Operating a distance determination system

Abstract

The invention relates to a method for operating a distance determination system (10) in order to determine at least one distance (12) between a mobile unit (14) and a stationary unit (16), wherein - a first radio signal (46) is transmitted by the mobile unit and a first transmission value is recorded, - the first radio signal is received by the stationary unit and a first reception value is recorded, - a second radio signal (48) is transmitted by the stationary unit and a second transmission value is recorded, - the second radio signal is received by the mobile unit (14) and a second reception value is recorded, and - the distance (12) is determined by means of an evaluation unit (18). According to the invention, a monitoring unit (78, 80) generates a reference signal (82), feeds the reference signal to an antenna port (26, 40) of the transmit / receive unit (22), and records a reference transmission value, - the reference signal is received by the transmit / receive unit and a reference reception value is recorded, and - a reference distance (28) is determined by means of the evaluation unit and is compared with a predefined comparison value.

Description

[0001] Description

[0002] Operating a distance measurement system

[0003] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0004] The invention relates to a method for operating a distance determination system, which serves to determine at least a distance between at least two units of the distance determination system, comprising a mobile unit and a control unit, using radio communication, wherein the mobile unit and the station unit are arranged at two different positions, wherein a first radio signal is transmitted by the mobile unit by means of a transmitter / receiver of the mobile unit, wherein the mobile unit detects a first transmitted value, which is determined depending on a time of transmission of the first radio signal by the transmitter / receiver of the mobile unit, the first radio signal is received by the station unit by means of a transmitter / receiver of the station unit, wherein the station unit detects a first received value,which is determined depending on the time of reception of the first radio signal by the transmitter / receiver of the station unit, a second radio signal is transmitted by the station unit in response to the reception of the first radio signal by means of the transmitter / receiver of the station unit, wherein the station unit detects a second transmitted value which is determined depending on the time of transmission of the second radio signal by the transmitter / receiver of the station unit, the second radio signal is received by the mobile unit by means of the transmitter / receiver of the mobile unit, wherein the mobile unit detects a second received value which is determined depending on the time of reception of the second radio signal by the transmitter / receiver of the mobile unit,The invention relates to distance determination systems, wherein the distance between the mobile unit and the station unit is determined by means of an evaluation unit, at least depending on the first and second transmitted values ​​and depending on the first and second received values. Furthermore, the invention relates to distance determination systems, wherein the distance determination system serves to determine at least a distance between at least two units of the distance determination system using radio, wherein the distance determination system comprises a mobile unit as one of the at least two units and a station unit as a second of the at least two units, as well as at least one evaluation unit, wherein the mobile unit and the station unit can be arranged at two different positions, wherein the distance determination system is configured such that the mobile unit transmits a first radio signal by means of a transmit / receive part of the mobile unit, wherein the mobile unit detects a first transmitted value.the first radio signal is determined by the transmitting / receiving part of the mobile unit, the station unit receives the first radio signal by means of a transmitting / receiving part of the station unit, the station unit records a first received value which is determined by the transmitting / receiving part of the station unit, the station unit transmits a second radio signal by means of the transmitting / receiving part of the station unit in response to receiving the first radio signal, the station unit records a second transmitted value which is determined by the transmitting / receiving part of the station unit, the mobile unit receives the second radio signal by means of the transmitting / receiving part of the mobile unit, the mobile unit records a second received value,The evaluation unit, which is configured to determine the distance between the mobile unit and the station unit, is determined by the time of receipt of the second radio signal by the transmitting / receiving unit of the mobile unit. This determination depends on at least the first and second transmitted values ​​as well as the first and second received values. Finally, the invention also relates to a mobile unit for the distance determination system and a station unit for the distance determination system.

[0005] Methods and distance determination systems, as well as mobile and stationary units for these purposes, are known in the prior art, so that, in principle, no separate written documentation is required. At least partially automated machines, such as robots, at least partially autonomous vehicles, or the like, are increasingly being used in work areas that overlap, at least partially, with areas occupied by people, particularly work areas. Especially when such machines and people share a work area simultaneously, occupational safety with regard to the workers is of particular importance. It must be ensured that no person can be harmed during the operation of the machine.To meet this requirement, it is sometimes common practice in the prior art to adjust the machine's operating speed, particularly to reduce it, so that sufficient time is available to intervene in the machine's operation in such a way that the machine can be controlled or stopped appropriately when a person approaches or is present, thus preventing injury to the person. In this way, collision avoidance can be achieved, for example, by using suitable sensors to detect when a person enters the machine's working area.

[0006] Furthermore, it is possible, for example by using suitable touch sensors, to prevent injuries such as being trapped. This is particularly advantageous for autonomous vehicles. Especially in autonomous vehicles where sensors utilize lasers, it may not be possible to reliably detect all relevant areas or areas occupied by the vehicle, such as corners. This can lead to situations where a person suddenly walks into the path of an autonomous vehicle. For this reason, autonomous vehicles are often designed to travel very slowly, ensuring that even in such situations, timely braking to avoid a collision is reliably achieved.

[0007] However, problems can also arise when controlling machines such as machine tools, robots, or similar equipment. On the one hand, it may be desirable for the control personnel required to operate the machine to be located as close as possible to the machine. At the same time, it must also be ensured that the control personnel are far enough away from the machine to prevent injury during normal operation. For example, a defined operating area can be established to prevent injury while controlling the machine.The effective area can be realized, for example, by ensuring that a control device operated by the control personnel cannot be moved further away from the machine than a specified maximum distance, while at the same time a device such as a fence, a light curtain or the like can be used to ensure that the control personnel do not approach the machine closer than specified in order to largely avoid the risk of injury.

[0008] Another possibility is to determine a person's position relative to the machine. This allows the distance between the machine and the person to be determined, making it possible to ascertain when the person is approaching the machine in a dangerous manner. For this purpose, a distance detection system can be used. This system can, for example, consist of a mobile unit and a stationary unit. The mobile unit can be carried by the person who might enter the machine's vicinity. The stationary unit, on the other hand, can be fixed in a predetermined position. The stationary unit can be located, for example, on the machine itself, particularly on a machine part such as a robot arm or similar component.The distance measurement system can wirelessly determine the distance between the mobile unit and the base station, thereby calculating the distance between a person and a machine. For this purpose, suitable radio signals can be exchanged between at least two units. By evaluating the radio signal propagation times, it is then possible to determine the distance between the two units. In this context, the use of Ultra Wideband (UWB) can be employed, as specified, for example, in the IEEE 802.15.4z / 2020 standard.

[0009] However, it has been shown that such a distance measurement system can, under certain circumstances, be at least partially malfunctioning, causing it to output an incorrect distance reading. Due to this malfunction, the system could potentially report a shortened or even an increased distance. This could significantly impact the safety and endanger people in the vicinity of the machine. In particular, an excessively large calculated distance can pose a serious risk to people.

[0010] The invention is based on the objective of improving the reliability of a radio-based distance determination system in the aforementioned application.

[0011] The invention proposes as a solution methods, distance determination systems, a mobile unit and a station unit according to the independent claims.

[0012] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0013] With regard to a generic method, the invention, according to a first aspect, particularly proposes that at least one monitoring unit is provided for the mobile unit and / or for the station unit, each configured to perform internal functional monitoring with respect to the transmission and reception of radio signals of the respective transmitting / receiving part, and that the at least one monitoring unit of the distance determination system generates a reference signal, the monitoring unit transmits the reference signal to an antenna connection of the transmitting / receiving part of the unit comprising the monitoring unit, wherein the unit comprising the monitoring unit detects a reference transmission value which is determined depending on a time of transmission of the reference signal to the antenna connection, and the reference signal is received by the transmitting / receiving part of the unit comprising the monitoring unit.wherein the unit comprising the monitoring unit acquires a reference received value, which is determined by the transmit / receive part of the unit comprising the monitoring unit depending on a time of receipt of the reference signal, a reference distance is determined by the evaluation unit at least depending on the reference transmitted value and depending on the reference received value, and the reference distance is compared with a predetermined comparison value.

