, can be detected and recorded in this way.In particular, such deviations can be detected in a particularly simple way and used to draw conclusions about interference fields.

[0042] In one embodiment of the method for determining a relative position P, detected magnetic field distortions or interference fields are stored, in particular updated, and / or merged, in a magnetic field map, in particular a two-dimensional or three-dimensional magnetic field map. "Merging" is understood to mean, in particular, "overwriting," "averaging," "interpolating," "extrapolating," "correlating," or the like with other sensor data. In this way, detected magnetic field inhomogeneities and / or interference fields can be taken into account when implementing the method for determining a relative position.

[0043] In one embodiment of the method for determining a relative position P, two additional magnetic field detection devices i are used. In particular, the three magnetic field detection devices i are arranged in a triangular arrangement relative to one another. In this way, the relationships, in particular magnetic field gradients, can be easily determined in two independent directions, in particular two orthogonal directions.

[0044] In one embodiment of the method for determining a relative position P, the presence of at least one magnetic field BSQ from an external radiation source, in particular a magnetic field generating device not associated with the reference object, is detected in a further method step. In this way, it can be detected whether, in addition to the magnetic fields B1, B2, B3 generated to carry out the method for determining a relative position, further magnetic fields are present, for example interference fields from other magnetic field sources or magnetic fields from other reference objects. In particular, this detection can be carried out repeatedly, in particular regularly, for example quasi-continuously or continuously. According to the invention, this information can be used to adapt or improve the method for determining a relative position P.

[0045] In one embodiment of the method for determining a relative position P, the presence of the at least one magnetic field BSQ is detected by the magnetic field detection device of the first object and / or by the magnetic field generation device associated with the reference object and / or by at least one additional receiver. In particular, it is conceivable that the presence of the at least one magnetic field BSQ is detected by the magnetic field detection device through a "receive spectrum" modified due to the magnetic field BSQ, in the sense of the expected magnetic fields B1, B2, B3 and their associated modulation frequencies f1, f2, f3. Furthermore, it is conceivable that the presence of the at least one magnetic field BSQ is detected by the magnetic field generation device by operating it in a receive mode.This reception mode can be implemented, for example, by briefly connecting one or more emitter coils to a receiving electronics during a transmission pause of the magnetic field generating device. An additional receiver can be implemented as a magnetic field sensor of any design, for example, a Hall sensor or the like.

[0046] In one embodiment of the method for determining a relative position P, the modulation frequencies f1, f2, f3 are selected, in particular modified, depending on the presence of the at least one magnetic field BSQ. In an alternative or additional embodiment of the method for determining a relative position P, pause times in the modulation t1, t2, t3 of the magnetic fields B1, B2, B3 are selected, in particular modified, depending on the presence of the at least one magnetic field BSQ. In a yet alternative or additional embodiment of the method for determining a relative position P, pause times in the generation T1, T2, T3 of the magnetic fields B1, B2, B3 are selected, in particular modified, depending on the presence of the at least one magnetic field BSQ.In particular, the modulation frequencies f1, f2, f3 and / or pause times in the modulation t1, t2, t3 and / or pause times in the generation T1, T2, T3 can be modified or selected such that the generation of the radiation source is adapted to the external radiation source. Alternatively or additionally, the presence of the at least one magnetic field BSQ can also be output to a user of the method for determining a relative position P.

[0047] In one embodiment of the method for determining a relative position P, the detection of the presence of at least one magnetic field BSQ of an external radiation source comprises at least determining a modulation frequency fSQ of the at least one magnetic field BSQ. The modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 can advantageously be selected to be different from the modulation frequency fSQ. In this way, the frequency range of the magnetic field BSQ can be explicitly excluded, so that the modulation frequencies f1, f2, f3 used are distinguishable, i.e., in particular, are sufficiently far apart from fSQ in the frequency band. The spacings in the frequency band can be selected, in particular, depending on the quality of the detection of the magnetic fields B1, B2, B3, so that these spacings can be smaller with high quality (and consequently a fairly precise determination of the relative position P).

[0048] In one embodiment of the method for determining a relative position P, the detection comprises determining pause times in the modulation tSQ and / or pause times in the generation TSQ of the at least one magnetic field BSQ. The pause times in the modulation t1, t2, t3 or the pause times in the generation T1, T2, T3 of the magnetic fields B1, B2, B3 can advantageously be selected such that the modulation of the magnetic fields B1, B2, B3 occurs during the pause times in the modulation tSQ or the generation of the magnetic fields B1, B2, B3 occurs during the pause times in the generation TSQ of the at least one magnetic field BSQ. In this way, targeted pause times in the external magnetic field BSQ - in its modulation and / or in its generation, ie emission - can be used explicitly when generating the magnetic fields B1, B2, B3, by generating the modulation with the modulation frequency f1, f2, f3 during these pause times.During these pauses, the generation of the magnetic fields B1, B2, and B3 actually occurs. Furthermore, time intervals—between the generation of the magnetic fields or between the modulations of the magnetic fields—can be selected to ensure the most interference-free and overlap-free detection of the magnetic fields B1, B2, and B3.

