Methods for identifying sensors on a bus by a control unit, as well as a control unit

Abstract

Method for identifying temperature sensors (201, 202) on the exhaust system of a vehicle by means of a control unit (220), wherein the temperature sensors (201, 202) are connected to the control unit (220) by means of a bus (210), wherein at least a first temperature sensor (201) and a second temperature sensor (202) send physical payload data to the control unit (220) via the bus (210) and wherein the physical payload data is evaluated by the control unit (220) for controlling a function, characterized in that - the physical data of the first temperature sensor (201) and the second temperature sensor (202) are compared with each other and / or with predefined expected values ​​and - the identification of the first temperature sensor (201) and the second temperature sensor (202) by the control unit (220) is carried out by comparison and on the basis of differences in the physical data characteristic of the first temperature sensor (201) and the second temperature sensor (202).

Description

State of the art

[0001] The invention relates to a method for identifying sensors on a bus by a control unit and a control unit.

[0002] Bus systems for connecting sensors in automotive applications are still relatively uncommon. However, such systems will be used more frequently in the future due to their numerous advantages. For a sensor to be used in such a system, it must be uniquely identifiable; otherwise, the control unit cannot distinguish which signal originates from which sensor. Defining a sequence via the bus topology is theoretically possible (first sensor on the bus, second sensor, etc.), but such a daisy-chain configuration leads to complex wiring, which is precisely what a bus system is designed to avoid. A favorable star topology is therefore not possible. In the case of multiple identical or similar sensors on a single bus, logistically complex (poka-yoke) or technically demanding (wiring) solutions must be employed to ensure unambiguous identification.

[0003] In the prior art DE 100 23 355 A1 it is disclosed that identical acceleration sensors used at different locations on the same bus are identified by the respective signal which they send to a control unit, wherein the signal is generated by generating mechanical vibrations in the vicinity of each identical acceleration sensor during an addressing phase for the purpose of addressing.

[0004] US Patent 5,401,956 A discloses a system for diagnosing an optical sensor. In this system, sensors on a bus are identified by comparing sensor data with expected values.

[0005] From DE 10 2005 008 977 A1, a method for transmitting sensor data for secure identification is known. In this process, the sensors generate identifiers and transmit these, along with data values, to a control unit for identification purposes.

[0006] US Patent 7,039,507 B2 discloses a device for diagnosing a vehicle. A processor on board the vehicle monitors sensors to determine the vehicle's condition.

[0007] US Patent 7,324,891 B2 discloses a method for controlling an internal combustion engine. This method involves reading two pressure sensors and identifying the defective sensor if the signals from the two pressure sensors differ.

[0008] From the subsequently published DE 11 2009 003 536 T5, a method and an arrangement for identifying wireless sensors are known. In this method, the sensors can be identified based on an expected property of the sensor signal. Disclosure of the invention

[0009] The present invention is based on the objective of providing a method for identifying temperature sensors on the exhaust system of a vehicle that does not require complex wiring.

[0010] The problem is solved by the method according to claim 1. Advantageous further developments are the subject of the dependent claims. Advantages of the invention

[0011] The invention according to the independent claims relates to a method for identifying sensors on a bus by a control unit, as well as a control unit and a sensor for this purpose. The invention makes it possible to identify sensors, in particular sensors of the same type or construction, on a common bus based on the characteristics of their physical data, thus eliminating the need for complex logistics beforehand to mark the position of each sensor. It also eliminates the need to generate signals specifically for addressing purposes in order to identify the sensors. This therefore discloses a particularly simple and thus cost-effective identification method for sensors on a bus.

[0012] Further advantages and improvements result from the characteristics of the dependent claims.

[0013] In an advantageous embodiment, the control unit compares the physical user data with predefined expected values ​​and identifies the sensors based on this comparison. This embodiment has the advantage that control units typically possess means that are also suitable for use according to the invention, such as memory or access to memory to store the expected values, as well as means to perform a comparison of the physical user data with each other and / or with the expected values, e.g., a processing unit. Therefore, no or only minimal additional effort is required to implement the invention in this embodiment with existing components.

[0014] Another advantageous embodiment assumes that each sensor compares the physical data with predefined expected values, that the transmission of the physical data to the control unit occurs in a characteristic time sequence based on this comparison, and that the control unit identifies the sensors based on this characteristic time sequence. This advantageously shifts the comparison process according to the invention to the sensors themselves, and the temporal sequence of sensor messages avoids potential congestion or collision problems. This embodiment can be particularly advantageous, for example, if the sensors for the intended application already possess the means to implement the inventive procedure without additional upgrades or at least with minimal additional effort.