[0014] The system includes at least one monitoring unit in addition to the station unit and at least one mobile unit to generate or receive the reference signal and is integrated into the station unit and / or the at least one mobile unit.

[0015] In other words, the station unit or mobile unit includes the monitoring unit, in addition to its transmit / receive section, to verify the correct functioning of the transmit / receive section by feeding the generated reference signal into or receiving the reference signal at the antenna connection.

[0016] In other words, the reference signal of the station unit or the mobile unit is only used internally, i.e., it only circulates within each unit and is not transmitted from one to another.

[0017] Furthermore, the reference distance for functional testing is determined, and it is checked whether this distance lies within specified limits or corresponds to a specified comparison value, taking into account a specified tolerance range.

[0018] Alternatively, it would be possible to provide redundant transmission and reception paths, but this would lead to significantly higher complexity and increased data traffic over the air interface.

[0019] The solution according to the invention offers a significantly simpler method for functionally testing the entire system, including transmitter and receiver, and does not require any additional data traffic between the mobile unit and the station unit.

[0020] With regard to a generic method according to a second aspect, the invention particularly proposes that at least one monitoring unit is provided for the mobile unit and / or for the station unit, each configured to perform internal functional monitoring with regard to the transmission and reception of radio signals of the respective transmitting / receiving part, and that the at least one monitoring unit of the distance determination system receives a reference signal, wherein the unit comprising the monitoring unit transmits a reference signal to an antenna connection of the transmitting / receiving part of the unit comprising the monitoring unit by means of the transmitting / receiving part of the unit comprising the monitoring unit, wherein the unit comprising the monitoring unit detects a reference transmission value which is determined depending on a time of transmission of the reference signal by the transmitting / receiving part.The reference signal is received by the monitoring unit, wherein the monitoring unit records a reference reception value, which is determined depending on a time of receipt of the reference signal by the monitoring unit, a reference distance is determined by the evaluation unit at least depending on the reference transmission value and depending on the reference reception value, and the reference distance is compared with a predetermined comparison value.

[0021] With regard to a generic method, a third aspect of the invention particularly proposes that a monitoring unit of the distance determination system receives the first radio signal by receiving the first radio signal at an antenna connection of the transmit / receive part of the unit comprising the monitoring unit, wherein the monitoring unit acquires a reference received value, which is determined by the monitoring unit depending on a time of receipt of the first radio signal, a reference distance is determined by the evaluation unit at least depending on the first transmitted value and depending on the first reference received value, and the reference distance is compared with a predetermined comparison value.

[0022] With regard to a generic distance determination system, the invention, according to the first aspect, particularly proposes that the distance determination system comprises a monitoring unit configured to generate a reference signal and to transmit the reference signal to an antenna connection of the transmit / receive part of the unit comprising the monitoring unit, wherein the unit comprising the monitoring unit is configured to detect a reference transmit value that is determined depending on a time of transmission of the reference signal to the antenna connection, and wherein the transmit / receive part of the unit comprising the monitoring unit is configured to receive the reference signal, and wherein the unit comprising the monitoring unit is configured to detect a reference receive value that is determined depending on a time of reception of the reference signal by the transmit / receive part of the unit comprising the monitoring unit.and the evaluation unit is designed to determine a reference distance, at least depending on the reference transmission value and the reference reception value, and to compare the reference distance with a predefined comparison value.

[0023] With regard to a generic distance determination system, it is specifically proposed, according to the second aspect, that the distance determination system comprises a monitoring unit configured to receive a reference signal, wherein the unit comprising the monitoring unit is configured to transmit the reference signal to an antenna connection of the transmit / receive section of the unit comprising the monitoring unit by means of the transmit / receive section of the unit comprising the monitoring unit and to acquire a reference transmit value which is determined depending on a time of transmitting the reference signal by the transmit / receive section, the monitoring unit is configured to acquire a reference receive value which is determined depending on a time of receiving the reference signal by the monitoring unit, the evaluation unit is configuredto determine a reference distance, at least depending on the reference transmission value and the reference reception value, and to compare the reference distance with a predefined comparison value.

[0024] With regard to a generic distance determination system, it is particularly proposed, according to the third aspect, that the distance determination system includes a monitoring unit configured to receive the first radio signal at an antenna connection of the transmit / receive part of the unit comprising the monitoring unit and to acquire a reference received value which is determined depending on a time of receipt of the first radio signal by the monitoring unit, wherein the evaluation unit is configured to determine a reference distance at least depending on the first transmitted value as well as depending on the reference received value, and to compare the reference distance with a predefinable comparison value.

[0025] The invention is based, among other things, on the idea that interference in the transmitter / receiver unit, which can lead to incorrect distance measurements, can be identified. This makes it possible to detect deviations from the intended function of the respective unit, in particular the mobile unit or the base station unit, and to emit a corresponding signal, especially a fault signal, in the event of such a deviation. A higher-level control system can then trigger a corresponding response in the machine's control system, for example, limiting the operating time or operating area, or reducing the speed. Deactivating the machine is also conceivable.This allows for a high level of safety, largely eliminating the need for conventional safety measures such as low operating speeds, barriers like safety fences, or similar devices. The invention is based on the principle of two-way ranging (TWR). It thus makes it possible to provide a two-dimensional or three-dimensional positioning or distance measurement system that ensures a minimum distance is reliably maintained and prevents, in particular, shortened distance measurements that could create a hazardous area potentially endangering people during machine operation.In particular, the invention makes it possible to identify errors or disturbances that may occur in the transmitting / receiving part, especially if they would result in shortened distance measurements.

[0026] The invention enables this through a reference distance measurement aimed at determining a virtual distance, i.e., a reference distance, within the respective unit. For this purpose, a reference signal or a primary signal is used within the respective unit. By determining the respective transmit and receive values, in particular reference receive values, the evaluation unit can then determine a reference distance and compare it with a predetermined or predefinable comparison value. The comparison value is preferably selected according to a signal propagation delay, for example, at least partially corresponding to a signal propagation delay of the transmit / receive section. The comparison value can be a predetermined single fixed value.However, the comparison value can also encompass a range of values, so that a tolerance band can be determined within which the reference distance must be in order to assume reliability or freedom from interference.

[0027] Depending on the comparison, it is possible to estimate or determine the functionality of the unit containing the monitoring unit, in particular the functionality of the transmitting / receiving section. Specifically, it can also be estimated or determined whether the determination of the distances is reliable and correct during normal operation, so that the unit containing the monitoring unit can be assumed to be free of malfunctions. For example, functionality can be assumed to be positive if the comparison value is defined by a tolerance band and the reference distance has a value within the tolerance band. Preferably, the reference signal is a signal that is only used within the respective unit. It is therefore not transmitted by one unit to be received by another.

[0028] This functionality does not need to be included in every unit. However, it is preferably included in every unit, especially the mobile unit and the station unit. The distance measurement system does not need to consist of only two units. It may be provided that, in addition to a mobile unit, several station units are possible. For example, two or even three station units may be provided.

[0029] This makes it possible to determine the spatial position of the mobile unit by measuring the distance between the respective station units and the mobile unit. It is preferably assumed that the positions of the station units are known. Furthermore, the invention is not limited to the application of a single mobile unit. Of course, several mobile units can also be provided, whereby the distances of the mobile units to at least one station unit can be determined independently of one another. It proves particularly advantageous if the respective distance measurements are provided using time-division multiplexing, so that the mobile units and the station units can essentially use the same frequency range for the radio signals.In principle, however, it is also possible to use at least partially station-unit-specific or mobile-unit-specific frequencies or frequency ranges for determining the distance between several units. This can enable distance determinations to be carried out at least partially simultaneously. According to the invention, the unit to be monitored, in particular the mobile unit or the station unit, can include the monitoring unit.

