A body controller with CAN bus load rate dynamic adjustment based on signal priority

Abstract

The utility model provides a kind of vehicle body controller with CAN bus load rate dynamic adjustment based on signal priority, including main control unit and CAN transceiver, CAN controller is built-in in main control unit, CAN controller is connected with CAN transceiver, CAN transceiver is connected with CAN bus;CAN controller is connected with load rate monitoring module, load rate monitoring module is connected with signal priority dynamic adjustment module and hierarchical flow control module respectively, priority dynamic adjustment module is connected with hierarchical flow control module, hierarchical flow control module is connected with CAN controller.The utility model passes through real-time monitoring CAN bus load rate and dynamically adjusts signal priority, ensures that key control signal can still be preferentially transmitted when bus high load, effectively avoids the delay or loss of key signal, improves response speed and safety reliability;Limited bus bandwidth is preferentially allocated to high priority signal, relieves bus congestion, improves bus utilization.

Description

Technical Field

[0001] This utility model relates to the technical field of automotive electronic control, and in particular to a body controller with dynamic adjustment. Background Technology

[0002] As automotive electronic systems become increasingly complex, the Body Control Controller (BCM) needs to manage a large number of vehicle signals, including numerous safety-critical signals with extremely high real-time requirements (such as braking and steering commands) and comfort signals with lower real-time requirements (such as window controls and ambient lighting). Current CAN bus communication generally uses a fixed priority ID mechanism, meaning that signal priorities are fixed during system design and cannot be dynamically adjusted based on actual bus load. This leads to unacceptable transmission delays, or even data loss, for even critical safety signals under high bus load due to the continuous transmission of low-priority signals, severely impacting vehicle safety and reliability.

[0003] To address these issues, existing technologies typically employ solutions such as increasing bus bandwidth (e.g., upgrading to CAN FD (CAN Flexible Data-Rate), Ethernet, etc.) or adding hardware redundancy (e.g., multiple CAN buses running in parallel). However, these solutions often come with high hardware costs, complex system modifications, and significant space requirements, and in certain specific scenarios, they still struggle to completely avoid bus congestion. It is particularly noteworthy that existing technologies rarely offer an integrated solution that, through specific hardware construction or a combination thereof, achieves real-time monitoring of the CAN bus load rate within the core product—the body controller—and dynamically adjusts CAN signal priorities accordingly.

[0004] Therefore, how to dynamically adjust the CAN signal priority based on real-time load status without significantly increasing hardware cost and complexity, so as to achieve bus load balancing and priority protection of critical control signals, has become an important research direction for optimizing the communication of the vehicle body controller, especially improving its real-time performance and reliability.

[0005] Patent application number 202310203043.9 discloses a method for reducing CAN bus load, which includes at least: real-time monitoring to obtain the current load rate of all network nodes on the same channel of the CAN bus; when the monitored current load rate is greater than a preset maximum load rate threshold, obtaining the priority information of each CAN message sent by all network nodes in the current period of the channel; obtaining a strategy corresponding to the priority level of each network node's CAN message, and adjusting the load reduction of at least one priority CAN message, wherein the load reduction adjustment includes at least: dynamic peak-shifting transmission, and / or extending the transmission cycle. The invention also provides corresponding systems, computing devices, storage media, and vehicles. Implementing the invention can dynamically reduce bus load and ensure the real-time nature of critical information, improving the stability and efficiency of CAN bus communication. However, the invention does not dynamically adjust the signal priority of the CAN bus, and safety-related or important messages may not be sent in a timely manner, potentially leading to accidents. Utility Model Content

[0006] To address the technical problems of poor communication efficiency and real-time performance caused by fixed priorities in existing CAN bus communication, and the high hardware cost of improved solutions, this utility model proposes a vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority. By integrating specific hardware structures and logic units within the vehicle body controller, real-time monitoring of CAN bus load rate and dynamic adjustment of signal priority are achieved. The controller features a novel structure, convenient function optimization, and low hardware cost.

[0007] To achieve the above objectives, the technical solution of this utility model is as follows: a vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority, comprising a main control unit and a CAN transceiver. The main control unit has a built-in CAN controller, which is connected to the CAN transceiver, and the CAN transceiver is connected to the CAN bus. The CAN controller is connected to a load rate monitoring module, which is connected to a signal priority dynamic adjustment module and a hierarchical flow control module. The priority dynamic adjustment module is connected to the hierarchical flow control module, and the hierarchical flow control module is connected to the CAN controller.

