CAN communication network multi-rate adaptive transmission control system, control method and vehicle electronic control system

Abstract

The invention relates to the technical field of data transmission, in particular to a CAN communication network multi-rate adaptive transmission control system, a control method and a vehicle electronic control system. According to the CAN communication network multi-rate adaptive transmission control system, dynamic rate adjustment and intelligent load balancing are realized through four core modules: a data classification module divides data into a security class, a power class, a comfort class and an entertainment class, and calculates a dynamic weight; the network state monitoring module adopts a sliding window algorithm to calculate a network load rate in real time; the rate decision module dynamically selects the transmission rate according to the priority and the load rate; and the multi-path control module selects an optimal standby path based on the comprehensive score of the path load rate, the hop count and the link quality, and distributes traffic through a weighted polling algorithm. The system breaks through the limitation of a traditional CAN fixed rate, realizes low-delay transmission of high-priority data and efficient utilization of network resources, and is particularly suitable for a high-load communication scene of an intelligent automobile.

Description

Technical Field

[0001] The present invention relates to the technical field of data transmission, and in particular to a CAN communication network multi-rate adaptive transmission control system, a control method and a vehicle electronic control system. Background Art

[0002] Currently, traditional CAN networks primarily rely on fixed-rate data transmission. In the standard CAN 2.0A protocol, the data rate is typically fixed at 1 Mbps. While the data segment rate has been increased (up to 5 Mbps) in the CAN FD (Flexible Data Rate) protocol, once the rate is determined, nodes exchange data at this fixed rate throughout the communication process. For example, in communications between a car's engine management system and transmission controller, the data transmission rate over the CAN network remains constant, regardless of engine operating conditions, such as idling, low speed, or high speed.

[0003] This fixed-rate transmission solution can meet basic communication needs when network loads are low and data types are simple. However, with the rapid increase in the complexity of automotive electronic systems, such as the introduction of large amounts of sensor data in advanced driver assistance systems (ADAS) and the multimedia data transmission involved in intelligent cockpit systems, fixed-rate transmission has exposed many drawbacks. For one thing, signals with extremely high real-time requirements but extremely small data volumes, such as airbag trigger signals, can only be transmitted at a fixed rate even when the network is idle, making it impossible to further reduce transmission latency. Furthermore, when the network contains a large amount of non-urgent but large data volumes (such as the periodic upload of vehicle status monitoring data), this data consumes valuable network bandwidth, hindering the transmission of urgent data, causing communication delays and even packet loss. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in order to solve the problems in the prior art of the above-mentioned background technology that fixed-rate transmission cannot adapt to dynamic loads, high-priority data delay is limited, low-priority data occupies bandwidth, resulting in poor real-time performance, low resource utilization, and emergency data blocking, a CAN communication network multi-rate adaptive transmission control system is provided, which realizes dynamic rate adjustment, load balancing and priority guarantee through the coordinated work of data classification module, network status monitoring module, rate decision module and multi-path transmission control module.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a CAN communication network multi-rate adaptive transmission control system, comprising: a data classification module, configured to determine priorities and dynamic weights based on data types, the data types including at least safety, power, comfort, and entertainment; The network status monitoring module is used to monitor the bus idle time, the number of data transmission conflicts and the data transmission volume per unit time in real time, and calculate the network load rate; A rate decision module dynamically selects a transmission rate based on data priority and network load rate, wherein high-priority data is transmitted at a first rate when the network load rate is below a first threshold, and an alternate path is activated or load reduction is waited for when the network load rate is above the first threshold; The multi-path transmission control module is used to select a backup path based on the comprehensive score of path load rate, number of hops and link quality when the load of the main path exceeds the preset condition, and perform load balancing through a weighted polling algorithm.

[0006] The data classification module categorizes CAN network data into safety, power, comfort, and entertainment categories, assigning different priorities to ensure that critical data (such as airbag signals) is transmitted first. The network status monitoring module monitors bus idle time, collision counts, and data volume in real time, accurately calculating the network load factor to inform rate decisions. The rate decision module dynamically adjusts the transmission rate based on data priority and network load factor. When the primary path is congested, the multipath transmission control module selects the optimal backup path based on path load factor, hop count, and link quality, avoiding communication interruptions caused by overloading a single path. A weighted round-robin (WRR) algorithm is used to balance traffic and ensure the stability of backup paths.