[0030] The evaluation unit can be a separate unit that communicates with the unit containing the monitoring unit. However, the evaluation unit can also be at least partially encompassed by the unit containing the monitoring unit. The evaluation unit can also be at least partially captured by a unit that does not contain the monitoring unit. The station unit can, in particular, include a gateway or similar device.

[0031] Two-way positioning can be implemented, for example, by the mobile unit transmitting an initial radio signal using its transceiver. The mobile unit then detects an initial transmitted value, which is determined by its transceiver depending on the time of transmission. This initial radio signal can then be received by the base unit using its transceiver. The base unit detects an initial received value, which is also determined by its transceiver depending on the time of reception. After receiving the initial radio signal, the base unit transmits a second radio signal using its transceiver in response to the initial signal.The base station receives a second transmitted signal, which is determined by the transceiver of the base station based on the time of transmission of the second radio signal. The mobile unit receives this second radio signal via its transceiver. The mobile unit then receives a second received signal, which is also determined by its transceiver based on the time of reception of the second radio signal. The transmitted and received values ​​can be stored and retrieved in their respective units. Alternatively, the transmitted and received values ​​can be transmitted to an evaluation unit for analysis.

[0032] The mobile unit and / or the base station unit may include a control unit that regulates the functionality of the respective unit. The control unit may also initiate or perform the acquisition and / or storage of the respective transmitted or received value.

[0033] The transmitted or received value can be a specific point in time. It can also be, for example, the reading of a continuous counter operating in the respective unit. Alternatively, the transmitted or received value can be dependent on the reading of an externally controlled counter. This can improve the synchronization of the recorded values. The transmitted or received value can, for example, be a time stamp (TS).

[0034] The recorded values ​​can be transmitted to the evaluation unit, which can then determine the distance between the mobile unit and the base station based on these values. For transmission, a third radio signal can be sent from the respective unit to the evaluation unit, or to the unit containing the evaluation unit. This third radio signal can contain the corresponding values ​​recorded by the unit transmitting the third radio signal. For example, the evaluation unit may be enclosed within the base station. In this case, the mobile unit can then transmit the third radio signal to the base station, so that all recorded values—namely, the transmitted and received values—are available to the base station to determine the distance.In principle, it is of course also possible that the functionalities of the mobile unit and the base station unit are at least partially reversed without abandoning the core concept of the invention. The third radio signal can also be referred to as the final signal.

[0035] The monitoring unit of the distance measurement system is preferably located in at least one of the units for which monitoring is to be carried out. This can, of course, be the case for any of the units. However, the monitoring unit can also be located in only one of the mobile units or one of the station units. It should be noted, however, that only the unit that has a monitoring unit can be monitored. The monitoring unit can be at least partially integrated into the respective control unit of the unit in question. Alternatively, it can be located as a separate unit within the unit that contains the monitoring unit.

[0036] The mobile unit is preferably a single, easily handled, and in particular portable, unit that is as compact and lightweight as possible so that it can be easily carried by a person, for example. The mobile unit may be designed like a mobile communication device or the like, or at least partially provided by one. In principle, however, the base unit may also be at least partially mobile.

[0037] Preferably, the current position of the station unit in space is known, preferably even when it is moving. The station unit can therefore, for example, be fixed in place. Alternatively or additionally, the station unit can be mobile and moved, at least temporarily. The station unit can, for example, be mounted on a vehicle.

[0038] In particular with regard to the first aspect, it is further proposed that the unit comprising the monitoring unit, in response to receiving the reference signal, transmits a response signal by means of the transmit / receive part of the unit comprising the monitoring unit, wherein the unit comprising the monitoring unit detects a response end value which is determined depending on a time of transmission of the response signal by the transmit / receive part of the unit comprising the monitoring unit, wherein the response signal is received by the monitoring unit, wherein the monitoring unit detects a response receive value which is determined depending on a time of reception of the response signal by the monitoring unit, and wherein the reference distance is additionally determined by means of the evaluation unit depending on the response end value and the response receive value.The response signal can, in principle, be formed as a combination of the reference signal and the second radio signal. The use of the response output value and the response reception value can serve, among other things, to determine the reference distance when the monitoring unit and the transmit / receive section of the unit containing the monitoring unit are not synchronized, for example, if they have different time bases or similar issues.

[0039] With regard to the second aspect in particular, it is further proposed that the monitoring unit transmits a response signal in response to receiving the reference signal. The monitoring unit detects a response end value, which is determined depending on the time of transmission of the response signal by the monitoring unit. The response signal is received by the unit containing the monitoring unit. The unit containing the monitoring unit detects a response receive value, which is determined depending on the time of reception of the response signal by the unit containing the monitoring unit. The reference distance is additionally determined by the evaluation unit depending on the response end value and the response receive value. Here too, the response signal can, in principle, be formed, for example, as a combination of the reference signal and the second radio signal.The use of the response end value and the response receive value can be used, among other things, to determine the reference distance if the monitoring unit and the transmit / receive part of the unit containing the monitoring unit are not synchronized, for example, if they have different time bases or the like.

[0040] With regard to the first and second aspects in particular, it is further proposed that the transmission and reception of the first and second radio signals take place in respective predetermined, temporally separated communication periods, wherein the transmission and reception of the reference signal, and preferably also the transmission and reception of the response signal, as well as the associated evaluation and comparison, occur in a respective, preferably predetermined, monitoring period that lies between two successive, preferably predetermined, communication periods. This makes it possible to perform the monitoring functionality with respect to the respective unit, which has a monitoring unit, within a period in which signal processing with respect to the first and second radio signals does not need to be carried out.This makes it possible to use parts or units for the monitoring operation of the respective unit that are required in normal operation for transmitting and receiving at least the first and second radio signals. This reduces resources and effort. A time-division multiplexing operation can be particularly advantageous in this regard. The transmission and reception of the reference signal, preferably also the transmission and reception of the response signal, as well as the associated evaluation, can preferably be carried out for all units with a monitoring unit within the same monitoring period.

[0041] Furthermore, it is proposed that only two units, in particular the mobile unit and the station unit, communicate with each other during any given communication period. This enhancement enables communication between multiple mobile units and at least one station unit, or between at least one mobile unit and multiple station units. Preferably, communication between two units can be established through individually assignable communication periods. In this way, communication windows for communication between two units can be created and repeated cyclically. This allows for the near-continuous recalculation of distances and thus keeps the determination of the respective positions up-to-date.The communication periods assigned to each pair of units can be defined by a central control signal. It can also be provided that the respective communication periods follow each other cyclically, at least partially automatically, in a predetermined sequence. To enable monitoring functionality for each unit, the communication periods can be separated from each other, at least partially, by a monitoring period. The communication periods preferably have essentially the same duration. However, if necessary, this duration can vary. Furthermore, the monitoring period can be essentially the same duration as the communication periods.Furthermore, it is proposed that the reference value be specified depending on the respective signal propagation time of the transmitted signal or the reference signal within the unit containing the monitoring unit. This enhancement makes it possible to determine the reference value in a simple manner. It can also be provided that the reference value is supplied as a range of values, preferably continuous, within which the reference distance lies during interference-free operation. The comparison can thus involve not only a comparison with a single reference value, but also a comparison with an upper and a lower reference value. The reference value can, for example, be determined empirically through tests with one or more of the respective units.It may also be stipulated that the reference value is determined and specified, at least partially, during the manufacturing of the respective unit as part of a measurement procedure for measuring the signal propagation time. The reference value can be stored in the respective unit.