[0049] In one embodiment of the method for determining a relative position P, the magnetic field BSQ of the external radiation source, in particular of the magnetic field generating device not associated with the reference object, is used to extend the range of the method for determining the relative position P of the first object. It is conceivable that additional "satellite reference objects" are installed at the maximum range of the first reference object (i.e., at a distance at which a magnetic field B1, B2, B3 can still be detected), which transmit on different frequencies, for example, during transmission pauses. In principle, however, the "satellite reference objects" can also transmit on the same frequencies f1, f2, f3 if a different frequency sequence—for example, f2, f1, f3—is used and monitored.

[0050] In one embodiment of the method for determining a relative position P, the magnetic field BSQ of the external radiation source, in particular of the magnetic field generating device not associated with the reference object, originates from a parallel-operated method according to one of the preceding claims. In this way, it is possible to operate several methods for determining a relative position P—equivalent to several systems that implement the method—in parallel with one another. For example, several autonomous lawnmowers can be operated in parallel using the method according to the invention, as may be the case in a neighborhood. Pause times of a robot system (comprising a reference object and a first object integrated into the robot) are determined, with the further robot system then scheduling its own transmission activities during previously determined pause times.In particular, the other robot systems then transmit on different frequencies and / or during the other robot systems' pause times. Furthermore, the aforementioned swarm of robots can also be realized using this embodiment of the method.

[0051] In one embodiment of the method for determining a relative position P, the first object is implemented as a handheld electrical device, in particular a laser rangefinder, a handheld power tool, a gaming controller, or the like, and a function, in particular of the handheld electrical device, is controlled depending on the relative position P. The reference object can be fixedly positioned in space. The implementation of the method serves to determine the position of the electrical device in space, in particular three-dimensionally. The electrical device can be implemented, for example, as a laser rangefinder, wherein, depending on a relative position of the laser rangefinder, a further measuring functionality, in particular a measurement of indirect distances, is enabled, as disclosed, for example, in DE 102016211742.4 A1 or DE 102018201692.5 A1.An implementation of the method can also be used to spatially track the relative position (here, relative location and orientation) of a tracking device, allowing the spatial progression of tracking objects, for example, hidden in a wall, to be recorded in a position-dependent and three-dimensional manner. The data, including tracking information and relative position, can then be used for documentation and further planning in digital models (see "Building Information Modeling").

[0052] In contrast to inertial sensor technology, as is often used in the prior art, the method according to the invention can also be advantageously used to determine the relative position of a vibrating machine, for example, a hammer drill. In the case of a drill, for example, depending on a user specification, e.g., "executing a horizontal hole," the user can be informed, based on the determined relative position of the drill, how the target alignment is achieved and when the target alignment is achieved. Furthermore, in particular, the accuracy in determining the position can be significantly increased compared to inertial sensor technology. Likewise conceivable are electrical entertainment electronics devices such as AR glasses, game controllers, or the like, whose relative position is determined using the method according to the invention.

[0053] In one embodiment of the method for determining a relative position P, the first object is realized as a, in particular autonomous, robot, in particular a robotic vehicle such as a logistics robot, a vacuum cleaner or lawnmower or the like, and a function, in particular of the robotic vehicle, is controlled depending on the relative position P. A, in particular autonomous, robot should be understood in particular as an at least partially automatic mobile device which performs a task, for example processing a surface, at least partially independently. Furthermore, a device should be understood in particular as one which at least moves independently and / or moves autonomously in a predetermined area, in particular in a work area or in a processing area.Typical applications for such robotic vehicles include a wide range of activities, such as sweeping, vacuuming, cleaning, mowing, collecting, sorting, watering, fertilizing, mapping, and the like. The reference object can be positioned in a fixed location, for example, as a docking station (base station) for the robot, such as the docking station of an autonomous lawnmower in the garden. Implementing this method allows docking maneuvers (e.g., to the docking station) to be performed with particular precision. Furthermore, the relative position can be determined over a large area—advantageously without boundary wire, as used in the prior art (cf. DE 102014226077.9 A1)—with high precision, particularly by eliminating the need for complex and inaccurate sensors such as odometry sensors (which are susceptible to slippage of the drive mechanism).For robots that work indoors in a domestic environment, it is conceivable to use a coil of an induction hob and / or a coil of an inductive charging station (e.g., the docking station) as at least one emitter coil Tx1, Tx2, Tx3 of the magnetic field generating device.

