Electronic control unit

Abstract

To avoid localized increases in bus load before they occur.SOLUTION: An electronic control device 1 performs bidirectional data communication with other electronic control devices 3 to 5 via a bus 2. The electronic control device 1 includes a bus load calculation unit 6a that measures and calculates a bus load in a measurement section, a bus load estimation unit 6b that estimates a bus load in an estimation section following the measurement section based on calculation results of the bus load calculation unit, and a bus load increase suppression unit 6c that suppresses a bus load increase in the estimation section when the bus load in the estimation section is estimated by the bus load estimation unit to be higher than a theoretical load.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electronic control device. [Background technology]

[0002] For example, an electronic control unit (hereinafter referred to as an ECU (Electronic Control Unit)) mounted on a vehicle performs bidirectional data communication with other ECUs via a bus. In a configuration in which data transmission timing is arbitrated between ECUs, data that wins arbitration is transmitted and data that loses arbitration is put on hold, which can cause delays in data transmission and hinder intended control. Since the frequency of arbitration losses is proportional to the bus load, it is ideal to monitor the bus load and prevent local increases in the bus load before they occur. For example, Patent Document 1 discloses a configuration for monitoring bus load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-36366 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed in Patent Document 1 merely monitors the bus load and does not go so far as to prevent a local increase in the bus load before it occurs.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic control device that can prevent a local increase in bus load before it occurs. [Means for solving the problem]

[0006] According to the invention described in claim 1, in an electronic control device that performs bidirectional data communication with a node via a bus, a bus load calculation unit (6a) measures and calculates a bus load in a measurement section. A bus load estimation unit (6b) estimates a bus load in an estimation section subsequent to the measurement section. 、 Calculation result of the bus load calculation unit The degree of deviation between the actual load, which indicates the actual bus load in the measurement section, and the theoretical load, which indicates the average bus load at each time in the measurement section. The bus load increase suppression unit (6c) estimates the bus load in the estimated section based on the following: In the estimated section When the bus load estimation unit estimates that the bus load will increase above the theoretical load, By distributing and leveling the bus load, Suppress the rise in

[0007] The bus load in the measurement section is measured and calculated, and if it is estimated that the bus load in the estimation section following the measurement section will be higher than the theoretical load, the increase in the bus load in the estimation section is suppressed, thereby preventing local increases in bus load. [Brief explanation of the drawings]

[0008] [Figure 1] Functional block diagram showing the overall configuration of the first embodiment [Figure 2] A diagram explaining the transition of bus load [Figure 3] A diagram explaining the transition of bus load [Figure 4] A diagram explaining the process of advancing the timing of data transmission [Figure 5] A diagram explaining the transition of bus load [Figure 6] Flowchart showing main processing [Figure 7] Flowchart showing section determination processing [Figure 8] Flowchart showing bus load calculation processing [Figure 9] Flowchart showing bus load increase suppression processing [Figure 10] Diagram explaining receive interrupts [Figure 11] Flowchart showing main processing [Figure 12] Flowchart showing main processing [Figure 13] Flowchart showing main processing [Figure 14] FIG. 10 illustrates a process for delaying the timing of transmitting data according to the second embodiment. [Figure 15] A diagram explaining the transition of bus load [Figure 16] Flowchart showing bus load increase suppression processing [Figure 17] FIG. 10 illustrates a process for stopping data transmission according to the third embodiment. [Figure 18] A diagram explaining the transition of bus load [Figure 19] Flowchart showing bus load increase suppression processing DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, the description of parts that overlap with the preceding embodiments will be omitted. (First embodiment) The first embodiment will be described with reference to FIGS. As shown in FIG. 1 , ECU 1 is, for example, an in-vehicle ECU, and is connected to other ECUs 3 to 5 via bus 2. ECU 1 is a device that performs, for example, drive system control, powertrain control, and ADAS (Advanced Driving Assistant System) control. Bus 2 is, for example, CAN (Controller Area Network) (registered trademark). In this embodiment, a configuration is illustrated in which other ECUs 3 to 5 are connected to ECU 1 via bus 2. However, the other ECUs 3 to 5 are not limited to these, and devices such as various sensors and actuators may also be connected to ECU 1 via bus 2. The other ECUs 3 to 5 and devices connected to ECU 1 via bus 2 are referred to as nodes, and the number of nodes is arbitrary. Furthermore, bus 2 may be based on other CSMA / CD (Carrier Sense Multiple Access with Collision Detection) communication protocols, such as CAN FD (Controller Area Network with Flexible Data Rate), ETHERNET (registered trademark), or the like.

