Method for operating a sensor arrangement in a motor vehicle based on a DSI protocol

Abstract

Method for operating a sensor arrangement (2) in a motor vehicle (1) based on a distributed system interface protocol, wherein - the sensor arrangement (2) comprises a central unit (3) as master and a plurality of sensor units (S1, S2, S3) as slaves controlled by the master, - the central unit (3) and the sensor units (S1, S2, S3) are connected to a bus line (4) and - communication takes place between the central unit (3) and the sensor units (S1, S2, S3) via the bus line (4), characterized by the following process steps: - Sending a message from the central unit to the sensors (S1, S2, S3) that prohibits the sensors (S1, S2, S3) from sending a reply message (A1, A2, A3) to a message (F1, F2, F3) received from the central unit, - Sending a first message (F1) from the central unit (3) to a first sensor (S1) and subsequently - Sending a second message (F2) from the central unit (3) to a second sensor (S2) without waiting for the central unit (3) to receive a reply message (A1) from the first sensor (S1). the sending of the second message (F2) is started immediately after the sending of the first message (F1) is completed, where the first sensor (S1) does not send a reply message (A1) upon receiving the first message (F1), and wherein the messages (F1, F2) sent by the central unit (3) to the sensors include various payload data.

Description

[0001] The invention relates to a method for operating a sensor arrangement in a motor vehicle based on a DSI protocol, wherein the sensor arrangement comprises a central unit as master and a plurality of sensor units as slaves controlled by the master, the central unit and the sensor units are connected to a bus line, and communication between the central unit and the sensor units takes place via the bus line. The invention further relates to the use of such a method in a motor vehicle, a sensor arrangement, and a motor vehicle with such a sensor arrangement.

[0002] In the automotive sector, the DSI3 bus and the DSI protocol can be used for communication with sensors in vehicles. The DSI protocol (Distributed System Interface), see: DSI3 Bus Standard, Revision 1.00 dated February 16, 2011, the specification of which is hereby explicitly incorporated into the disclosure of the present invention, is a protocol that allows a sensor network to be built using simple two-wire cabling, in which a master communicates with one or more slaves via a bus line. The DSI protocol is primarily intended for use in motor vehicles to query and / or control multiple slaves, particularly sensors and actuators, using the master.

[0003] The DSI protocol specification stipulates that such a sensor array can be operated in one of two operating classes: the "Signal Function Class" and the "Power Function Class." Furthermore, the protocol provides for three fundamentally different types of bus usage between the master and the slaves: • In CRM mode (Command and Response mode), bidirectional communication takes place between the master and the slaves. The master sends a command, to which the slaves respond. This method is used, for example, to configure the slaves or to query specific values ​​from a slave.

[0004] In PDCM (Periodic Data Collection Mode), the slaves transmit comparatively large amounts of data to the master within a predefined time slot. The master's transmission activity is limited to providing the slaves with a reference point for determining this time slot via a synchronization signal (Broadcast Read Command). The slaves have already been pre-configured with information about their respective time slot, enabling them to determine their transmission interval in response to the synchronization signal and, based on this, send their sensor data to the master.

[0005] During the power phase, comparatively large amounts of electrical energy are transferred to supply the slaves with high energy demands with sufficient energy.

[0006] The Signal Function Class (SFC) mentioned above, as specified above, primarily serves to connect low-power slaves with a comparatively high data throughput that must be transmitted from the slave to the master. After commissioning a sensor array of the SFC, an initial communication phase takes place between the master and the slave in CRM mode. During this phase, the slave is typically configured, for example, with regard to the parameters of its PDCM time slot. Once this phase is complete, the sensor array transitions to PCDM mode. In this mode, the slaves transmit the acquired data to the central instance in their respective assigned time slots, always in response to the master's synchronization signal. This PDCM phase is typically maintained until the sensor array is deactivated.A power phase is not provided for according to the Signal Function Class and is also not required due to the low energy consumption of the slaves.

[0007] The aforementioned Power Function Class primarily serves to connect slaves with comparatively high energy demands and relatively low data volumes to be transmitted from the master to the slave. During the operation of a sensor array of this Power Function Class, communication phases between the master and slave in CRM mode alternate with power phases. The power phases typically predominate. By supplying the slaves with a comparatively high amount of energy during these phases, at a higher voltage compared to CRM mode, actuators in particular can be operated. This is usually based on control commands previously transmitted from the master to the slaves during the CRM phase. According to the Power Function Class, PDCM mode is not used, as it is unnecessary for the aforementioned actuators due to their low data volume.