[0015] Furthermore, depending on the process, it may be useful to compare the values ​​of the physical data from the sensors with each other and / or with the predefined expected values, or with the time course of a value of the physical data, at specific times, or to perform a combined comparison. This approach allows sensors to be identified not only based on characteristic values ​​of the physical data but also based on characteristic trends of this data, thus enabling a very flexible method.

[0016] Advantageously, the specific points in time at which the comparison of the physical data takes place can be predetermined by a state of the controlled function. This allows, firstly, the characteristic expected values ​​for specific situations (i.e., the specific states of the controlled function) to be stored, enabling particularly unambiguous identification. Such an approach thus makes it possible to compare the physical data depending on the functions controlled by the control unit or at least those registered by the control unit or sensor. Secondly, it can be advantageous to trigger identification at specific points in time (for example, at the start of a device), so that an unambiguous identification is then established (e.g., from the start).

[0017] In a further advantageous embodiment, the specific times are determined not by the controlled function but by a loss of identification information. This makes it possible to initiate an immediate re-identification in the event of identification loss (for example, due to EMC interference), thus ensuring trouble-free operation even in such cases.

[0018] The invention presented is particularly advantageous in the case of several sensors of the same type (e.g., only temperature sensors or only pressure sensors) or several sensors of the same construction (e.g., identical temperature sensors or identical pressure sensors), since in these cases, identifying or indicating the position on the bus of the respective sensor in advance is particularly complex according to the prior art, and thus the greatest savings in effort and costs through the invention occur in such cases. Drawings

[0019] Exemplary embodiments of the invention are shown in the drawings and explained in more detail in the following description. The drawings are merely illustrative and do not limit the general concept of the invention. In the drawings, reference numerals with two identical final digits denote identical or similar elements.

[0020] They show: Fig. 1 a non-inventive implementation using pressure sensors on an intake manifold in a motor vehicle, Fig. 2 an embodiment using temperature sensors on an exhaust system in a motor vehicle. Description of the exemplary implementations

[0021] Fig. Figure 1 shows a non-inventive implementation of the described method using pressure sensors on the intake manifold of an internal combustion engine with a turbocharger. Two identical pressure sensors 101 and 102 are used, which are connected to a control unit 120 via a star-shaped bus 110. The pressure sensors 101 and 102 are installed on the intake manifold 130, pressure sensor 101 upstream of the throttle valve 131 of the intake manifold 130, and pressure sensor 102 between the throttle valve 131 and the internal combustion engine 140. Thus, pressure sensor 101 measures the pressure upstream of the throttle valve 131 (boost pressure), and pressure sensor 102 measures the pressure between the throttle valve 131 and the internal combustion engine 140 (intake manifold pressure). The pressure data from these measurements are communicated by the pressure sensors 101 and 102 via the bus 110 to the control unit 120, whereby the control unit 120 uses these physical data to control functions, e.g., it is involved in the engine control of the internal combustion engine 140.

[0022] Since both pressure sensors 101 and 102 are identical in construction and connected to the control unit 120 via a bus line 110, the question arises as to how to address the pressure sensors 101 and 102, or rather, how the control unit 120 can detect them. It is proposed that the control unit 120 identify the sensors 101 and 102 on bus 110 based on the physical data, in this case, pressure data. To do this, the control unit 120 compares the received data, i.e., the pressure data required for control, from pressure sensors 101 and 102 with predefined expected values ​​and uses this comparison to identify the positions of the pressure sensors 101 and 102 on the intake manifold 130.

[0023] During the start-up of the combustion engine 140, with the throttle valve 131 typically largely closed, sensors 101 and 102 can be identified based on the characteristics of the pressure data for boost pressure and intake manifold pressure: The pressure in the intake manifold 130 between the throttle valve 131 and the combustion engine 140 drops sharply, while the pressure upstream of the throttle valve 131 remains almost constant. This allows for the assignment of the respective sensor signal, even though the two sensors 101 and 102 may differ only by a different serial number and are otherwise identical.

[0024] In this example, the control unit 120 stores the expected pressures and their expected time profiles at the positions "before the throttle valve 131" and "between the throttle valve 131 and the combustion engine 140" as expected values ​​for comparison with the physical data (pressure values). By comparing the received pressure values ​​with these expected values, particularly at specific times defined by the controlled function (here, the engine control unit), pressure sensor 101 can be assigned to the position "before the throttle valve 131" and pressure sensor 102 to the position "between the throttle valve 131 and the combustion engine 140," and corresponding identification and addressing by the control unit 120 can then take place.