[0007] According to one embodiment of the present invention, the calculation of the dynamic weight of the data classification module includes: Weight before correction = (0.4×R+0.3×T+0.3×N)×S, Among them, R is the failure risk level, T is the real-time requirement, N is the functional necessity, and S is the scenario coefficient; Weight after correction = weight before correction × K, Where L is the network load rate, K is the load correction factor, K=1+(L / 100)×0.5; The corrected weights are mapped to the interval [2,10] through linear mapping, and the weight of safety data after mapping > the weight of power data after mapping > the weight of comfort data after mapping > the weight of entertainment data after mapping; the mapping formula is: Weight = 2 + (post-correction score - pre-correction score) × (10-2) / (post-correction score - pre-correction score).

[0008] Before correction, weight calculation incorporates failure risk level (R), real-time requirements (T), functional necessity (N), and scenario factor (S) to quantify data priority. The load correction factor (K) dynamically adjusts weights based on the network load rate (L). Higher loads increase the weighting of high-priority data, further ensuring bandwidth for critical data. Weight linear mapping maps the corrected weights to the range [2, 10], making the priority differences between different types of data more pronounced.

[0009] According to one embodiment of the present invention, the failure risk level R is specifically divided as follows: Fatal risks correspond to safety data, and serious risks correspond to power data; Slight risk corresponds to comfort data, and no substantial risk corresponds to entertainment data; Among them, fatal risk: R=5, serious risk: R=4, minor risk: R=2, no substantial risk: R=1.

[0010] Safety data is defined as a fatal risk (R=5), power data as a serious risk (R=4), ensuring that data on the core functions of the vehicle has absolute priority; entertainment data is defined as no substantial risk (R=1), and transmission can be suspended during network congestion to avoid affecting safety-critical data.

[0011] According to one embodiment of the present invention, the network status monitoring module calculates the network load rate L by a sliding window algorithm, specifically: First, set the window size to N data frame transmission cycles, and count the number of bus busy cycles M within the window; The network load rate L is then calculated using the formula L=(M / N)×100%, and cross-validated with the data transmission volume per unit time.

[0012] Using N data frame periods as a window, the number of busy periods is counted to calculate the network load rate L = (M / N) × 100%. This method has better real-time performance than the global average load calculation. It also combines cross-validation with the data transmission volume per unit time to avoid transient noise. The interference window size is adjustable, making it suitable for different CAN network sizes and highly flexible.

[0013] According to one embodiment of the present invention, the rate selection logic of the rate decision module is specifically as follows: Security data is transmitted at 10 Mbps when the network load rate L is less than 30%. When the network load rate is 30%≤L<70%, it is transmitted at 5 Mbps on the backup path. When the network load rate is greater than or equal to 70%, the data is loaded and then waits for load shedding. Power data is transmitted at 1Mbps when L<50%, reduced to 500kbps when 50%≤L<80%, and reduced to 250kbps when L≥80%; Comfort and entertainment data are transmitted at 500kbps and 250kbps respectively when L is less than 70%. When L is greater than or equal to 70%, the rates are reduced to 250kbps and 125kbps respectively, or transmission is suspended.

[0014] When L<30%, the rate is 10 Mbps (maximizing real-time performance); when 30%≤L<70%, the rate is 5 Mbps (balancing speed and reliability); when L≥70%, the rate is subject to load shedding (to prevent worsening congestion); when L≥80%, the rate is reduced to 250 kbps, ensuring basic power control functions while reserving bandwidth for safety-related data. When L≥70%, the rate is reduced to the lowest possible rate or even paused, directly reducing network usage by non-critical data and resolving the issue of entertainment data blocking safety data in traditional CAN.

[0015] According to one embodiment of the present invention, the path comprehensive score calculation method of the multi-path transmission control module is: Comprehensive score = (1-L_path / 100%) × 0.5 + (1-current hop count / H_max) × 0.3 + (0.6 × S + 0.4 × (1-E)) × 0.2; Among them, L_path is the path load rate, H_max is the maximum possible number of hops on the path, S is the signal strength, and E is the bit error rate. The load rate of a single node L_node = (M / N) × 100%, and the path load rate L_path is: L_path = (L_node1 + L_node2 + ... + L_noden) / n × 100%, where n is the total number of nodes included in the path.

[0016] The path load ratio prioritizes low-load paths. The fewer hops, the lower the latency. Link quality ensures transmission reliability. By weighted summation, the quality of paths is quantified, improving path switching accuracy.

[0017] According to one embodiment of the present invention, the path with the highest comprehensive score is selected as the backup path. After the backup path is determined, the node implements path switching through the intelligent routing module. During the switching process, a weighted round-robin algorithm is used for load balancing, specifically including: Dynamically assign weights to backup paths based on their bandwidth and real-time load. Paths with higher bandwidth and lower load have higher weights. The transmission path is selected in round-robin mode according to the assigned weight ratio. The path with higher weight is more likely to be selected. Monitor the load changes of each path in real time and dynamically update the weight to avoid overloading a single path.