[0008] In PDCM mode, data transmission follows a fixed scheme defined by the master. Typically, each slave is assigned a fixed time slot, i.e., a predetermined duration relative to a synchronization signal sent by the master, within which the respective slave must transmit data to the master.

[0009] Today's ultrasonic parking assistance systems in motor vehicles are increasingly being integrated into functions that extend beyond the classic parking process. In addition to the cross-functional use of these sensors, such as for automatic braking, reliability and safety classification with regard to ASIL (Automotive Safety Integrity Level) are playing an increasingly important role. In this context, reference should also be made to the ISO 26262:2011 standard "Road vehicles - Functional safety," which represents an internationally valid standard in the automotive sector for electrical and electronic systems of motor vehicles. The ASIL classification is a risk classification system defined in the aforementioned standard, which uses three parameters to determine the level of safety for specific situations.Under certain circumstances, an ASIL level can be determined, from which various classes can be derived, which relate, among other things, to permissible failure probabilities. • ASIL A: recommended failure probability less than 10⁻⁶ per hour • ASIL B: recommended failure probability less than 10⁻⁷ per hour • ASIL C: required failure probability less than 10⁻⁷ per hour • ASIL D: required failure probability less than 10⁻⁸ per hour

[0010] ASIL levels A, B, C, and D are associated with corresponding requirements for the respective system. For example, if the vehicle does not accelerate despite a corresponding request from the driver, only ASIL B applies, while ASIL D generally applies to systems for fully autonomous driving.

[0011] For such functions, and especially for functions based on artificial neural networks (ANNs), a large amount of data must be transmitted from the sensors (slaves) to the electronic control unit (ECU), which contains the central processing unit (master). Regular operation of such a sensor array using an ANN would no longer be guaranteed, for example, if the achievable data rate during transmission from the sensors to the central processing unit is insufficient to transmit all the data required for reliable ANN operation to the central processing unit quickly enough. While the ANN may still be operational with a smaller amount of available data, the reliability of the ANN's output data is then expected to decrease, potentially making it impossible to maintain a specified ASIL level.

[0012] WO 2016 / 054345 A1 describes an ultrasonic system for monitoring the condition or integrity of a structure, such as those used in the oil, gas, or energy generation industries. The system comprises multiple ultrasonic sensors and at least one digital sensor interface.

[0013] German patent DE 10 2013 226 376 A1 describes a method for operating a sensor system with an ultrasonic sensor and a control unit, wherein data from the ultrasonic sensor to the control unit is transmitted via current modulation and data from the control unit to the ultrasonic sensor is transmitted via voltage modulation. This solution, after modification of a corresponding PSI5 data bus interface, allows this data bus and a LIN data bus to be combined for data transmission, thus utilizing the advantages of both bus systems.

[0014] German patent DE 10 2012 103 907 A1 describes a method for operating a receiving unit of a motor vehicle control unit connected to a transmitting unit. The receiving unit adds an identifier to the received signal, which contains a virtual address of the transmitting unit. This can be used to connect a sensor unit according to the PSI5 version 1 standard to a motor vehicle control unit that processes signals in the PSI version 2 standard.

[0015] EP 2 263 102 B1 describes an ultrasound-based driver assistance system with multiple sensors. Each sensor is assigned an individual identification code that can be read by a control unit via an interface. The interface is a 2-wire bus interface designed according to the Peripheral Sensor Interface (PSI) standard.

[0016] German patent DE 10 2017 118 574 A1 discloses a method for optimizing the bandwidth of a DSI protocol sensor array in vehicles. It solves the problem of limited communication time in conventional, rigid "power-supply-communication" cycles, which arises from designing for the most energy-intensive application (worst-case scenario). The core of the invention is dynamic energy management: If a sensor reports a power shortage during communication, the communication phase is temporarily interrupted to insert an on-demand, additional power-supply phase. Communication then resumes. This eliminates the need for an oversized initial power-supply phase, significantly extends the effective communication duration, and increases the data bandwidth.

[0017] DE 10 2017 103 117 A1 discloses an improved method for operating an active sensor arrangement, such as ultrasonic sensors, in a motor vehicle based on the DSI protocol. To overcome the disadvantage of the existing standard, which does not efficiently meet the requirements of active sensors for high power consumption and simultaneously high data throughput, the invention introduces a repeated communication sequence consisting of three phases: a CRM phase for command transmission, a power phase for energy supply, which simultaneously allows the sensor to emit a signal, and a PDCM phase for efficient feedback of the sensor data.In addition, for flexible handling of variable data volumes, for example in the case of multiple echo signals, additional “virtual” time slots (virtual slaves) are defined, which can be dynamically assigned to a real sensor in the CRM phase if required, so that it can send an increased amount of data in the subsequent PDCM phase.