[0054] In one embodiment of the method for determining a relative position P, the first object is realized as a flying object, in particular as a drone, and depending on the relative position P, a function, in particular of the flying object, in particular of the drone, is controlled.

[0055] In one embodiment of the method for determining a relative position P, a boundary of a workspace, in particular a workspace of a robot, is determined using the first object by guiding the first object along at least one boundary of the workspace and successively determined relative positions P being recorded and / or evaluated. In particular, the reference object can already be placed at a location, wherein the workspace is then localized using the first object - which is designed, for example, as a hand-held rod - by guiding the rod along the boundary of the workspace. The trajectory recorded in this way can be digitized and then used to carry out further methods, for example navigation methods of the robot.In this way, the method according to the invention can be used to teach a robot with respect to an activity area—for example, an autonomous lawnmower with respect to an area to be mowed in the garden. Due to the high precision in determining the relative position, the method allows for a particularly fine resolution of the boundaries of the working area, which is not achievable, or only with great effort, with a boundary wire (see prior art above).

[0056] In one embodiment of the method for determining a relative position P, a distance, in particular a distance or a length of a path, between a first point and a second point is determined using the first object by guiding the first object, in particular along the path, from the first point to the second point, and successively determined relative positions P are recorded and / or evaluated. Furthermore, the evaluation of a trajectory traveled by the first object—for example, between two points—allows the distance between these points along the trajectory to be determined. The first object can also be implemented in the form of a hand-held rod.

[0057] In one embodiment of the method for determining a relative position P, at least the first object is assigned to a robot arm, in particular the reference object is also assigned to the robot arm, and a movement and / or a function, in particular of the robot arm, is controlled using successively determined relative positions P. For example, a fully integrated robot arm can be realized in this way, which can evaluate and consequently control the exact position of each movable part of the robot arm at any time without additional complex sensor technology (such as inertial sensors, protractors, distance meters, or the like). For example, the reference object can be assigned to a fuel filler neck of a vehicle, so that an autonomously operating refueling robot can automatically align its filling nozzle, which is equipped with the first object, and consequently automatically refuel the vehicle.

[0058] In one embodiment of the method for determining a relative position P, the reference object is assigned to a monitoring system, in particular a smoke detector or fire alarm, and a relative position P of a person equipped with the first object is detected. For example, the reference object can be integrated into the smoke detector. In this way, movement profiles of people relative to the smoke detector can be advantageously detected, which can be used, for example, during fire service operations to coordinate and protect the deployed firefighters. It is conceivable that each person carries a first object assigned to their body, the relative position of which is determined.Furthermore, it is conceivable that further information - for example regarding a room size, a position of the smoke detector in the room, dangerous goods located in the room, a room name or the like - is encoded via the frequencies f1, f2, f3 and is transmitted to the first object in such a way that further processing or output of the information can take place.

[0059] Furthermore, a system is proposed, comprising a first object, at least one reference object, and an evaluation device. The system, in particular the evaluation device, is configured to carry out the method according to the invention. All of the above statements regarding the method and the components used in the method, in particular regarding the magnetic field detection device, the magnetic field generation device, the evaluation device, etc., are also considered to be disclosed for the system.

[0060] Likewise, a first object and / or a reference object for use in a system according to the invention or for application in a method according to the invention is proposed. In particular, a first object is proposed that is implemented as a handheld electrical device, in particular a laser rangefinder, a handheld power tool, a gaming controller, or the like; as a robot, in particular an autonomous robot, in particular a robotic vehicle such as a vacuum cleaner or lawnmower or the like; as a flying object, in particular as a drone; as a handheld rod, and / or as part of a robot arm. In particular, a reference object is proposed that is implemented as a docking station or as a smoke detector. Drawings

[0061] The invention is explained in more detail in the following description with reference to exemplary embodiments illustrated in the drawings. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will expediently consider the features individually and combine them into useful further combinations. Like reference numerals in the figures denote like elements.

[0062] They show: Figure 1 shows an embodiment of a system according to the invention comprising a first object and a reference object; Figure 2 shows a second embodiment of a system according to the invention comprising a first object and a reference object; Figure 3 shows a process diagram for an exemplary embodiment of the method according to the invention for determining a relative position; Figure 4 shows an exemplary magnetic field, as generated by a magnetic field generating device of a reference object; Figures 5a-5f show different scenarios of how the method according to the invention can be applied; Figure 6 shows time-dependent curves of magnetic field signals (a) for an exemplary system (b). Description of the embodiments

[0063] The method according to the invention relates to the determination of a relative position P of a first object 100 with respect to at least one reference object 200. In Figure 1 and2 Two exemplary systems 300a, 300b are shown, each comprising a first object 100a, 100b, at least one reference object 200a, 200b, and an evaluation device 302. The evaluation device 302 is configured to implement the method 10 according to the invention, cf. Figure 3 , to execute.