[0018] Paths with high bandwidth and low load are given greater weight, and traffic is distributed proportionally. Continuous monitoring of path load and updating of weights avoids the problem of "overload after the backup path becomes the primary path," thereby improving network stability.

[0019] A control method for the CAN communication network multi-rate adaptive transmission control system described in the above solution is also provided, characterized in that it includes the following steps: S1. Dynamically calculate data weights and prioritize queues based on the data type's security level, real-time requirements, and functional necessity. S2. Count the number of busy and idle cycles of the bus through a sliding window, and calculate the network load rate in real time by combining the number of error frames and the amount of data per unit time. S3. Based on data priority and network load rate, the transmission rate is dynamically selected according to the preset policy. When the network load rate of high-priority data exceeds the threshold, an alternative path search or a speed reduction wait is triggered. S4. When the load on the primary path exceeds the limit, the backup path is switched based on the comprehensive path score, and data traffic is distributed through a weighted round-robin algorithm.

[0020] From data classification to load monitoring, to rate decision-making, and finally to path switching, a closed-loop control is formed to achieve millisecond-level adaptive response.

[0021] According to one embodiment of the present invention, in step S3, for security data, if the network load rate L is ≥ 70% and there is no available backup path, a delay compensation mechanism is adopted, specifically: Record the timestamp of the current data and the maximum allowed delay; Continuously monitor the network load. If L drops below 30% before the maximum allowed delay expires, immediately send at 10 Mbps. If the data is not sent before the timeout, the low-priority data transmission will be interrupted and the bandwidth will be seized.

[0022] Record the maximum allowable delay for safety-related data and forcibly seize bandwidth before timeout to ensure absolute real-time performance. Directly suspend entertainment data transmission to resolve the defect of "inability to seize bandwidth" in traditional CAN, and ensure that urgent data is delivered on time.

[0023] A vehicle electronic control system is also provided, utilizing the multi-rate adaptive transmission control system for the CAN communication network described in the aforementioned solution. This system is designed to achieve real-time, reliable transmission of safety-related data and dynamic allocation of network resources. Through dynamic rate and path management, overall network utilization is improved while ensuring deterministic latency for safety-related data.

[0024] Beneficial effects of the present invention: (1) Improve system reliability: Reduce transmission delays and packet loss rates for emergency data, and reduce vehicle safety risks caused by communication failures; for example, data from safety-related systems can be transmitted reliably and promptly, allowing the vehicle to operate stably under complex driving conditions.

[0025] (2) Optimize network resource allocation: Flexibly allocate bandwidth according to data characteristics and network status to improve overall network utilization. Different types of data have different demands for network resources at different times. Multi-rate adaptive transmission can accurately match resources and avoid resource waste. For example, when a vehicle is traveling at high speed, the power and safety systems occupy more bandwidth. Multi-rate adaptive transmission can automatically adjust to ensure communication of key systems. When the vehicle is stationary, bandwidth can be appropriately allocated to non-critical systems such as entertainment.

[0026] (3) Enhanced system scalability: When new electronic devices or functions are added to the vehicle, multi-rate adaptive transmission can better adapt to changes in network scale and data traffic; after the new device is connected, the transmission rate can be automatically adapted according to its data characteristics without the need for large-scale adjustments to the network architecture. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] Figure 1 It is a control block diagram of the control system of the present invention.

[0029] Figure 2 It is a control principle diagram of the control system of the present invention.

[0030] Figure 3 It is a flow chart of the rate decision module in the control system of the present invention.

[0031] Figure 4 It is a flow chart of the control method of the present invention. DETAILED DESCRIPTION

[0032] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0033] The data transmission situation of the existing CAN network is shown in Table 1.

[0034] Table 1

[0035] The transmission rate of CAN 2.0B cannot meet the transmission requirements of large amounts of data (such as camera and radar data) in modern vehicles; the rate of CAN-FD requires static configuration and cannot dynamically adapt to changes in network load; CAN-XL requires dedicated hardware support and has poor compatibility with existing CAN / CAN-FD equipment, and has not yet been widely commercialized; traditional gateways cannot achieve true real-time multi-rate coordinated transmission.

[0036] Example 1 In view of the above-mentioned prior art, Figure 1 As shown, this embodiment provides a multi-rate adaptive transmission control system for a CAN communication network, which includes a data classification module, a network status monitoring module, a rate decision module and a multi-path transmission control module, wherein the data classification module is used to determine the priority and dynamic weight according to the data type, and the data type includes at least safety, power, comfort and entertainment; the network status monitoring module is used to monitor the bus idle time, the number of data transmission conflicts and the data transmission volume per unit time in real time, and calculate the network load rate; the rate decision module dynamically selects the transmission rate according to the data priority and the network load rate, wherein high-priority data is transmitted at a first rate when the network load rate is lower than a first threshold, and an alternative path is enabled or the load is waited for to be reduced when the network load rate is higher than the first threshold; the multi-path transmission control module is used to select an alternative path based on the comprehensive score of the path load rate, the number of hops and the link quality when the load of the main path exceeds the preset condition, and perform load balancing through a weighted polling algorithm.