[0008] Preferably, the main control unit is a microcontroller, and the CAN controller has a timer, which is connected to the load rate monitoring module.

[0009] Preferably, it also includes a signal buffer area, and the hierarchical flow control module is connected to the signal buffer area.

[0010] Preferably, the CAN transceiver is connected to the CAN controller interface point built into the main control unit.

[0011] Preferably, the timer collects the transmission occupancy time and reception storage time of the CAN bus in real time, and the load rate monitoring module (11) generates a real-time load rate signal of the CAN bus based on the transmission occupancy time, reception storage time and preset statistical period; the preset statistical period is configured to be 100ms to 500ms.

[0012] Preferably, in the priority encoding, the signal priority dynamic adjustment module retains bits 7-0 of the 11-bit standard CAN ID as the original device ID, and uses bits 10-8 as dynamic priority bits, with an encoding range of 000 to 111.

[0013] Preferably, the signal buffer is the RAM area inside the main control unit, and the signal buffer has a first-in-first-out queue structure.

[0014] Preferably, the hierarchical flow control module divides the CAN bus load into at least three levels based on the real-time load rate signal, and adopts different signal transmission control strategies for different levels.

[0015] Preferably, when the real-time load rate is <55%, the tiered flow control module allows the sending of all priority signals; When the real-time load rate is 55%-75%, the graded flow control module suppresses the transmission of signals with priority codes ≥0x4; When the real-time load rate is >75%, the hierarchical flow control module only allows signals with priority codes 0x0 to 0x2 to be sent.

[0016] Preferably, the signal priority dynamic adjustment module uses an existing exponential smoothing algorithm to dynamically adjust the priority; The timer obtains the transmission time of the CAN signal by monitoring the start and end events of the CAN controller's transmission mailbox; the timer also monitors the message storage time of the receive first-in-first-out queue structure to obtain the reception time. The real-time load rate signal is transmitted to the signal priority dynamic adjustment module through the microcontroller's internal interrupt mechanism or shared memory.

[0017] This invention achieves dynamic optimization of CAN bus communication by integrating a load rate monitoring module, a dynamic signal priority adjustment module, and a hierarchical flow control module into the internal structure of the vehicle body controller, and combining them with a first-in-first-out (FIFO) signal buffer. Compared with existing technologies, this invention has the following significant advantages: 1. Significantly improves communication real-time performance and reliability: By monitoring the CAN bus load rate in real time and dynamically adjusting signal priority, it ensures that critical control signals can still be transmitted with priority when the bus is under high load, effectively avoiding the delay or loss of critical signals under the traditional fixed priority mechanism, thereby greatly improving the response speed and safety reliability of the vehicle body control system.

[0018] 2. Effectively alleviate bus congestion: The hierarchical flow control strategy can intelligently suppress the transmission of non-critical signals and prioritize the allocation of limited bus bandwidth to high-priority signals, thereby effectively alleviating bus congestion and improving bus utilization.

[0019] 3. Signal integrity guarantee: The independent FIFO buffer queue structure can effectively buffer suppressed low-priority signals and send them when the bus load decreases, avoiding unnecessary signal loss and ensuring data integrity.

[0020] 4. High compatibility and easy upgradeability: By retaining the original CAN ID device function bits, this utility model can be well compatible with the existing CAN network structure, reducing the difficulty and cost of system upgrades and modifications.

[0021] 5. Integration and cost-effectiveness: Integrating core functions into a single MCU avoids additional hardware redundancy, reduces overall system cost and complexity, and improves system integration. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the present invention.

[0024] Figure 2 This is a flowchart illustrating the load rate calculation process for the load rate monitoring module of this utility model.

[0025] Figure 3 This is a flowchart illustrating the dynamic priority adjustment process of the signal priority adjustment module of this utility model.

