Automotive network bus message suppression for reducing battery consumption

Abstract

The present disclosure provides "Automotive network bus message suppression for reducing battery consumption." An electronic controller module in a vehicle is powered by a battery during a "key-off" state. The electronic controller module has a bus interface for transmitting messages to and receiving messages from a multiplexed bus, where the messages include a periodic sequence of network management (NM) messages transmitted during a normal operating mode. A control circuit in the module is configured to detect an "off" state of the vehicle in which use of power from the battery is limited within the vehicle, to detect a state of charge (SOC) of the battery, and to compare the detected SOC to a critical battery threshold. The control circuit is further configured to determine an elapsed time from when the "off" state is detected and the SOC is no longer above the critical battery threshold, and to inhibit the sequence of NM messages when the elapsed time is greater than a time threshold.

Description

Technical Field

[0001] The present invention generally relates to bus communication between automotive electronic control units, and more specifically, to bus message control during the period when the electronic control unit should enter sleep mode to maintain battery power reserves when the vehicle is turned off. Background Technology

[0002] Typical automotive electrical systems rely on a battery to start the internal combustion engine (and / or shut off the high-voltage contactor in hybrid vehicles) and to power electrical accessories when the engine is not running. Many modern electronic vehicle systems operate continuously, even when the vehicle is parked and unattended, relying on the battery as the only available power source. Some electronic modules that must always be powered include those that perform functions while parked (e.g., anti-theft systems and remote entry systems) and those that require only reduced power to maintain memory contents or monitor / measure various conditions or electrical communication signals (e.g., in sleep mode). Other modules can continue to operate for a specified time after the driver turns off the vehicle, but can be de-energized after that time (e.g., door-controlled lighting).

[0003] Because vehicles may be parked for extended periods, limiting battery consumption is crucial to ensure that when the user returns, there is still sufficient battery state of charge to start the vehicle (e.g., starting the internal combustion engine in a gas-powered vehicle, or turning off the main contactor in an electric or hybrid vehicle). Vehicle manufacturers typically specify limits on the current drawn by various modules under each possible condition. Specifically, a "Key Off Load" (KOL) strategy can be specified, which sets quiescent current limits for modules. Different KOL modes with different limits can be applied to different modules based on (i) the time the vehicle's ignition switch has been "off" for a given period of time and there has been no user activity, and / or (ii) the battery's state of charge. The sum of all quiescent currents is intended to be low enough to extend the vehicle's ability to start for a sufficiently long time. However, after a period of time, the battery may still be depleted and unable to start the engine / hybrid system.

[0004] When a vehicle fails to start due to a discharged battery, even if the vehicle's idle time is shorter than what a normal battery could handle, battery replacement is common, assuming a defect. However, battery depletion can sometimes be caused by minor software glitch that fails to reduce battery consumption to resting levels. For example, if one or more electronic modules wake up when they should be in sleep mode, this can cause premature battery depletion. These minor software glitch may not be permanent and can be difficult to detect because the software may fully recover after the next ignition cycle. Therefore, battery replacement may be unnecessary.

[0005] Serial multiplexed communication between electronic modules within a vehicle is widely adopted. For example, Controller Area Network (CAN) is a commonly used communication protocol that effectively supports distributed real-time control with a high level of reliability. Interconnected modules include engine control units, infotainment modules, navigation components, sensor units (e.g., cameras, radar, ultrasonic sensors), anti-lock braking systems, electric power steering systems, and other systems. The CAN bus interconnecting these modules can have a bit rate of up to 1 Mbit / s. The use of multiplexing systems reduces wiring harness size while improving communication speed and flexibility.

[0006] A pair of twisted-pair cables can be used to form a multiplexed (e.g., CAN) bus that interconnects bus transceivers in corresponding nodes (i.e., control units or modules). Each module receives its power from a power line carrying a DC supply voltage (e.g., 12VDC), extending from a distribution box. Each module is capable of entering one or more low-power modes, such as a ready-to-sleep mode and a sleep (fully off) mode. Each particular module includes its own specific programming based on the functions to be performed and the conditions under which the module must wake up or can enter a low-power mode. Typically, a module adopts a ready-to-sleep mode before actually entering a sleep mode, where at least some functions (including bus message transmission and reception) are maintained. For example, the Autosar open system architecture specifies that a module in wake-up mode will periodically transmit network management (NM) messages during the time it needs other modules on the same bus to remain awake and available. When a particular module detects a condition that it should be able to enter sleep mode, it enters a ready-to-sleep mode and monitors for NM messages indicating that it needs to postpone its full sleep mode. The module will only enter a power-off state (e.g., sleep mode or complete shutdown) after no more NM messages have been received within a specified time period.