[0037] By providing a high-speed transmission channel for emergency data, critical information such as airbag trigger signals and brake system feedback can be delivered to the target node in the shortest possible time, effectively improving vehicle safety. For example, during emergency braking at high speeds, traditional CAN networks can experience delays in braking command transmission due to fixed rates and network congestion. Multi-rate adaptive transmission, however, allows braking signals to be transmitted instantaneously at the highest possible rate, ensuring a timely response to braking needs.

[0038] The system also dynamically adjusts the transmission rate of non-urgent data. When the network load is low, it appropriately increases the transmission rate of non-urgent data to fully utilize the network bandwidth. When the network is busy, it automatically reduces the rate to avoid interference with urgent data transmission. For example, during the initial vehicle startup, there is a large amount of sensor data upload and system self-test data, which puts a heavy network load. At this time, the data transmission rate of non-critical in-car entertainment systems is reduced to prioritize the transmission of critical data such as the powertrain and chassis systems.

[0039] The following is a further description of how each module processes and transmits data. The control principle diagram is as follows Figure 2 shown.

[0040] In the data classification module, safety data includes airbag activation signals and ESP control commands; power data includes engine control data and transmission shift signals; comfort data includes temperature control commands and seat adjustment signals; and entertainment data includes multimedia playback data and navigation voice information. Safety data is given the highest priority, with a weight of 10; power data is given the next highest priority, with a weight of 7; comfort data has a weight of 4; and entertainment data has a weight of 2. Data priorities and weights can be flexibly adjusted based on actual vehicle needs.

[0041] The weight calculation is as follows: Weight before correction = (0.4×R+0.3×T+0.3×N)×S, Weight after correction = weight before correction × K, The modified weight is mapped to the interval [2,10] through linear mapping. The mapping formula is: Weight = 2 + (weight after correction - weight before correction) × (10-2) / (weight after correction - weight before correction).

[0042] In the above calculation formula, R is the failure risk level, which refers to the consequences caused by data transmission failure / delay, and is divided into five levels: R=5, indicating fatal risk (such as airbag signal failure), R=4, indicating serious risk (such as engine control failure), R=3, indicating moderate risk (such as transmission delay), R=2, indicating minor risk (such as air conditioning adjustment delay), and R=1, indicating no substantial risk (such as entertainment suspension).

[0043] T is the real-time requirement, which refers to the maximum allowable delay of the data (ms). It uses an inverse quantization method, such as T = 100 / maximum allowable delay (the smaller the delay, the larger the T value. For example, if the security data delay is 10ms, then T=10, and if the entertainment data delay is 1000ms, then T=0.1).

[0044] N stands for functional necessity, which refers to the degree to which data is necessary for vehicle functions. It is scored according to a 5-level method: N=5 indicates core safety necessity (such as ESP instructions), N=4 indicates power necessity (such as engine data), N=3 indicates comfort necessity (such as air conditioning instructions), N=2 indicates experience-related (such as seat adjustment), and N=1 indicates non-essential (such as navigation voice).

[0045] S is the scenario coefficient, which refers to the data demand added by the vehicle's current scenario. The default value is S=1. Special scenarios: in autonomous driving, the safety category S=1.2; in sports mode, the power category S=1.2; in comfort mode, the comfort category S=1.2; in parking entertainment, the entertainment category S=1.2.

[0046] K is the load correction factor, which refers to the dynamic adjustment of the network load to the weight. It is calculated as follows: K=1+ (L / 100)×0.5.

[0047] L is the network load rate. The higher the load, the greater the weight bonus of high-priority data.

[0048] In the calculation formula of the weight before correction, 0.4, 0.3 and 0.3 are the importance weights of each factor, and the failure risk accounts for the highest proportion.

[0049] The initial "2" in the mapping formula serves as the base term, representing the minimum weight (corresponding to the lowest weight for entertainment data in the initial settings) and serving as the starting point for the mapping. "(Adjusted Weight - Minimum Adjusted Weight)" calculates the offset of the current data's "Adjusted Weight" relative to the "Minimum Adjusted Weight" of all data. If a data point's adjusted score equals the "Minimum Adjusted Score," this portion of the result is 0, resulting in a final weight of 2 (the minimum value). Higher scores increase this offset, resulting in a higher final weight. "(10 - 2)" represents the total span of the weight (maximum 10 minus minimum 2), i.e., the allowable range of weight variation. "(Maximum Adjusted Score - Minimum Adjusted Score)" represents the total span of the "Adjusted Score" of all data points (the difference between the highest and lowest scores) and is used to normalize the offset.