[0042] Furthermore, it is proposed that the reference signal contain data that identifies it as a reference signal. The reference signal, like the radio signals, can contain specific data that identifies each signal accordingly. For example, the reference signal can be configured to contain a string of characters identifying the reference signal as data within a specific, predetermined section of the signal. Preferably, this string is unique to each individual reference signal.

[0043] The radio signals may preferably contain data that identifies the respective radio signal as such. For example, the radio signals may contain an individual identifier of the respective transmitting / receiving unit of the respective device transmitting the radio signal. Furthermore, the respective radio signal may, of course, also contain other data, such as data relating to a received value of a previously received radio signal, a transmitted value of a previously transmitted radio signal, identification data of the respective device transmitting the radio signal, data relating to the time period between the reception of a radio signal and the subsequent transmission of the radio signal, and / or the like. The data may be encoded as required.

[0044] According to a training course, it is proposed that at least the station unit or the mobile unit should include the evaluation unit. It can be particularly advantageous to have the evaluation unit integrated into both the mobile unit and the station unit. This eliminates the need for a separate or centrally located evaluation unit. This can improve communication efficiency and the speed of distance determination. The evaluation unit can, for example, be at least partially integrated into the control unit of the respective unit. Alternatively, the evaluation unit can be a separate component of the respective unit.

[0045] It is further proposed that at least the unit containing the monitoring unit has a coupling unit for coupling the antenna connection to an antenna unit of the unit containing the monitoring unit, wherein the monitoring unit is connected to the coupling unit. The coupling unit enables the monitoring unit to check the signal propagation time within the respective unit containing the monitoring unit. The signal propagation time of the respective unit containing the monitoring unit is preferably determined by a signal propagation time of the transmit / receive section.

[0046] The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combination specified but also in other combinations without leaving the scope of the invention.

[0047] The embodiments described below are preferred embodiments of the invention. The features and combinations of features specified above in the description, as well as those mentioned in the following description of embodiments and / or shown individually in the figures, are not only usable in the combinations specified, but also in other combinations. Thus, embodiments are also encompassed by the invention or are considered disclosed that are not explicitly shown and explained in the figures, but can be derived and generated from the described embodiments by separate combinations of features.The features, functions, and / or effects illustrated by the exemplary embodiments can each, considered independently, represent individual features, functions, and / or effects of the invention, each of which further develops the invention independently. Therefore, the exemplary embodiments are intended to include combinations other than those described in the embodiments. Furthermore, the described embodiments can also be supplemented by additional features, functions, and / or effects of the invention already described. In the figures, identical reference numerals denote identical features or functions.

[0048] This shows:

[0049] FIG 1 shows a schematic block representation of a distance determination system with a mobile unit and a station unit.

[0050] FIG 2 shows a schematic representation of an initial signal,

[0051] FIG 3 shows a schematic representation of a response signal,

[0052] FIG 4 shows a schematic representation of a closing signal,

[0053] FIG 5 shows a schematic representation of a signal diagram for determining a distance between the mobile unit and the station unit according to FIG 1 using signals according to Figures 2 to 4 in a first embodiment,

[0054] FIG 6 shows a schematic representation of a signal diagram for the continuous determination of the distance between the mobile unit and the station unit according to FIG 1 using radio signals based on Figures 2 to 4 in a second embodiment.

[0055] FIG 7 shows a schematic block representation of the distance determination system based on FIG1, wherein internal function monitoring is provided for the mobile unit and the station unit.

[0056] FIG 8 shows a schematic block representation of the station unit according to FIG 1 with a function monitor, and

[0057] FIG 9 shows a schematic diagram representation of a distance measurement system with multiple mobile units and multiple station units, wherein functional monitoring, as explained with reference to FIG 8, is provided for the mobile units and the station units. FIG 1 shows a schematic block diagram of a distance measurement system 10 with a mobile unit 14 and a station unit 16 as two units of the distance measurement system 10. The mobile unit 14 is designed as a portable, compact unit so that it can be easily carried by a person. The mobile unit 14 can, for example, be designed in the form of a transponder.

[0058] Figure 1 does not show that the mobile unit 14 has its own power supply, which may include an electrical energy storage device such as a battery or the like. The mobile unit 14 has a control unit 34, which communicates with a transmitter / receiver unit 20. The transmitter / receiver unit 20 also has an antenna connector 26 to which an antenna unit 32 is connected. The transmitter / receiver unit 20 is configured to transmit and receive radio signals via the antenna unit 32. In this embodiment, the radio signals are those utilizing the Ultra-Wideband (UWB) radio standard. This radio standard is subject to standardization, which is why detailed explanations are omitted here. However, the invention is not limited to the use of UWB and can also be used based on other radio standards.

[0059] The transmitter / receiver unit 20 further comprises a sensing unit 42, which includes, among other things, a counter with a time base. The sensing unit 42 makes it possible to determine the time of transmission of radio signals by the transmitter / receiver unit 20 of the mobile unit 14. Likewise, the receiving unit 42 makes it possible to determine the time of reception of radio signals by the transmitter / receiver unit 20 of the mobile unit 14. In the present embodiment, the sensing unit 42 is designed to record the respective counter values ​​of the sensing unit 42 and store them, assigned to the respective radio signal. For this purpose, the mobile unit 14 has a storage unit (not shown) which is also controllable by the control unit 34 and is in communication with it.

[0060] The station unit 16 is stationary at a fixed, predetermined position, for example, in the area of ​​a robot or other machine mounting. The station unit 16 also has a transmitter / receiver 22, which communicates with a control unit 36. Furthermore, the transmitter / receiver 22 has an antenna connector 40 to which an antenna unit 38 is connected. The transmitter / receiver 22 also has a sensor 44, which is essentially designed like the sensor 42 of the mobile unit 14. The station unit 16 is also designed to transmit and receive radio signals based on the UWB radio standard.

[0061] Figure 1 schematically illustrates that the mobile unit 14 and the base station 16 are spatially separated by a distance 12. This distance 12 can be determined, as will be explained in more detail below, by means of radio signals exchanged between the mobile unit 14 and the base station 16. For this purpose, the mobile unit 14 transmits a first radio signal, or initial signal (poll signal) 46, which is received by the base station 16. In response to the reception of the first radio signal 46, the base station 16 transmits a second radio signal, a response signal 48, which is received by the mobile unit 14. Finally, it is preferably provided that the mobile unit 14 transmits a third radio signal, a final signal 50, which is received by the base station 16.As will be explained in more detail below, the distance 12 can be determined by evaluating the radio signals and the corresponding counter readings using an evaluation unit 18 of the control part 36.

[0062] FIG. 2 shows a schematic representation of the structure of the initial signal 46. The initial signal 46 contains data in coded form, which results from the structure shown in FIG. 2. The initial signal 46 begins with a sequence number in a first signal area 52. Signal area 52 is followed by a signal area 54, in which a destination address for the initial signal 46 is specified. Signal area 54 is followed by a signal area 56, in which a source address is specified. In this case, the destination address corresponds to the address of the station unit 16, whereas the source address corresponds to the address of the mobile unit 14. Signal area 56 is followed by a signal area 58, in which a corresponding function code relating to the initialization is specified.