[0007] Whenever a minor software glitch or other error prevents a module from properly entering its power-down state, it can continue transmitting NM messages, preventing other modules receiving those NM messages from exiting their ready-to-sleep mode. Therefore, an error in one module has a cascading effect, where power consumption remains high during the time when all or most modules should be sleeping. Summary of the Invention

[0008] In one aspect of the invention, an electronic controller module for a vehicle is provided, wherein the vehicle includes a battery for powering the electronic controller module. The electronic controller module has a bus interface for transmitting messages to and receiving messages from a multiplexed bus, wherein the messages include a periodic sequence of network management (NM) messages transmitted during normal operating mode. Control circuitry is configured to: detect a “off” state of the vehicle, wherein the use of power from the battery is restricted within the vehicle; detect the state of charge (SOC) of the battery; and compare the detected SOC with a critical battery threshold. The control circuitry is also configured to determine an elapsed time starting when the “off” state is detected and the SOC is no longer higher than the critical battery threshold, and when the elapsed time is greater than the time threshold, to prohibit (i.e., pause or block) the sequence of NM messages. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing an electronic module connected via a CAN bus.

[0010] Figure 2 This is a block diagram illustrating one embodiment of an electrical architecture for distributing power and multiplexing communication signals, in which KOL power management is implemented.

[0011] Figure 3 This is a flowchart illustrating a method used by the module to monitor NM messages and enter sleep mode when appropriate.

[0012] Figure 4 This is a state diagram illustrating one embodiment of the process of selectively interrupting the transmission of NM messages.

[0013] Figure 5 This is a block diagram illustrating a control arrangement for selectively stopping NM messages according to an embodiment of the present invention.

[0014] Figure 6 This is a flowchart illustrating a preferred embodiment of the present invention.

[0015] Figure 7 This is a graph showing the variable time threshold selected based on the battery's state of charge.

[0016] Figure 8 This is a table showing the incremental supplement of variable time thresholds based on the number of independent subnets that the module can communicate with. Detailed Implementation

[0017] Figure 1A multiplexing network is illustrated, in which an electronic control unit or module 10 is connected via connector 11 to a CAN multiplexing bus 12, the multiplexing bus comprising twisted pairs of lines labeled CAN-H and CAN-L. A DC power line 13 supplies DC power to module 10 and to modules 14 and 15, each of which includes the same multiplexing functionality as shown for module 10.

[0018] Module 10 receives and utilizes DC power via wired connection 16. Bus transceiver 17 works in conjunction with CAN controller 18. Bus transceiver 17 has output terminals 20 and 21 for transmitting or receiving complementary signals following the CAN protocol. Output terminals 20 and 21 are connected to interface circuitry 22 and to isolator circuitry 23. Isolator circuitry 23 is normally in a non-isolated state, which allows CAN bus messages to flow between bus 12 and bus transceiver 17. Figure 1 An example embodiment for blocking the transmission of NM messages under predetermined conditions is shown. For example, when controller 18 detects these predetermined conditions, it can signal interface circuitry 22, which then reconfigures isolator 51 to block outgoing messages from transceiver 17. In some alternative embodiments, controller 18 may instead include software instructions to block the initiation of any such NM messages under predetermined conditions.

[0019] Figure 2 An example power distribution within an electrical system 25 is shown, which has a battery 26 connected to a battery monitoring system (BMS) 27. The BMS 27 can be a conventional component, specifically measuring the battery current flowing from the battery 26 to electrical loads. Both the Body Control Module (BCM) 30 and the BMS 27 are contained within and communicate via a bus network 31 (such as a CAN bus). Bus communication lines (not shown) of the bus network 31 circulate between the BMS 27, BCM 30, modules 30, 33 to 35, 37, and 44, and the Powertrain Control Module (PCM) 40. The bus network 31 interconnects with a gateway 32, which is also connected to additional bus networks 45 and 46 that may operate using the same or different protocols. When different, the gateway 32 reformatts and transmits messages between the networks, enabling modules in different bus networks to exchange communication signals known in the art. Power bus 28 distributes the output of battery 26 to various modules, including BCM 30 and many other modules, including modules 33 to 35 interconnected via bus network 31. Module 37 and PCM 40 are controlled by BCM 30 to use battery power as a separate subnet 36. Control messages from BCM 30 may also include commands to control power delivery to slave components of the control module (e.g., sensors 41 and actuators 42 that receive power via PCM 40).