[0050] That is to say, first calculate the relative proportion of the current score in the "all score range" (value range 0 to 1) through (corrected score - minimum corrected score) / (maximum corrected score - minimum corrected score), then multiply it by the total weight span 8 to obtain the "relative offset" of the current score in the weight range, and finally add the minimum weight value 2 to obtain the mapped weight.

[0051] The specific situation is shown in Table 2.

[0052] Table 2

[0053] When a node has data to send, it places it into the corresponding priority queue based on its priority level. Specifically, data in the high-priority queue is processed first, and the transmission rate is determined based on the real-time network load. Network load calculation uses a sliding window algorithm, setting the window size to N data frame transmission cycles. The number of busy bus cycles M within the window is counted, and the network load ratio L = M / N × 100%.

[0054] like Figure 3 As shown, the rate selection logic of the rate decision module is specifically as follows: If the data is security data and the network load rate L is less than 30%, directly set the transmission rate to 10Mbps; If 30%≤L<70%, try to find a backup path, if found and backup path load rate L 备用 < 50%, then send at 5Mbps rate on backup path, otherwise wait for network load to decrease and then send at 10Mbps; if L≥70%, continuously wait for network load to decrease to below 30% before sending at 10Mbps.

[0055] For power class data, when L<50%, set the rate to 1Mbps; when 50%≤L<80%, reduce the rate to 500kbps; when L≥80%, reduce the rate to 250kbps.

[0056] Comfort and entertainment class data are sent at rates of 500kbps and 250kbps respectively when L<70%; when L≥70%, further reduce the rates to 250kbps and 125kbps, or pause transmission according to system policy.

[0057] Data is divided into four categories: security, power, comfort, and entertainment, and weights are assigned according to priority. Rate decision is dynamically adjusted according to network load, with priority given to ensuring the reliability of security class transmission, maintaining basic stability for power class, and reducing speed or pausing for comfort and entertainment classes, to achieve core function priority and efficient allocation of resources. This division not only meets the core demands of vehicle electronic systems "safety first, performance second, experience third", but also maximizes the use of limited network resources, avoiding bandwidth waste or congestion.

[0058] In the network state monitoring module, to accurately obtain the network state, parameters such as bus idle time, data transmission conflict frequency, and transmitted data volume are comprehensively monitored. For bus idle time monitoring, after each data frame transmission period ends, the bus idle time T 空闲 is recorded, and if T 空闲 > T 阈值 (set according to different rates, such as T 阈值 = 10us at 10Mbps rate), it is considered that the bus is currently relatively idle. Through the error frame detection mechanism of CAN protocol, the number of error frames C 冲突 caused by data transmission conflicts in a unit of time (such as 1 second) is counted, and the more C 冲突 , the busier the network. The node maintains a data volume counter, and every time a frame of data is successfully sent or received, the counter value D 总量 is updated according to the data frame length (standard frame 8 bytes, extended frame 64 bytes), and the data transmission volume in a unit of time is calculated based on the time window.

[0059] Further, the data transmission volume in a unit of time is calculated based on the "time window + data frame accumulation" mechanism, as follows: Set a fixed time window of 1 second as the statistical period; within the window time, each time a node successfully sends / receives a frame of data, it updates the counter according to the frame type: standard frame (8 bytes) plus 8, extended frame (64 bytes) plus 64, and the total amount of data in the window is accumulated to obtain D 总量 (unit is byte); when the window ends, use D 总量 Divide by the window length (e.g., 1 second) to get the transmission volume per unit time (bytes / second). The rate (kbps) conversion method is: 1 byte = 8 bits, so the transmission volume per unit time (bytes / second) × 8 ÷ 1000 is the rate kbps value.

[0060] In the multipath transmission control module, multiple backup paths are pre-defined for key nodes during network topology design. When the primary path becomes overloaded or experiences a failure, the node initiates a backup path search. This path search strategy uses a breadth-first search algorithm, starting from the source node and searching outward layer by layer for a path to the target node. During the search, information such as the number of nodes traversed by each path and link quality (assessed through signal strength and bit error rate) is recorded. Path evaluation metrics comprehensively consider path load, hop count, and link quality.