[0010] The ECU 1 includes a control unit 6 and a data transmission / reception unit 7. The control unit 6 is mainly configured as a microcomputer having a CPU, RAM, ROM, I / O ports, etc. The control unit 6 controls the operation of the ECU 1 by executing software processing by having the CPU execute a computer program stored in a non-transitory physical storage medium, and by controlling hardware processing by a dedicated electronic circuit. The data transmission / reception unit 7 is a controller and transceiver that transmits and receives data to and from nodes via the bus 2, and transmits and receives data according to a communication protocol such as CAN.

[0011] Let us now consider bus load. Bus load is an index indicating the degree of congestion of data transmitted through bus 2. If the amount of data simultaneously transmitted through bus 2 is large, the bus load increases; if the amount of data simultaneously transmitted through bus 2 is small, the bus load decreases. When bus load increases, data transmission delays may occur, potentially impairing intended control. As shown in Figures 2 and 3, the vertical axis represents bus load (%) and the horizontal axis represents time (μs), showing the bus load over time in graphs. A bus load of 100% corresponds to the maximum amount of data that bus 2 can transmit. As the bus load approaches 100%, data transmission delays become more likely to occur. In a system including ECUs 1, 3, 4, 5, the total amount of data transmitted through bus 2 is uniquely determined, so the average bus load at each time can be calculated in advance as a theoretical load. In other words, the theoretical load represents a horizontal line on the graph. However, the actual bus load is not always constant; instead, there are always localized highs and lows, resulting in peaks and valleys on the graph rather than a straight line.

[0012] If a certain section where the bus load has already been measured is defined as the measurement section, and a certain section following the measurement section is defined as the estimation section, then Case 1 and Case 2 can be assumed for the relationship between the bus load in the measurement section and the estimation section. As shown in FIG. 2, Case 1 is a steady load state (shown by the solid line) in which the deviation between the theoretical load and the actual load is relatively small within the measurement section. In this case, it is estimated that the steady load state (shown by the dashed line) will also be relatively small within the estimation section. On the other hand, as shown in FIG. 3, Case 2 is a low load state (shown by the solid line) in which the deviation between the theoretical load and the actual load is relatively large in parts of the measurement section, and the actual load is significantly lower than the theoretical load in parts. In this case, it is estimated that the deviation between the theoretical load and the actual load is relatively large within the estimation section, and the actual load will be significantly higher than the theoretical load in a high load state (shown by the dashed line). For these reasons, the control unit 6 takes measures to prevent an increase in bus load in the estimation section in case 2, which is a possible case.

[0013] The control unit 6 includes a bus load calculation unit 6a, a bus load estimation unit 6b, and a bus load increase suppression unit 6c. The bus load calculation unit 6a measures and calculates the bus load in the measurement section. The bus load estimation unit 6b estimates the bus load in the estimation section following the measurement section based on the calculation result of the bus load calculation unit 6a. The bus load estimation unit 6b calculates the average bus load in the measurement section and compares the calculated average with a threshold. If the calculated average is not less than the threshold, the bus load estimation unit 6b estimates that the estimation section will be in a steady load state with a relatively small deviation between the theoretical load and the actual load. On the other hand, if the calculated average is less than the threshold, the bus load estimation unit 6b estimates that the bus load in the estimation section will be higher than the bus load in the measurement section, and the deviation between the theoretical load and the actual load will be relatively large in the estimation section, resulting in a high load state in which the actual load is significantly higher than the theoretical load.

[0014] When the bus load estimation unit 6b estimates that the bus load in the estimated section will be higher than the theoretical load, the bus load increase suppression unit 6c takes measures to prevent an increase in the bus load in the estimated section. The bus load increase suppression unit 6c, for example, determines the transmission priority of data for which a transmission request has occurred, and classifies the data to be transmitted in the estimated section into data with a short transmission cycle and data with a long transmission cycle. Data with a short transmission cycle is mainly designed to be equivalent to data with a high transmission priority, such as data directly related to vehicle control, such as driving, stopping, and turning. On the other hand, data with a long transmission cycle is mainly designed to be equivalent to data with a low transmission priority, such as data not directly related to vehicle control, such as fuel economy, driving diagnosis results, and entertainment such as music.

[0015] As shown in Fig. 4, the bus load increase suppression unit 6c shortens the transmission period of data with a short transmission period to advance the transmission timing while maintaining the transmission timing of data with a long transmission period, thereby eliminating bus load concentration and dispersing and leveling the bus load. The ratio by which the transmission period is shortened may be a value determined by a prior evaluation, for example, about 80%. By performing the above-mentioned processing by the bus load increase suppression unit 6c, as shown in Fig. 5, it is possible to reduce the maximum bus load (P1) when processing is performed compared to the maximum bus load (P0) when processing is not performed, thereby preventing local increases in bus load.

