EP4268438A1

EP4268438A1 - Method for determining components of a sensor network within an in-vehicle ethernet network in a motor vehicle

Info

Publication number: EP4268438A1
Application number: EP21843878.6A
Authority: EP
Inventors: Helge ZINNER
Original assignee: Continental Automotive Technologies GmbH
Current assignee: Continental Automotive Technologies GmbH
Priority date: 2020-12-01
Filing date: 2021-12-01
Publication date: 2023-11-01
Also published as: US20240007325A1; DE102020215086A1; CN116601924A; WO2022117168A1

Abstract

The invention relates to a method for determining components of a sensor network within an in-vehicle Ethernet network in a motor vehicle between at least two ECU nodes (ECU A, ECU B) and at least one further ECU node (ECU 5 C), wherein at least one ECU node (ECU A, ECU B) responds to a received payload (P1) with a payload (P2) only after a delay, the delay (tBUS) fulfilling the condition tBUS ≥ tB + (tP + tC) n, where tB is a beacon time of the ECU node (A, B), tC is the commit time of the further ECU node (C), tP is the maximum payload at maximum length and n is the number of ECU nodes (A, B, C).

Description

Method for determining components of a sensor network within an on-board Ethernet network in a motor vehicle

FIELD

The present invention relates to a method for determining components of a sensor network within an on-board Ethernet network in a motor vehicle, a control device and an on-board Ethernet network

STATE OF THE ART

With 10 Mbit/s (IEEE802.3ch), in addition to 100 Mbit/s; 1000 Mbit/s and the ongoing multi-gigabit standardization, another Ethernet standard for automotive applications is available.

The new standard differs significantly from the other variants, since its aim is to be able to design Ethernet more cost-effectively and thus also to address simpler control devices. This standard does not require switches (switch ICs) but is designed as a bus similar to CAN. This halves the number of required PHYs (transceivers). In this way, Ethernet becomes a serious alternative to CAN/CAN-FD and FlexRay, as it significantly reduces system costs.

Fig. 1 compares the essential features of Switched Ethernet and "Bus Ethernet" (called MultiDrop). The most important difference is that the resources (the bus access) are exclusively available with Switched Ethernet, which means that each Ethernet node (ECU) can send at any time without collisions occurring. The new Ethernet bus implementation uses a shared medium and bus access must wait for resources to become available.

The PIEEE802.3cg standard uses a newly defined mechanism (PLCA Physical Layer Collision Avoidance) to avoid collisions when accessing the bus and get fair access. Only one PHY (transceiver) gets access to the bus at exactly one point in time. This prevents collisions. Access is designed according to a so-called round robin procedure. Each ECU (node) on the BUS is given the opportunity to send within a defined cycle. A so-called headnode determines the cycle and transmits a "beacon" on the bus per cycle. The nodes start a timer depending on their previously assigned ID (determines the sequence when they are allowed to send) and after this you are allowed to send.

DE 19710971 A1 describes a method for determining the runtime of a telegram between two participants in a bus system, with a first participant sending a telegram to a second participant and after sending the telegram a time measuring device starts - that the second participant immediately after receiving the telegram sends a reply telegram to the first participant and - that the first participant stops the time measuring device upon arrival of the reply telegram and calculates the running time of a telegram from the measured time.

DE 19947657 A1 discloses an operating method for a data bus for multiple participants with flexible, time-controlled access, characterized by the following features, the participants are synchronized, the bus telegrams are sent with a hierarchical transmission sequence by the participants and at least in part only as required, between the participants and A switching element is located on the data bus, which only enables bus access for the respective participant and for as long as the participant is allowed to transmit.

EP 1473864 A1 Method for transmitting data telegrams between at least two radio devices (A, B) and at least one repeater (R), wherein at least one radio device (A, B) responds to a received data telegram (request telegram) only after a delay with a data telegram (response telegram ) answers. DESCRIPTION AND ADVANTAGES OF THE INVENTION

In contrast to a switched network (as with 100/1000... Mbit/s), with 10Mbit/s, as described, the bus cannot be accessed immediately, but the respective point in time must be awaited. Only the headnode (master node which controls the bus) knows the entire bus and the connected nodes (ECUs and sensors). The respective node itself does not know how many nodes are connected to the bus. I.e. he (applies to all nodes) does not know how long the maximum delay will be before he or others are allowed to send (again). This information is helpful because the technology is also being planned in critical areas such as ADAS.

The Ethernet MAC and the above software layers have no information regarding possible and future transmission windows. This causes higher costs in ECU design and planning of the already very complicated communication in the on-board network.

