Data recording method for control system and electronic control device

Abstract

Provided is a data recording method for a control system (1) comprising a plurality of processors (3A, 3B), a plurality of non-volatile storage devices (4A, 4B), and a plurality of electronic control devices (2A, 2B) each composed of at least one of the plurality of processors and at least one of the plurality of non-volatile storage devices, wherein: remaining lifespans (LA, LB) of the plurality of non-volatile storage devices are calculated on the basis of data expressing the usage statuses of the plurality of non-volatile storage devices; one non-volatile storage device is selected from the plurality of non-volatile storage devices on the basis of the calculated remaining lifespans of the plurality of non-volatile storage devices; and data acquired by the plurality of electronic control devices is recorded in selected non-volatile storage device.

Description

Data recording method for control system and electronic control device

[0001] The present invention relates to a data recording method and an electronic control device for a control system.

[0002] In a control system equipped with multiple electronic control units (hereinafter also referred to as ECUs), a technology for recording data from a first ECU (own device) in a recording device (storage device) of a second ECU (other device) is described in JP 2013-84284 A (Patent Document 1).

[0003] This document discloses that in an electronic control system having three or more electronic control devices connected to each other so that data communication is possible, when one of the electronic control devices detects an abnormality, a determination is made as to whether or not data can be recorded in that one electronic control device, and if the determination is yes, specified data is recorded in that one electronic control device, and if the determination is no, the specified data is sent to one of the other electronic control devices that are capable of recording instead of the one electronic control device, and recorded therein.

[0004] JP 2013-84284 A

[0005] Many modern electronic control devices are equipped with nonvolatile memory (nonvolatile storage device) as their storage device (recording device), and the lifespan of the nonvolatile memory can vary depending on its usage (e.g., the number of times it is written).

[0006] In the system of Patent Document 1, the electronic control device to which data is recorded (i.e., the recording device of the electronic control device) is changed depending on whether data can be recorded to the electronic control device when an abnormality is detected, but the usage status of each recording device is not taken into consideration when selecting the recording device to which data is recorded. Therefore, if the recording devices of each electronic control device are non-volatile memories and writing is concentrated in one of them, the lifespan of that non-volatile memory will be shorter than that of the other non-volatile memories, and as a result, the lifespan of the system may be shortened due to the lifespan of the memory.

[0007] This problem is not limited to systems equipped with multiple electronic control units, but also applies to a single electronic control unit incorporating multiple storage devices (non-volatile memories).

[0008] The present invention has been made in view of the above circumstances, and its object is to provide a data recording method and an electronic control device that take into consideration the lifespan of each storage device in a control system.

[0009] The present application includes multiple means for solving the above problem, and one example is a data recording method for a control system having multiple processors and multiple non-volatile storage devices, and having multiple electronic control devices each configured by at least one of the multiple processors and at least one of the multiple non-volatile storage devices, wherein the method calculates the remaining life of the multiple non-volatile storage devices based on data related to the usage status of the multiple non-volatile storage devices, selects one non-volatile storage device from the multiple non-volatile storage devices based on the calculated remaining life of the multiple non-volatile storage devices, and records data acquired by the multiple electronic control devices in the selected one non-volatile storage device.

[0010] According to the present invention, the storage device to which data is to be recorded is selected taking into consideration the remaining lifespan of each storage device, making it easier to equalize the remaining lifespan of each storage device and thereby extending the lifespan of the system. Note that other issues, configurations, and effects will become clear from the description of the following embodiments.

[0011] FIG. 1 is a system configuration diagram showing an example of a control system according to a first embodiment of the present invention. FIG. 2 is a flowchart showing an example of a procedure for switching between non-volatile storage devices 4A and 4B as a data storage destination by a usage status monitoring unit 5 (control system 1) according to the first embodiment of the present invention. FIG. 3 is a flowchart showing an example of a procedure for saving data to non-volatile storage devices 4A and 4B by ECUs 2A and 2B (control system 1) according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram of effects achieved by the first embodiment. FIG. 5 is a flowchart showing an example of a procedure for saving data to non-volatile storage devices 4A and 4B by ECUs 2A and 2B (control system 1) according to a second embodiment of the present invention. FIG. 6 is a system configuration diagram showing an example of a control system according to a third embodiment of the present invention. FIG. 7 is a flowchart showing an example of a procedure for switching between non-volatile storage devices 4A and 4B as a data storage destination by a usage status monitoring unit 5 according to the third embodiment of the present invention. FIG. 8 is a flowchart showing an example of a procedure for saving data to non-volatile storage devices 4A and 4B by processors 3A and 3B according to the third embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] First Embodiment Fig. 1 is a system configuration diagram illustrating an example of a control system according to a first embodiment of the present invention. The control system 1 includes a plurality of ECUs 2A, 2B (a first ECU 2A, a second ECU 2B). Each of the ECUs 2A, 2B includes at least one processor (a first processor 3A, a second processor 3B) and at least one non-volatile storage device (a first non-volatile storage device 4A, a second non-volatile storage device 4B). At least one sensor (a first sensor 6A, a second sensor 6B) is connected to each of the ECUs 2A, 2B, and data detected by the sensors 6A, 6B is input to the connected ECUs 2A, 2B. The ECUs 2A, 2B are connected to each other so as to be able to communicate with each other. A usage status monitoring unit 5 is connected to each of the ECUs 2A, 2B so as to be able to communicate with each other.

[0014] The usage status monitoring unit 5 is a part that manages the remaining life of each of the nonvolatile storage devices 4A, 4B calculated based on data (also referred to as usage status data) related to the usage status of the nonvolatile storage devices 4A, 4B of the connected ECUs (ECUs 2A, 2B), and the data stored in each of the nonvolatile storage devices 4A, 4B (for example, which nonvolatile storage device stores data from the sensor 6A detected during a certain period). The remaining life may be calculated by the usage status monitoring unit 5 itself.