[0064] The Figure 1The system 300, 300a shown shows a perspective view of a first object 100, 100a, which is implemented as a handheld electrical device, here as a laser rangefinder. The laser rangefinder has a housing, a display 104, and actuating elements 106 for switching the laser rangefinder on and off and for starting or configuring a measuring process. During a measuring process, the laser rangefinder emits laser radiation 110. Such laser rangefinders are known from the prior art. The position of the first object 100, 100a in three-dimensional space—indicated here by the bidirectional arrow, which represents free mobility of the laser rangefinder—is determined according to the method 10 according to the invention as a relative position P with respect to at least one reference object 200, 200a.The reference object 200, 200a is placed in a stationary position, for example, on the floor of the room to be measured. The reference object 200, 200a comprises a magnetic field generating device 202 for generating at least three directed magnetic fields B1, B2, B3 (see . Figure 3 , process step 16 and Figure 4, reference numeral 210) with distinguishable modulation frequencies f1, f2, f3. The magnetic field generating device 202 comprises three emitter coils Tx1, Tx2, Tx3 with reference numerals 204a, 204b, 204c, which are mutually aligned orthogonally to one another. The first object 100, 100a has a magnetic field detection device 112 for detecting magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and modulation frequencies f1, f2, f3 of the three magnetic fields B1, B2, B3. The magnetic field detection device 112 comprises three magnetic field sensors 114a, 114b, 114c, which are designed here as Hall sensors, each having a sensitivity aligned orthogonally to one another. Furthermore, the system 300, 300a, here the first object 100, 100a, has an evaluation device 302 which, in order to determine the relative position P of the first object 100, 100a with respect to the reference object 200, 200a, carries out the method step of determining the relative position P (cf. Figure 3, method step 24). Depending on the determined relative position P, a function of the laser rangefinder is controlled, for example the execution and / or assignment of a distance measurement.

[0065] The Figure 2The system 300, 300b shown shows a perspective view of a first object 100, 100b, which is implemented as a robot, here an autonomous lawnmower or an autonomous vacuum cleaner. The autonomous lawnmower has a housing 102. Such autonomous lawnmowers are known from the prior art. The position of the first object 100, 100a in three-dimensional space—here also indicated by the bidirectional arrow, which represents free mobility of the autonomous lawnmower—is determined according to the inventive method 10 as a relative position P with respect to at least one reference object 200, 200b. The reference object 200, 200b is implemented as a docking station (base station) of the autonomous lawnmower and is stationary on the floor of the work area to be worked on.The reference object 200, 200b comprises a magnetic field generating device 202 for generating at least three directed magnetic fields B1, B2, B3 (cf. . Figure 3 , process step 16 and Figure 4, reference numeral 210) with distinguishable modulation frequencies f1, f2, f3. The magnetic field generation with distinguishable modulation frequencies f1, f2, f3. The magnetic field generation device 202 comprises three emitter coils Tx1, Tx2, Tx3 (reference numerals 204a, 204b, 204c), which are mutually aligned orthogonally to one another. The first object 100, 100b has three magnetic field detection devices 112a, 112b, 112c. Each of the three magnetic field detection devices i - reference numerals 112a, 112b, 112c - is for detecting magnetic field strengths |Bx i (P)|, |By i (P)|, |Bz i (P)| and modulation frequencies f1, f2, f3 of the three magnetic fields B1, B2, B3 and comprises three receiver coils (not shown in detail here) implemented as RF coils. The three magnetic field detection devices 112a, 112b, 112c, in particular the receiver coils contained therein, each have a defined arrangement relative to one another.Here, three receiver coils are aligned in parallel pairs, with the three pairs of three in turn being aligned orthogonally to each other. The robot, provided it is in the immediate vicinity of the docking station, is charged by means of at least one emitter coil (here, for example, 204b) of the magnetic field generating device 202. Energy is inductively transmitted from the emitter coil to at least one receiver coil, thereby inductively charging an energy storage device of the robot. Furthermore, the first object 100, 100b also has a wireless communication device 116, which serves to communicate between the first object 100, 100b and the evaluation device 302.In this system 300, 300b, the evaluation device 302 is implemented in a separate unit, for example in a cloud, which, in order to determine the relative position P of the first object 100, 100b with respect to the reference object 200, 200b, carries out at least the method step of determining the relative position P (cf. Figure 3 , method step 24). The evaluation device 302 is also configured for wireless communication (see radio symbol on the box) with the first object 100, 100b and the reference object 200, 200b. Furthermore, the first object 100, 100b has an odometry sensor 120a as a further internal sensor device 120, which detects a movement of the wheels 118 and uses this to determine further position data to increase precision (see Figure 3, method step 24a). The odometry sensor 120a also serves as a rotation-sensitive sensor device 122, by means of which a change in the direction of movement, in particular a reversal of the direction of movement by 180°, of the first object 100, 100b can be detected. The reference object 200, 200b also has a further position sensor designed as a GPS sensor, which is not shown in detail here. Depending on the determined relative position P, a function of the robot is controlled, for example, the navigation of the robot or the processing of the work area to be processed.