[0020] In another example of power management, PCM 30 is connected to relay 43, which receives power from power bus 28 and can optionally transfer power to module 44. Relay 45 may include, for example, an ignition relay. Module 44 is also connected to bus network 31. Relay 43 can be controlled via a direct signal connection to BCM 30 or alternatively via multiplexed messages. However, depending on the "on" / "off" state of relay 45, module 46 does not have a sleep mode, but is either fully powered or completely powered down. On the other hand, most modules (including modules 33 to 35 in subnet 36, as well as modules 37 and 40) are always powered from power bus 28, but each invokes appropriate power-reducing modes, such as sleep mode, when needed.

[0021] During the time the vehicle's ignition switch is on or in an accessory state, the electronic control unit connected to the multiplexed bus can typically be awake (i.e., in power-on mode). For network management purposes and to coordinate the power-down of different modules into appropriate sleep modes according to a KOL strategy, it may be necessary for each module to broadcast regular network management (NM) messages to all other nodes on the bus upon waking. For example, modules may transmit periodic sequences of NM messages at a predetermined frequency of several hertz (e.g., a heartbeat). Typically, modules are programmed to recognize when conditions indicate they should attempt to enter a reduced-power mode (e.g., sleep mode). Once this is recognized, the module can enter a ready-to-sleep mode, where it listens for NM messages broadcast by other modules on the bus (modules in ready-to-sleep mode do not transmit messages). Figure 3 The procedure for operation in a module that has entered a sleep preparation mode in step 50 is illustrated. In step 51, an NM timeout timer is started (or restarted) to determine the elapsed time since the last NM message was received. In step 52, a check is performed to determine if an NM message has been detected. If an NM message is detected, the NM timeout timer is restarted in step 51. If no NM message is detected, the value of the timeout timer is compared to a predetermined time threshold (e.g., 90 seconds). If it is less than the threshold, the process returns to step 52 to monitor for NM messages. Once the elapsed time exceeds the threshold, the module transitions to sleep mode in step 54. By delaying sleep modes in all modules on the bus, each module actively communicating on the bus has the ability to complete its message sequence before the entire group of modules on the bus enters sleep mode.

[0022] Therefore, a module will only enter its sleep mode (where it stops monitoring bus messages) if no NM message is received within a threshold time period. Whenever a particular module fails to correctly enter its ready-to-sleep mode, it will continue to broadcast its NM messages, and these messages will prevent other modules in their ready-to-sleep mode from transitioning to their sleep mode. In these situations, the battery power consumption rate is higher than the expected rate under the KOL strategy.

[0023] This invention helps ensure that a module experiencing a fault will still stop broadcasting NM messages and allow other modules to enter their sleep modes, which would otherwise prevent the module from stopping NM message broadcasting. To avoid becoming a module that incorrectly prevents other modules from entering their sleep modes, a watchdog-type program is incorporated into the module's operation. This program may preferably include programming instructions in each module configured to stop the module from broadcasting NM messages under certain trigger conditions. These trigger conditions may include one or more of the following: (1) the battery state of charge is below a predetermined percentage, (2) the ignition state is "off", and (3) the duration of broadcasting NM messages exceeds a time threshold. Specifically, the trigger conditions may consist of: the battery SOC being below a predetermined percentage (e.g., 40%) or decreasing at a certain rate after falling below a slightly higher threshold (e.g., a 2% decrease in SOC per hour once it falls below 55%). Preferably, conditions 1 through 3 may all be true in order to stop NM messages. In some embodiments, a fourth trigger condition is utilized, which requires the absence of any abnormal conditions that override any concern for maintaining battery power. Abnormal conditions (i.e., conditions under which the module does not need to stop its NM messages) may include periods in which a particular module is part of any feature that should allow the battery to run to zero charge, such as the flashing of an external signaling (warning) light, operation of a wireless transceiver, or vehicle security (e.g., door lock operation). Once the module has determined to stop the NM messages, the pause in broadcasting the NM messages preferably continues until the next normal wake-up of the network bus.

[0024] Figure 4A state diagram is shown illustrating the operation of a controller module according to an embodiment of the invention. The module is initially in state 56, where broadcasting of NM messages is unrestricted. After a set of triggering conditions (designated as condition set #1) occurs, it transitions to state 57, where a timer is activated to detect whether broadcasting of NM messages continues for an extended period (e.g., approximately 5 seconds). Condition set #1 may consist of the following: the vehicle is "off" (i.e., inactive and / or unoccupied) and the battery SOC is less than a critical threshold. State 57 continues as long as condition set #1 remains true and broadcasting of NM messages remains active. If condition set #1 becomes false, the transition returns to state 56. If the timer expires in state 57, the transition proceeds to state 58. While in state 58, communication is cut off, causing NM messages to stop. The module controller waits in state 58 until an external wake-up action or operation is detected, at which point the transition returns to state 56. Similarly, if any aspect of condition set #1 becomes false (e.g., the vehicle ignition switch is turned on), the transition returns to state 56.