[0015] The usage status monitoring unit 5 may be, for example, an ECU or computer other than the two ECUs 2A and 2B. Although the usage status monitoring unit 5 is shown in FIG. 1 as being separate from the two ECUs 2A and 2B, it may be stored in a nonvolatile storage device (e.g., nonvolatile storage device 4A) as a program executed by a processor (e.g., processor 3A) of one of the ECUs (e.g., ECU 2A) within the two ECUs 2A and 2B. In other words, either of the connected ECUs 2A and 2B may function as the usage status monitoring unit 5. The usage status monitoring unit 5 may also be an interface or communication device that inputs necessary data (e.g., the remaining life of each nonvolatile storage device 4A and 4B and the contents of the stored data) from an external device.

[0016] The data related to the usage status of the two nonvolatile storage devices 4A, 4B used to calculate the remaining life includes at least one of the cumulative write amount of the two nonvolatile storage devices 4A, 4B and the cumulative number of writes to the two nonvolatile storage devices 4A, 4B. The data related to the usage status may also include at least one of temperature data of each ECU 2A, 2B and data related to alternate sectors (e.g., the number of alternate sectors) in the two nonvolatile storage devices 4A, 4B. An alternate sector is a sector that is assigned to replace a defective sector in the nonvolatile storage device if one exists. The calculation of the remaining life of the nonvolatile storage device will be described later.

[0017] Each of the nonvolatile memory devices 4A and 4B has a predetermined lifespan, including a maximum number of writes, a maximum amount of data written, and a number of years for which data can be retained, which may vary depending on the ambient temperature (i.e., ECU temperature) and the number of spare sectors.

[0018] The control system 1 can be applied to an in-vehicle system installed in a vehicle. Here, an example will be described in which the control system 1 is an in-vehicle system configured with two ECUs 2A and 2B as shown in FIG.

[0019] The control system 1 can function as an event data recorder (EDR) that records data in the event of an accident or event, and as a data storage system for automated driving (DSSAD) that records a series of data during an automated driving sequence. Data recorded in the EDR or DSSAD includes sensor data acquired by sensors, vehicle speed, time, steering data (e.g., steering angle), etc.

[0020] Information about the interior and exterior of the vehicle acquired by the sensors 6A and 6B is input to the ECUs 2A and 2B from the sensors 6A and 6B. The information about the interior and exterior of the vehicle includes image data of the surroundings of the vehicle captured by an image sensor (camera), point cloud data of obstacles around the vehicle acquired by LiDAR, radar, etc., object data, etc. The types of sensors 6A and 6B can be different.

[0021] Each ECU 2A, 2B in the control system 1 is composed of at least one processor 3A, 3B and at least one non-volatile memory device 4A, 4B out of the multiple processors 3A, 3B and multiple non-volatile memory devices 4A, 4B installed in the control system 1.

[0022] The processors 3A and 3B use the outputs of the sensors 6A and 6B to perform fusion processing, recognition processing, image compression processing, sensor information processing, vehicle control processing, etc. of external recognition devices such as cameras, radars, and LiDAR. A multi-core processor may be used as each of the processors 3A and 3B.

[0023] The nonvolatile storage devices 4A and 4B are storage devices having rewritable nonvolatile storage areas, such as EEPROM, flash memory, etc. The nonvolatile storage device 4A is connected to the processor 3A so as to be able to communicate with it, and the nonvolatile storage device 4B is connected to the processor 3B so as to be able to communicate with it.

[0024] The processors 3A and 3B control the writing and reading of data to and from the nonvolatile storage devices 4A and 4B. The nonvolatile storage devices 4A and 4B store EDR data, DSSAD data, map data, program data, the cumulative amount of data written to the nonvolatile storage devices 4A and 4B, the cumulative number of writes to the nonvolatile storage devices 4A and 4B, cumulative temperature information for the ECUs 2A and 2B, and data related to replacement sectors of the nonvolatile storage devices 4A and 4B. The EDR and DSSAD data include information about inside and outside the vehicle processed by the processors 3A and 3B using data from the sensors 6A and 6B, the time of an event occurrence, version information for each data, and identification information for the ECUs 3A and 3B that processed each data. By using the identification information for the ECUs 3A and 3B that processed each data, for example, when uploading EDR data or DSSAD data to an external center, it is possible to quickly identify which ECU processed each data. Different program data can be stored in each nonvolatile storage device 4A and 4B.

[0025] FIG. 2 is a flowchart showing an example of a procedure for switching between the nonvolatile storage devices 4A and 4B as data storage destinations by the usage status monitoring unit 5 (control system 1) according to the first embodiment of the present invention.

[0026] The usage status monitoring unit 5 (control system 1) starts the flow chart of FIG. 2 at a predetermined timing (step 101), and proceeds to step 102.

[0027] In the initial setting at the time of system startup, it is preferable to select one of the nonvolatile storage devices 4A, 4B to store the data of each of the ECUs 2A, 2B. In this description, it is assumed that each of the ECUs 2A, 2B is set to store the data of the sensors 6A, 6B in the nonvolatile storage device 4A of the ECU 2A.

[0028] In step 102, the usage status monitoring unit 5 acquires data relating to the usage status of the multiple nonvolatile storage devices 4A, 4B in the multiple ECUs 2A, 2B that make up the control system 1. Specifically, the usage status monitoring unit 5 acquires the cumulative amount of data written in the two nonvolatile storage devices 4A, 4B, the cumulative number of times data has been written, temperature information of the ECUs 2A, 2B, information about alternative sectors, etc.