[0061] The calculation of the path load rate is centered around the "real-time load status of all nodes on the path" and is achieved through sliding window statistics and weighted averaging. Specifically, the following method is used: Identify all nodes included in the currently evaluated path (e.g., if the path is node A→B→C, then nodes A, B, and C are the nodes that make up the path). Calculate the load rate of each individual node. For each node, use a sliding window algorithm (with a window size of N data frame transmission cycles) to count the number of cycles, M, that the node within the window is in the "data transmission busy" state. The load rate of each node, L_node, is calculated as (M / N) × 100%. The path load rate, L_path, is aggregated, and the average load rate of all nodes on the path is taken as the overall load rate of the path, i.e.: Path load rate L_path = (L_node1 + L_node2 + ... + L_noden) / n × 100%, where n is the total number of nodes included in the path.

[0062] This calculation method not only reflects the real-time busyness of each node on the path, but also eliminates the impact of instantaneous fluctuations of a single node through averaging, ensuring that the evaluation results can truly reflect the load pressure of the entire path and provide an accurate basis for the comprehensive path score.

[0063] Fewer hops result in lower transmission latency; better link quality results in higher data transmission reliability. A weight is assigned to each indicator (e.g., 0.5 for load factor, 0.3 for hop count, and 0.2 for link quality) to calculate a comprehensive score for each path. The comprehensive score for each path is calculated based on the standardized quantified values ​​of the three indicators: load factor, hop count, and link quality, combined with preset weights. The specific calculation formula is as follows: Comprehensive score = (normalized value of path load ratio × 0.5) + (normalized value of hop count × 0.3) + (normalized value of link quality × 0.2).

[0064] Specifically, the lower the path load, the better the path. The normalized value = 1 - (L_path / 100%) (e.g., a load of 30% = 0.7; a load of 80% = 0.2). Fewer hops means lower latency and a better path. Assuming the maximum possible number of hops is H_max (e.g., the maximum number of hops in the network topology is 5), the normalized value = 1 - (current hop count / H_max) (e.g., if the number of hops is 2 and H_max = 5, the normalized value is 0.6; if the number of hops is 1, the normalized value is 0.8). Based on a comprehensive quantification of signal strength (S, 0-100%) and bit error rate (E, 0-100%), the better the link quality (strong signal, low bit error), the higher the value. Normalized value = 0.6 × (S / 100%) + 0.4 × (1 - E / 100%) (For example, if the signal strength is 90% and the bit error rate is 5%, the normalized value = 0.6 × 0.9 + 0.4 × 0.95 = 0.91).

[0065] The path with the highest score is selected as the backup transmission path. Specifically, after determining the backup path, the node uses the intelligent routing module to implement path switching. During the switching process, a weighted round-robin (WRR) algorithm is used for load balancing. Weights are assigned to each path based on its bandwidth and load. Paths with higher weights are more likely to be selected for data transmission. This ensures that data traffic is properly distributed across multiple paths, preventing transmission bottlenecks caused by overload on a single backup path.

[0066] The core principle of multi-rate adaptive transmission technology lies in enabling CAN network nodes to dynamically adjust their transmission rates based on data urgency and real-time network load. Each node is equipped with a rate decision module, which monitors the priority tag (data urgency indicator) of its pending data and the network load (determined by parameters such as bus idle time and the number of data transmission conflicts). The system pre-defines different levels of data urgency, such as assigning the highest priority to airbag triggering signals and brake system feedback, medium priority to engine status monitoring data, and low priority to interior lighting control commands. When a node has data to send, the rate decision module first determines the data's priority. If the data is high-priority and the network load is below a certain threshold (e.g., 30%), it selects the highest transmission rate (e.g., 10 Mbps) for transmission. If the network load is high (e.g., over 70%), it attempts to find a relatively idle backup path (if the topology supports multi-path transmission). If one is found, the data is transmitted over the backup path at a higher rate (e.g., 5 Mbps). If no such path is found, the data is transmitted again at the highest rate (e.g., 5 Mbps). If no such path is found, the data is transmitted again at the highest rate after the network load decreases. For low- and medium-priority data, when the network load is low, it is sent at a moderate rate (such as 1Mbps). As the network load increases, the rate is gradually reduced (for example, to 500kbps, 250kbps, etc.). At the same time, the node continuously monitors the network. If it detects an increase in the demand for high-priority data transmission, it will proactively further reduce the transmission rate of its own low- and medium-priority data to make bandwidth available for high-priority data.

[0067] Regarding data generation and urgency assessment, after a node generates data, it immediately assesses its urgency and categorizes the data into three priority levels: high, medium, and low. For high-priority data, the network load is first assessed. If the network load is low, the highest rate is set for transmission. If the network load is high, the system checks for multiple paths. If a backup path exists and its load is low, the data is sent at the next highest rate. If the backup path is unavailable or is also heavily loaded, the system waits for the network to idle before sending at the highest rate. For medium-priority data, a rate between 1Mbps and 500kbps is selected based on network load. Low-priority data is sent at 500kbps when the network load is below 70%, and at 250kbps when it is above 70%. The transmitter encapsulates the data frame, adds a rate identifier, and transmits it over the CAN bus. The receiver interprets the rate identifier, receives, and processes the data at the corresponding rate.