[0063] FIG. 3 shows a schematic representation of the response signal 48, which, like the initial signal 46, essentially has four consecutive sections. The response signal 48 differs from the initial signal 46 only in that, instead of signal section 58, a signal section 60 is provided in which a corresponding function code relating to the response is specified. FIG. 4 shows a schematic representation of the closing signal 50, as it may preferably be provided in an embodiment according to FIG. 1. The closing signal 50 differs from the initial signal 46 and the response signal 48 in that, instead of signal sections 58 and 60, signal sections 62 to 66 are provided. Signal sections 52 to 56 correspond to signal sections 52 to 56 of the initial signal 46 according to FIG. 2, which is why further explanation of these is omitted here.Signal area 56 is followed by signal area 62, which specifies a function code for the final signal 50. Signal area 62 is followed by signal area 64, which specifies data on the time difference between the reception of the response signal 58 and the initial signal 46. Signal area 64 is followed by signal area 66, which specifies data on the time difference between the transmission time of the final signal 50 and the reception time of the response signal 48. The final signal 50 thus transmits the corresponding data available in the mobile unit 14 to the station unit 16. All data is therefore available in the station unit 16, so that, based on the signal propagation times of the radio signals 46, 48, and 50 thus determined, the distance 12 can be calculated using the evaluation unit 18.

[0064] FIG. 5 shows a schematic representation of a signal diagram for determining the distance 12 between the mobile unit 14 and the station unit 16 according to FIG. 1, using signals according to FIGS. 2 to 4, as previously explained in a first embodiment. As can be seen from FIG. 5, the mobile unit 14 first transmits the initial signal 46, which is received by the station unit 16. For this purpose, the mobile unit 14 acquires a first transmission value, which is determined by the counter reading – as previously explained. The first transmission value is determined by the transmit / receive unit 20 of the mobile unit 14 depending on the time of transmission of the initial signal 46.

[0065] The initial signal 46 is received by the station unit 16 via its transceiver 22. The station unit 16 acquires a first received value, which is determined by its transceiver 22 depending on the time of receipt of the initial signal 46. In response to receiving the initial signal 46, the station unit 16 transmits a reply signal 48 via its transceiver 22. The station unit 16 acquires a second transmitted value, which is determined by its transceiver 22 depending on the time of transmission of the second radio signal 48. The reply signal 48 is received by the mobile unit 14 via its transceiver 20.The mobile unit 14 acquires a second received value, which is determined depending on the time of receipt of the response signal 48 by the transmit / receive unit 20 of the mobile unit 14. The response signal 48 is transmitted by the station unit 16 after a reaction time of 68.

[0066] After a reaction time of 70 to the reception of the reply signal 48 by the mobile unit 14, the mobile unit 14 transmits the final signal 50, which is received by the station unit 16. The final signal 50 transmits, among other things, the recorded transmit / receive values ​​of the mobile unit 14 to the station unit 16, as can be seen in FIG. 4. It can thus be determined that all data relating to the signals are now available in the station unit 16, so that, among other things, the signal propagation times for the radio signals 46, 48, 50 (time of flight; TOF) can be determined. This is done in the station unit 16 by means of the evaluation unit 18, which is included in this case by the control unit 36. The evaluation unit 18 determines, among other things, the distance 12 between the mobile unit 14 and the station unit 16, depending on the first and second transmit values ​​as well as the first and second receive values.

[0067] FIG. 6 shows a schematic representation of a signal diagram as in FIG. 5 for the continuous determination of the distance 12 between the mobile unit 14 and the station unit 16 according to FIG. 1 using radio signals based on FIG. 2 to 4 in a second embodiment. As can be seen from FIG. 6, the signal sequence according to FIG. 5 differs from the signal sequence according to FIG. 6, among other things, in that no end signal 50 is provided. The initial signal 46 according to FIG. 5 is replaced by an initial signal 72 as the first signal according to FIG. 6. In this case, the initial signal 72 also includes data areas of the end signal 50. This makes it possible to continue to transmit the necessary data, in particular transmit / receive values, from the mobile unit 14 to the station unit 16.Therefore, the corresponding transmit / receive values ​​are continuously updated and available on the station unit 16, allowing the evaluation unit 18 to continuously determine the distance, as explained in FIG. 5. The distance 12 can thus be kept cyclically updated. This is particularly advantageous in dynamic processes where a person and / or the machine are moving within a shared work area.

[0068] FIG. 7 shows a schematic block diagram of the distance determination system 10 according to FIG. 1, including the mobile unit 14 and the station unit 16, each of which has internal function monitoring for transmitting and receiving radio signals. As can be seen in FIG. 7, a redundant control unit 74 and a monitoring unit 78 are additionally provided for the mobile unit 14. The monitoring unit 78 communicates with the redundant control unit 74. Furthermore, the redundant control unit 74 communicates with the control unit 34. The monitoring unit 78 is also coupled to the transmit / receive unit I 20 of the mobile unit 14.

[0069] Accordingly, station unit 16 is supplemented. Compared to station unit 16 according to FIG. 1, station unit 16 additionally has a redundant control unit 76, which is in communication connection with the control unit 36. Furthermore, station unit 16 has a monitoring unit 80, which is in communication connection with the redundant control unit 76. The monitoring unit 80 is also coupled to the transmit / receive unit 22 of station unit 16, as will be explained in more detail below.

[0070] The functional monitoring systems for the mobile unit 14 and the control unit 16 are essentially identical in their present configuration. Therefore, the following explanation of the functional monitoring system will focus solely on the functionality of the station unit 16. However, the corresponding explanations are equally applicable to the mobile unit 14.

[0071] FIG. 8 shows a more detailed view than FIG. 1 of a station unit 16 with a function monitoring system. The station unit 16 includes the components already described for station unit 16 with reference to FIG. 1, and therefore reference is made to the corresponding descriptions. As can be seen from FIG. 8, in this configuration, the antenna unit 38 is coupled to the antenna connector 40 of the station unit 16 via a coupling unit 30. The coupling unit 30 serves to couple the antenna connector 40 to the antenna unit 38 for the purpose of transmitting or receiving a radio signal.

[0072] Station unit 16 also includes a redundant control unit 76, which is connected to the control unit 36 ​​via communication. Furthermore, station unit 16 includes a monitoring unit 80, which is in communication communication with the redundant control unit 76. The monitoring unit 80 also includes a separate transmit / receive unit (not shown) which provides an output port 90 that is connected to the coupling unit 30 via signal transmission. This allows the monitoring unit 80 to supply the antenna port 40 with a reference signal 82. Additionally, if the transmit / receive unit 22 outputs a reference signal 82 at the antenna port 40, the reference signal 82 can be received by the monitoring unit 80 via the coupling unit 30. This will be explained in more detail below.The coupling unit 30 thus makes it possible to connect the transmitter / receiver unit 22 to the antenna unit 38 or the monitoring unit 80 as required. This makes it possible to monitor the function of the transmitter / receiver unit 22 and at least partially the function of the control unit 36.

[0073] In a first embodiment for functional monitoring, the monitoring unit 80 of the distance determination system 10 generates a reference signal 82. For this purpose, the redundancy control unit 76 outputs a corresponding generator signal (not shown) to the monitoring unit 80. The monitoring unit 80 generates the reference signal 82 and outputs it to the antenna connection 40 of the transmit / receive unit 22 of the unit containing the monitoring unit 80, here the station unit 16. For this purpose, the reference signal 82 is output to the antenna connection 40 via the coupling unit 30 at connection 90.

[0074] The station unit 16 acquires a corresponding reference transmit value, which is determined depending on the time of transmission of the reference signal 82 to the antenna connection 40. In this case, it is provided that the reference transmit value is acquired by means of the monitoring unit 80 and transmitted to the reference control unit 76. For this purpose, it may be provided that the monitoring unit 80 uses its own corresponding acquisition unit or the acquisition unit 44 of the transmit / receive unit 22.

[0075] The reference signal 82 is received by the transmit / receive unit 22 of the station unit 16. For this purpose, the station unit 16 acquires a reference received value, in this case corresponding to the acquisition of received values ​​for initial signals 46. The reference received value is determined by the transmit / receive unit 22 of the station unit 16 depending on the time of receipt of the reference signal 82. The reference received value is transmitted to the control unit 36. Likewise, the redundant control unit 76 transmits the reference transmitted value to the control unit 36. The control unit 36 ​​thus has the necessary values ​​available to determine a reference distance 28.