[0066] Figure 3 shows an embodiment of the method 10 according to the invention. The method 10 is used to determine a relative position P of a first object 100, 100a, 100b - for example the object shown in Figure 1 laser rangefinder shown or the one shown in Figure 2represented robot - with respect to at least one reference object 200, 200a, 200b.

[0067] In a first optional method step 12, the presence of at least one magnetic field BSQ of an external radiation source, in particular a magnetic field generating device 202 not associated with the reference object 200, 200a, 200b, is first detected. The presence is detected by means of the magnetic field detection device 202 of the first object 100, 100a, 100b and / or by means of the magnetic field generating device 202 associated with the reference object 200, 200a, 200b. The detection comprises determining a modulation frequency fSQ of the magnetic field BSQ and detecting pause times TSQ in the generation of the magnetic field BSQ. Depending on these determined modulation frequencies fSQ and pause times in the generation TSQ of the magnetic field BSQ, both the modulation frequencies f1, f2, f3 and pause times in the generation T1, T2, T3 of the magnetic fields B1, B2, B3 are adjusted.The pause times T1, T2, and T3 in the generation of the magnetic fields B1, B2, and B3 are selected such that the generation of the magnetic fields B1, B2, and B3 occurs during the pause times in the generation TSQ of the magnetic field BSQ. Furthermore, the frequencies f1, f2, and f3 are selected such that they differ from the modulation frequency fSQ.

[0068] Furthermore, in the first optional method step 12, an influence of an interference field on the first object 100, 100a, 100b is detected (which can later be used in method step 16 to compensate for the interference field).

[0069] In a further optional method step 14, the modulation frequencies f1, f2, f3 (optionally selected or modified in method step 12) are transmitted from the magnetic field generating device 202 of the reference object 200, 200a, 200b to the magnetic field detecting device 112 of the first object 100, 100a, 100b by means of the wireless communication connection (here implemented as a radio connection) and used as a reference signal of a lock-in amplifier (not shown in detail here) of the magnetic field detecting device 112, so that in method step 20, a significant improvement in a signal-to-noise ratio when determining the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and consequently the relative position P can be realized.

[0070] In process step 16, three directed magnetic fields B1, B2, B3 (cf. Figure 4, reference numeral 210) with the (possibly previously modified) distinguishable modulation frequencies f1, f2, f3 using the magnetic field generating device 202 of the reference object 200, 200a, 200b.

[0071] In optional method step 18, the influence of the interference field previously determined in optional method step 12 is used to compensate for it by controlling and / or regulating an electromagnetic superposition field emitted by at least one compensation coil (not shown in detail). In particular, the emission of the superposition field is maintained during the detection of the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| in method step 20.

[0072] In method step 20, by means of the magnetic field detection device 112, 112a of the first object 100, 100a, 100b, magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 are detected at the point in space at which the first object 100, 100a, 100b is located at this time.

[0073] In optional method step 22, magnetic field strengths |Bx 2,3 (P)|, |By 2,3 (P)|, |Bz 2,3 (P)| and modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 can be detected by means of at least one further magnetic field detection device i 112, 112b, 112c of the first object 100, 100b, which can later be used for evaluation in optional sub-method step 24b.

[0074] In method step 24, the relative position P of the first object 100, 100a, 100b with respect to the at least one reference object 200, 200a, 200b is determined by means of the evaluation device 302 of the system 300, 300a, 300b from the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)|, which can be assigned to the directed magnetic fields B1, B2, B3 via the detected modulation frequencies f1, f2, f3. This can be done either by mathematical calculation or by comparing the detected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| with a magnetic field map. In this exemplary embodiment, a combination of both variants is used to increase precision. The magnetic field map contains the expected magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| for the entire (possible) range of motion of the first object 100, 100a, 100b. This magnetic field map can, for example, be created initially and continuously updated (seeSub-process step 24c) in order to be able to take into account, in particular, the influences of temporary interference fields. The determination of the relative position in process step 24 also includes the transmission of the required measurement data to the evaluation device 302.