[0026] In the diagram, 1 is the main control unit, 2 is the CAN receiver, 3 is the CAN bus, 10 is the CAN controller, 11 is the load rate monitoring module, 12 is the signal priority dynamic adjustment module, 13 is the hierarchical flow control module, and 14 is the signal buffer. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Example 1 like Figure 1 As shown, a vehicle body controller with dynamic CAN bus load rate adjustment based on signal priority includes a main control unit 1 and a CAN transceiver 2. The main control unit 1 houses a CAN controller 10, which converts software signals into hardware signals and receives and sends CAN messages. Some automotive communication information, such as brake and light switches, is transmitted via CAN messages. The CAN controller 10 is connected to the CAN transceiver 2, which is physically connected to the CAN bus 3 to enable CAN message transmission. The main control unit 1 uses an NXP S32K148 microcontroller (MCU) as the core processing unit of the vehicle body controller. It integrates the hardware resources of the CAN controller 10 and carries the software logic for load rate monitoring, dynamic priority adjustment, and hierarchical flow control. Based on the NXP S32K148 microcontroller (MCU), real-time monitoring of the CAN bus load rate and dynamic adjustment of signal priority can be achieved, improving the communication efficiency and real-time performance of the vehicle body controller's CAN bus and ensuring the priority transmission of critical control signals. CAN transceiver 2 is connected to the CAN controller interface point of CAN controller 10 to realize the signal transmission and reception of the CAN bus 3 physical layer. The model of CAN transceiver 2 is TJA1042.

[0029] The main control unit 1 includes a load rate monitoring module 11, a signal priority dynamic adjustment module 12, and a hierarchical flow control module 13. The load rate monitoring module 11 is connected to the built-in timer of the CAN controller 10, and the load rate monitoring module 11 is also connected to the signal priority dynamic adjustment module 12. Both the load rate monitoring module 11 and the signal priority dynamic adjustment module 12 are connected to the hierarchical flow control module 13, which is in turn connected to the CAN controller 10. It also includes a signal buffer 14, which is connected to the hierarchical flow control module 13.

[0030] The load rate monitoring module 11 is integrated inside the main control unit 1. Utilizing the CAN controller timer built into the MCU, the timer collects the real-time transmission occupancy time (TxMailbox transmission occupancy time) and reception storage time (RxFIFO reception storage time) of the CAN bus. Based on the transmission occupancy time, reception storage time, and a preset statistical period, it generates a real-time load rate signal for the CAN bus. The formula for calculating the load rate is: The statistical period can be configured from 100ms to 500ms to balance real-time performance and stability. This load rate metric comprehensively reflects the resource utilization of bus transmission and reception, accurately reflecting the current bus load status.

[0031] The signal priority dynamic adjustment module 12 is integrated inside the main control unit 1 and connected to the load rate monitoring module 11. Its function is to dynamically adjust the priority encoding of the CAN signal based on the real-time load rate signal output by the load rate monitoring module 11. It dynamically adjusts the encoding of the priority bit fields (bits 10-8) in the 11-bit standard CAN ID, with the priority bit field encoding range from 000 to 111. Specifically, in the 11-bit standard CAN ID, bits 7-0 are retained as the original device ID, compatible with the existing system architecture; bits 10-8 are used as dynamic priority bits, as shown in Table 1, with an encoding range from 000 (highest priority, emergency signal) to 111 (lowest priority). The correspondence between priority encoding and levels is shown in Table 2. Through priority encoding, emergency signals (such as safety-related, steering and braking-related signals) can be sent in a timely manner, avoiding accidents caused by delays.

[0032] Dynamic priority adjustment employs a smooth transition mechanism to avoid communication jitter caused by frequent switching. The priority adjustment algorithm is based on a smoothing coefficient and historical priority states, combined with an adaptive control strategy. The priority adjustment algorithm uses an existing exponential smoothing algorithm, as shown in the following formula: Among them, 𝑃 𝑛𝑒𝑤 For the new priority encoding, 𝑃 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 For the current calculation priority, 𝑃 𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠 The previous priority level is set to , and is the smoothing coefficient, ranging from 0.1 to 0.5, with 0.3 recommended. 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 , 𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠 The value is a priority code, and the corresponding value is 0-7.

[0033] When the real-time load rate signal exceeds a preset threshold, the signal priority dynamic adjustment module 12 adjusts the priority encoding of the CAN signal, thereby adjusting its priority. The priority of the CAN message is adjusted to obtain a new CAN message ID.

[0034] The hierarchical flow control module 13 is integrated inside the main control unit (MCU) 1 and is connected to the load rate monitoring module 11 and the signal priority dynamic adjustment module, respectively. The function of the hierarchical flow control module 13 is to divide the CAN bus load into three levels according to the real-time load rate signal, and to adopt different signal transmission control strategies for different levels to suppress the transmission of low-priority signals.

[0035] Low load (load rate <55%): Allows sending all priority signals.

[0036] Medium load (load rate 55%-75%): suppress signal transmission with priority code >0x4 (100).

[0037] High load (load rate > 75%): Only signals with priority codes 0x0 to 0x2 (000, 001, 010) are allowed to be transmitted.