[0025] Figure 5 The diagram illustrates a logic circuitry system for determining when to stop NM message transmission. Vehicle state logic block 60 uses ignition switch state (“on” or “off”), gear selector position (“park” or not “park”), vehicle speed (stationary or not stationary), or door state (open or closed) to determine the vehicle state. If all these factors are consistent with the vehicle being inactive, a high logic level signal is sent from block 60 to the input of AND gate 61. Battery level logic block 62 compares the SOC value from the battery monitor with a predetermined battery percentage representing a critical battery level. When the battery SOC is at or below the critical level, a high logic level signal is sent from battery level logic block 62 to the other input of AND gate 61. Message activity logic block 63 compares the duration for which NM messages have cycled after both the critical battery level and the vehicle state being “off” are detected. When the duration exceeds a time threshold, a high logic level signal indicating an extension of the NM message activity duration is sent from logic block 63 to the other input of AND gate 61. The exception logic block 64 can use a lookup table or other electronic resources (e.g., available via a multiplexed bus) to determine if any exception condition exists. If not, a high logic level signal is sent to the other input of AND gate 61. When all four inputs of AND gate 61 are high, a high logic level output is provided from AND gate 61, which can be used to employ a state within the controller module that prevents the transmission of NM messages on the multiplexed bus until a wake-up of the entire bus system or a change in the vehicle occurs, causing one of the original conditions to be false.

[0026] Figure 6 A method of the present invention is illustrated, wherein a specific module connected to a multiplexed bus determines whether to send a regular NM message upon its wake-up. In step 70, a check is performed to determine if the vehicle state is “off.” The “off” state can be predicted based on the ignition switch being in the “off” position (this can also be verified by determining that the vehicle is stationary at zero speed or the transmission selector is in the “park” position). Once step 70 detects that the vehicle state is “off,” a check is performed in step 71 to determine if the battery state of charge has reached a critical level (e.g., below a predetermined percentage). If no critical battery level is detected and the vehicle remains in the “off” state, the battery level is repeatedly checked in step 71. Once the battery SOC drops below the critical level, a check is performed in step 72 to determine if the module is in a normal operating (wake-up) state with a regular cycle of NM messages. As long as the NM message cycle is not occurring, the module does not prevent other modules from entering a sleep state and no action is required. If an NM message cycle exists, a timer is started in step 73. The timeout threshold for the timer can be approximately 5 seconds or other time periods (e.g., in the range of approximately 2 to 10 seconds), which are selected to help ensure that any legitimate ongoing communication functions required by the module have time to complete before the message pause begins.

[0027] In step 74, a check is performed to determine whether the NM message loop continues. If it continues, a check is performed in step 75 to determine whether a timer has expired. If a timer expiration is detected in step 75, a check is performed in step 76 to determine if any override exceptions exist. If an exception is detected (e.g., a specific module is involved in executing a feature with high priority, which should be allowed to continue regardless of battery SOC), communication is not disabled in step 77. Otherwise, the NM message loop is disabled in step 78. Preferably, the NM message loop remains disabled until the next bus wake-up event occurs or until one of the triggering conditions (e.g., the ignition switch is turned to the "on" state) changes.

[0028] As mentioned above, the time threshold for the NM message loop to have lasted can be approximately 5 seconds. In some embodiments, the time threshold can be a dynamic parameter that changes in response to different levels of battery SOC. Figure 7 The relationship between the threshold time and battery SOC is illustrated 80, where the threshold time becomes shorter as the battery's state of charge decreases, allowing other modules on the multiplexing circuitry to transition from a ready-to-sleep mode to a sleep mode more quickly. Similarly, the time threshold can be further adjusted using battery life or battery state of health (SoH). For example, a shorter time threshold can be used as battery life increases.

[0029] On the other hand, in situations where several multiplexed buses communicate via a gateway, a longer time threshold can be useful because message propagation between nodes on different bus segments may take longer. For example... Figure 8 As shown, incremental supplementation can be included in the time threshold based on the number of buses that may exist within the multiplexing network of a particular vehicle. The supplementary time increment can be proportional to the number of bus segments. For example, when there are two interconnected buses, the time threshold can be increased by 1 second, and when there are four buses, the time increment can consist of a 4-second supplement.

