Method for detecting a temperature change within a cable and vehicle

Abstract

Method for measuring a temperature change (TINC) in a cable (K) of a vehicle, wherein the cable (K) connects at least two control units (A and B) of the vehicle, the cable (K) is configured at least to transmit signals between the control units (A, B), and each control unit (A, B) includes a crystal for time measurement, wherein this time measurement is configured to determine a hardware time of the control unit (A, B), where It is taken into account that a temperature change (TINC) of the cable (K) slows down the transmission of the signals carried through the cable (K), and To measure the temperature change (TINC), a measurement of the transit time change of at least one signal between the control units (A and B) is carried out, whereby a. To synchronize the hardware times of two control units (A and B), an Ethernet-based time synchronization protocol is used, in which one control unit (A, B) is a master and the other control unit (B, A) is a slave, the hardware time of the slave (B, A) is synchronized with the hardware time of the master (A, B), and to distinguish whether measured values ​​obtained from the measurement originate from the crystal of at least one control unit (A, B) or have resulted from the temperature change (TINC) of the cable (K), control unit (A) and control unit (B) each assume the role of master (A, B) once during one execution of the steps specified by the time synchronization protocol, thus the measurement is carried out in two configurations, while the other control unit (B, A) assumes the role of slave.and a delay in the arrival of the messages in both constellations is used to infer the temperature increase (TINC) of the cable (K) and / or , b. To detect an average temperature change (TINC), a number N of sets, each with at least one measured value, are compared, wherein at least a part of the time window during which the measured values ​​were obtained is divided into N intervals, and each measured value of an i set from the N sets was obtained at a time point which lies in the i interval of the considered part of the time window, a point representative of the measured values ​​of each of the N sets is determined, these points are arranged such that the representative point of set i is positioned on a time axis before the representative point of set i+1, and an average temporal change of temperature (TINC) is determined from this and / or c. a temperature-changing control unit (A, B) can be inferred from the knowledge of a cable routing in the vehicle and from the knowledge of the temperature change (TINC) in at least one cable (K) whose cable routing is known.

Description

[0001] The invention relates to a method for measuring a temperature change in a vehicle cable. This cable is designed to transmit signals between two vehicle control units. The invention also relates to a vehicle designed to carry out the method.

[0002] The expansion of networking and data communication during vehicle development requires more electronic devices, which also brings with it more potential sources of electrical faults in the vehicle, such as short circuits or overheating power components. Therefore, everything must be protected, making the communication network an expensive component.

[0003] To prevent electrical faults in the vehicle's electrical system, or at least in one cable, a fuse is used to de-energize at least one component upon fault detection. This is typically achieved using a standard fuse, or more recently, an efuse or smart fuse.

[0004] At the same time, it is also known that a malfunctioning control unit is characterized, for example, by a high data demand, which leads to a high data transfer to and / or from the malfunctioning control unit. This, in turn, causes the control unit to heat up, resulting in a higher temperature than it would have when functioning correctly. Therefore, an increase in the temperature of the control unit, and consequently also of its surroundings, can be an indicator of a malfunctioning control unit.

[0005] German patent application DE 10 2020 215 247 A1 discloses a method for determining the control unit temperature using a time synchronization protocol, which is intended to make it possible to detect changes in the temperature of a control unit (or a quartz crystal in the control unit). However, it is not possible to distinguish whether the problem is with the cable or with a problem within the control unit itself.

[0006] The article by YJ Kim, BM Cheon, JH Kim and JW Jean, “Time synchronization method of IEEE 802.1AS through automatic optimal sync message period adjustment for in-car network,” 2015 IEEE International Conference on Information and Automation, Lijiang, China, 2015, pp. 1485-1490, doi: 10.1109 / ICInfA.2015.7279520, describes a use of the IEEE 802.1AS protocol for time synchronization in a vehicle, determining the optimal period for performing the synchronization.

[0007] DE 10 2016 210 601 A1 discloses a method for monitoring a line by injecting measuring pulses and determining a superposition of the measuring pulses with reflective components of those same measuring pulses.

[0008] DE 10 2013 227 051 A1 discloses a temperature measurement using a sensor cable.

[0009] The invention is based on the objective of providing a method for software-based detection of the presence of at least one source of error when the source of error is accompanied by a temperature increase.

[0010] The problem is solved by the subject matter of the independent patent claims. Advantageous further developments of the invention are described by the dependent patent claims, the following description, and the figures.

[0011] The invention provides a solution comprising a method for measuring temperature changes in a vehicle cable. The cable is configured to connect at least two vehicle control units (ECUs), A and B. Furthermore, the cable is configured to transmit signals between the ECUs. For the sake of simplicity, the method will be described below only for ECUs A and B and the cable connecting them. Analogously, the method can be extended to the general case as follows. This is done based on the described configuration where ECU A is connected to ECU B via a cable. If there is more than one cable connection, the configuration is considered individually for each connection, and then the entire configuration is considered.Similarly, the case of multiple control units from the described constellation, where control unit A is connected to control unit B via a cable, can be obtained by considering connected pairs of control units and then combining the results obtained for each pair. At the same time, both of the aforementioned cases can be combined arbitrarily, so that by describing the constellation where control unit A is connected to control unit B via a cable, all cases with any number of control units, each connected via any number of cables, can be obtained in the described manner.