[0068] The multi-rate adaptive transmission control system of the CAN communication network will now be described with reference to a specific embodiment.

[0069] Imagine a smart car equipped with an ADAS system driving on a highway. The vehicle ahead suddenly brakes. The vehicle's millimeter-wave radar quickly detects this dangerous situation and generates an emergency braking trigger signal (high-priority data). Simultaneously, the vehicle's engine management system is periodically transmitting real-time engine status data (medium-priority data) to other nodes, and the in-car entertainment system is also transmitting music data (low-priority data). The rate decision module of the millimeter-wave radar node detects the emergency braking signal and identifies it as high-priority data. At this point, the network load is approximately 40%. Due to the high load on the primary path, the node initiates a backup path search and finds one with a load of 30%. It then rapidly transmits the emergency braking signal at 5Mbps to the braking system's ECU. The braking system responds quickly, and the vehicle brakes in time. The engine management system node detects the high network load and proactively reduces the engine status data rate, originally transmitted at 1Mbps, to 500kbps to prevent impacting critical data transmission. The in-car entertainment system node detects network congestion and further reduces the music data rate from 500kbps to 250kbps to ensure bandwidth for critical data.

[0070] Braking signals are transmitted via a backup path at 5Mbps, and the ECU response time can be less than 5ms, avoiding collision accidents. The entertainment data rate is reduced by 50%, but the impact on user experience is minimal. Dynamic speed reduction reduces the overall network load from 40% to 35%, greatly reducing the number of conflicts.

[0071] Example 2 like Figure 4 As shown, the control method of the CAN communication network multi-rate adaptive transmission control system of embodiment 1 includes the following steps: S1. Dynamically calculate data weights and prioritize queues based on the data type's security level, real-time requirements, and functional necessity. S2. Count the number of busy and idle cycles of the bus through a sliding window, and calculate the network load rate in real time by combining the number of error frames and the amount of data per unit time. S3. Based on data priority and network load rate, the transmission rate is dynamically selected according to the preset policy. When the network load rate of high-priority data exceeds the threshold, an alternative path search or a speed reduction wait is triggered. S4. When the load on the primary path exceeds the limit, the backup path is switched based on the comprehensive path score, and data traffic is distributed through a weighted round-robin algorithm.

[0072] In step S3, for security data, if the network load rate L ≥ 70% and there is no available backup path, a delay compensation mechanism is used, specifically: Record the timestamp of the current data and the maximum allowed delay; Continuously monitor the network load. If L drops below 30% before the maximum allowed delay expires, immediately send at 10 Mbps. If the data is not sent before the timeout, the low-priority data transmission will be interrupted and the bandwidth will be seized.

[0073] Dynamic adjustments are made throughout the entire process, from data classification to path switching, without the need for manual intervention. A delay compensation mechanism ensures that safety-related data is delivered within the maximum allowable delay. This control method is adaptable to CAN 2.0B / CAN-FD hardware and does not require modification of the existing in-vehicle network.

[0074] Example 3 A vehicle electronic control system employs the CAN communication network multi-rate adaptive transmission control system of embodiment 1 to achieve real-time reliable transmission of safety-related data and dynamic allocation of network resources. Thus, multi-rate transmission can be achieved based on existing CAN hardware.

[0075] With the above-described preferred embodiments of the present invention as inspiration, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A CAN communication network multi-rate adaptive transmission control system, characterized in that: include: a data classification module, configured to determine priorities and dynamic weights based on data types, the data types including at least safety, power, comfort, and entertainment; The network status monitoring module is used to monitor the bus idle time, the number of data transmission conflicts and the data transmission volume per unit time in real time, and calculate the network load rate; A rate decision module dynamically selects a transmission rate based on data priority and network load rate, wherein high-priority data is transmitted at a first rate when the network load rate is below a first threshold, and an alternate path is activated or load reduction is waited for when the network load rate is above the first threshold; The multi-path transmission control module is used to select a backup path based on the comprehensive score of path load rate, number of hops and link quality when the load of the main path exceeds the preset condition, and perform load balancing through a weighted polling algorithm.