[0076] For this purpose, the evaluation unit 18 has a reference evaluation area 84. The reference evaluation area 84 has a reference distance determination part 24, which determines the reference distance 28 from the provided values ​​for the reference transmission value and the reference reception value. The reference distance 28 is then supplied to a comparison unit 88 of the reference evaluation area 84, which compares the reference distance 28 with a predetermined comparison value (not shown further). In this configuration, the comparison value represents a tolerance band.

[0077] The internal function monitoring with regard to the sending and receiving of radio signals means that the reference signal only circulates within the respective unit, i.e., it is not transmitted between the mobile unit 14 and the first station unit 16 or vice versa.

[0078] If the comparison shows that the reference value is within the tolerance band, this is considered normal operation of station unit 16. However, if the comparison yields a reference value that lies outside the tolerance band, the reference evaluation area 84 outputs a corresponding alarm signal 86. The alarm signal 86 can be transmitted to a higher-level control system, which evaluates this signal and, depending on the evaluation, detects a fault in the distance determination area of ​​the distance determination system 10. Depending on the alarm signal 86, the higher-level control system can initiate further measures.

[0079] However, the station unit 16 can alternatively or additionally be used for functional monitoring according to a second embodiment. For this purpose, this embodiment provides that the monitoring unit 80 receives a reference signal 82. The reference signal 82 is transmitted to the antenna connection 40 of the transmitter / receiver 22 of the station unit 16 by means of the transmitter / receiver 22. The station unit 16 acquires a reference transmit value, as already explained in the previous examples. For this purpose, the acquisition of the reference transmit value can be carried out by means of the acquisition unit 44 in the same way as the acquisition of the transmit value for the response signal 48 according to the above explanations. The reference transmit value is determined depending on the time of transmission of the reference signal 82 by the transmitter / receiver 22.

[0080] The reference signal 82 is received by the monitoring unit 80, which records a reference received value that is determined based on the time of receipt of the reference signal 82 by the monitoring unit 80. This can be done in the same way as previously explained for the radio signals. The reference transmitted value is sent from the transmit / receive unit 22 to the control unit 36. Similarly, the reference received value is sent from the monitoring unit 80 to the redundant control unit 76 and finally also to the control unit 36. Here, too, the corresponding reference values ​​are now available to perform the necessary determination of the reference distance 28 and the subsequent comparison, as previously explained, using the evaluation unit 18, in particular the reference evaluation area 84.The further course of proceedings can therefore be carried out in essentially the same way as explained above.

[0081] Alternatively or additionally to the previously described configuration, it can also be provided that no separate reference signal 82 is used for function monitoring, but rather, in the present case of the station unit 16, the response signal 48. As explained with reference to FIGS. 1 to 6, the corresponding radio signal, here the response signal 48, is provided at the antenna connection 40 of the transmit / receive unit 22 of the station unit 16. The response signal 48 can also be received by the monitoring unit 80 via the coupling unit 30. The monitoring unit 80 again records a reference reception value in this regard, which is determined depending on the time of receipt of the response signal 48 by the monitoring unit 80. The reference reception value is sent to the redundancy control unit 76 and finally to the

[0082] Control unit 36 ​​transmits the data so that, using the reference evaluation area 84, the aforementioned signal processing for determining the reference distance can be carried out depending on the reference received value and the transmitted value in relation to the response signal 48. Further processing then takes place as already explained for the two previous configurations.

[0083] Overall, the aforementioned embodiments make it possible to at least partially implement a monitoring functionality for the operation of the station unit 16. However, the invention is not limited to monitoring only the station unit 16. It can, of course, be applied analogously to the mobile unit 14. For this purpose, it can be provided that the mobile unit 14 transmits reference values ​​and / or reference values ​​to the

[0084] Station unit 16 transmits the signal and performs the evaluation with regard to the reference distance 28 and the comparison. Alternatively, mobile unit 14 may have its own reference evaluation unit 84. The message signal 86 can then be transmitted by mobile unit 14, for example, directly to the higher-level control system or to station unit 16. This allows not only mobile unit 14 but also station unit 16 to be integrated into the functional monitoring system.

[0085] FIG. 9 shows a schematic diagram for a configuration of a distance measurement system 10 with several mobile units 14 and several station units 16. Functional monitoring is provided for the mobile units 14 and the station units 16, as explained for the station units 16 in FIG. 8. The signal diagram according to FIG. 9 shows exemplary signal waveforms for one mobile unit 14 in conjunction with four station units 16 arranged at intervals. The mobile unit 14 and the station units 16 are equipped according to the design explained with reference to FIG. 7.

[0086] Communication between the mobile unit 14 and the station units 16 is carried out as explained with reference to FIG. 6. That is, there is continuous communication between units 14 and 16, whereby the communication does not include a termination signal 50. Instead, the initial signal 72 is provided for the communication. The signal processing is carried out as explained in particular with reference to FIG. 6.

[0087] The present configuration provides that the transmission and reception of the initial signal 72 and the corresponding response signals 48 take place in predefined, sequential communication periods. Each communication period is assigned an individual channel number 92. In the present configuration, the communication implemented in this time-division multiplexing configuration comprises 100 communication periods, numbered with channel numbers 92 from 0 to 99. Only one radio signal 48, 72 is transmitted in each communication period. Channel number 99 specifies a monitoring period, which, in the present configuration, corresponds to the duration of the communication periods. The communication periods themselves are of the same duration.The previously explained transmission and reception of the reference signal 82, as well as the associated evaluation and comparison, takes place in a respective monitoring period with channel number 99, whereby the monitoring period is temporally between two consecutive communication periods, namely in this case between communication period 98 and communication period 0.

[0088] Distance determination system 10 is configured accordingly so that the coupling unit operates depending on the monitoring period. FIG. 9 shows a section of the communication between units 14 and 16, as explained with reference to FIG. 6. During a given communication period with channel number 50, the mobile unit 14 transmits an initial signal 72 via its transceiver 20. The initial signal 72 is received by the station units 16 via their respective transceivers 22, which in FIG. 9 are designated 22A, 22B, 22C, and 22D. Thus, the initial signal 72 is available in each of the station units 16.Consequently, the initial signal 72 is received by the transmit / receive unit 22A of the first station unit 16, by the transmit / receive unit 22B of the second station unit 16, by the transmit / receive unit 22C of the third station unit 16, and by the transmit / receive unit 22D of the fourth station unit 16. Therefore, exactly one fixed communication period is defined for transmitting the initial signal 72.

[0089] Predefined communication periods are also specified for sending the response signals 48, namely, in the present configuration, communication periods with channel numbers 0 to 3. The communication period with channel number 0 is designated for the first station unit 16. During this period, the transmit / receive unit 22A sends its response signal 48A. In the following communication period with channel number 1, the transmit / receive unit 22B of the second station unit 16 sends its signal 48B. This is followed by the communication period with channel number 2 assigned to the third station unit 16, in which the transmit / receive unit 22C sends its response signal 48C. Similarly, the transmit / receive unit 22D of the fourth station unit 16 sends its response signal 48D in the communication period with channel number 3.The signal processing basically takes place as previously explained, so that the following initial signal 72 transmits the corresponding transmit / receive values ​​of the mobile unit 14 to the station units 16.

[0090] In the present configuration, the first station unit 16 is designed to act as the master for assigning communication periods. This determines the communication process, in particular the assignment of communication periods to the respective station units 16.

[0091] During the monitoring period with channel number 99, the previously described functional monitoring is scheduled to be carried out for both mobile unit 14 and the first station unit 16. Accordingly, the respective reference signals 82 are generated internally at each unit 14 and 16, transmitted internally, received, and further processed to determine the respective reference distances 28. In addition, the respective comparisons are performed, and, if necessary, the alarm signals 86 are transmitted.