[0018] US Patent 2003 / 0034883 A1 discloses an obstacle detection and communication device for a motor vehicle, comprising a central control unit (ECU) and several ultrasonic sensors installed at predetermined positions on the vehicle. The essential feature of the system is that each ultrasonic sensor has its own independent computing capability, enabling it to fully perform the entire process from emitting ultrasonic waves and receiving echo signals to calculating the distance to an obstacle. It then transmits the calculated digital distance information via a communication bus to the central control unit, which generates an alarm signal based on the received information.

[0019] Furthermore, US 2003 / 0034883 A describes a communication method for automatically assigning a unique identifier (ID) to each sensor (slave) based on the physical connection sequence of the sensors in a daisy-chain topology relative to the master control unit. DE 10 2005 054 390 A1 discloses a driver assistance system in which a control unit is connected to multiple sensors via a bus system configured as a serial shift register. The core of the invention lies in the fact that the system enables efficient and real-time information exchange between the control unit and the sensors by automatically addressing the sensors according to their physical position at startup and by assigning a dedicated bit for each sensor in the data stream.

[0020] The DSI3 bus standard specification discloses a communication protocol known as DSI3 for automotive safety systems, enabling half-duplex communication between master and slave nodes using a command-response method. The protocol is characterized by the use of a voltage-modulated forward channel and a current-modulated reverse channel. It supports various topologies, including daisy-chain connections, and defines an automatic address assignment mechanism. Furthermore, the protocol defines a periodic mode for high-speed data acquisition and a power mode for controlling actuators, ensuring the integrity of all data transmissions through CRC error checking.

[0021] The object of the invention is to specify such a method for operating a sensor arrangement in a motor vehicle in which communication between the master and the slaves is regularly possible with a high data rate while simultaneously ensuring a predetermined ASIL level.

[0022] This problem is solved by the subject matter of the independent patent claims. Preferred embodiments of the inventions are described in the dependent claims.

[0023] According to the invention, a method for operating a sensor arrangement in a motor vehicle is thus provided based on a DSI protocol, wherein • the sensor arrangement has a central unit as master and a plurality of sensor units as slaves controlled by the master, • the central unit and the sensor units are connected to a bus line and • Communication between the central unit and the sensor units takes place via the bus line, characterized by the following process steps: • Sending an initial message from the central unit to an initial sensor and subsequently • Sending a second message from the central unit to a second sensor without waiting for the central unit to receive a reply message from the first sensor.

[0024] When it is stated that this is a procedure based on a DSI protocol, this means that the procedure uses the DSI protocol, but not that the procedure must fully comply with the DSI3 standard. Rather, the procedure can go beyond or extend the standard. Here, a configurable mode for the DSI3 standard is provided, which allows messages to be sent to the various sensors very efficiently, namely in a short time. This mode can be set for specific situations, after which it can switch back to a conventional mode.

[0025] According to the invention, the transmission of the second message is initiated immediately after the transmission of the first message is completed. Even if a reply message is received after the first message is sent, no waiting is made for its receipt. Rather, the second message is sent immediately after the first message is sent, regardless of whether a reply message is received. According to the invention, the first sensor does not send a reply message upon receiving the first message. This provides a mode that, in contrast to the CRM mode described above, saves time by either foregoing a reply message to a message received from a sensor or by not waiting for such a reply message to be received.

[0026] Preferably the following procedural step is provided, which follows the sending of the second message: • Sending another message from the central unit to another sensor without waiting for the central unit to receive a reply message from the sensor to which a message was sent immediately before. An advantageous embodiment is one in which the sending of the further message is started immediately after the transmission of the immediately preceding message is completed. Preferably, the sensor to which a message was sent immediately before does not send a reply message in response to the message it received.

[0027] According to a preferred embodiment of the invention, this method is continued for further sensors. The method is preferably designed such that the process step of sending another message from the central unit to another sensor, without the central unit waiting for the receipt of a reply message from the sensor to which a message was sent immediately before, is repeated at least once for yet another sensor.

[0028] According to the invention, the messages sent from the central unit to the sensors can comprise various types of payload data. Preferably, however, the messages sent from the central unit to the sensors contain configuration commands for the individual sensors.