[0012] Furthermore, every control unit is characterized by the fact that it contains a quartz crystal (oscillator) for time measurement, which is configured to determine the control unit's hardware time. This means that each control unit contains a quartz crystal, each oscillating at a specific frequency. Time measurement can therefore be performed via this oscillation. However, the oscillation frequency of one quartz crystal can differ from that of another, as each control unit uses its own quartz crystal for time measurement. Consequently, the time determined by one control unit can differ from the time determined by another control unit using a different quartz crystal due to the different frequencies of the various quartz crystals. For this reason, the time determined by a control unit via a quartz crystal is referred to as (local) hardware time.Consequently, the hardware timing of two control units can differ.

[0013] The invention utilizes the fact that a temperature change in a cable affects signal transmission within that cable. It is a physical property of a cable that a change in temperature alters the transmission time of at least one signal carried through the cable. Transmitting a signal through a warmer cable takes longer than transmitting the same signal through a cooler cable.

[0014] This can now be used to measure temperature changes by measuring the propagation time of a signal between control units A and B. This means measuring how long it takes for at least one signal to be transmitted between control units A and B. By repeatedly measuring the duration of this transmission between control units A and B, changes in this transmission time can be registered. If this propagation time changes, this can be attributed to a temperature change, particularly an increase in the cable temperature. This could be caused, for example, by a control unit in the vicinity of the cable that has a defect and whose temperature changes as a result. This propagation time measurement can be implemented using software.

[0015] This offers the advantage that a software-based solution can be used to identify a defect, for example, in a control unit and / or cable. This can prevent the need for conventional fuses such as plug-in fuses and / or effus, which only trigger above a certain threshold, while this method allows for the early detection of a problem.

[0016] In addition, the invention comprises at least one of the following features: a. The invention may provide that an Ethernet-based time synchronization protocol is used to synchronize the hardware times of two control units A and B, in which one control unit is a master and the other a slave, and the hardware time of the slave is synchronized with the hardware time of the master. This means that the time measurement of the control unit assigned the role of slave is adjusted to the time measurement of the other control unit assigned the role of master. This is made possible via a protocol based on Ethernet and thus on the cable connection between the control units. The time synchronization protocol thus serves to compensate for the differences in time measurement that arise from the different frequencies in the oscillations of the quartz crystals. Therefore, the invention can provide, in order to distinguish whether the measured values ​​obtained from the measurement originate from the quartz crystal of at least one control unit or have resulted from the temperature change of the cable, that control unit A and control unit B each assume the role of master during one execution of the steps specified by the time synchronization protocol, thus performing the measurement in two configurations, while the other control unit assumes the role of slave.The steps of the time synchronization protocol are therefore carried out once with control unit A as master and control unit B as slave, and once with control unit A as slave and control unit B as master, resulting in the two described constellations. This allows the effect of the different oscillations of the quartz crystals, which can result in different hardware timings of the control units and which is compensated for by executing the time synchronization protocol in only one direction (i.e., only one master / slave configuration), to be distinguished from the overall observed change in propagation time. This leaves only the effect of a propagation time change due to temperature variation. Thus, the advantage is that a delay in the arrival of messages in both configurations can be attributed to the temperature increase of the cable, since nothing else exhibits a similar effect. b. The invention may provide that, in order to detect an average temperature change, a number N of quantities or groups of measurements, each with at least one measurement, are compared with one another, wherein at least a part of the time window during which the measurements were taken is divided into N intervals, and each measurement of an i. quantity from the N quantities was taken at a time point which lies in the i. interval of the considered part of the time window, a point representative of the measurements of the quantity is determined from each of the N quantities, these points are arranged such that the representative point of quantity i is arranged on a time axis before the representative point of quantity i+1, and an average change in temperature over time is determined from this. This means that, at least for a portion of the time during which the measurements—i.e., the data exchange and thus the procedure—are performed, this time is divided into several intervals. Within each of these intervals, at least one measurement, i.e., one data exchange, is carried out. Subsequently, a representative point is determined for each interval, characterized by its representativeness of the signal's propagation time or the data transmitted during the data exchange. This could, for example, be a point representing the average propagation time, or the point could be determined using the median, always considering only the measurements assigned to the corresponding interval. The points obtained in this way for each interval (one point for each of the multiple intervals) can then be sorted chronologically.This means that a point assigned to interval i will be placed before a point assigned to interval i+1 if interval i is before interval i+1 in terms of time. By considering these representative points, the advantage arises that individual fluctuations in transit time are smoothed out, thus enabling a more precise determination of transit time and therefore a more accurate differentiation between the various transit times. This is particularly advantageous because the measurement accuracy of the method is of a similar order of magnitude to the transit time differences, and thus, by using representative values ​​from multiple measurements, a more reliable result can be obtained as opposed to comparing individual measurements. c. The invention can provide that, based on knowledge of the cable routing in the vehicle and knowledge of the temperature change in at least one cable, the routing of which is known, a conclusion can be drawn about the presence of a temperature-changing control unit. This means that the location of each control unit in the vehicle and the routing of the cables within the vehicle are known, so that it is also known which cables run near each control unit. "Near" here describes the environment of a control unit within which a change in the temperature of the control unit has an effect on a cable running through this environment and thus an effect on the propagation time of the signals through this cable. Once this information is known and it has been determined which cables experience a change in propagation time due to temperature changes, the cable routing and the locations of the control units can be used to identify the control unit(s) causing the temperature change. In particular, the magnitude of the propagation time change can be used to determine the proximity of at least one section of the cable to the at least one temperature-changing control unit, thus allowing for a more precise identification of that control unit.