[0029] In step 103, the usage monitoring unit 5 calculates the remaining life L of each of the nonvolatile storage devices 4A, 4B from which the usage data was obtained, based on the usage data obtained in step 102.

[0030] The method for calculating the remaining life L of the nonvolatile memory device in this embodiment will be described below. For simplicity of explanation, it is assumed that the nonvolatile memory devices 4A and 4B are the same.

[0031] (Remaining Lifespan Lt Based on Number of Writes) First, we will explain how to calculate the remaining lifespan Lt [years] of the nonvolatile memory devices 4A, 4B based on the number of writes. Prior to calculating the remaining lifespan Lt, the usage status monitoring unit 5 first acquires cumulative temperature data of the ECUs 2A, 2B, calculates the average value of the usage temperature (environmental temperature) of each nonvolatile memory device 4A, 4B from the temperature data, and calculates a preset maximum number of writes for the average value. For example, if the average temperature is 25°C, the maximum number of writes is set to 5 million, and if the average temperature is 85°C, the maximum number of writes is set to 500,000,000, etc.

[0032] If the maximum number of writes to the nonvolatile memory devices 4A and 4B when used in an n° C. environment is Tmn [times], the cumulative number of writes to the nonvolatile memory devices 4A and 4B since their initial use is T1 [times], and the average number of writes to the nonvolatile memory devices 4A and 4B per year is T2 [times / year], the remaining lifespan Lt [years] of the nonvolatile memory devices 4A and 4B based on the number of writes can be calculated using the following formula (1). Note that T2 may also be calculated by dividing T1 by the number of years the nonvolatile memory devices have been in use.

[0033] Lt = (Tmn - T1) / T2 Formula (1) For example, when used in a 25°C environment, if the maximum number of writes Tm25 = 5 million, the cumulative number of writes T1 = 500,000, and the average number of writes per year T2 = 500,000, the remaining life Lt is 9 years. Also, when used in an 85°C environment, if the maximum number of writes Tm80 = 1 million, the cumulative number of writes T1 = 500,000, and the average number of writes per year T2 = 500,000, the remaining life Lt is 1 year.

[0034] (Remaining Lifespan Lc Based on Written Amount) Next, the calculation of the remaining lifespan Lc [years] of the nonvolatile storage devices 4A, 4B based on the written amount will be described. Let Cm [terabytes (TB)] be the predetermined maximum written amount of the nonvolatile storage devices 4A, 4B, C1 [TB] be the cumulative written amount of the nonvolatile storage devices 4A, 4B since the start of use, and C2 [TB / year] be the average written amount of the nonvolatile storage devices 4A, 4B per year. The usage status monitoring unit 5 calculates the remaining lifespan Lc [years] of the nonvolatile storage devices 4A, 4B based on the written amount using the following formula (2). Note that C2 may also be calculated by dividing C1 by the number of years the nonvolatile storage devices have been in use.

[0035] Lc=(Cm-C1) / C2 (Equation (2)) For example, if the maximum write amount Cm=100 TB, the cumulative write amount up to now C1=20 TB, and the average write amount per year C2=20 TB, the remaining life Lc is 4 years.

[0036] Note that the calculation of the remaining lives Lt and Lc using the above formulas (1) and (2) is merely an example, and other calculation methods may be used. For example, the remaining life may be calculated taking into account information about replacement sectors, or the remaining life may be calculated by comprehensively determining the number of writes and the amount of writes.

[0037] (Remaining Lifespan L) The usage monitoring unit 5 calculates the remaining lifespan L for all nonvolatile storage devices included in the control system 1. If multiple calculation methods are set (the two methods exemplified above are equations (1) and (2)), the remaining lifespan is calculated for each nonvolatile storage device according to all methods. That is, in this embodiment, two remaining lives Lt and Lc are calculated for the nonvolatile storage device 4A, and two remaining lives Lt and Lc are calculated for the nonvolatile storage device 4B. The calculated remaining lives Lt and Lc for each nonvolatile storage device 4A and 4B are compared, and the smallest one is used as the remaining lifespan L for that nonvolatile storage device. That is, in the above example, if the operating temperature is 25°C, Lt = 9 > Lc = 4, so the remaining lifespan L = Lc = 4. If the operating temperature is 85°C, Lt = 1 < Lc = 4, so the remaining lifespan L = Lt = 1. Here, the remaining lifespan of the nonvolatile storage device 4A is denoted as LA, and the remaining lifespan of the nonvolatile storage device 4B is denoted as LB.

[0038] Here, multiple types of remaining lives Lt, Lc are calculated and the smallest one is taken as the final remaining life L, but it is also possible to calculate only one type of remaining life (for example, Lt or Lc) and use that as the final remaining life L.

[0039] In step 104, the usage status monitoring unit 5 determines whether the remaining life LA of the nonvolatile memory device 4A is longer than the remaining life LB of the nonvolatile memory device 4B, and if the remaining life LA is longer, proceeds to step 105, and if the remaining life LB is longer, proceeds to step 106.

[0040] If there are three or more nonvolatile storage devices in the control system 1, the usage status monitoring unit 5 may compare the remaining lifespans of the nonvolatile storage devices calculated in step 103, and execute a process to identify the nonvolatile storage device with the longest remaining lifespan.

[0041] In step 105, the usage status monitoring unit 5 determines whether the previously selected device was the non-volatile storage device 4A, and if the previously selected device was the non-volatile storage device 4A, the selection is maintained and the flow ends (step 109). On the other hand, if the previously selected device was the non-volatile storage device 4B, the usage status monitoring unit 5 selects the non-volatile storage device 4A in step 107, notifies each ECU 2A, 2B in the control system 1 of this fact, and ends the flow (step 109).