Today's approaches are not yet sufficiently optimized with regard to the possibilities of the dynamic use of software. The planning of communication (e.g. sensor data streams) is essential for the high-precision execution of actions based on sensor data. If no transmission delays or bus access times are specified, then this leads to higher costs in the planning of such systems - the reuse for other platforms is also severely restricted, which in turn increases our implementation costs again.

With semi-automated and highly automated driving, there are increasing demands on the vehicle that require hard real-time support from the transmission network and the protocols (as is already the case today in aircraft or industrial automation). Time synchronization plays an important role in this. The more accurate the time, the better the associated functions such as sensor fusion. Furthermore, a vehicle electrical system will be much more flexible in the future than it is today. Nodes are shut down during operation when they are not are required (this is also called subnetting or partial networking). This in turn means that the vehicle electrical system will change dynamically at runtime. These functions are already being implemented and will be mass-produced for 2020.

The object of the invention is to provide a solution for dealing with variable communication partners involved in the communication in a motor vehicle network.

The object is advantageously achieved by the method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle with the features of claim 1, and the control unit according to claim 4, the Ethernet on-board network according to claim 5, the computer program product according to claim 6, The computer-readable medium of claim 7 and the vehicle of claim 8.

An advantageous embodiment of the method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle, between at least two ECU nodes (ECU A, ECU B) and at least one further ECU node (ECU C), at least one ECU node ( ECU A, ECU B) only responds to a received payload (P1) with a payload (P2) after a delay time, the delay time (tßus) satisfies the condition tßus ^ tß + (tp + tc) n, with tß being a beacon Time of the ECU node (A, B), with tc the commit time of the further ECU node (C), with tp the maximum payload with maximum length and with n the number of ECU nodes (A, B, C). is characterized in that an ECU node (ECU A, ECU B) of the Ethernet vehicle electrical system the length of time of an unused cycle (Zo), in which no payload (P1, P2)) should be sent, by means of a transmit Opportunity Timers (TOT) calculated after calculation of the pure cycle length (TL ), which is determined by the transmission of the beacons time at the point in time tß, through the transmission window of an ECU node (ECU A, ECU B, ECU C) it is calculated what number of nodes n are in the Ethernet vehicle network. An advantageous embodiment of the method according to the invention is characterized in that a detection of the beginning of a new cycle (Zo), a search for the start time of cycle +1 (Zi), it being checked whether between the new cycle (Zo) and the cycle (Zi) a payload (P1, P2) was transmitted, and in a transmission of the cycle (Zi) is set to the cycle (Zo), a dynamic calculation of the cycle length TL takes place.

A particularly advantageous embodiment of the method is characterized in that the number of nodes n of the ECU nodes (ECU A, ECU B) located in the Ethernet vehicle network is determined by the ratio of the cycle length (TL) to the value of the transmit opportunity timer (TOT ) is formed, with the transmit opportunity timer (TOT) being queried beforehand to form the ratio of the cycle length (TL) to the value of the transmit opportunity timer (TOT).

The object is achieved in a particularly advantageous manner by a control unit for an Ethernet vehicle electrical system which, as a first ECU node, is designed as a control unit for sending a signal to a second control unit of the Ethernet vehicle electrical system and receiving the signal from the second control unit; determine a propagation time of the signal on a connection path to the second control unit; determine a maximum speed of the connection path based on the propagation time; and to determine a type of transmission medium of the connection path on the basis of the maximum speed, at least comprises a microprocessor, a volatile memory and non-volatile memory, at least two communication interfaces, one which can be synchronized

Timer, the non-volatile memory contains program instructions when they are executed by the microprocessor, wherein at least one embodiment of the method according to the invention can be implemented and executed.

A further advantageous embodiment of the Ethernet vehicle electrical system for a motor vehicle, with a first control unit and a second control unit, is characterized in that the control units have at least one connection path are connected to one another, and at least the first control unit is designed to carry out the method according to the invention.

A further advantageous embodiment of the Ethernet vehicle electrical system is characterized in that the Ethernet vehicle electrical system has a third control unit which is only indirectly connected to the first control unit and is connected directly to the second control unit via a third connection path, with the third control unit being is designed to determine a transit time of a third signal on the third connection path, the first control unit being designed to trigger the determination of the transit time of the third signal by a service message to the third control unit.

TECHNICAL ADVANTAGES OF THE INVENTION

The quality of the execution of software-based applications (e.g. automated driving, data logger, diagnosis, 5G) can advantageously be increased by the invention, in particular without additional financial outlay. With the use of the newly introduced Ethernet protocol in automobiles, mechanisms are necessary that make use of simple techniques and given properties of technologies in order to be able to do without expensive implementations and other additional hardware. The network system according to the invention is improved in terms of cost and reliability. Continental can use software-based processes to get the best out of its ECU or the network and offer the customer more functionality

The Ethernet technologies are advantageously optimized by the invention in terms of costs and implementation effort for use in the automotive sector.