[0017] The invention also includes further developments that result in additional advantages.

[0018] A further development now proposes using the IEEE 802.1AS protocol for time synchronization. This protocol is known from the prior art and is now being extended to include the functionality that allows the IEEE 802.1AS protocol to be executed in the aforementioned two configurations, thereby enabling conclusions to be drawn about the temperature increase.

[0019] The advantage here is that this protocol is already used as standard in many vehicles for time synchronization, so that the basis for the method according to the invention is already given in many vehicles and thus the method can be easily implemented in the vehicles by making a small adjustment to the software.

[0020] However, it is not only the case that a defective control unit, which consequently heats up, affects the temperature of at least one adjacent cable and thus the transmission time of the signal running within it, but there are also other temperature-influencing factors. For this reason, further training stipulates that at least one factor be included that influences the vehicle's temperature and thus also the potentially operational temperature changes of at least one cable within the vehicle.

[0021] This offers the advantage that when determining a temperature change in a cable, environmental factors are also taken into account, which also result in a temperature change in the cable, but which does not represent a fault. Thus, it can be verified whether the temperature change is a normal change, for example due to engine heating, or whether the temperature change occurs due to an undesirable condition, such as a defect in a control unit.

[0022] In this context, at least one of the following quantities can be considered as temperature-influencing factors: • the engine speed • the setting and / or use of the air conditioning system • the heating setting • the engine temperature • the temperature of the cooling water • the engine speed • the power generated in the engine • the speed of the vehicle • the battery temperature • the change in the position of the accelerator pedal.

[0023] The parameters listed here are influencing factors that can contribute to temperature changes in cables within a vehicle, even when the vehicle is functioning correctly. Therefore, if a temperature change in a cable is observed, at least one of these parameters can be considered as a possible cause before concluding that a defect is present. This allows further conclusions to be drawn about the source of the temperature change and thus determine whether it is a normal temperature fluctuation in a properly functioning vehicle or a temperature change due to a defect.

[0024] In particular, this allows a distinction to be made as to whether the effect of the temperature change is due to the intended operation of the vehicle and a corresponding temperature increase, or due to a defect.

[0025] A further training program now stipulates that the outside temperature be included when considering changes in travel time. This allows for the comparison of journeys made at different times under the same or similar outside temperature conditions. "Similar temperatures" are defined here as temperatures whose difference is less than a certain value. This value can be fixed, so that, for example, similar temperatures exist if they differ by less than 3°C, 5°C, 8°C, or 10°C. Alternatively, a percentage (e.g., 10%, 20%, or 25%) can be specified. The value assigned to the corresponding percentage is then determined based on the larger or smaller temperature for which a similarity comparison is to be made. Similarity of the temperatures is defined as a difference of less than the value determined by the percentage.

[0026] This allows researchers to determine whether, over a period of time, for example, several journeys, there is a change in the temperature profile of at least one cable, even if the ambient temperature remains within the same range during each measurement. A change in this profile could then indicate that a control unit functioned correctly during previous journeys but is now faulty and therefore runs hotter than during those earlier journeys. This can be observed by a change in the temperature profiles under similar driving conditions, particularly at similar ambient temperatures.

[0027] Similar driving conditions can be determined using parameters typical for a vehicle journey, such as engine speed, vehicle speed, acceleration, time since engine start, distance traveled, and / or idle time. By checking for similar driving conditions, at least one of these parameters can be determined for the time under consideration and compared with that parameter at a specific point in time during another journey or the same journey. Similar driving conditions are then present if the difference in the values ​​of the at least one parameter under consideration lies within a specific, defined interval, preferably starting at zero.

[0028] This offers the advantage that defects that develop slowly, i.e., only over several journeys, and / or worsen, are detected and signaled by changes in the temperature profile during various comparable or similar journeys. This eliminates the need to exceed a threshold value, as is the case with conventional fuses. This allows for early replacement and reduces the likelihood of a control unit failure.

[0029] These slowly developing defects can be advantageously detected by executing the method for detecting a temperature change in a cable while at least one of the devices is still booting up. For example, it can take 100 ms to 200 ms for at least one part, particularly a specific part, or alternatively all control units, to fully boot up after the vehicle has started. If signals for measuring propagation delay changes are already being transmitted between different control units during this time, then at least one cable between control units can be checked for a temperature change even while the vehicle is still booting up.If one considers several start-up processes under similar outside temperatures, a comparison of the different start-up processes can determine whether this results in an unusual temperature change, i.e., whether the temperature change varies across different start-up processes under similar driving conditions.

[0030] This allows for a particularly advantageous conclusion to be drawn about a defect, since the start-up processes are generally similar to each other, i.e., the driving conditions during start-up are similar, signals can already be exchanged between the control units during the start-up period, and thus a sufficient data basis for considering the temperature change during start-up is available, and other influencing factors such as different engine speeds have no influence.