[0042] In step 106, the usage status monitoring unit 5 determines whether the previously selected device was the non-volatile storage device 4B, and if the previously selected device was the non-volatile storage device 4B, the selection is maintained and the flow ends (step 109). On the other hand, if the previously selected device was the non-volatile storage device 4A, the usage status monitoring unit 5 selects the non-volatile storage device 4B in step 108, notifies each ECU 2A, 2B in the control system 1 of this fact, and ends the flow (step 109).

[0043] The "predetermined timing" for starting the flow of FIG. 2 may be any time between the start and end of the ECUs 2A and 2B, even while the vehicle is running. For example, the flow may be started periodically. However, considering that data is uploaded from the control system 1 (non-volatile storage devices 4A and 4B) to an external center or the like for data analysis, it is preferable to start the flow when the ignition or power to the ECU in the vehicle equipped with the control system 1 is turned on. The start of the flow when the ignition or power to the ECU is turned on may be limited to once a day. In this case, since the data storage destination is likely to change from day to day, it becomes easier to determine which ECU's non-volatile storage device 4 stores the data. Here, the timing for selecting one non-volatile storage device as the data storage destination is controlled by changing the start timing of the flow of FIG. 2 . However, the storage destination storage device 4 may be changed by, for example, deferring (suspending) the execution of steps 107 and 108 until the "predetermined timing." For example, if the result of step 105 or 106 is No, the process of step 107 or step 108 may be delayed until the ignition is turned on as a "predetermined timing," and the process of step 107 or step 108 may be executed, i.e., selection and notification of the non-volatile memory device may be performed, when the ignition is turned on.

[0044] Next, a procedure for each of the ECUs 2A and 2B to store data in the nonvolatile storage device selected in the flow of Fig. 2 will be described with reference to Fig. 3. Fig. 3 is a flowchart showing an example of a procedure for storing data in the nonvolatile storage devices 4A and 4B by the ECUs 2A and 2B (control system 1) according to the first embodiment of the present invention.

[0045] The control system 1 (ECU 2A, ECU 2B) starts the flow chart of FIG. 3 at a predetermined cycle (step 201), and proceeds to step 202.

[0046] In step 202, the control system 1 monitors whether an event (e.g., a car collision) that requires data storage in the EDR or DSSAD has occurred, and when an event occurs, each ECU 2A, 2B (processor 3A, 3B) acquires data (EDR data or DSSAD data) from a predetermined period before the event occurred to a predetermined period after the event occurred. Note that at this time, each ECU 2A, 2B (processor 3A, 3B) may process the acquired data as needed, and the processed data may be added to the data (EDR data or DSSAD data) stored in steps 204 and 205.

[0047] In step 203, each ECU 2A, 2B (processor 3A, 3B) checks which nonvolatile storage device has been selected in the flow of Fig. 2. In the example shown, it is determined whether the nonvolatile storage device 4A has been selected, and if the nonvolatile storage device 4A has been selected, the process proceeds to step 204, and if the nonvolatile storage device 4B has been selected, the process proceeds to step 205.

[0048] In step S204, the ECU 2B transmits the EDR data and DSSAD data acquired and processed by the processor 3B to the ECU 2A. The ECU 2A stores the EDR data and DSSAD data acquired and processed by the processor 3A and the data transmitted from the ECU 2B in the nonvolatile storage device 4A, and then terminates the process (step S206). That is, in step S204, data acquired by the remaining ECUs 2B (excluding the ECU 2A) from the plurality of ECUs 2A and 2B is transmitted to the ECU 2A equipped with the selected nonvolatile storage device 4A, and the data acquired by the ECU 2A and the data transmitted from the remaining ECUs 2B are recorded in the single nonvolatile storage device 4A. As a result, all data acquired by the plurality of ECUs 2A and 2B in the control system 1 is recorded in the single nonvolatile storage device 4A.

[0049] In step 205, the ECU 2A transmits the EDR data and DSSAD data acquired and processed by the processor 3A to the ECU 2B. The ECU 2B stores the EDR data and DSSAD data acquired and processed by the processor 3B and the data transmitted from the ECU 2A in the nonvolatile storage device 4B, and then terminates the process (step 206). That is, in step 205, data acquired by the remaining ECUs 2A (excluding the ECU 2B) among the multiple ECUs 2A and 2B is transmitted to the ECU 2B equipped with the selected nonvolatile storage device 4B, and the data acquired by the ECU 2B and the data transmitted from the remaining ECUs 2A are recorded in the single nonvolatile storage device 4B. As a result, all data acquired by the multiple ECUs 2A and 2B in the control system 1 is recorded in the single nonvolatile storage device 4B.

[0050] (Features of the First Embodiment) The features included in the data recording method performed by the control system according to the first embodiment can be summarized as follows.

[0051] (1) A data recording method for a control system 1 having a plurality of processors 3A, 3B and a plurality of non-volatile memory devices 4A, 4B, and a plurality of ECUs 2A, 2B each configured by at least one of the plurality of processors 3A, 3B and at least one of the plurality of non-volatile memory devices 4A, 4B, characterized in that the method calculates remaining lives LA, LB of the plurality of non-volatile memory devices 4A, 4B based on data relating to the usage status of the plurality of non-volatile memory devices 4A, 4B, selects one non-volatile memory device from the plurality of non-volatile memory devices 4A, 4B based on the calculated remaining lives LA, LB of the plurality of non-volatile memory devices 4A, 4B, and records data acquired by the plurality of ECUs 2A, 2B in the selected one non-volatile memory device.