[0025] In Fig. Figure 2 shows, as an embodiment in which identification according to the invention is advantageous, the use of temperature sensors on the exhaust system of a motor vehicle. Two identical temperature sensors are designated 201 and 202, which are used on the exhaust system 270 for temperature measurement and are connected to a control unit 220 via a bus 210. The temperature information is transmitted from the sensors 201 and 202 to the control unit 220 via the bus line 210, which controls a function in the motor vehicle, e.g., is involved in engine control. By controlling the sensors 201 and 202 in the exhaust system 270 in this way with a bus 210, e.g., a digital bus system PSI5, cable length, number of connectors, and installation space are saved. In the present embodiment, for example, an ASIC is installed in the connector of the temperature sensor, which converts the typically analog resistance or voltage signal of the temperature sensors into a digital signal.The signal line to the control unit consists, for example, of two wires for the power supply of the ASIC and the signal transmission via current modulation.

[0026] How to Fig. As described in the case of pressure sensors 101 and 102, it is also the case in the example in Fig. 2. It is advantageous to use identical sensors for both temperature sensors 201 and 202 on the exhaust system 270 in order to save (primarily logistical) effort. However, the various temperature sensors 201 and 202 along the exhaust system 270 must be uniquely identifiable via bus 220. Addressing the temperature sensors 201 and 202 is possible by validating the temperature signals, in particular by comparing the temperature signals with expected values, essentially as a kind of self-arbitration.

[0027] During a cold engine start, for example, the installation position on the exhaust system 270 is detected based on reaching a specific, application-dependent temperature threshold. Only when this temperature threshold is exceeded does the ASIC activate the respective sensor 201 or 202, and the address alignment with the control unit 220 takes place. For a warm start with an undefined temperature distribution along the exhaust system (e.g., a warm start after a previous diesel particulate filter regeneration), the temperature profile over time is used as a second criterion. For this purpose, for example, exceeding a relative temperature threshold, based on the initial temperature at engine start, is used for address assignment: Regardless of the temperature distribution along the exhaust pipe 270 for the stationary vehicle during a warm start, the temperature rise of, for example, 20 K, i.e.,The time at which the threshold (T_before_engine_start + 20K) is exceeded occurs sequentially along the exhaust manifold 270. As in the cold start scenario described above, sensor 201 or 202 reports its status after exceeding the threshold (which varies depending on the initial conditions) and is assigned an address (the first sensor is identified as position 1, the second as position 2, and so on along the exhaust manifold 270). Due to the relative inertia of the temperature profile in the exhaust manifold 270 (the time for temperature jumps is on the order of a few seconds) compared to the time required for address assignment by the control unit 220 (on the order of a few milliseconds), address conflicts are avoided during sensor assignment.

[0028] In the Fig. In the example shown, bus 210, as described, is preferably a PSI5 bus. This PSI5 bus is based on the principle that within a message frame initiated by a synchronization pulse sent by the control unit 220 (master), each sensor 201, 202 (slaves) is assigned its own timeslot for its messages to the control unit 220. Since these messages are encoded via current modulation, only the control unit 220 (the master) can receive their content. Before self-arbitration, the sensors 201, 202 are unaware of their assigned timeslots. Therefore, once the temperature criterion described above is reached, the sensors 201 and 202 initially transmit on an additional timeslot (e.g., the first one), which is reserved solely for arbitration and remains unused after its completion. The control unit 220 acknowledges such measurement data on the arbitration channel (or...).Arbitration time slot) with a channel assignment via the ECU-to-sensor channel, which, according to the PS15 specification (option for bidirectional PSI5 variants), is implemented by targeted suppression of individual synchronization pulses. After EMC disturbances that, for example, reset only individual sensors 201 or 202 of the bus, the ECU 220 can detect the situation based on the absence of messages on certain assigned time slots and messages on the arbitration channel and react accordingly with time slot assignments. A prerequisite for the success of this... Fig. The feature described in section 2 of the embodiment of the method according to the invention, when more than one sensor is affected by the EMC interference, is that, for example, characteristic temperature values ​​or characteristic temperature profiles over time are present or triggered after such an EMC interference.

[0029] In the Fig. In the schematically illustrated embodiment 2, the comparison in the control unit 220 is not made with expected values ​​for the temperature values ​​of temperature sensors 201 and 202 or the time course of the temperature values ​​of temperature sensors 201 and 202, but rather the decisive factor is the time sequence in which the temperature values ​​reach the control unit 220. This sequence, in turn, depends on the temperature values ​​registered in sensors 201 and 202 or the time course of the temperature values ​​registered in sensors 201 and 202. For example, by exceeding certain threshold values ​​or by certain value curves, first one of the sensors 201 and 202, and then the second of the sensors 201 and 202, is enabled for bus communication via bus 210.The control unit 220 has now stored expected values ​​for this timing of the incoming communication from sensors 201 and 202 and can address sensors 201 and 202 by comparing the timing of the incoming sensor data with the expected timing.