[0031] A further development provides that the data from the time synchronization protocol is used, and additionally, only those signals are produced that result from the use of both configurations instead of just one. This ensures that the data exchange is carried out in the form of signals with the same frequency and at the same time as the data exchange for the time synchronization protocol. This means that the data exchange, which is carried out at a specific frequency during the time synchronization protocol, is used for at least some of the steps of the method according to the invention. Thus, when the time synchronization protocol is executed, a data exchange takes place in which one control unit is the master, while the other control unit is the slave, with corresponding data being exchanged in this configuration.In the course of the process, this data exchange is also performed, but the constellation in which the roles of master and slave are reversed is additionally considered. The further development therefore provides to use the data exchange from the time synchronization protocol and additionally to generate only that data exchange which occurs due to the additionally considered constellation with the role reversal. Thus, the data exchange of the time synchronization protocol is assigned two functions: firstly, the function within the time synchronization protocol itself, and secondly, the function as part of the method according to the invention. The runtime measurement is thus embedded in the time synchronization protocol.

[0032] This has the advantage that the load on the transmitting cable is kept low, since some of the data already transmitted via this cable is reused, resulting in a smaller amount of additional data transfer than if all data for the process were generated independently of the time synchronization protocol.

[0033] This leads to the particularly advantageous further development of using the same frequency of data exchange in the time synchronization protocol to also perform the additional data exchange required for the method according to the invention at this same frequency. At the same time, more frequent measurements, and thus more frequent data exchange, can be particularly useful when a temperature change is detected, in order to obtain more measurement results within a given time. This allows for more comprehensive statistics, counteracts individual fluctuations in the measurements, and thus provides a better means of monitoring the temperature change. In this way, the temperature change can be more easily distinguished from a measurement error and / or a disturbance in the measurement.Thus, the training stipulates that data exchange for time synchronization is carried out at certain intervals based on the time synchronization protocol, but additional data exchange to increase the frequency of measurement takes place when a temperature change is detected that exceeds a predetermined threshold.

[0034] Further training now stipulates that a warning signal is issued when a temperature change is detected and / or a threshold is exceeded. This threshold can be fixed and / or based on environmental factors such as the outside temperature. The warning signal can include at least one of the following elements: a visual and / or audible signal to the driver, for example, a light illuminating, a message being displayed and / or read aloud, and / or a warning tone sounding; an entry in the vehicle's fault memory; an action by the vehicle, for example, deactivating at least one function, such as a driver assistance system; an emergency stop of the vehicle; the transmission of information to at least one third party, such as a central server, a workshop, and / or the manufacturer; and / or the prevention of the use of certain vehicle functions.

[0035] This offers the advantage that at least one action requiring the control unit and / or cable identified as defective due to the temperature increase is no longer executed, thus preventing a malfunction. Additionally or alternatively, the driver can be notified early on that a control unit and / or cable may be defective, allowing for timely repairs and potentially preventing a failure of functions.

[0036] Further training now stipulates that, based on knowledge of the cable routing in the vehicle and knowledge of the temperature change in at least one cable whose routing is known, it can be concluded that a cable is causing temperature changes. In particular, if it is determined that only one cable is affected by the temperature change, it can be concluded that the cable is the source of the temperature change and thus that a defect in the cable is present.

[0037] For use cases or application situations that may arise during the procedure and are not explicitly described here, it may be provided that, according to the procedure, an error message and / or a request for user feedback is issued and / or a default setting and / or a predetermined initial state is set.

[0038] The invention presents, as a further solution, a vehicle comprising at least one cable and at least two control units, which is configured to infer a temperature change in the cable between the at least two control units via signal transmission or data exchange by measuring the transmission duration and comparing this measured duration with the durations of previous transmissions. Knowing that a temperature change in the cable affects the transmission time between the two control units, a change in the transmission duration, and thus a change in the propagation time, can therefore indicate a temperature change in the cable.

[0039] The invention also includes further developments of the vehicle, which have already been described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the vehicle are not described again here.

[0040] As a further solution, the invention also includes a computer-readable storage medium comprising program code which, when executed by a processor circuit, causes the processor to execute an embodiment of the method according to the invention. The storage medium can be provided at least partially as a non-volatile data storage medium (e.g., as flash memory and / or as an SSD - solid state drive) and / or at least partially as a volatile data storage medium (e.g., as RAM - random access memory). The storage medium can be located within the processor circuit. Alternatively, the storage medium can be operated, for example, as an app store server and / or a cloud server on the internet. The program code can be provided as binary code and / or assembly code and / or as source code of a programming language (e.g., C) and / or as a program script (e.g., Python).

[0041] The method can be implemented using at least one processor unit of the vehicle. For this purpose, the processor unit can comprise at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Processing Unit) can be used as the microprocessor. Furthermore, the at least one processor unit can comprise program code configured to execute the embodiment of the method according to the invention when carried out by the processor unit. The program code can be stored in a data memory of the processor unit. The processor unit can, for example, be based on at least one circuit board and / or on at least one SoC (System on Chip).

[0042] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1 a schematic representation of an embodiment of the vehicle according to the invention in which an embodiment of the method according to the invention is carried out; and Fig. 2 a further schematic representation of an embodiment of the vehicle according to the invention, in which an embodiment of the method according to the invention is carried out.

[0043] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0044] In the figures, identical reference symbols denote functionally equivalent elements.