The advantage of the application-specific determination of a more precise and predictable delay results in an improvement in the planning and execution of communication in the vehicle. As a result, existing bus systems can be better utilized and the jump to an expensive one Technology (bandwidth) can be avoided. This can also have an impact on buffer storage that would otherwise be required, which can then be dispensed with (or designed to be smaller). fusions by accident Data (e.g. camera + radar) can be improved and interpreted more precisely. Furthermore, the logging of data can be made even more precise.

Today applications are sold, tailored and adapted to an OEM or exactly one project. With this invention, methods are presented that allow software development to be more flexible and make the best of the underlying system without having to program it in software beforehand. The invention allows software developers and architects to offer software/applications that can be tailored more flexibly and precisely to the requirements of the application. By incorporating the above processes into software, specific optimization can be carried out in each case. This means that software platforms can be implemented more independently.

In future architectures, a specific application is no longer necessarily linked to a specific control unit, but can also be executed by different control units. If an application is moved, it is necessary to create the appropriate environment for the new scenario, e.g. at least the same quality of clock synchronization.

The new technologies can no longer be stopped in the automobile. Protocols like IP, AVB, and TSN have thousands of pages of specifications and test suites. The controllability of these new protocols in the automotive sector is not directly given. An advantage of this invention is that the current hardware does not have to be changed, but the existing hardware can continue to be used. The new method can be integrated into an existing network without damaging existing devices. The standard is not violated since the existing protocol can be used. Today's vehicle networks are configured statically, ie the data communication (transmitter, receiver and data relationship) is fixed at the latest when the vehicle is programmed at the end of the production line. The upcoming architectures and the desire for service-oriented communication contradict today's approach and call for new concepts. For the next generations after motor vehicle networks, it will not always be clear who the recipient of the data is and which way the data will go. Each recipient can therefore have different requirements for data transmission, e.g. external ECU is in a cloud solution, or it is an unprotected ECU. Therefore, the requirements of the recipient must be addressed dynamically and the data transmission mechanisms must be adapted if necessary. The invention advantageously determines that if the transmission time can be predicted, more precise data can be used, which increases the quality of the sensor data and its fusion.

DRAWINGS

An embodiment of the invention is shown in the drawings and is described in more detail below. Show it:

Fig. 1 Simplified representation of the differences between an Ethernet bus (1 OMbit/s) and a switched network (all other automotive variants such as 100Mbit/s);

2 general method for the dynamic calculation of the maximum delay in the sensor network;

Fig. 3 calculation of the cycle length;

Fig. 4 Calculation of the number of users on the bus. DESCRIPTION OF EXEMPLARY EMBODIMENTS

Fig. 1 shows the simplified differences between an Ethernet bus (1 OMbit/s) and a switched network, which occur in a motor vehicle environment with all other automotive variants such as 100Mbit/s and the ECU nodes ECU-A, ECU- B, ECU-C symbolically represent.

2 represents the general solution to the problem described above. A node (ECU) of the bus, with the exception of the head node, measures the time length of an unused cycle, in which case no user data may be sent. This can be repeated and verified as often as you like. After determining the pure cycle length Ti_, which can be recognized by the transmission of a so-called beacon, the transmission window of an ECU node (ECU A, ECU B, ECU C) can be used to calculate how many participants are on the bus. Finally, the minimum and maximum delay during bus access can be determined dynamically without this being preconfigured.

The invention disclosure proposes a method for determining the minimum and maximum bus access time. After the beacon has been sent, a timer starts, which is only interrupted if other data is received.

If no data, payload is received from other ECU nodes (ECU A, ECU B, ECU C) until the next beacon, then the cycle length can be calculated. This mechanism can and should be repeated dynamically in order to detect dynamic changes in the network or in the on-board Ethernet network or to avoid measurement errors.

After receiving a so-called beacon, the 1st ECU node (ID = 0) typ. 20 bit times to send out data. If it does not do this within this time, the ECU node with the next higher ID is allowed to send, etc. Timers are started for all nodes n so that you know when you can start sending at the earliest. The Transmit_Opportunity is configured the same for all nodes and can be read out locally by the application software from the ECU node (network stack). will. The cycle length TL can then be used for the first time to calculate how many nodes n, ie ECUs, are connected to the network or Ethernet vehicle electrical system. In other words, it can be calculated how many nodes are allowed to transmit before me and how many are allowed to transmit after me.

If, for example, 140 bits is assumed as the cycle length and the Transmit_Oportunity is 20 bits, then it can be calculated independently on each node that exactly 7 nodes are connected to the Ethernet on-board network or bus.

With knowledge of the number of connected ECUs, the minimum and maximum bus access time can be calculated deterministically depending on the ID (position on the bus).