[0029] Finally, according to the invention, the following process step is provided prior to sending the first message: • Sending a message from the central unit to the sensors, which prohibits the sensors from sending a reply message to a message received from the central unit. This switches the entire system into a mode that, unlike CRM mode, does not require reply messages from the sensors in order to save time, but rather prohibits them.

[0030] According to the invention, the use of a method as described above is provided for in a motor vehicle.

[0031] Furthermore, the invention also relates to a non-volatile, computer-readable storage medium with instructions stored on it which, when executed on a processor, effect a method as described above.

[0032] The invention also relates to a sensor arrangement configured for operation by means of a method as described above. Preferably, the sensor arrangement comprises ultrasonic sensor units for transmitting and / or receiving ultrasonic signals.

[0033] It is therefore within the scope of the invention that the master, for example by sending a configuration message to all slaves, instructs all slaves to behave in such a way that no response is sent to received messages. This allows both the master and the slaves to know whether a CRM mode is in operation, in which a response message from the slaves is requested, or a mode without a response message from the slaves. The mode without a response message enables the rapid sequencing of multiple messages from the master to the slaves.

[0034] This enables rapid configuration of the slaves, resulting in a quick start-up of the entire system. Furthermore, reduced power consumption is advantageous, as no response messages need to be generated. Finally, it is also beneficial that, in the case of an application-specific integrated circuit (ASIC), the master does not require additional memory for response messages from the slaves, making it inexpensive and easy to manufacture. This is particularly advantageous for ultrasonic sensors, as these sensors require a lot of configuration data compared to others, sometimes even during measurement, and have comparatively slow measurement cycles due to the travel time of sound in air.

[0035] The invention is explained in more detail below with reference to the drawings and a preferred embodiment. The features shown can represent an aspect of the invention, either individually or in combination.

[0036] They show • Fig. 1. schematically, a vehicle with a sensor arrangement according to a preferred embodiment of the invention, comprising a central unit as master and three sensor units as slaves in a “daisy chain” configuration and • Fig. 2 a, b schematically compares the CRM mode with a communication mode according to an embodiment of the invention, in which the central unit communicates with sensors without the sensors sending response messages.

[0037] Out of Fig. Figure 1 schematically shows a vehicle 1 with a sensor arrangement according to a preferred embodiment of the invention. The sensor arrangement 2 comprises a central unit 3 and three sensor units S1, S2, and S3. The master 3 and the sensor units S1, S2, and S3 are connected to each other via a bus line 4, which is designed as a two-wire line. Furthermore, the three sensor units S1, S2, and S3 are connected to the central unit 3 in series, i.e., in a so-called "daisy chain" configuration.

[0038] The central unit 3, as defined in the aforementioned DSI3 specification, acts as a master and is connected via bus line 4 to the three sensor units S1, S2, and S3, which function as slaves according to the DSI3 specification, thus forming a bus as defined in the DSI3 specification. Furthermore, the sensor units S1, S2, and S3 are ultrasonic sensor units for transmitting and / or receiving ultrasonic signals and are part of a parking assistance system.

[0039] Communication between the central unit 3 and the sensor units S1, S2, S3 takes place in such a mode as, as shown from Fig. As can be seen, the central unit sends 3 commands F1, F2, F3 to the sensor units S1, S2, S3.

[0040] The mode according to the preferred embodiment of the invention described herein, in which messages are sent from the central unit 3 to the sensor units S1, S2, S3, differs significantly from the CRM mode as described above. For this purpose, Fig. 2a and b are referred to.

[0041] Fig. Figure 2a shows the communication between the central processing unit (CPU) 3 and the sensor units S1, S2, and S3 according to a conventional CRM mode. The diagram illustrates the sequence of how the CPU 3 sends CRM messages CRM1, CRM2, and CRM3 to the sensor units S1, S2, and S3, with a pause between each CRM message. During these pauses, the respective sensor units S1, S2, and S3 send responses R1, R2, and R3 back to the CPU. These responses R1, R2, and R3 can, for example, be confirmations that a command sent by the CPU 3 to the sensors S1, S2, and S3 has been understood. However, the responses R1, R2, and R3 can also provide information about data that has been collected by the sensors S1, S2, and S3. The total communication time for sending the CRM messages CRM1, CRM2, and CRM3 and the responses R1, R2, and R3 is tCRM.