[0045] Fig. Figure 1 shows an exemplary embodiment of the method in which a measurement of a change in the propagation time in the transmission of at least one signal is carried out based on an exemplary embodiment of a time synchronization protocol TSYNC. For this purpose, Fig. 1. The exemplary case of communication between control unit A and control unit B via a cable K in a vehicle F, whereby it can be applied to any number of control units and cables. The time t is plotted downwards, with the arrow pointing further down the line. Fig. The later the action related to the arrow starts, the later it starts, always taking into account the hardware time of the control unit that is in the same column as the reference sign belonging to the beginning or end of the arrow.

[0046] The time synchronization protocol TSYNC can be implemented using the IEEE 802.1AS protocol, which will be described below, forms part of the described embodiment of the method, and is characterized by the steps within the section described below. Fig. 1. Box marked with TSYNC. As an example, let's assume control unit A is the slave and control unit B the master; however, the TSYNC time synchronization protocol can also be executed by another control unit – for example, control unit B – as the slave and, correspondingly, by a control unit other than the slave as the master, without loss of generality.

[0047] The first step of the TSYNC time synchronization protocol involves control unit A, acting as a slave, sending an initial message to control unit B, acting as the master, at time t1. This message arrives at control unit B at time t2. It's important to note that these are always the hardware times of the respective control units. Hardware time, in this context, refers to the time measured by the control unit based on its internal clock, which is typically a quartz crystal. Each control unit can have its own hardware time; for example, the hardware time of control unit A may differ from that of control unit B. Therefore, t1 refers to the hardware time of control unit A, while t2 refers to the hardware time of control unit B.

[0048] After this first message is exchanged, a second message is exchanged, which is transmitted from control unit B to control unit A at time t3 (hardware time of control unit B), arrives at control unit A at time t4 (hardware time of control unit A), and in which the arrival time t2 of the first message is transmitted in a transmission step St2. Furthermore, at a time that lies after t3 in terms of the hardware time of control unit B, another message is transmitted from control unit B to control unit A, whereby in this transmission step St3 the time t3 of the sending of the preceding message is transmitted.

[0049] In this way, control unit A now has access to the four time points t1, t2, t3, and t4 – t1 and t4 being in the hardware time of control unit A, while t2 and t3 are in the hardware time of control unit B. Control unit A can then synchronize its hardware time with that of control unit B. The messages, which correspond to the signals between the control units, are transmitted via cable K.

[0050] The procedure can now be configured so that the time synchronization protocol TSYNC is executed not only with control unit A as slave and control unit B as master, exchanging times t1, t2, t3, and t4 in this process, but also in reverse. This means that the time synchronization protocol TSYNC is also executed in the second configuration with control unit A as master and control unit B as slave. This results in the corresponding times t5, t6, t7, and t8, where t5 and t8 were measured in the hardware time of control unit B, t6 and t7 were measured in the hardware time of control unit A, and in transmission steps St6 and St7, times t6 and t7 are transmitted from control unit A to control unit B via cable K. This provides control unit B with the times t5, t6, t7, and t8.

[0051] These steps described above can now be repeated cyclically or at predetermined intervals. For this purpose, the frequency specified for the TSYNC IEEE 802.1AS time synchronization protocol can be used, for example. The IEEE 802.1AS protocol is designed to execute the steps of the TSYNC time synchronization protocol once per second in order to measure the frequency offsets of the crystal oscillator of the control unit acting as the slave relative to the crystal oscillator of the control unit acting as the master.

[0052] Since the time synchronization protocol TSYNC can be part of the process, it can be advantageous to also use the signals or messages transmitted during the execution of the TSYNC time synchronization protocol for the process itself, thus generating only the data necessary for the execution of the time synchronization protocol in both configurations. This means that, in this embodiment, corresponding messages or signals are already sent via the TSYNC time synchronization protocol at a frequency of, for example, one execution per second, thereby exchanging the time points t1, t2, t3, and t4, with control unit A acting as the slave and control unit B as the master.This is also a partial step in the embodiment of the method, whereby the second constellation, in which control unit A assumes the role of the master and control unit B the role of the slave, must also be taken into account. The method thus includes both constellations and the fact that the message or signal / data exchange is performed repeatedly. If the frequency at which the time synchronization protocol TSYNC is repeated is chosen for the repeated execution, then the steps performed during the time synchronization protocol TSYNC can also be used for the method, and, in addition, for the embodiment of the method, only the data exchange with control unit A in the role of the master and control unit B in the role of the slave needs to be carried out.This ensures that only those messages or signals corresponding to times t5, t6, t7, and t8 are sent. However, other frequencies can also be chosen for repeating the aforementioned steps of the procedure.

[0053] If a temperature change occurs in cable K, the propagation time of messages or signals traveling from control unit A to control unit B and vice versa also changes. In this example, we will consider a temperature increase TINC; however, a general temperature change can also be analyzed using an analogous method. This method can be based on Ethernet. Therefore, a temperature change, and thus a temperature increase TINC in cable K, affects message or signal transmission equally in both directions, i.e., from control unit A to control unit B and from control unit B to control unit A. Consequently, due to the symmetry of the effects on both transmission directions of cable K, the change in propagation time of the transmitted signals or messages is the same in both directions.