[0075] In the optional sub-process step 24a, when determining the relative position P, further position data, such as those acquired, for example, by the internal sensor device 120 in the form of the odometry sensor 120a (see Figure 2), are included to increase precision by using this further position data to compare the relative positions obtained according to the method according to the invention. For example, a method for detecting outliers can be applied, as is known from DE 102017213577.8 A1. Furthermore, in the exemplary embodiment, the Figure 2the reference object 200, 200b in the form of the docking station has a GPS sensor by means of which the determined relative position of the first object 100, 100b can be converted into an absolute position.

[0076] In optional sub-process step 24b, a relation of the magnetic field strengths in the form of a magnetic field gradient is determined by means of the evaluation device 302 as a component-wise difference |Bx i (P)| - |Bx(P)|, |By i (P)| - |By(P)|, or |Bz i (P)| - |Bz(P)|, where i = 2, 3 denotes the values ​​of the further magnetic field detection device 112, 112b, 112c. In each case, those values ​​provided by parallel-aligned receiver coils are subtracted. Based on the sign of the relation, a unique identification of the relative position P to a quadrant of the magnetic field is performed. At the same time, a change in the direction of movement, in particular a reversal of the direction of movement by 180°, of the first object 100, 100b is detected by means of the rotation-sensitive sensor device 122 in the form of the odometry sensor 120a, wherein in the case of a reversal of the direction of movement, a reversal of the sign of the relation is not taken into account (orthe sign is multiplied by "-1").

[0077] In the optional sub-process step 24c, during a movement of the first object 100, 100b, deviations in the relationship from the expected target relationships according to the defined arrangement of the magnetic field detection device 112, 112a and the two further magnetic field detection devices 112, 112b, 112c (i=2, 3) are evaluated to detect magnetic field distortions. These deviations indicate corresponding magnetic field distortions or the influence of interference fields. If detected, these magnetic field distortions are stored in the magnetic field map by updating it or merging the existing values ​​with the new ones.

[0078] In the optional sub-process step 24d, system information coded jointly in each modulation frequency f1, f2, f3 of the magnetic fields B1, B2, B3 and / or in the totality of the modulation frequencies f1, f2, f3 is finally decoded by the evaluation device 302.

[0079] Finally, in method step 26, at least the determined relative position P, optionally the absolute position calculated therefrom and optionally the decoded system information are provided at an output of the evaluation device 302 for further use or processing.

[0080] In Figure 4An exemplary magnetic field 210 is shown, as it is generated in a plane by two mutually orthogonally arranged emitter coils 204a, 204c of a magnetic field generating device 202 of a reference object 200, 200a, 200b. The magnetic field is divided into four quadrants Q1, Q2, Q3, Q4, in each of which - neglecting magnetic field distortions - symmetrically equal magnetic field strengths are present, for example at the four exemplary points 206. In order to enable a one-to-one assignment of the relative position P to one of the quadrants, the first object 100, 100b - here the robot in the form of the autonomous lawnmower from Figure 2- three magnetic field detection devices 112a, 112b, 112c, which are arranged in a defined arrangement relative to one another. Here, the connecting lines of the rear two magnetic field detection devices 112b, 112c are perpendicular to the connecting lines of the two magnetic field detection devices 112a, 112c, with the latter connecting line being parallel or collinear to the direction of travel of the robot (represented by an arrow). For simplification, it is assumed that the magnetic field magnitude of the magnetic field is considered as an example for magnetic field B1 (here, for example, generated by emitter coil 204a) – with all other fields being masked out. Of this magnetic field B1, all three magnetic field detection devices 112a, 112b, 112c measure the x-, y-, and z-components (denoted by |Bx i B1< (P)|, |By i B1< (P)|, |Bz i B1< (P)| and i=1,2,3), from which the magnitude of the magnetic field acting at the respective location of the magnetic field detection device 112a, 112b, 112c is formed.If the robot now moves toward a quadrant boundary 208, the detected magnetic field strength |Bx(P)| (of the magnetic field B1) decreases, initially at the first magnetic field detection device 112a, followed by the two further magnetic field detection devices 112b, 112c. The following applies: |Bx 2 B1< (P)| - |Bx B1< (P)| > 0, |Bx 3 B1< (P)| - |Bx B1< (P)| > 0, where the indices 2, 3 stand for the two magnetic field detection devices 112b, 112c (the index for i=1 has been omitted).