[0052] In a conventional data recording method for a control system having the function of recording data acquired by multiple ECUs, each ECU records data in its own nonvolatile storage device. However, this method has raised concerns that the amount of data written to the nonvolatile storage device of an ECU managing relatively large amounts of data, such as camera images, is biased, potentially resulting in the nonvolatile storage device's lifespan expiring sooner than that of other nonvolatile storage devices. In contrast, when recording data as in this embodiment, data acquired by multiple ECUs 2A, 2B is recorded in a single nonvolatile storage device selected based on the remaining lifespans LA and LB of each storage device 4A, 4B. In other words, the storage device to which data is to be recorded is selected taking into account the remaining lifespans LA and LB of each storage device 4A, 4B, making it easier to equalize the remaining lifespans of each storage device and thereby extending the lifespan of the system.

[0053] The effects of this embodiment will be further explained using FIG. 4 . FIG. 4 is an explanatory diagram of the effects achieved by this embodiment. In the example of this figure, it is assumed that ECU 2A records 700 MB of EDR data and ECU 2B records 300 MB of EDR data per event, and four events (EDR1, EDR2, EDR3, EDR4) have occurred. (a) in the upper part of FIG. 4 shows the data capacity of the two nonvolatile storage devices 4A and 4B when a conventional method of recording data in each ECU 2A and 2B is adopted, and (b) in the lower part of FIG. 4 shows the data capacity of the two nonvolatile storage devices 4A and 4B when the method of this embodiment is adopted for data recording.

[0054] If the conventional method (a) is used, after four events have occurred, 700 MB x 4 times = 2.8 GB of data will be written to the nonvolatile storage device 4A, and 300 MB x 4 times = 1.2 GB of data will be written to the nonvolatile storage device 4B. In other words, data will be recorded disproportionately in the nonvolatile storage device 4A.

[0055] In contrast, when the method of this embodiment (b) is used, when a first event occurs, nonvolatile storage device 4A is selected, and 700 MB of data is written to storage device 4A from ECU 2A and 300 MB from ECU 2B, i.e., a total of 1 GB of data. When a second event occurs, nonvolatile storage device 4B, which has a relatively small write capacity, is selected, and a total of 1 GB of data is written to storage device 4B from the two ECUs 2A and 2B, as in the first event. When a third event occurs, nonvolatile storage device 4A is selected, and a total of 1 GB of data is written to storage device 4A from the two ECUs 2A and 2B. When a fourth event occurs, nonvolatile storage device 4B, which has a relatively small write capacity, is selected, and a total of 1 GB of data is written to storage device 4B from the two ECUs 2A and 2B, as in the first event. In other words, after four events have occurred, 2 GB of data will be written to nonvolatile storage device 4A, and 2 GB of data will also be written to nonvolatile storage device 4B.

[0056] According to this embodiment, data is prevented from being stored unevenly in the two non-volatile memory devices 4A and 4B, and the remaining lifespan of each memory device 4A and 4B is equalized, thereby ultimately achieving a longer lifespan for the system.

[0057] (2) In (1) above, it is preferable that the data relating to the usage status of the plurality of non-volatile memory devices 4A, 4B includes at least one of the cumulative amount of writing to the plurality of non-volatile memory devices 4A, 4B and the cumulative number of writings to the plurality of non-volatile memory devices 4A, 4B.

[0058] Since the lifespan of nonvolatile memory devices 4A and 4B is determined by the maximum amount of writing and the maximum number of times of writing, by calculating the remaining lifespan using the cumulative amount of writing and the cumulative number of times of writing of memory devices 4A and 4B, the remaining lifespan of memory devices 4A and 4B can be calculated with high accuracy from each of them.

[0059] (3) In (1) or (2) above, it is preferable that the data relating to the usage status of the plurality of non-volatile memory devices 4A, 4B further includes at least one of temperature data of the plurality of ECUs 2A, 2B and data relating to replacement sectors in the plurality of non-volatile memory devices 4A, 4B.

[0060] The lifespan of the nonvolatile storage devices 4A, 4B can vary depending on the temperature data of the ECU and the number of replacement sectors, so taking this information into consideration allows the remaining lifespan of the storage devices 4A, 4B to be calculated with higher accuracy.

[0061] (4) In any one of (1) to (3) above, it is preferable that the selected nonvolatile memory device is the nonvolatile memory device with the longest calculated remaining life LA, LB among the plurality of nonvolatile memory devices 4A, 4B.

[0062] By selecting storage devices in this way, the number of writes and write capacity of the storage device with the longest remaining life are increased preferentially, making it easier to equalize the remaining life of each storage device and extending the life of the system.

[0063] (5) In any of the above (1) to (4), it is preferable that the selection of the one nonvolatile storage device is performed at a predetermined timing.

[0064] When selecting storage devices in this way, the remaining lifespan of each storage device is taken into consideration when selecting storage devices, making it even easier to equalize the remaining lifespan of each storage device.

[0065] (6) The predetermined timing in (5) above is preferably when the ignition of a vehicle equipped with the control system is turned on.

[0066] By determining the predetermined timing in this manner, the storage device to be used for recording data is selected when the vehicle is first used, which makes data management easier and enables more efficient uploading to a center, etc.

[0067] Second Embodiment In the second embodiment, the flow in which each ECU 2A, 2B saves data is different from that in the first embodiment, but the other configurations, that is, the hardware configuration in Fig. 1 and the flowchart relating to the selection of the nonvolatile storage device in Fig. 2 are the same as those in the first embodiment. Here, the differences from the first embodiment will be described.