[0054] If the temperature rises TINC in cable K, this simultaneously causes a propagation delay in the transmitted messages or signals within cable K. This means, for example, that a message sent from control unit A to control unit B at time t1' as part of the time synchronization protocol implemented in one embodiment of the method may not arrive at control unit B at time t2", but at a later time t2'. Consequently, the message from control unit B to control unit A, which includes the transmission step St2' for transmitting time t2', may only be sent at the later time t3' and not at time t3", and may therefore arrive at time t4' and not t4". As a result, the second message from control unit B to control unit A may also transmit time t3' and not time t3" in a transmission step St3'.Thus, the temperature increase TINC can result in new times t2", t3", and t4", which differ from the times t2', t3', and t4' that would be expected without the temperature increase TINC of cable K. Only t1' can remain the same; therefore, time t1' is the only time that can be independent of the temperature increase TINC of cable K.

[0055] The same principle applies to the configuration in which control unit A acts as the master and control unit B as the slave, and in which, in addition to the previously described configuration, the time synchronization protocol can also be implemented accordingly. Thus, a message or signal can be transmitted from control unit B to control unit A via the cable at time t5', whereby this message, due to the temperature increase TINC of cable K, cannot be received at time t6", but rather at time t6'.Accordingly, a message containing information about time t6' can be transmitted from control unit A to control unit B via the cable not at time t7", but at time t7'. This message can then be received by control unit B at time t8', not at time t8", where t8" would be the time at which the message would have arrived at control unit B without the temperature increase TINC of cable K. Similarly, in this scenario, the temperature increase TINC of cable K can result in different times t6', t7', and t8', whereas without the temperature increase TINC, the times t6", t7" and t8" would have occurred instead.

[0056] Therefore, the temperature increase TINC can cause changes in propagation times and thus in the measured times in both directions – from control unit A to control unit B and from control unit B to control unit A. Since these changes in propagation times occur in both directions and are symmetrical, the influence of different frequencies of the crystals in control units A and B can be factored out. This allows us to determine the magnitude of the delay resulting solely from the temperature increase TINC of cable K.

[0057] It can be provided that, in the event of indications of a temperature change, the frequency of data exchange—that is, the frequency with which the individual steps of the procedure are carried out—is increased so that more data is available within a certain period. Furthermore, it can be provided that individual measurements are not considered, and thus, as described above, a temperature change is not inferred by comparing the time points between a measurement and a previous measurement (where a measurement includes carrying out the steps of the time synchronization protocol in both scenarios and thus, for example, determining the times t1, t2, t3, t4, t5, t6, t7, and t8). Instead, at least one statistical mean from several measurements is considered and then compared with at least one statistical mean from several measurements.Thus, N measurements can be grouped together, and the statistical means of the time differences t2'-t2 and t6'-t6 from each of these can be considered. These means can then be compared with corresponding statistical means from other M measurements (M can be equal to or different from N, but no measurement may appear in both sets) that were performed later than the previous N measurements. This allows for the analysis of the average change in transit time over several measurements, which can be useful due to the small transit time delay associated with a temperature increase of the cable K.

[0058] Subsequently, by knowing the cable length and the corresponding propagation delay in cable K, the temperature change in that cable can be determined. A characteristic curve can be used for this purpose. Furthermore, if several control units and cables are installed in a vehicle F, by knowing which cables have experienced a propagation delay change and thus a temperature increase, as well as by knowing the cable routing and the positions of the control units, conclusions can be drawn about where in the vehicle F the temperature change occurred and thus which control unit is potentially responsible for the temperature change. This allows for the early detection of a defect in that control unit.

[0059] Furthermore, it may be provided that the procedure is available as an add-on and / or purchaseable and / or selectable function, since only software needs to be retrofitted, while the hardware is already set up to execute the procedure, as it is at least set up to execute a time synchronization protocol.

[0060] Overall, this embodiment demonstrates a method for detecting overheating of the cable harnesses or at least one cable by means of at least one software-based synchronization measurement. A particularly preferred embodiment is given below: While it is technically quite simple to shut down at least one control unit in case of problems, this can have undesirable functional consequences, as the unit may be used for automated driving, for example to fuse sensor data or perform calculations. The earlier a fault can be detected, the better, because then safety measures can still be initiated (such as an emergency stop).

[0061] For automated and electric driving, the demands on the reliability of all subsystems increase. Extended diagnostic functionality plays a crucial role in ensuring the reliability of at least one subsystem. This requires the secure and error-free exchange of diagnostic data. A key challenge in the coming years will be the secure and reliable transmission of status information (such as errors) and the redundant provision and transmission of this data. This will necessitate the development of new network management concepts that maintain a comprehensive overview of the system at all times – potentially even from the cloud.

[0062] The known solutions (plug-in fuses, efuses) are very expensive. Furthermore, none of these solutions can detect changes; instead, each activates only when a certain threshold is exceeded. This means that each of the existing solutions (especially the plug-in fuses) heats up when the resistance increases and, at a defined point, burns out, thus disconnecting the circuit. If an overvoltage / problem develops slowly, it will only become apparent with this solution once a threshold is reached.

[0063] Plug-in fuses and eFuses are both hardware-based solutions. Flexibility or "readjustment" is not possible. Further information, such as monitoring, cannot be obtained.