[0016] Next, the operation of the above-described configuration will be described with reference to FIGS. After starting the ECU 1 or after the previous main processing ends, the control unit 6 starts the main processing and proceeds to the section determination processing (see FIG. 7) (S1). When the control unit 6 starts the section determination processing, it determines whether the current section determination processing is the first processing after the ECU 1 is started (S11). If the control unit 6 determines that the current section determination processing is the first processing after the ECU 1 is started (S11: YES), it sets the start timing of the measurement section to the current time (S12).

[0017] On the other hand, if the control unit 6 determines that the current interval determination process is not the first process since the ECU 1 was started, i.e., that the first process since the ECU 1 was started has already been performed (S11: NO), it determines whether or not the bus load increase suppression process was performed in the previous measurement interval (S13). If the control unit 6 determines that the bus load increase suppression process was performed in the previous measurement interval (S13: YES), it sets the start timing of the measurement interval to the start timing of the previous estimation interval (S14). If the control unit 6 determines that the bus load increase suppression process was not performed in the previous measurement interval (S13: NO), it sets the start timing of the measurement interval to a first predetermined time after the start timing of the previous estimation interval (S15). The first predetermined time is, for example, the minimum time that the control unit 6 can process, such as several milliseconds.

[0018] After setting the start timing of the measurement interval in this manner, the control unit 6 sets the end timing of the measurement interval to a second predetermined time after the start timing of the measurement interval (S16). The second predetermined time is, for example, an optimal value determined by a preliminary evaluation, and is, for example, approximately several tens of milliseconds. The control unit 6 sets the start timing of the estimation interval to a first predetermined time after the end timing of the measurement interval (S17). The control unit 6 sets the end timing of the estimation interval to a second predetermined time after the start timing of the estimation interval (S18), terminates the interval determination process, and returns to the main process.

[0019] When the control unit 6 returns to the main processing, it proceeds to the bus load calculation processing (see FIG. 8) (S2). When the control unit 6 starts the bus load calculation processing, it acquires data on the bus 2 by a receive interrupt as shown in FIG. 10 (S21). Note that the control unit 6 needs to be set up in advance to issue a receive interrupt for all data on the bus 2. The control unit 6 acquires the current time when the receive interrupt occurred as the current interrupt time (S22), and calculates the time difference from the previous interrupt time to the current interrupt time (S23). The control unit 6 overwrites the previous interrupt time with the current interrupt time and saves the current interrupt time as the latest interrupt time (S24). The control unit 6 calculates the bus load using the following equation, where "L" is the length of the measurement section, "F" is the time difference from the previous interrupt time to the current interrupt time, and "A" is the bus load (S25). A = (F / L) x 100 After calculating the bus load in this way, the control unit 6 ends the bus load calculation process and returns to the main process.

[0020] When the control unit 6 returns to the main processing, it saves the current bus load as the latest history (S3). The control unit 6 determines whether the bus load history has reached the end of the measurement interval (S4). If the control unit 6 determines that the bus load history has not reached the end of the measurement interval (S4: NO), it returns to step S2. If the control unit 6 determines that the bus load history has reached the end of the measurement interval (S4: YES), it calculates an average value from the bus load history (S5) and compares the calculated average value with a threshold (S6). The threshold value is, for example, a value that ensures that no data transmission delay occurs, i.e., that data is transmitted normally, based on a pre-evaluation. In this case, if the above-described case 1 applies, the average value is equal to or greater than the threshold value and does not fall below the threshold value. If the control unit 6 determines that the average value is not less than the threshold value (S6: NO), it ends the main processing and waits for the start of the next main processing.

[0021] On the other hand, if the case corresponds to the above-mentioned Case 2, the average value is less than the threshold value. When the control unit 6 determines that the average value is less than the threshold value (S6: YES), the control unit 6 proceeds to the bus load increase suppression process (see FIG. 9) (S7). When the control unit 6 starts the bus load increase suppression process, it classifies the data to be transmitted into data with a short transmission cycle and data with a long transmission cycle (S31). The control unit 6 shortens the transmission cycle of the data with a short transmission cycle to advance the transmission timing (S32), ends the bus load increase suppression process, returns to the main processing, and ends the main processing.