[0068] 5 is a flowchart showing an example of a procedure for storing data in nonvolatile storage devices 4A and 4B by ECUs 2A and 2B (control system 1) according to the second embodiment of the present invention. Steps 204A and 205A are different from those in FIG. 3, but the other steps are the same as those in FIG. 3. Below, the description of the steps that are the same as those in FIG. 3 will be omitted, and only steps 204A and 205A will be described.

[0069] In step 204A, the ECU 2B transmits to the ECU 2A a portion of the EDR data and DSSAD data acquired and processed by the processor 3B that satisfies a predetermined condition. The ECU 2A stores the EDR data and DSSAD data acquired and processed by the processor 3A and the data transmitted from the ECU 2B in the non-volatile storage device 4A. The ECU 2B then stores the remaining data, excluding the portion of the EDR data and DSSAD data acquired and processed by the processor 3B that was transmitted to the ECU 2A, in the non-volatile storage device 4B, and terminates the process (step 206). Examples of the "predetermined condition" include the amount of data being smaller than a predetermined threshold, the amount of data being greater than a predetermined threshold, or the data being of a predetermined type (e.g., image data). That is, in step S204A, data that satisfies a predetermined condition among data acquired by the remaining ECUs (ECUs 2B) excluding ECU 2A from the plurality of ECUs 2A and 2B is transmitted to ECU 2A equipped with the selected non-volatile storage device 4A, and the data acquired by ECU 2A and the data acquired by the remaining ECUs that satisfies the predetermined condition are recorded in the single non-volatile storage device 4A, and the data acquired by the remaining ECUs that does not satisfy the predetermined condition is recorded in the non-volatile storage device of the remaining ECU. As a result, a portion of the data acquired by ECU 2A and ECU 2B in control system 1 that satisfies the predetermined condition is recorded in the single non-volatile storage device 4A, and the remaining data acquired by ECU 2B that does not satisfy the predetermined condition is recorded in the non-volatile storage device 4B.

[0070] In step 205, the ECU 2A transmits to the ECU 2B a portion of the EDR data and DSSAD data acquired and processed by the processor 3A that satisfies a predetermined condition. The ECU 2B stores the EDR data and DSSAD data acquired and processed by the processor 3B and the data transmitted from the ECU 2A in the non-volatile storage device 4B. The ECU 2B then stores the remaining data, excluding the portion of the EDR data and DSSAD data acquired and processed by the processor 3B that was transmitted to the ECU 2A, in the non-volatile storage device 4B, and terminates the process (step 206). Note that the "predetermined condition" may be the same as that in step 204A. In other words, in step 205A, data that satisfies specified conditions among the data acquired by the remaining ECUs (ECU 2A) excluding ECU 2B from the multiple ECUs 2A, 2B is transmitted to ECU 2B equipped with the selected non-volatile memory device 4B, and the data acquired by ECU 2B and data acquired by the "remaining ECUs" that satisfies the specified conditions are recorded in one non-volatile memory device 4B, and data acquired by the "remaining ECUs" that does not satisfy the specified conditions are recorded in the non-volatile memory device of the "remaining ECU."

[0071] As described above, in this embodiment, when data acquired by multiple ECUs 2A, 2B is recorded in a selected non-volatile storage device (4A or 4B), a portion of the data acquired by the remaining ECUs (2B or 2A) excluding the ECU equipped with the selected non-volatile storage device is transmitted to the ECU (2A or 2B) equipped with the selected non-volatile storage device, and the data acquired by the ECU equipped with the selected non-volatile storage device and the portion of the data transmitted from the remaining ECUs are recorded in the selected non-volatile storage device. In this way, by transmitting and recording only the portion of the data that satisfies the conditions from the remaining ECUs, the amount and number of writes to the non-volatile storage device to which data is sent and recorded can be appropriately controlled based on the conditions, thereby making it possible to appropriately control the remaining life of the non-volatile storage device to which data is sent and recorded.

[0072] Third Embodiment Next, a third embodiment of the present invention will be described. The same parts as those in the first and second embodiments described above are designated by the same reference numerals, and the description of these same parts may be omitted as appropriate.

[0073] 6 is a system configuration diagram showing an example of a control system according to embodiment 3. The illustrated control system 100 includes a plurality of ECUs 2C, 2D, and 2E that are connected to each other so as to be able to communicate with each other. Each of the plurality of ECUs 2C, 2D, and 2E includes at least one processor and at least one nonvolatile storage device.

[0074] The ECU 2C includes multiple processors 3A, 3B that can communicate with each other and acquire data, and multiple nonvolatile storage devices 4A, 4B that store the data acquired by the multiple processors 3A, 3B. Each processor in the ECU 2C is paired with at least one nonvolatile storage device, and data can be stored in the nonvolatile storage device from the processors in the same pair. In the example of FIG. 6, the first processor 3A is paired with the first nonvolatile storage device 4A, and the second processor 3B is paired with the second nonvolatile storage device 4B. Note that multi-core processors may be used as each of the processors 3A, 3B.

[0075] At least one sensor (first sensor 6A, second sensor 6B) is connected to each of the multiple processors 3A, 3B within the ECU 2C, and data detected by the sensors 6A, 6B (e.g., information inside and outside the vehicle) is input to the connected processors 3A, 3B.

[0076] The usage status monitoring unit 5 is connected to the multiple processors 3A, 3B in the ECU 2C and the multiple non-volatile storage devices 4A, 4B in the ECU 2C so that they can communicate with each other. The usage status monitoring unit 5 calculates the remaining lifespans of the multiple non-volatile storage devices 4A, 4B based on data related to the usage status of the multiple non-volatile storage devices 4A, 4B in the ECU 2C, and selects one non-volatile storage device from the multiple non-volatile storage devices 4A, 4B as a recording destination for data from the multiple processors 3A, 3B in the ECU 2C based on the calculated remaining lifespans of the multiple non-volatile storage devices 4A, 4B.