[0042] In Fig. Figure 2b shows the mode according to the preferred embodiment of the invention described herein. It can be seen that only messages CM1, CM2, CM3 are sent from the central unit 3, which are not answered by the sensors S1, S2, S3. Therefore, there are no reply messages for the central unit 3 to detect. Consequently, the messages CM1, CM2, CM3 can be sent immediately one after the other. This takes a total of time tCM, so that the time Δt required to send the messages CM1, CM2, CM3 from the central unit 3 to the sensors S1, S2, S3 is less than in the [reference to figure]. Fig. CRM mode shown in 2a.

[0043] A key feature of the preferred embodiment of the invention described here is that the messages CM1, CM2, CM3 sent to sensors S1, S2, S3 are always intended for only one sensor S1, S2, or S3 at a time. This means that message CM1 is intended by the central unit 3 for sensor S1, message CM2 by the central unit 3 for sensor S2, and message CM3 by the central unit 3 for sensor S3. This distinguishes the mode described here and the messages sent by the central unit 3 from a situation provided for in the DSI3 standard, in which a command designated as a "Global Command" can be sent by the central unit 3 simultaneously to all sensors S1, S2, and S3 without any response from the sensors S1, S2, and S3. This "Global Command" therefore does not allow the sensors S1, S2, and S3 to be addressed individually.This is also reflected in the fact that the command “Global Command” is always associated with address “0” (i.e. “to all”).

[0044] Overall, the mode described here for the preferred embodiment of the invention enables rapid, individual configuration of the sensors S1, S2, and S3, thereby also achieving rapid readiness of the entire sensor arrangement 2. Since no response messages need to be generated by the sensors S1, S2, and S3, power consumption is also reduced, thus providing an efficient way to ensure rapid response to these sensors S1, S2, and S3 in cases where a response from these sensors is not required. Reference symbol list 1 motor vehicle 2 Sensor arrangement 3 Central unit 4 Bus line S1 sensor unit S2 sensor unit S3 sensor unit

Claims

[1] Method for operating a sensor arrangement (2) in a motor vehicle (1) based on a distributed system interface protocol, wherein - the sensor arrangement (2) comprises a central unit (3) as master and a plurality of sensor units (S1, S2, S3) as slaves controlled by the master, - the central unit (3) and the sensor units (S1, S2, S3) are connected to a bus line (4) and - communication takes place between the central unit (3) and the sensor units (S1, S2, S3) via the bus line (4), characterized by the following procedural steps: - Sending a message from the central unit to the sensors (S1, S2, S3) that prohibits the sensors (S1, S2, S3) from sending a reply message (A1, A2, A3) to a message (F1, F2, F3) received from the central unit, - Sending a first message (F1) from the central unit (3) to a first sensor (S1) and subsequently - Sending a second message (F2) from the central unit (3) to a second sensor (S2) without waiting for the central unit (3) to receive a reply message (A1) from the first sensor (S1). the sending of the second message (F2) is started immediately after the sending of the first message (F1) is completed, where the first sensor (S1) does not send a reply message (A1) upon receiving the first message (F1), and wherein the messages (F1, F2) sent by the central unit (3) to the sensors include various payload data. [2] Method according to any one of the preceding claims, characterized by The following procedure step follows the sending of the second message (F2): - Sending another message (F3) from the central unit (3) to another sensor (S3) without waiting for the central unit (3) to receive a reply message (A2) from the sensor (S2) to which a message (F2) was sent immediately before. [3] Method according to claim 2, characterized by , that the sending of the next message (F3) will be started immediately after the sending of the previously sent message (F2) has been completed. [4] Method according to claim 2 or 3, characterized by , that the sensor (S2), to which a message (F2) was sent immediately before, does not send a reply message (A2) in response to the message (F2) it received. [5] Method according to claim one of claims 2 to 4, characterized by, that the procedure step of sending another message (F3) from the central unit (3) to another sensor (S3), without the central unit (3) waiting for the receipt of a reply message (A2) from the sensor (S2) to which a message (F2) was sent immediately before, is repeated at least once for another sensor. [6] Method according to any one of the preceding claims, characterized by , that the messages sent by the central unit (3) to the sensors (S1, S2, S3) contain configuration commands for the individual sensors (S1, S2, S3). [7] Use of a method according to any of the preceding claims in a motor vehicle (1). [8] Non-volatile, computer-readable storage medium containing instructions stored on it which, when executed on a processor, effect a method according to any one of claims 1 to 6. [9] Sensor arrangement configured for operation by means of a method according to any one of claims 1 to 6. [10] Sensor arrangement according to claim 9, comprising as sensor units (S1, S2, S3) ultrasonic sensor units for transmitting and / or receiving ultrasonic signals.

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