[0022] The above describes an example in which data to be transmitted is divided into two categories depending on the length of the transmission cycle, but it may also be divided into three or more categories depending on the length of the transmission cycle, and data with short transmission cycles may be further divided. For example, the transmission cycle of data with the shortest transmission cycle, i.e., the highest transmission priority, may be shortened by, for example, about 80%, and the transmission cycle of data with the next shortest transmission cycle, i.e., the next highest transmission priority, may be shortened by, for example, about 90%.

[0023] While the above example illustrates a case in which an average value is calculated from the bus load history and compared with a threshold, a median, minimum, or differential value may be calculated and compared with a threshold instead of the average value. That is, as shown in Fig. 11, when the control unit 6 determines that the bus load history has reached the length of the measurement section (S4: YES), it may calculate a median from the bus load history (S41), compare the calculated median with a threshold (S42), and, if it determines that the median is less than the threshold (S42: YES), proceed to bus load increase suppression processing (S7). Also, as shown in Fig. 12, the control unit 6 may calculate a minimum value from the bus load history (S51), compare the calculated minimum with a threshold (S52), and, if it determines that the minimum is less than the threshold (S52: YES), proceed to bus load increase suppression processing (S7). Furthermore, as shown in FIG. 13, the control unit 6 may calculate a differential value from the bus load history (S61), compare the calculated differential value with a threshold value (S62), and if it determines that the differential value is less than the differential value threshold value (S62: YES), proceed to bus load increase suppression processing (S7).

[0024] As described above, according to the first embodiment, the following advantageous effects can be obtained. The ECU 1 measures and calculates the bus load in the measurement section, and if it estimates that the bus load in the estimation section will be higher than the theoretical load, it suppresses the increase in the bus load in the estimation section, thereby preventing a local increase in the bus load.

[0025] In the ECU 1, by successively comparing the predetermined value of the bus load with a threshold value, it is possible to estimate in real time whether the bus load in the estimation section will increase more than the bus load in the measurement section. By using the average value, median value, minimum value, and differential value as the predetermined value of the bus load, it is possible to estimate the transition of the bus load in the estimation section based on the average value, median value, minimum value, and differential value.

[0026] In the ECU 1, the transmission period of data with a short transmission period is shortened to advance the transmission timing, and the bus load is distributed and leveled, thereby making it possible to prevent a local increase in the bus load from occurring.

[0027] (Second embodiment) The second embodiment will be described with reference to Figures 14 to 16. The first embodiment is configured to shorten the transmission period of data with a short transmission period to advance the transmission timing, while the second embodiment is configured to extend the transmission period of data with a long transmission period to delay the transmission timing.

[0028] The bus load increase suppression unit 6c classifies data to be transmitted in the estimation section into data with short transmission cycles and data with long transmission cycles, and, as shown in Figure 14, extends the transmission cycle of data with long transmission cycles while maintaining the transmission timing of data with short transmission cycles, thereby delaying the transmission timing and eliminating bus load concentration, thereby dispersing and leveling the bus load. The ratio by which the transmission cycle is extended may be a value determined by a prior evaluation, for example, approximately 120%. In this case, too, by performing the above-mentioned processing by the bus load increase suppression unit 6c, it is possible to reduce the maximum bus load (P2) when processing is performed compared to the maximum bus load (P0) when processing is not performed, as shown in Figure 15, and to prevent local increases in bus load.

[0029] 16, when the control unit 6 starts the bus load increase suppression process, it classifies the data to be transmitted into data with a short transmission cycle and data with a long transmission cycle (S71). The control unit 6 extends the transmission cycle of the data with a long transmission cycle to delay the transmission timing (S72), ends the bus load increase suppression process, returns to the main process, and ends the main process.

[0030] In this case, the data to be transmitted may be divided into three or more categories depending on the length of the transmission cycle, and data with long transmission cycles may be further divided. For example, the transmission cycle of the data with the longest transmission cycle, i.e., the data with the lowest transmission priority, may be shortened by, for example, about 120%, and the transmission cycle of the data with the next longest transmission cycle, i.e., the data with the next lowest transmission priority, may be shortened by, for example, about 110%.

[0031] As described above, according to the second embodiment, the following advantageous effects can be obtained. In ECU1, by extending the transmission period of data with a long transmission period and delaying the transmission timing, and distributing and leveling the bus load, it is possible to prevent local increases in bus load, as in the first embodiment.

[0032] (Third embodiment) The third embodiment will be described with reference to Figures 17 to 19. The first and second embodiments are configured to shorten the data transmission cycle to advance the transmission timing or extend it to delay the transmission timing, but the third embodiment is configured to stop the transmission of some of the data to be transmitted. In other words, the first and second embodiments are configured to control the transmission timing to distribute and level the bus load, but the third embodiment is configured to stop the data transmission itself to level the bus load without distributing it.