[0077] Each of the plurality of processors 3A, 3B in the ECU 2C is configured to be able to record acquired data in one nonvolatile storage device selected by the usage status monitoring unit 5.

[0078] The usage status monitoring unit 5 manages the remaining life of each of the nonvolatile storage devices 4A, 4B, which is calculated based on data relating to the usage status of the nonvolatile storage devices 4A, 4B in the ECU 2C, and the data stored in each of the nonvolatile storage devices 4A, 4B. The data relating to the usage status of the nonvolatile storage devices 4A, 4B in the ECU 2C can be the same as that in the first embodiment.

[0079] The usage status monitoring unit 5 may be, for example, an ECU or a computer other than the ECU 2C. Although the usage status monitoring unit 5 is shown in FIG. 6 as being separate from the two processors 3A and 3B, it may be stored in a non-volatile storage device (4A or 4B) paired with one of the two processors 3A and 3B as a program executed by that processor. In other words, one of the multiple processors 3A and 3B in the ECU 2C may function as the usage status monitoring unit 5. The usage status monitoring unit 5 may also be an interface or communication device that inputs necessary data (i.e., the remaining life of each non-volatile storage device 4A and 4B and the contents of the data stored therein) from the outside.

[0080] 7 is a flowchart showing an example of the procedure for switching the nonvolatile storage devices 4A and 4B as data storage destinations by the usage status monitoring unit 5 according to the third embodiment of the present invention. Steps 1107 and 1108 are different from those in FIG. 2, but the other steps are the same as those in FIG. 2. Below, the description of the steps that are the same as those in FIG. 2 will be omitted as appropriate, and steps 1107 and 1108 will be mainly described.

[0081] If it is determined in step 105 that the previous selection was the non-volatile memory device 4B, the usage monitoring unit 5 selects the non-volatile memory device 4A in step 1107, notifies each processor 3A, 3B in the ECU 2C of this, and ends the flow (step 109).

[0082] Also, if it is determined in step 106 that the previous selection was the non-volatile memory device 4A, the usage monitoring unit 5 selects the non-volatile memory device 4B in step 1108, notifies each processor 3A, 3B in the ECU 2C of this fact, and ends the flow (step 109).

[0083] The "predetermined timing" for starting the flow of FIG. 7 and the "predetermined timing" for selecting one nonvolatile memory device in the flow of FIG. 7 can be the same as in the first embodiment.

[0084] 8 is a flowchart showing an example of a procedure for saving data to nonvolatile storage devices 4A and 4B by processors 3A and 3B according to the third embodiment of the present invention. Steps 1204 and 1205 are different from those in Fig. 3, but the other steps are the same as those in Fig. 3. Below, the description of the steps that are the same as those in Fig. 3 will be omitted as appropriate, and steps 1204 and 1205 will be mainly described.

[0085] In step 1204, processor 3B transmits the EDR data and DSSAD data acquired and processed by processor 3B to processor 3A. Processor 3A stores the EDR data and DSSAD data acquired and processed by processor 3A and the data transmitted from processor 3B in non-volatile storage device 4A, and then terminates processing (step 206). That is, in step 1204, data acquired by the remaining processor 3B (excluding processor 3A) from the multiple processors 3A and 3B is transmitted to the processor 3A paired with the selected non-volatile storage device 4A, and the data acquired by processor 3A and the data transmitted from the remaining processor 3B are recorded in the single non-volatile storage device 4A. As a result, all data acquired by the multiple processors 3A and 3B in ECU 2C is recorded in the single non-volatile storage device 4A.

[0086] In step 1205, processor 3A transmits the EDR data and DSSAD data acquired and processed by processor 3A to processor 3B. Processor 3B stores the EDR data and DSSAD data acquired and processed by processor 3B and the data transmitted from processor 3A in non-volatile storage device 4B, and then terminates processing (step 206). That is, in step 1205, data acquired by the remaining processors 3A, excluding processor 3B, from the multiple processors 3A and 3B is transmitted to the processor 3B paired with the selected non-volatile storage device 4B, and the data acquired by processor 3B and the data transmitted from the remaining processor 3A are recorded in the single non-volatile storage device 4B. As a result, all data acquired by the multiple processors 3A and 3B in ECU 2C is recorded in the single non-volatile storage device 4B.

[0087] In this embodiment, the ECU 2C includes multiple sets of processors 3A, 3B and nonvolatile storage devices 4A, 4B. The remaining life of each nonvolatile storage device 4A, 4B is calculated, and data acquired by the multiple processors 3A, 3B in the ECU 2C is stored in one nonvolatile storage device (4A or 4B) selected based on the calculated remaining life. This configuration of the ECU 2C prevents data from being unevenly stored in the two nonvolatile storage devices 4A, 4B, and equalizes the remaining life of each storage device 4A, 4B, thereby extending the system's lifespan. In particular, in this embodiment, as in the first embodiment, the nonvolatile storage device selected by the usage monitoring unit 5 is the one with the longest remaining life among the multiple nonvolatile storage devices 4A, 4B in the ECU 2C, thereby further extending the system's lifespan.

[0088] 8, a predetermined condition may be set for the data to be transmitted, as in the second embodiment, and only a portion of the data that satisfies the predetermined condition may be transmitted to the target processor (3A or 3B). That is, in the ECU 2C, one processor connected to one non-volatile storage device selected by the usage status monitoring unit 5 may be excluded from the plurality of processors in the ECU 2C, and the remaining processors may transmit a portion of the data acquired by the remaining processor that satisfies the predetermined condition to the one non-volatile storage device, and the first processor may record the data acquired by the first processor and the portion of the data transmitted from the remaining processor in the one non-volatile storage device.