[0064] This embodiment describes a novel mechanism by which a temperature change, in particular a temperature change in the cable harness or in at least one cable, can be observed and / or detected. A hardware-supported time synchronization protocol can be used to detect changes in synchronization, in particular time synchronization, and then, by means of analysis, to draw conclusions about the cable harness or the at least one cable.

[0065] An Ethernet-based protocol for time synchronization is implemented using the IEEE 802.1AS protocol. In this protocol, a crystal in each ECU provides the clock signal to a PLL, which is then synchronized by software to the best clock in the network or among the control units in the vehicle. This protocol is already used in vehicles for synchronizing clocks and crystals and therefore does not need to be reimplemented or specified.

[0066] The physical properties of a quartz crystal and its quality, as well as the wiring harness or at least one cable, which exhibits altered properties due to temperature and age, are crucial for the accuracy of time synchronization (e.g., PTP). For a small network (e.g., up to 7 links between measuring stations, where a measuring station can be understood as a control unit and a link describes a connection between two ports on control units via a cable), time synchronization can achieve an accuracy in the nanosecond range. The invention disclosure utilizes the physically inherent "weaknesses" of the cable (where the cable can be made of copper, for example, or be an optical fiber), meaning that the cable reacts to temperature changes with a change in propagation time.

[0067] The basic principle of this embodiment of the method is as follows: in this embodiment, propagation delay measurements are performed by means of message or signal exchange between two control units. Using these messages and their hardware arrival times, the link can be measured bidirectionally, i.e., in both directions, between the control units. This requires successive measurements, which is referred to here as monitoring.

[0068] The first step involves identifying the links on which the measurement can and / or must be performed. For example, a control unit might have more than one Ethernet port, meaning more than one cable connection. The procedure can then be carried out independently on each of the necessary ports. Furthermore, it can also be initiated remotely from a central component.

[0069] In this process, at least one PDelay_Request message (the first message from one control unit to another) is sent via the link. Fig. For example, this is the message transmitted from control unit A to control unit B at time t1, or the message transmitted from control unit B to control unit A at time t5. The link partner, i.e., the other control unit, responds with at least one PDelay_Response and at least one PDelay_Response_FollowUP message, provided it supports the protocol or is capable of doing so. These two messages are the responses of the other control unit to the first message from the first control unit, during which the times t2 and t3, and t6 and t7, respectively, are transmitted via transmission steps St2 and St3, and St6 and St7.

[0070] If no measurements are yet available or the last measurement was too long ago, the measurements can be repeated cyclically and / or at short intervals. Alternatively, the measurements can also be repeated continuously cyclically or at short intervals. The measurement in this context refers to the exchange of messages between the two control units, during which the various times of arrival and transmission of specific messages are recorded. For this purpose, the default value from the IEEE 802.1AS time synchronization protocol, which is one measurement per second, is suitable. The time synchronization protocol allows the frequency offset relative to the control unit's own clock, or the frequency offset between the crystals of the two control units, to be measured.

[0071] If the steps described above are performed by only one link partner, i.e., only in one direction or only for one configuration and not for both configurations of the control units, then only the frequency offset of the link partner relative to its own clock (i.e., between the crystal of one control unit and the crystal of the other) can be measured, but no conclusions can yet be drawn about the cable. Therefore, the analysis is expanded by combining the link measurements from both directions and calculating the deviations. This means that the measurement is performed in both configurations and the results are combined. For this, a precise time assignment is necessary. To achieve this, it is checked whether both t2'-t2 and t6'-t6 are smaller than the corresponding value of the next measurement.Only in this way can the quartz crystal be excluded or factored out, and conclusions drawn about the cable or a temperature change within the cable. A cable used in a vehicle that heats up due to overvoltage, especially with copper, has a symmetrical effect on both link partners, i.e., both control units, since in the case of Automotive Ethernet there are no separate wire pairs for RX and TX as with Gigabit Ethernet, but rather both cables (twisted pair) are used.

[0072] The data is then analyzed after determining the link properties, such as type and / or length, which allows conclusions to be drawn about the cause.

[0073] It can be implemented that the frequency is adjusted when a temperature change is detected. This ensures that, for example, an overvoltage and / or a cable that is heating up (i.e., a cable undergoing a temperature change) can be detected. Based on the slope and a predicted change at the next measurement time, a decision can be made as to which new frequency should be selected for the measurement.

[0074] In particular, the default value of one second, as defined by the time synchronization protocol, especially the IEEE 802.1AS protocol, may no longer be sufficient. Frequency adjustment of the propagation delay measurements, i.e., adjusting the frequency of measurements within a specific time period, can be activated, for example, when a predefined threshold or slope is exceeded. Starting with the normal interval, i.e., using the frequency specified by the time synchronization protocol for the measurements, is preferable to avoid overloading the bus system with measurements, as messages are already being sent in at least one direction due to the execution of the time synchronization protocol.

[0075] As the cable temperature increases, the propagation delay, and therefore the spacing between incoming Pdelay messages, can increase. The distance between t2 and t2', as well as between t6 and t6', can thus increase with each measurement. In a purely theoretical case, the NRR (neighbor rate ratio) can still be at the ideal value of 1, which can mean that both crystals are traveling at the same speed. A monitoring component, which can be part of control unit A and / or control unit B, can detect that the delays occur on both sides. A single link partner, i.e., when measuring in only one direction or when measuring only one configuration, cannot detect this.