[0038] The suppression mechanism of the hierarchical flow control module 13 is implemented by controlling the sending permissions of the sending queue. The suppressed low-priority signals will be buffered in the signal buffer area.

[0039] The signal buffer 14 can physically be the RAM area inside the main control unit 1. It is constructed as a first-in, first-out (FIFO) queue structure, acting as a buffer. Messages to be sent are sequentially placed into this queue, and the CAN controller sends CAN messages onto the bus according to the FIFO principle. The signal buffer 14 is logically connected to the hierarchical flow control module to buffer low-priority signals that are suppressed from transmission due to excessive bus load. When the bus load decreases, signals in the buffer will be sent preferentially to ensure signal integrity and prevent loss.

[0040] The CAN controller 10 is responsible for converting the software-defined CAN into physical CAN messages, while the CAN transceiver 2 converts the physical signals into 2.5V differential CAN messages for easy transmission over twisted-pair cables.

[0041] like Figure 3As shown, in the dynamic priority adjustment and flow control, the signal priority dynamic adjustment module 12 performs default priority encoding, and the hierarchical flow control module 13 obtains the real-time load rate signal of the CAN bus and determines whether to send a priority signal or buffer the signal in the signal buffer area 14 based on the load rate. When the bus load rate decreases, the hierarchical flow control module 13 checks whether there is a signal to be sent in the signal buffer area 14. If there is, it attempts to send the buffered signal according to the current load rate and priority rules (priority encoding). If the transmission is successful, the buffered signal is removed from the signal buffer area 14; otherwise, it continues to buffer. If there is no signal to be sent, the CAN signal priority encoding is dynamically adjusted according to the load rate and historical priority, and the hierarchical flow control module 13 obtains the real-time load rate signal of the CAN bus and repeats the process.

[0042] The structural innovation of this utility model is as follows: Integrated design: The CAN bus load rate monitoring, dynamic signal priority adjustment and hierarchical flow control functions are integrated into the main control unit (S32K148 MCU) of a single body controller through the tight combination of software logic and hardware resources, rather than being distributed independent modules, which significantly improves the real-time performance and reliability of the system.

[0043] Dynamic priority coding and hardware register utilization: By utilizing the CAN controller features of the S32K148 MCU, and through specific software logic and configuration of the CAN controller registers, the priority bits of the CAN signal ID can be dynamically adjusted, avoiding the latency of traditional software layers.

[0044] Independent FIFO buffer queue construction: For suppressed low-priority signals, a buffer with a first-in-first-out (FIFO) physical or logical structure is designed to ensure signal integrity and prevent loss, which is an effective supplement to the traditional CAN bus congestion handling mechanism.

[0045] Example 2 like Figure 1 As shown, a vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority is disclosed. The load rate monitoring module 11 utilizes the hardware timer resources of the S32K148 MCU's built-in CAN controller. Specifically, the timer monitors the start and end events of the CAN controller's transmit mailbox (TxMailbox) to calculate the transmission time of the CAN signal; simultaneously, the timer monitors the message storage time of the receive FIFO (RxFIFO) to obtain the reception time. The calculation time is controlled by the timer's timing function. The statistical period is set to 200ms, and the load rate is calculated once per period. The load rate data is transmitted to the signal priority dynamic adjustment module 12 via the MCU's internal interrupt mechanism or shared memory.

[0046] like Figure 2 As shown, during the load rate calculation process, the microcontroller initializes the counter and sets the statistical period to 200ms. The statistical period is started by a timer. The timer calculates the CAN bus transmission time in real time and collects the CAN bus reception storage time in real time. After waiting for the statistical period to end, the load rate monitoring module 11 calculates the current period bus load rate through simple mathematical calculations and outputs the real-time load rate signal. If the system is still running, it returns to start the statistical period.

[0047] The other structures and implementation methods are the same as in Example 1.

[0048] Example 3 like Figure 1 As shown, a vehicle body controller with dynamic CAN bus load rate adjustment based on signal priority is described. During system initialization, bits 7-0 of the 11-bit standard CAN ID for all CAN signals are retained as the original device ID, while bits 10-8 (dynamic priority bits) are set to medium priority by default (e.g., encoded as 010). When the load rate signal output by the load rate monitoring module 11 exceeds a preset threshold (e.g., 55%), the signal priority dynamic adjustment module 12 will adjust the priority of the CAN signal according to the following strategy: For example, if the original door lock ID is 0x011 (binary 000000010001), and its dynamic priority bits (bits 10-8) are set to medium priority (010) by default during system initialization, then the actual transmission ID is 0x211 (binary 001000010001). When the load rate signal exceeds 55%, if the signal is determined to need to be downgraded, the signal priority dynamic adjustment module 12 will calculate a new priority based on an exponential smoothing algorithm. In this case, α takes the value 0.3, and its bits 10-8 are adjusted to a lower priority encoding, for example, adjusted to 100 (medium-low priority), then the new send ID becomes 0x411 (binary 010000010001).