[0089] Furthermore, although the ECU 2C in FIG. 6 is configured to have two processors 3A, 3B and two non-volatile storage devices 4A, 4B, it may also be configured to have three or more processors and three or more non-volatile storage devices.

[0090] The present invention is not limited to the above-described embodiments, and includes various modifications within the scope of the gist of the present invention. For example, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted. Furthermore, some of the configurations according to one embodiment can be added to or replaced with configurations according to other embodiments.

[0091] Furthermore, the components of the ECU described above, as well as their functions and execution processes, may be partially or entirely implemented in hardware (e.g., by designing logic for executing each function as an integrated circuit). The components of the ECU described above may also be implemented as programs (software) that are read and executed by a processor (e.g., a CPU) to implement the functions of the ECU. Information related to the programs may be stored in, for example, semiconductor memory (flash memory, SSD, etc.), magnetic storage devices (hard disk drives, etc.), and recording media (magnetic disks, optical disks, etc.).

[0092] In addition, in the above description of each embodiment, the control lines and information lines are those that are considered necessary for the description of the embodiment, but they do not necessarily represent all the control lines and information lines related to the product. In reality, it can be considered that almost all components are interconnected.

[0093] REFERENCE SIGNS LIST 1... control system, 2A... electronic control unit (ECU), 2B... electronic control unit (ECU), 3A... processor (first processor), 3B... processor (second processor), 4A... non-volatile storage device (first non-volatile storage device), 4B... non-volatile storage device (second non-volatile storage device), 5... usage status monitoring unit, 6A... sensor (first sensor), 6B... sensor (second sensor), 100... control system

Claims

1. A data recording method for a control system having a plurality of processors and a plurality of non-volatile storage devices, each of which is configured by at least one of the plurality of processors and at least one of the plurality of non-volatile storage devices, the method comprising: calculating the remaining lifespan of the plurality of non-volatile storage devices based on data relating to the usage status of the plurality of non-volatile storage devices; selecting one non-volatile storage device from the plurality of non-volatile storage devices based on the calculated remaining lifespan of the plurality of non-volatile storage devices; and recording data acquired by the plurality of electronic control devices in the one selected non-volatile storage device.

2. A data recording method for a control system according to claim 1, characterized in that the data relating to the usage status includes at least one of the cumulative amount of writing to the plurality of non-volatile memory devices and the cumulative number of writings to the plurality of non-volatile memory devices.

3. A data recording method for a control system according to claim 2, characterized in that the data relating to the usage status further includes at least one of temperature data of the plurality of electronic control devices and data relating to replacement sectors in the plurality of non-volatile storage devices.

4. A data recording method for a control system according to claim 1, wherein said one non-volatile storage device is the non-volatile storage device having the longest calculated remaining life among said plurality of non-volatile storage devices.

5. A data recording method for a control system according to claim 1, wherein the selection of said one non-volatile storage device is performed at a predetermined timing.

6. A data recording method for a control system according to claim 5, wherein the predetermined timing is when the ignition of a vehicle in which the control system is mounted is turned on.

7. A data recording method for a control system according to claim 1, characterized in that recording the data acquired by the plurality of electronic control devices in the single non-volatile storage device includes: transmitting data acquired by the remaining electronic control devices among the plurality of electronic control devices, excluding the first electronic control device, to a first electronic control device equipped with the single non-volatile storage device; and recording the data acquired by the first electronic control device and the data transmitted from the remaining electronic control devices in the single non-volatile storage device.

8. A data recording method for a control system according to claim 7, characterized in that a portion of the data acquired by the remaining electronic control devices which satisfies a predetermined condition is transmitted to the first electronic control device, and the data acquired by the first electronic control device and the portion of the data transmitted from the remaining electronic control devices are recorded in the single non-volatile storage device.

9. An electronic control device comprising: a plurality of processors capable of communicating with each other and each acquiring data; and a plurality of non-volatile storage devices in which the data acquired by the plurality of processors is recorded, further comprising a usage status monitoring unit that calculates the remaining lifespan of the plurality of non-volatile storage devices based on data relating to the usage status of the plurality of non-volatile storage devices, and selects one non-volatile storage device from among the plurality of non-volatile storage devices based on the calculated remaining lifespan of the plurality of non-volatile storage devices, wherein each of the plurality of processors records the acquired data in the one non-volatile storage device selected by the usage status monitoring unit.

10. In the electronic control device of claim 9, the data relating to the usage status includes at least one of the cumulative amount of writing to the plurality of non-volatile memory devices and the cumulative number of writings to the plurality of non-volatile memory devices.

11. An electronic control device according to claim 10, wherein the data relating to the usage status further includes at least one of temperature data of the electronic control device and data relating to replacement sectors in the plurality of non-volatile storage devices.

12. An electronic control device according to claim 9, wherein said one nonvolatile storage device is the nonvolatile storage device having the longest calculated remaining life among said plurality of nonvolatile storage devices.

13. The electronic control device according to claim 9, wherein the selection of said one non-volatile memory device is performed at a predetermined timing.

14. The electronic control device according to claim 13, wherein the predetermined timing is when the ignition of a vehicle in which the electronic control device is mounted is turned on.

15. In the electronic control device of claim 9, the remaining processors, excluding the first processor connected to the one non-volatile storage device, from the plurality of processors transmit a portion of the data acquired by the remaining processors that satisfies a predetermined condition to the one non-volatile storage device, and the first processor records the data acquired by the first processor and the portion of the data transmitted from the remaining processors in the one non-volatile storage device.

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