[0092] Even though the present embodiment according to FIG. 9 provides that only the first station unit 16 performs the functional monitoring, functional monitoring can of course also be provided for one, more, or all of the further station units 16. This can then also be carried out during the monitoring period with channel number 99.

[0093] Figure 9 further shows that the communication slots with channel numbers 4 to 49 and 51 to 98 are currently unused. Therefore, these communication slots can be used to establish communication with one or more additional mobile units 14. Communication can then proceed as previously described.

[0094] In the configuration shown in FIG. 9, it is possible to determine the position of the mobile unit 14 in space. For this purpose, the fact that the station units 16 have predefined positions can be used. For example, the exact position of the mobile unit 14 can then be determined using trilateration. To this end, the respective distances 12 of the mobile unit 14 to the respective station units 16 can be determined and processed. This configuration therefore makes it possible to determine the exact position of the person carrying the mobile unit 14 in space or on a plane. This is particularly advantageous when the person is in the working area of ​​a machine operating as intended or an autonomously guided vehicle.For example, it is possible for a higher-level control system to process relevant positions of the machine or the autonomously guided vehicle together with the previously explained position of the person in order to determine a risk to the person and, depending on the risk potential, to intervene in a controlling manner in the machine or the autonomously guided vehicle.

[0095] The invention thus makes it possible to better comply with safety standards, so that machines or autonomously guided vehicles can be operated at higher speeds.

[0096] The exemplary embodiments serve solely to illustrate the invention and are not intended to limit it. List of reference numerals

[0097] 10 Distance determination system

[0098] 12 distance

[0099] 14 Mobile Unit

[0100] 16 station units

[0101] 18 evaluation units

[0102] 20 Transmit / Receive section

[0103] 22 Transmit / receive section

[0104] 24 Reference distance determination section

[0105] 26 Antenna connection

[0106] 28 Reference distance

[0107] 30 coupling unit

[0108] 32 antenna units

[0109] 34 Control unit

[0110] 36 Control unit

[0111] 38 antenna units

[0112] 40 antenna connections

[0113] 42 Recording section

[0114] 44 Recording section

[0115] 46 first radio signal

[0116] 48 second radio signal

[0117] 50 third radio signal

[0118] 52 to 66 signal range

[0119] 68 reaction time

[0120] 70 reaction time

[0121] 72 first radio signal

[0122] 74 Redundancy control section

[0123] 76 Redundancy control section

[0124] 78 Monitoring unit

[0125] 80 monitoring units

[0126] 82 Reference signal

[0127] 84 Reference evaluation area

[0128] 86 Meldeterminal

[0129] 88 comparison unit

[0130] 90 connection

Claims

Patent claims 1. Method for operating a distance determination system (10) which serves to determine at least a distance (12) between at least two units (14, 16) of the distance determination system (10), which comprise a mobile unit (14) and a station unit (16), using radio communication, wherein the mobile unit (14) and the station unit (16) are arranged at two different positions, wherein - a first radio signal (46) is transmitted by the mobile unit (14) by means of a transmitter / receiver part (20) of the mobile unit (14), wherein the mobile unit (14) detects a first transmission value which is determined depending on a time of transmission of the first radio signal (46) by the transmitter / receiver part (20) of the mobile unit (14), - the first radio signal (46) is received by the station unit (16) by means of a transmitting / receiving part (22) of the station unit (16), wherein the station unit (16) records a first received value which is determined depending on a time of receipt of the first radio signal (46) by the transmitting / receiving part (22) of the station unit (16), - in response to receiving the first radio signal (46), the station unit (16) transmits a second radio signal (48) by means of the transmit / receive part (22) of the station unit (16), the station unit (16) recording a second transmission value which is determined depending on the time of transmission of the second radio signal (48) by the transmit / receive part (22) of the station unit (16), - the second radio signal (48) is received by the mobile unit (14) by means of the transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) records a second received value which is determined depending on a time of receipt of the second radio signal (48) by the transmit / receive part (20) of the mobile unit (14), - by means of an evaluation unit (18) the distance (12) between the mobile unit (14) and the station unit (16) is determined at least depending on the first and second transmitted values ​​as well as depending on the first and second received values, characterized in that at least one monitoring unit (78, 80) is provided for the mobile unit (14) and / or for the station unit (16), each of which is configured to have an internal To perform functional monitoring with regard to the sending and receiving of radio signals of the respective transmitting / receiving part (20,22), wherein - which at least one monitoring unit (78, 80) of the distance determination system (10) generates a reference signal (82), - the monitoring unit (78, 80) transmits the reference signal (82) to an antenna connection (26, 40) of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) detects a reference transmit value which is determined depending on a time of transmission of the reference signal (82) to the antenna connection (26, 40), - the reference signal (82) is received by the transmitting / receiving part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) acquires a reference received value which is determined depending on a time of receipt of the reference signal (82) by the transmitting / receiving part (22) of the unit (16) comprising the monitoring unit (78, 80), - by means of the evaluation unit (18) a reference distance (28) is determined at least depending on the reference transmission value and depending on the reference reception value, and - the reference distance (28) is compared with a predefined reference value.

2. Method according to claim 1, characterized in that the unit (16) comprising the monitoring unit (78, 80) transmits a response signal in response to the reception of the reference signal (82) by means of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) detects a response end value which is determined depending on a time of transmission of the response signal by the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the response signal is received by the monitoring unit (78, 80), wherein the monitoring unit (78, 80) detects a response receive value which is determined depending on a time of reception of the response signal by the monitoring unit (78, 80).and wherein the reference distance (28) is additionally determined by means of the evaluation unit (18) depending on the response end value and the response receive value. 3 Methods for operating a distance determination system (10) which serves to determine at least a distance (12) between at least two units (14, 16) of the Distance determination system (10), comprising a mobile unit (14) and a station unit (16), to determine using radio, wherein the mobile unit (14) and the station unit (16) are arranged at two different positions, wherein - a first radio signal (46) is transmitted by the mobile unit (14) by means of a transmitter / receiver part (20) of the mobile unit (14), wherein the mobile unit (14) detects a first transmission value which is determined depending on a time of transmission of the first radio signal (46) by the transmitter / receiver part (20) of the mobile unit (14), - the first radio signal (46) is received by the station unit (16) by means of a transmitting / receiving part (22) of the station unit (16), wherein the station unit (16) records a first received value which is determined depending on a time of receipt of the first radio signal (46) by the transmitting / receiving part (22) of the station unit (16), - in response to receiving the first radio signal (46), the station unit (16) transmits a second radio signal (48) by means of the transmit / receive part (22) of the station unit (16), the station unit (16) recording a second transmission value which is determined depending on the time of transmission of the second radio signal (48) by the transmit / receive part (22) of the station unit (16), - the second radio signal (48) is received by the mobile unit (14) by means of the transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) records a second received value which is determined depending on a time of receipt of the second radio signal (48) by the transmit / receive part (20) of the mobile unit (14), - by means of an evaluation unit (18) the distance (12) between the mobile unit (14) and the station unit (16) is determined at least depending on the first and second transmitted values ​​as well as depending on the first and second received values, characterized in that at least one monitoring unit (78, 80) is provided for the mobile unit (14) and / or for the station unit (16), which is each configured to perform internal functional monitoring with regard to the transmission and reception of radio signals of the respective transmitting / receiving part (20, 22), wherein - at least one monitoring unit (78, 80) of the Distance determination system (10) receives a reference signal (82), - in which the monitoring unit (78, 80) comprising the unit (16) transmits the reference signal (82) to an antenna connection (26, 40) of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) acquires a reference transmit value which is determined depending on a time of transmission of the reference signal (82) by the transmit / receive part I (22), - the reference signal (82) is received by the monitoring unit (78, 80), wherein the monitoring unit (78, 80) records a reference reception value which is determined depending on a time of receipt of the reference signal (82) by the monitoring unit (78, 80), - by means of the evaluation unit (18) a reference distance (28) is determined at least depending on the reference transmission value and depending on the reference reception value, and - the reference distance (28) is compared with a predefined reference value.