The minimum bus access time is calculated from the beacon time, commit time and the maximum Ethernet payload*number of nodes that have a smaller ID.

The next bus access time (from the moment I sent, so when can I send again) is calculated from the total number of nodes*(maximum payload+commit time) + beacon time.

Since each ECU node has a timer, or it recognizes when the beacon is sent out, the ECU node can use this method to calculate at any time when it is allowed to send again. In the same way, it can be determined when all other ECU nodes are allowed to send again and when one has to adjust to receiving data.

Each ECU node (ECU A, ECU B, ECU C) knows its own ID, which also determines its position on the bus, but no node knows how many nodes are connected to the bus after it. This new insight can be of great use when planning communication, for example when it comes to the design of buffer storage. The information is also helpful to check whether the Data (sensor data) are still valid or new data are already available before the node has the opportunity to send again.

Claims

patent claims

1 . Method for determining components of a sensor network within an Ethernet on-board network in a motor vehicle between at least two ECU nodes (ECU A, ECU B) and at least one further ECU node (ECU C), wherein at least one ECU node (ECU A, ECU B) only responds to a received payload (P1) with a payload (P2) after a delay time, the delay time (tßus) fulfills the condition tßus > tß + (tp + tc) n, with tß being a beacon time of the ECU Node (A, B), with tc the commit time of the further ECU node (C), with tp the maximum payload with maximum length and with n the number of ECU nodes (A, B, C) is characterized that a node (ECU) of the bus, apart from the headnode, measures the length of time of an unused cycle, in which no user data was sent, whereby this is repeated and verified as often as desired, after determining the pure cycle length TL, which can be recognized by the Transmission of a beacon s, the transmission window of an ECU node (ECU A, ECU B, ECU C) is used to calculate how many participants are on the bus. Finally, the minimum and maximum delay during bus access can be determined dynamically without this being preconfigured.

2. The method according to claim 1, characterized in that an ECU node (ECU A, ECU B) of the Ethernet vehicle electrical system sends the time length of an unused cycle (Zo) in which no payload (P1, P2). should be calculated using a Transmit Opportunity Timer (TOT), after calculating the pure cycle length (TL), which is determined by the transmission of the beacons time at the point in time tß, through the transmission window of an ECU node (ECU A, ECU B , ECU C) calculates the number of nodes n in the on-board Ethernet network.

3. The method according to claim 1, characterized in that

- a detection of the beginning of a new cycle (Zo)

- a search for the start time of cycle +1 (Zi ), - It is checked whether a payload (P1, P2) was transmitted between the new cycle (Zo) and the cycle (Zi), and the cycle (Zi) is set to the cycle (Zo) in the event of a transmission,

- a dynamic calculation of the cycle length TL takes place.

4. The method according to claim 1 or 2, characterized in that the number of nodes n of the ECU nodes (ECU A, ECU B) located in the Ethernet vehicle network is determined by the ratio of the cycle length (TL) to the value of the transmit opportunity timer ( TOT) is formed, with the Transmit Opportunity Timer (TOT) being queried beforehand to form the ratio of the cycle length (TL) to the value of the Transmit Opportunity Timer (TOT).

5. Control unit for an Ethernet vehicle electrical system, which is designed as the first ECU node as a control unit for this purpose:

- To send a signal to a second control unit of the Ethernet vehicle electrical system and to receive the signal from the second control unit;

- to determine a transit time of the signal on a connection path to the second control unit;

- to determine a maximum speed of the connection path based on the transit time; and

- to determine a type of transmission medium of the connection path based on the maximum speed, at least includes:

- a microprocessor,

- a volatile memory and non-volatile memory,

- at least two communication interfaces,

- a synchronisable timer, the non-volatile memory containing program instructions when they are executed by the microprocessor, characterized in that at least one embodiment of the method according to claims 1 to 3 is implementable and executable.

6. Ethernet vehicle electrical system for a motor vehicle, with a first control unit and a second control unit, wherein the control units are connected to one another via at least one connection path, and at least the first control unit is designed according to claim 4.

7. Ethernet vehicle electrical system according to claim 6, characterized in that the Ethernet vehicle electrical system has a third control unit which is only indirectly connected to the first control unit and is connected directly to the second control unit via a third connection path, the third control unit being designed for this purpose is to determine a transit time of a third signal on the third connection path, the first control unit being designed to trigger the determination of the transit time of the third signal by a service message to the third control unit.

8. Computer program product comprising instructions which, when the program is executed by a computer, cause the latter to execute the method according to one or more of claims 1-3.

A computer-readable medium on which the computer program product of claim 7 is stored.

10. Vehicle with multiple control units according to claim 4 comprehensive on-board Ethernet network.