[0033] The bus load increase suppression unit 6c classifies data to be transmitted in the estimated section into, for example, data necessary for the current control and data unnecessary for the current control, and stops transmission of unnecessary data while keeping the transmission timing of necessary data unchanged to eliminate concentration of bus load and distribute and level the bus load, as shown in Fig. 17. In this case, too, by the bus load increase suppression unit 6c performing the above-mentioned processing, it is possible to reduce the maximum bus load (P3) when processing is performed compared to the maximum bus load (P0) when processing is not performed, as shown in Fig. 18, and to prevent local increases in bus load.

[0034] As shown in Figure 19, when the control unit 6 starts the bus load increase suppression process, it classifies the data to be transmitted into data necessary for the current control and data unnecessary for the current control (S81). The control unit 6 stops transmitting the data unnecessary for the current control (S82), ends the bus load increase suppression process, and returns to the main process, thereby terminating the main process. Note that the control unit 6 may discard the data whose transmission has been stopped, or may wait for transmission. In other words, when the control unit 6 stops transmitting data unnecessary for the current control, it may discard the data, or may transmit it at the next transmission timing.

[0035] As described above, according to the third embodiment, the following advantageous effects can be obtained. In the ECU 1, transmission of data unnecessary for the current control is stopped and the bus load is leveled, so that a local increase in the bus load can be avoided in advance, as in the first embodiment.

[0036] (Other embodiments) Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0037] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. [Explanation of symbols]

[0038] In the drawing, 1 is an ECU (electronic control unit), 2 is a bus, 3 to 5 are other ECUs (nodes), 6 is a control unit, 6a is a bus load calculation unit, 6b is a bus load estimation unit, and 6c is a bus load increase suppression unit.

Claims

1. An electronic control device that performs bidirectional data communication with a node via a bus, a bus load calculation unit (6a) for measuring and calculating a bus load in a measurement section; a bus load estimation unit (6b) that estimates a bus load in an estimation section subsequent to the measurement section based on the degree of deviation between an actual load indicating an actual bus load in the measurement section and a theoretical load indicating an average bus load at each time in the measurement section as a calculation result of the bus load calculation unit; and a bus load increase suppression unit (6c) that, when the bus load estimation unit estimates that the bus load in the estimated section will increase above the theoretical load in the estimated section, suppresses the increase in the bus load by distributing and leveling the bus load in the estimated section.

2. 2. The electronic control device according to claim 1, wherein the bus load estimating unit compares the bus load in the measurement section with a predetermined value to estimate the bus load in the estimation section.

3. 3. The electronic control device according to claim 2, wherein the bus load estimation unit compares the average value of the bus load in the measurement section with a threshold value, and if it determines that the average value is less than the threshold value, estimates that the bus load in the estimation section will be higher than the theoretical load.

4. 3. The electronic control device according to claim 2, wherein the bus load estimation unit compares the median value of the bus load in the measurement section with a threshold value, and if it determines that the median value is less than the threshold value, estimates that the bus load in the estimation section will be higher than the theoretical load.

5. 3. The electronic control device according to claim 2, wherein the bus load estimation unit compares the minimum value of the bus load in the measurement section with a threshold value, and if it determines that the minimum value is less than the threshold value, estimates that the bus load in the estimation section will be higher than the theoretical load.

6. 3. The electronic control device according to claim 2, wherein the bus load estimation unit compares a differential value of the bus load in the measurement section with a threshold value, and if it determines that the differential value is less than the threshold value, estimates that the bus load in the estimation section will be higher than the theoretical load.

7. An electronic control device described in any one of claims 1 to 6, wherein when the bus load estimation unit estimates that the bus load in the estimated section will increase above the theoretical load, the bus load increase suppression unit suppresses the increase in the bus load in the estimated section by changing the transmission timing of data to be transmitted for which a transmission request has occurred in the estimated section based on the transmission period or transmission priority in the estimated section.

8. 8. The electronic control device according to claim 7, wherein the bus load increase suppression unit suppresses an increase in the bus load in the estimated section by advancing the transmission timing of the data to be transmitted that has a short transmission period or a high transmission priority in the estimated section.

9. 8. The electronic control device according to claim 7, wherein the bus load increase suppression unit suppresses an increase in the bus load in the estimated section by delaying the transmission timing of the data to be transmitted that has a long transmission period or a low transmission priority in the estimated section.

10. The electronic control device according to claim 7 , wherein the bus load increase suppression unit suppresses an increase in the bus load in the estimated section by stopping transmission of a part of data in the estimated section.

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