[0081] If the robot now moves beyond the quadrant boundary 208, the detected magnetic field strength initially increases at the first magnetic field detection device 112a, while the magnetic field strength detected by the two further magnetic field detection devices 112b, 112c continues to decrease. From a certain point onward, |Bx 2 B1< (P)| - |Bx(P)| < 0, |Bx 3 B1< (P)| - |Bx(P)| < 0, so that a transition to another quadrant can be inferred from the reversal of the sign of the relations |Bx 2 B1< (P)| - |Bx(P)| or |Bx 3 B1< (P)| - |Bx(P)|. If the starting position of the first object 100, 100b is known, a clear assignment of the relative position P can always be achieved despite the ambiguity of the magnetic field 210. The rotation-sensitive sensor also detects a change in the direction of movement of the robot, in particular a reversal of the direction of movement by 180°.If the robot reverses its direction of movement, the reversal of the sign of the relations is taken into account by multiplying the relation |Bx 2 B1< (P)| - |Bx(P)| or |Bx 3 B1< (P)| - |Bx(P)| by "-1".

[0082] Using the three magnetic field detection devices 112a, 112b, 112c, magnetic field distortions can also be detected. Due to the known alignment, in particular the known distances, of the magnetic field detection devices 112a, 112b, 112c, a comparison of the relationship between the expected target relationships according to the defined arrangement of the magnetic field detection devices 112a, 112b, 112c can be evaluated. If measured and expected values ​​differ, a magnetic field distortion can be inferred. As described, such detected magnetic field distortions can be stored in the magnetic field map (see Figure 3 optional sub-process step 24c).

[0083] In Figure 5a to 5f Different scenarios are shown how the method 10 according to the invention can be applied. In Figure 5a is - in analogy to Figure 1 or 2 - a relative position P of a first object 100 with respect to a reference object 200 is determined. The first object 100 is freely movable, the reference object 200 is stationary. In Figure 5b will be - analogous to Figure 5a - merely the relative relation (of position P) is reversed. Here, a relative position P of the reference object 200 with respect to the first object 100 is determined. The first object 100 is stationary, while the reference object 200 is freely movable. Furthermore, it is also possible to continue to keep the first object 100 freely movable while the reference object 200 is stationary. Figure 5cthe relative position P of the first object 100 is determined, in particular selectively, with respect to a plurality of reference objects 200. Each reference object 200 has an associated magnetic field generating device 202. In Figure 5d In contrast, a relative position P of a plurality of first objects 100 is determined, in particular selectively, with respect to at least one reference object 200. In Figure 5e A sequence of relative position determinations is proposed. In analogy to Figure 5a a relative position of a first object 100 with respect to a reference object 200 is determined. Furthermore, a relative position P' of the reference object 200 with respect to at least one further reference object 200 is determined. Nested constellations are also conceivable, as shown in Figure 5fis shown. Here, the relative positions P of two first objects 100 with respect to two further first objects 100 are determined, wherein all first objects 100 are simultaneously also reference objects 200. Furthermore, relative positions P' of at least two first objects are in turn determined with respect to a further reference object 200c. In this way, for example, a swarm of robots can navigate autonomously in that each robot can generate and receive its own magnetic field. This enables the robots to be localized relative to one another. This localization can be used as a basis for joint path planning.

[0084] Depending on previously determined magnetic fields BSQ - which here are given by the magnetic fields of the other robots - the modulation frequencies f1, f2, f3 and pause times in the generation T1, T2, T3 of the magnetic fields B1, B2, B3 are adjusted (cf. Figure 3 , optional method step 12). In particular, the modulation frequencies f1, f2, f3 of each reference object 200 are selected such that they differ sufficiently from the modulation frequencies fSQ of the other reference objects 200—here, the other robots. Furthermore, the pause times T1, T2, T3 in the generation of the magnetic fields B1, B2, B3 are selected such that the generation of the magnetic fields B1, B2, B3 occurs during the respective pause times in the generation TSQ of the magnetic fields (TSQ = set of all other pause times of the other magnetic fields) of the other reference objects 200. In this way, on the one hand, the range of the method for determining the relative position P of the first object 100 can be increased, and on the other hand, parallel operation of several methods according to the invention can be enabled.

[0085] For the constellation of Figure 6b (compare with Figure 5f ) is in Figure 6ashown how the frequencies f1 to f15 and pause times in the generation of the magnetic fields, here TDS (= docking station), TR1 to TR4, are adapted to one another in such a way that no frequencies occur twice and that each reference object 200 transmits in the pause times of the other reference objects 200.