2. The CAN communication network multi-rate adaptive transmission control system according to claim 1, characterized in that: The calculation of the dynamic weight of the data classification module includes: Weight before correction = (0.4×R+0.3×T+0.3×N)×S, Among them, R is the failure risk level, T is the real-time requirement, N is the functional necessity, and S is the scenario coefficient; Weight after correction = weight before correction × K, Where L is the network load rate, K is the load correction factor, K=1+(L / 100)×0.5; The corrected weights are mapped to the interval [2,10] through linear mapping, and the weight of safety data after mapping > the weight of power data after mapping > the weight of comfort data after mapping > the weight of entertainment data after mapping; the mapping formula is: Weight = 2 + (post-correction score - pre-correction score) × (10-2) / (post-correction score - pre-correction score).

3. The CAN communication network multi-rate adaptive transmission control system according to claim 2, characterized in that: The classification of the failure risk level R is as follows: Fatal risks correspond to safety data, and serious risks correspond to power data; Slight risk corresponds to comfort data, and no substantial risk corresponds to entertainment data; Among them, fatal risk: R=5, serious risk: R=4, minor risk: R=2, no substantial risk: R=1.

4. The CAN communication network multi-rate adaptive transmission control system according to claim 2, characterized in that: The network status monitoring module calculates the network load rate L through a sliding window algorithm, specifically: First, set the window size to N data frame transmission cycles, and count the number of bus busy cycles M within the window; The network load rate L is then calculated using the formula L=(M / N)×100%, and cross-validated with the data transmission volume per unit time.

5. The CAN communication network multi-rate adaptive transmission control system according to claim 4, characterized in that: The rate selection logic of the rate decision module is specifically as follows: Security data is transmitted at 10 Mbps when the network load rate L is less than 30%. When the network load rate is 30%≤L<70%, it is transmitted at 5 Mbps on the backup path. When the network load rate is greater than or equal to 70%, the data is loaded and then waits for load shedding. Power data is transmitted at 1Mbps when L<50%, reduced to 500kbps when 50%≤L<80%, and reduced to 250kbps when L≥80%; Comfort and entertainment data are transmitted at 500kbps and 250kbps respectively when L is less than 70%. When L is greater than or equal to 70%, the rates are reduced to 250kbps and 125kbps respectively, or transmission is suspended.

6. The CAN communication network multi-rate adaptive transmission control system according to claim 2, characterized in that: The path comprehensive score calculation method of the multi-path transmission control module is: Comprehensive score = (1-L_path / 100%) × 0.5 + (1-current hop count / H_max) × 0.3 + (0.6 × S + 0.4 × (1-E)) × 0.2; Among them, L_path is the path load rate, H_max is the maximum possible number of hops on the path, S is the signal strength, and E is the bit error rate. The load rate of a single node L_node = (M / N) × 100%, and the path load rate L_path is: L_path = (L_node1 + L_node2 + ... + L_noden) / n × 100%, where n is the total number of nodes included in the path.

7. The CAN communication network multi-rate adaptive transmission control system according to claim 6, characterized in that: The path with the highest overall score is selected as the backup path. After the backup path is determined, the node implements path switching through the intelligent routing module. During the switching process, a weighted polling algorithm is used for load balancing. Specifically, the following steps are performed: Dynamically assign weights to backup paths based on their bandwidth and real-time load. Paths with higher bandwidth and lower load have higher weights. The transmission path is selected in round-robin mode according to the assigned weight ratio. The path with higher weight is more likely to be selected. Monitor the load changes of each path in real time and dynamically update the weight to avoid overloading a single path.

8. A control method for a CAN communication network multi-rate adaptive transmission control system according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Dynamically calculate data weights and prioritize queues based on the data type's security level, real-time requirements, and functional necessity. S2. Count the number of busy and idle cycles of the bus through a sliding window, and calculate the network load rate in real time by combining the number of error frames and the amount of data per unit time. S3. Based on data priority and network load rate, the transmission rate is dynamically selected according to the preset policy. When the network load rate of high-priority data exceeds the threshold, an alternative path search or a speed reduction wait is triggered. S4. When the load on the primary path exceeds the limit, the backup path is switched based on the comprehensive path score, and data traffic is distributed through a weighted round-robin algorithm.

9. The control method of the CAN communication network multi-rate adaptive transmission control system according to claim 8, characterized in that: In step S3, for security data, if the network load rate L ≥ 70% and there is no available backup path, a delay compensation mechanism is used, specifically: Record the timestamp of the current data and the maximum allowed delay; Continuously monitor the network load. If L drops below 30% before the maximum allowed delay expires, immediately send at 10 Mbps. If the data is not sent before the timeout, the low-priority data transmission will be interrupted and the bandwidth will be seized.

10. A vehicle electronic control system, characterized in that: The CAN communication network multi-rate adaptive transmission control system according to any one of claims 1 to 7 is used to achieve real-time reliable transmission of safety-related data and dynamic allocation of network resources.

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