[0030] According to the present invention, a method for operating an electronic controller module for a vehicle, wherein the vehicle includes a battery for powering the electronic controller module, the method comprising the steps of: transmitting messages to and receiving messages from a multiplexed bus, wherein the messages include a periodic sequence of network management (NM) messages transmitted during normal operating mode; detecting a “off” state of the vehicle, wherein the use of power from the battery is restricted within the vehicle; detecting the state of charge (SOC) of the battery; comparing the detected SOC with a critical battery threshold; determining an elapsed time starting from when the “off” state is detected and the SOC is no longer higher than the critical battery threshold; and when the elapsed time is greater than the time threshold, then inhibiting the periodic sequence of NM messages.

[0031] In one aspect of the invention, when an abnormal condition exists that allows the consumption of battery power below the critical battery threshold, the prohibition of the periodic sequence of the NM message is prevented.

[0032] In one aspect of the invention, the time threshold is in the range of 2 to 10 seconds.

[0033] In one aspect of the invention, a time threshold is dynamically determined in response to a detected SOC.

[0034] In one aspect of the invention, when the multiplexed bus is interconnected to another bus segment via at least one gateway, the time threshold includes a supplementary time increment.

Claims

1. An electronic controller module for a vehicle, wherein the vehicle includes a battery for powering the electronic controller module, the electronic controller module comprising: A bus interface for transmitting messages to and receiving messages from a multiplexed bus, wherein the messages include a periodic sequence of network management (NM) messages transmitted during normal operation. as well as A control circuit, connected to the bus interface, is configured to: The vehicle is detected to be in a "shutdown" state, where the use of power from the battery is restricted within the vehicle. Detecting the state of charge (SOC) of the battery; and The detected SOC is compared with the critical battery threshold. The control circuit is further configured to: Determine the elapsed time starting from when the "off" state is detected and the SOC is no longer above the critical battery threshold; and When the elapsed time exceeds a time threshold, the periodic sequence of NM messages is prohibited.

2. The electronic controller module of claim 1, wherein the sequence of NM messages is disabled until the control circuit detects an external wake-up action.

3. The electronic controller module of claim 1, wherein the control circuit is further configured to prevent and disable the periodic sequence of the NM message when an abnormal condition exists that allows the consumption of battery power below the critical battery threshold.

4. The electronic controller module as claimed in claim 1, wherein the time threshold is in the range of 2 seconds to 10 seconds.

5. The electronic controller module of claim 1, wherein the time threshold is dynamically determined in response to the detected SOC.

6. The electronic controller module of claim 5, wherein the time threshold is determined according to a relationship in which a decrease in the detected SOC corresponds to a shorter time threshold.

7. The electronic controller module of claim 1, wherein when the multiplexed bus is interconnected to another bus segment via at least one gateway, the time threshold includes a supplementary time increment.

8. The electronic controller module of claim 7, wherein the supplemental time increment is proportional to the number of bus segments interconnected with the multiplexed bus.

9. The electronic controller module of claim 1, wherein the "off" state is detected in response to the "off" position of the ignition switch of the vehicle.

10. A transport vehicle comprising: Battery; Multiplexed bus; as well as An electronic controller module, the electronic controller module being powered by the battery, wherein the electronic controller module includes: A bus interface for transmitting messages to and receiving messages from the multiplexed bus, wherein the messages include a periodic sequence of network management (NM) messages transmitted during the normal operating mode of the electronic controller module. as well as A control circuit, connected to the bus interface, is configured to: (A) detect a "shutdown" state of the vehicle, wherein the use of power from the battery is restricted within the vehicle; (B) detect the state of charge (SOC) of the battery; (C) compare the detected SOC with a critical battery threshold; (D) determine an elapsed time starting from when the "shutdown" state is detected and the SOC is no longer higher than the critical battery threshold; and (E) when the elapsed time is greater than the time threshold, disable the periodic sequence of NM messages.

11. The transport vehicle of claim 10, wherein the periodic sequence of the NM messages is disabled until the control circuit detects an external wake-up action.

12. The transport vehicle of claim 10, wherein the control circuit is further configured to prevent a periodic sequence of NM messages when an abnormal condition exists that allows the consumption of battery power below the critical battery threshold.

13. The transport vehicle of claim 10, wherein the time threshold is in the range of 2 seconds to 10 seconds.

14. The transport vehicle of claim 10, wherein the time threshold is dynamically determined in response to the detected SOC.

15. The transport vehicle of claim 10, wherein when the multiplexed bus is interconnected to another bus segment via at least one gateway, the time threshold includes a supplementary time increment.

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