Claims

1. Method (10) for ascertaining a relative position P of a first object (100, 100a, 100b) with respect to at least one reference object (200, 200a, 200b), comprising: • generating at least three directed magnetic fields B1, B2, B3 having distinguishable modulation frequencies f1, f2, f3 by means of a magnetic-field-generating device (202) assigned to the reference object (200, 200a, 200b), wherein the magnetic-field-generating device (202) comprises at least three emitter coils Tx1, Tx2, Tx3 which alternately have a defined arrangement to one other, • measuring magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| and modulation frequencies f1, f2, f3 of the magnetic fields B1, B2, B3 by means of a magnetic-field-measuring device (112, 112a) of the first object (100, 100a, 100b), • ascertaining the relative position P of the first object (100, 100a, 100b) with respect to the at least one reference object (200, 200a, 200b) by means of an evaluation device (302) on the basis of the measured magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| which are able to be assigned to the directed magnetic fields B1, B2, B3 via the measured modulation frequencies f1, f2, f3, characterized in that a relative position P' of the at least one reference object (200, 200a, 200b) with respect to at least one further reference object (200, 200a, 200b) is ascertained, comprising: • generating at least three directed magnetic fields Bx', By', Bz' of distinguishable modulation frequencies f1', f2', f3' by means of a further magnetic-field-generating device (202) assigned to the further reference object (200, 200a, 200b), wherein the further magnetic-field-generating device (202) comprises at least three emitter coils Tx1', Tx2', Tx3', which alternately have a defined arrangement to one other, • measuring magnetic field strengths |Bx'(P')|, |By'(P')|, |Bz'(P')| and modulation frequencies f1', f2', f3' of the magnetic fields Bx', By', Bz' by means of a magnetic-field-measuring device (112, 112a) of the reference object (200, 200a, 200b), • ascertaining the relative position P' of the reference object (200, 200a, 200b) with respect to the at least one further reference object (200, 200a, 200b) by means of an evaluation device (302) on the basis of the measured magnetic field strengths |Bx'(P')|, |By'(P')|, |Bz'(P')| which are able to be assigned to the directed magnetic fields Bx', By', Bz' via the measured modulation frequencies f1', f2', f3'.

2. Method (10) according to Claim 1, wherein, in a further method step, the modulation frequencies f1, f2, f3 are transmitted from the magnetic-field-generating device (202) to the magnetic-field-measuring device (112, 112a) and / or to the evaluation device (302), wherein the transmitted modulation frequencies f1, f2, f3 are used to improve a signal-to-noise ratio when ascertaining the relative position P.

3. Method (10) according to Claim 2, wherein the transmitted modulation frequencies are used as a reference signal of a lock-in amplifier of the magnetic-field-measuring device (112, 112a) and / or of the evaluation device (302).

4. Method (10) according to either of preceding Claims 2 and 3, wherein the modulation frequencies f1, f2, f3 are transmitted by means of a radio connection.

5. Method (10) according to one of the preceding claims, wherein the relative position P of the first object (100, 100a, 100b) with respect to a plurality of reference objects (200, 200a, 200b) is ascertained, in particular optionally, wherein each reference object (200, 200a, 200b) comprises an assigned magnetic-field-generating device (202).

6. Method (10) according to one of the preceding claims, wherein a relative position P of a plurality of first objects (100, 100a, 100b) with respect to at least one reference object (200, 200a, 200b) is ascertained, in particular optionally.

7. Method (10) according to one of the preceding claims, wherein the magnetic-field-measuring device (112, 112a) comprises at least one magnetic-field sensor (114a, 114b, 114c) from a list of magnetic-field sensors, wherein the list comprises at least quantum sensors, Hall sensors, colour-centre-based magnetic-field sensors and receiver coils, in particular RF coils.

8. Method (10) according to one of the preceding claims, wherein an energy store of the first object (100, 100a, 100b) is inductively charged by means of at least one emitter coil Tx1, Tx2, Tx3 (204a, 204b, 204c) of the magnetic-field-generating device (202).

9. Method (10) according to one of the preceding claims, wherein each modulation frequency f1, f2, f3 of the magnetic fields B1, B2, B3 in each case codes system information and / or wherein all the modulation frequencies f1, f2, f3 together code system information.

10. Method (10) according to one of the preceding claims, wherein an influence of an interference field is measured and a measured magnetic field strength |Bx(P)|, |By(P)|, |Bz(P)| is corrected for the influence of the interference field by means of the evaluation device (302) and / or wherein the influence of the interference field is compensated for when measuring the magnetic field strengths |Bx(P)|, |By(P)|, |Bz(P)| by controlling and / or regulating an electromagnetic superposition field emitted by means of at least one compensation coil.

11. Method (10) according to one of the preceding claims, wherein, when ascertaining the relative position P, further position data, in particular further position data of a further internal and / or external sensor device (120, 120a), are included for increasing the precision and / or for ascertaining an absolute position.

12. System comprising a first object (100, 100a, 100b), at least one reference object (200, 200a, 200b) and an evaluation device (302), characterized in that the system, in particular the evaluation device (302), is configured to carry out a method (10) according to one of preceding Claims 1 to 11.