[0049] The other structures and implementation methods are the same as in Example 1.

[0050] Example 4: Implementation of a Hierarchical Flow Control Strategy like Figure 1 As shown, a vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority is described. The hierarchical flow control module 13 determines the current load level of the CAN bus based on the real-time load rate output by the load rate monitoring module 11, and controls the transmission queue of the CAN controller. Low load (load rate < 55%): The sending queue is not limited, and all priority signals are sent normally.

[0051] Medium load (load rate 55%-75%): The hierarchical flow control module suppresses the transmission of signals with priority codes >0x4. These suppressed low-priority signals will be buffered in the signal buffer (using a FIFO structure).

[0052] High load (load rate > 75%): Only signals with priority codes 0x0 to 0x2 are allowed to be transmitted; all other signals are suppressed and buffered in signal buffer 14. When the bus load decreases (e.g., from high load to medium or low load), the hierarchical flow control module 13 will send the buffered signals from signal buffer 14 in a first-in-first-out (FIFO) order until signal buffer 14 is emptied or the bus load increases again. This mechanism ensures signal integrity and avoids signal loss.

[0053] The other structures and implementation methods are the same as in Example 1.

[0054] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A body controller with CAN bus load rate dynamic adjustment based on signal priority, characterized in that, It includes a main control unit (1) and a CAN transceiver (2). The main control unit (1) has a built-in CAN controller (10). The CAN controller (10) is connected to the CAN transceiver (2). The CAN transceiver (2) is connected to the CAN bus (3). The CAN controller (10) is connected to the load rate monitoring module (11). The load rate monitoring module (11) is connected to the signal priority dynamic adjustment module (12) and the hierarchical flow control module (13) respectively. The priority dynamic adjustment module (12) is connected to the hierarchical flow control module (13). The hierarchical flow control module (13) is connected to the CAN controller (10).

2. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority as described in claim 1, characterized in that, The main control unit (1) is a microcontroller, and the CAN controller (10) is equipped with a timer, which is connected to the load rate monitoring module (11).

3. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority as described in claim 1 or 2, characterized in that, It also includes a signal buffer (14), and the hierarchical flow control module (13) is connected to the signal buffer (14).

4. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority as described in claim 3, characterized in that, The CAN transceiver (2) is connected to the CAN controller interface built into the main control unit (1).

5. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority according to claim 2, characterized in that, The timer collects the transmission time and reception storage time of the CAN bus in real time. The load rate monitoring module (11) generates the real-time load rate signal of the CAN bus based on the transmission time, reception storage time and preset statistical period. The preset statistical period is configured to be from 100ms to 500ms.

6. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority according to claim 4, characterized in that, In the priority encoding, the signal priority dynamic adjustment module (12) retains bits 7-0 of the 11-bit standard CAN ID as the original device ID and uses bits 10-8 as dynamic priority bits, with an encoding range of 000 to 111.

7. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority according to claim 2, characterized in that, The signal buffer (14) is the RAM area inside the main control unit (1), and the signal buffer (14) is a first-in-first-out queue structure.

8. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority as described in any one of claims 4-7, characterized in that, The graded flow control module (13) divides the CAN bus load into at least three levels based on the real-time load rate signal, and adopts different signal transmission control strategies for different levels.

9. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority according to claim 8, characterized in that, When the real-time load rate is less than 55%, the graded flow control module (13) allows all priority signals to be sent; When the real-time load rate is 55%-75%, the graded flow control module (13) suppresses the transmission of signals with priority codes ≥0x4; When the real-time load rate is >75%, the graded flow control module (13) only allows the transmission of signals with priority codes 0x0 to 0x2.

10. The vehicle body controller with dynamic adjustment of CAN bus load rate based on signal priority according to claim 9, characterized in that, The timer monitors the start and end events of the CAN controller's transmit mailbox to obtain the transmission time of the CAN signal; the timer monitors the message storage time of the receive first-in-first-out queue structure to obtain the reception time. The real-time load rate signal is transmitted to the signal priority dynamic adjustment module (12) through the microcontroller's internal interrupt mechanism or shared memory.

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