[0030] Here, the identification of sensors 201 and 202 is again achieved by comparing the physical data (here, the temperature data required by control unit 220 for control purposes) with predefined expected values. The comparison values ​​can relate to the value of the physical data, its temporal progression, or both. In contrast to, for example, Fig. 1 In this example, the comparison according to the invention is not carried out by the control unit 220 but by the sensors 201 and 202. The control unit 220 then identifies the sensors 201 and 202 based on the resulting time sequence of the bus registration of the sensors 201 and 202.

[0031] There are various possibilities for the timing of the comparison according to the invention. In the description of Fig. 2. For example, in the case of a motor vehicle, engine start times (cold start or warm start) are primarily mentioned. However, the comparison according to the invention can also be carried out when re-identification is necessary in the event of lost identification information (EMC influences) or at certain other times, which are preferably determined based on the controlled function. This is particularly the case if certain characteristic values ​​or value profiles are expected at these times, or if expected values ​​of the sensor data or the temporal sensor data profiles corresponding to these times are stored in the control unit for comparison. Thus, such a procedure makes it possible to compare the physical data depending on the functions controlled by the control unit or at least registered by the control unit or the sensor.Alternatively, a continuous comparison of the physical usage data with expected values ​​can be carried out, e.g. to constantly verify a successful identification.

[0032] The exemplary embodiments described how the physical data from the sensors is generated using predefined expected values, e.g., stored in the control unit or the sensors themselves. Additionally or alternatively, it can also be advantageous to compare the physical data from the different sensors with each other to achieve identification.

[0033] Naturally, identification according to the invention is also possible for more than two sensors and is particularly advantageous for larger numbers of sensors. Furthermore, only structurally identical sensors were used in the exemplary embodiments. However, the method is also conceivable for identifying not structurally identical, but only similar types, e.g., only temperature sensors.

[0034] The sensors are identified in both examples (description of Fig. 1 and description of Fig. 2) due to the characteristic values ​​or the characteristic time-dependent value profile of the physical data. Compared to the state of the art, there is no need to equip identical sensors with position data through complex logistics, nor to generate signals or data specifically for sensor identification.

Claims

[1] Method for identifying temperature sensors (201, 202) on the exhaust system of a vehicle by means of a control unit (220), wherein the temperature sensors (201, 202) are connected to the control unit (220) by means of a bus (210), wherein at least a first temperature sensor (201) and a second temperature sensor (202) send physical payload data to the control unit (220) via the bus (210) and wherein the physical payload data is evaluated by the control unit (220) for controlling a function, characterized by , that - the physical data of the first temperature sensor (201) and the second temperature sensor (202) are compared with each other and / or with predefined expected values ​​and - the identification of the first temperature sensor (201) and the second temperature sensor (202) by the control unit (220) is carried out by comparison and on the basis of differences in the physical data characteristic of the first temperature sensor (201) and the second temperature sensor (202). [2] Method according to claim 1, characterized by , that the control unit (220) compares the physical data of the first temperature sensor (201) and the second temperature sensor (202) with each other and / or with predefined expected values ​​and that the control unit (220) identifies the first temperature sensor (201) and the second temperature sensor (202) by comparing the physical data with the predefined expected values. [3] Method according to claim 1, characterized by, that at least the first temperature sensor (201) and the second temperature sensor (202) compare the physical payload data with predefined expected values, that the sending of the physical payload data to the control unit (220) takes place in a characteristic time sequence as a result of the comparison, and that the control unit (220) identifies the first temperature sensor (201) and the second temperature sensor (202) based on the characteristic time sequence. [4] Method according to any of the preceding claims, characterized by , that at certain times a comparison of a value of the physical user data takes place. [5] Method according to any one of claims 1-3, characterized by , that at certain times a comparison of a temporal progression of a value of the physical user data takes place. [6] Method according to claim 4 or 5, characterized by that the specific times are determined by the states of the controlled function. [7] Method according to claim 4 or 5, characterized by that the specific times are determined by a loss of identification information. [8] Method according to any of the preceding claims, characterized by , that the first and second temperature sensors (201, 202) are sensors of the same type or construction. [9] Control unit (220) which is configured to perform the method according to any one of claims 1 to 8.

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