[0076] If (t2'−t2)<(t2˜−t2') If the same applies in the other direction, then there is an increase in propagation delay. If the change or increase is the same on both sides, the cause can be traced back to the cable, which is associated with a higher temperature.

[0077] The formula refers to Fig. Figure 2, in which, for the sake of simplicity, only one direction is shown with control unit A as slave and control unit B as master. The other configuration results from the following: Fig. 1 in an analogous manner. Here, the embodiment of the method is extended by a further step in which another measurement is taken at a temperature increase TINC, which again differs from the previous measurement. Here, too, an exchange of messages or signals can take place analogously to the previous description, with the first message at time t1˜ is sent and at the time t2˜ arrives, while under the conditions at the beginning of the measurements, especially under the temperatures prevailing at time t1 in cable K, the message at time t2'˜ would have arrived. Accordingly, the responses from control unit B to control unit A are transmitted using the following steps. St2˜ and St3˜ for the transmission of the times t2˜ and t3˜ sent, so that the first response with transmission step St2˜ at the time t3˜ and not at an earlier time t3'˜ is sent and accordingly at the time t4˜ and not at an earlier time t4'˜ arrives.

[0078] The method for monitoring the wiring harness, or at least one cable, can be offered as a service (e.g., via SOMEIP) in the Ethernet network. A central component can handle this task and perform the calculations. Information about the links, i.e., the connections between the control units, can either be read from a database or determined using other methods.

Claims

[1] Method for measuring a temperature change (TINC) in a cable (K) of a vehicle, wherein the cable (K) connects at least two control units (A and B) of the vehicle, the cable (K) is configured at least to transmit signals between the control units (A, B), and each control unit (A, B) includes a crystal for time measurement, wherein this time measurement is configured to determine a hardware time of the control unit (A, B), where It is taken into account that a temperature change (TINC) of the cable (K) slows down the transmission of the signals carried through the cable (K), and To measure the temperature change (TINC), a measurement of the transit time change of at least one signal between the control units (A and B) is carried out, whereby a. To synchronize the hardware times of two control units (A and B), an Ethernet-based time synchronization protocol is used, in which one control unit (A, B) is a master and the other control unit (B, A) is a slave, the hardware time of the slave (B, A) is synchronized with the hardware time of the master (A, B), and to distinguish whether measured values ​​obtained from the measurement originate from the crystal of at least one control unit (A, B) or have resulted from the temperature change (TINC) of the cable (K), control unit (A) and control unit (B) each assume the role of master (A, B) once during one execution of the steps specified by the time synchronization protocol, thus the measurement is carried out in two configurations, while the other control unit (B, A) assumes the role of slave.and a delay in the arrival of the messages in both constellations is inferred from the temperature increase (TINC) of the cable (K) and / or, b. To detect an average temperature change (TINC), a number N of sets, each with at least one measured value, are compared, wherein at least a part of the time window during which the measured values ​​were obtained is divided into N intervals, and each measured value of an i set from the N sets was obtained at a time point which lies in the i interval of the considered part of the time window, a point representative of the measured values ​​of each of the N sets is determined, these points are arranged such that the representative point of set i is positioned on a time axis before the representative point of set i+1, and an average temporal change of temperature (TINC) is determined from this and / or c. a temperature-changing control unit (A, B) can be inferred from the knowledge of a cable routing in the vehicle and from the knowledge of the temperature change (TINC) in at least one cable (K) whose cable routing is known. [2] Method according to claim 1, wherein the time synchronization protocol is the IEEE802.1AS protocol. [3] Method according to one of the preceding claims, wherein at least one quantity is included which influences the temperature of the vehicle and thus also the temperature change (TINC) of at least one cable (K) in the vehicle. [4] Method according to claim 3, wherein at least one of the following quantities shall be considered as the temperature-influencing quantity: • the engine speed • the setting and / or use of the air conditioning system • the heating setting • the engine temperature • the temperature of the cooling water • the engine speed • the power generated in the engine • the speed of the vehicle • the battery temperature • the change in the position of the accelerator pedal. [5] Method according to claim 3 or 4, wherein the outside temperature is taken into account when considering the change in runtime. [6] Method according to claim 5, wherein at least one control unit of the vehicle is still in the process of starting up. [7] Method according to one of the preceding claims with reference to claim 1a, wherein the data from the time synchronization protocol are used and additionally only such signals are produced which result from the use of both constellations instead of only one constellation, whereby the data exchange is carried out in the form of signals with the same frequency and at the same time as the data exchange for the time synchronization protocol. [8] Method according to claim 7, wherein the data exchange for time synchronization is carried out at certain intervals based on the time synchronization protocol, but additional data exchange to increase the frequency of measurement takes place when a temperature change (TINC) is detected which exceeds a predetermined threshold. [9] Method according to any of the preceding claims, wherein a warning signal is issued upon detection of a temperature change (TINC) and / or upon exceeding a threshold value. [10] Method according to one of the preceding claims, wherein, based on knowledge of a cable routing in the vehicle and knowledge of the temperature change (TINC) in at least one cable (K), the cable routing of which is known, a temperature-changing cable (K) is inferred. [11] Vehicle comprising at least one cable (K) and at least two control units (A, B) which is configured to perform the method according to any of the preceding claims.

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