4. Method according to claim 3, characterized in that the monitoring unit (78, 80) sends out a response signal in response to receiving the reference signal (82), wherein the monitoring unit (78, 80) detects a response end value which is determined depending on a time of sending the response signal by the monitoring unit (78, 80), wherein the response signal is received by the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) detects a response receive value which is determined depending on a time of receiving the response signal by the unit (16) comprising the monitoring unit (78, 80), and wherein the reference distance (28) is additionally determined by the evaluation unit (18) depending on the response end value and the response receive value.

5. Method according to claim 3 or 4, characterized in that the reference signal (82) is formed by the first radio signal (46).

6. Method according to one of the preceding claims, characterized in that the transmission and reception of the first and the second radio signals (46, 48) takes place in respective predetermined, temporally spaced communication periods, wherein the transmission and reception of the reference signal (82) as well as the associated evaluation and comparison in a The respective monitoring period takes place, which is temporally between two successive communication periods.

7. Method according to one of the preceding claims, characterized in that the reference signal (82) contains data that identifies it as a reference signal (82).

8. Distance determination system (10) which serves to determine at least a distance (12) between at least two units (14, 16) of the distance determination system (10) using radio, wherein the distance determination system (10) comprises a mobile unit (14) as one of the at least two units (14, 16) and a station unit (16) as a second of the at least two units (14, 16) as well as at least one evaluation unit (18), wherein the mobile unit (14) and the station unit (16) can be arranged at two different positions, wherein the distance determination system (10) is configured such that - the mobile unit (14) transmits a first radio signal (46) by means of a transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) detects a first transmission value which is determined depending on a time of transmission of the first radio signal (46) by the transmit / receive part (20) of the mobile unit (14), - the station unit (16) receives the first radio signal (46) by means of a transmit / receive part (22) of the station unit (16), wherein the station unit (16) records a first received value which is determined depending on a time of receipt of the first radio signal (46) by the transmit / receive part (22) of the station unit (16), - the station unit (16) in response to receiving the first radio signal (46) transmits a second radio signal (48) by means of the transmit / receive part (22) of the station unit (16), wherein the station unit (16) detects a second transmitted value which is determined depending on a time of transmission of the second radio signal (48) by the transmit / receive part (22) of the station unit (16), - the mobile unit (14) receives the second radio signal (48) by means of the transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) records a second received value which is determined depending on a time of receipt of the second radio signal (48) by the transmit / receive part (20) of the mobile unit (14), - the evaluation unit (18) is designed to determine the distance (12) between the mobile unit (14) and the station unit (16) at least depending on the first and second transmitted values ​​as well as depending on the first and second received values, characterized in that at least one monitoring unit is provided for the mobile unit and / or for the station unit, each configured to perform internal functional monitoring with regard to the sending and receiving of radio signals of the respective transmitting / receiving part, and - the monitoring unit (78, 80) is configured to generate a reference signal (82) and to transmit the reference signal (82) to an antenna connection (26) of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80), wherein the unit (16) comprising the monitoring unit (78, 80) is configured to detect a reference transmit value which is determined depending on a time of transmission of the reference signal (82) to the antenna connection (26), - the transmitting / receiving part (22) of the unit (16) comprising the monitoring unit (78, 80) is configured to receive the reference signal (82), wherein the unit (16) comprising the monitoring unit (78, 80) is configured to detect a reference received value which is determined depending on a time of receipt of the reference signal (82) by the transmitting / receiving part (22) of the unit (16) comprising the monitoring unit (78, 80), and - the evaluation unit (18) is designed to determine a reference distance (28) at least depending on the reference transmission value and the reference reception value, and to compare the reference distance (28) with a predefinable comparison value.

9. Distance determination system (10) which serves to determine at least a distance (12) between at least two units (14, 16) of the distance determination system (10) using radio, wherein the distance determination system (10) comprises a mobile unit (14) as one of the at least two units (14, 16) and a station unit (16) as a second of the at least two units (14, 16) as well as at least one evaluation unit (18), wherein the mobile unit (14) and the station unit (16) can be arranged at two different positions, wherein the distance determination system (10) is configured such that - the mobile unit (14) transmits a first radio signal (46) by means of a transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) detects a first transmission value which is determined depending on a time of transmission of the first radio signal (46) by the transmit / receive part (20) of the mobile unit (14), - the station unit (16) receives the first radio signal by means of a transmit / receive part (22) of the station unit (16), wherein the station unit (16) records a first received value which depends on a time of receipt of the first radio signal (46) is determined by the transmitting / receiving part (22) of the station unit (16), - the station unit (16) in response to receiving the first radio signal transmits a second radio signal (48) by means of the transmit / receive part (22) of the station unit (16), wherein the station unit (16) detects a second transmission value which is determined depending on a time of transmission of the second radio signal (48) by the transmit / receive part (22) of the station unit (16), - the mobile unit (14) receives the second radio signal (48) by means of the transmit / receive part (20) of the mobile unit (14), wherein the mobile unit (14) records a second received value which is determined depending on a time of receipt of the second radio signal (48) by the transmit / receive part (20) of the mobile unit (14), - the evaluation unit (18) is configured to determine the distance (12) between the mobile unit (14) and the station unit (16) at least depending on the first and second transmitted values ​​as well as depending on the first and second received values, characterized in that at least one monitoring unit is provided for the mobile unit and / or for the station unit, which is configured to perform internal functional monitoring with regard to the transmission and reception of radio signals of the respective transmitting / receiving part, and - the monitoring unit (78, 80) is configured to receive a reference signal (82), - wherein the unit (16) comprising the monitoring unit (78, 80) is configured to transmit the reference signal (82) to an antenna connection (26) of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80) by means of the transmit / receive part (22) of the unit (16) comprising the monitoring unit (78, 80) and to acquire a reference transmit value which is determined depending on a time of transmission of the reference signal (82) by the transmit / receive part (22), - the monitoring unit (78, 80) is designed to detect a reference received value which is determined depending on a time of receipt of the reference signal (82) by the monitoring unit (78, 80), - the evaluation unit (18) is designed to determine a reference distance (28) at least depending on the reference transmission value and the reference reception value, and to compare the reference distance (28) with a predefinable comparison value.

10. Distance determination system according to one of claims 8 or 9, characterized in that at least the station unit (16) or the mobile unit (14) has the evaluation unit (18).

11. Distance determination system according to one of claims 8 to 10, characterized in that at least the unit (16) comprising the monitoring unit (78, 80) has a coupling unit (30) for coupling the antenna connection (26) with an antenna unit (32) of the unit (16) comprising the monitoring unit (78, 80), wherein the monitoring unit (78, 80) is connected to the coupling unit (30).

12. Distance determination system according to claim 11, characterized in that the distance determination system (10) is configured such that the transmission and reception of the first and second radio signals (46, 48, 72) takes place in respective predetermined, successive communication periods and the transmission and reception of the reference signal (82) as well as the associated evaluation and comparison takes place in a respective monitoring period which is temporally between two successive communication periods, wherein the distance determination system (10) is configured to operate the coupling unit (30) depending on the monitoring period.

13. Mobile unit (14) of the distance determination system (10) according to one of claims 8 to 12.

14. Station unit (16) of the distance determination system (10) according to one of claims 8 to 12.

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