Tractor-trailer combined vehicle steering control method and device, terminal and medium

Abstract

The invention relates to the field of vehicle steering control, and particularly provides a tractor-trailer combined vehicle steering control method and device, a terminal and a medium, and the method comprises the following steps: determining the longitudinal position of the mass center of a trailer through a pre-established mechanical model based on a vehicle static axle load measurement value in response to meeting a preset condition; based on the determined longitudinal position of the mass center, the stability risk category of the vehicle under the steering working condition is evaluated; the stability risk category at least comprises a first type of risk caused by centroid deviation and a second type of risk caused by centroid deviation; and according to the evaluated stability risk category, calling and executing a preset steering auxiliary control strategy corresponding to the category so as to carry out compensatory adjustment on steering control parameters of the vehicle. According to the method, low-cost and high-reliability estimation of the mass center position of the trailer is achieved, the steering stability risk is intelligently evaluated based on the method, then self-adaptive steering auxiliary control is executed, and the operation stability and safety of the vehicle are improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle steering control, and specifically to a steering control method, device, terminal, and medium for a tractor-trailer combination vehicle. Background Technology

[0002] In the commercial vehicle sector, especially for truck trains consisting of tractors and semi-trailers, driving stability and safety are of paramount importance. The handling stability of a vehicle, particularly under steering conditions, depends heavily on the load distribution of the entire vehicle, and the longitudinal position of the trailer's center of gravity is a key parameter determining the load distribution.

[0003] However, in actual operation, the cargo carried by trailers is diverse and non-fixed, causing the longitudinal position of its center of gravity to change with each transport task, making it time-varying and difficult to measure directly. Existing technologies for obtaining the trailer's center of gravity position have the following limitations: The preset point and test correction method pre-sets the center of gravity position to a fixed point and corrects it through subsequent tests. This method cannot adapt to dynamic load changes, has poor real-time performance, and the correction process is cumbersome. The multi-sensor direct measurement method installs pressure sensors at multiple support points of the trailer and calculates the center of gravity by measuring the load at each point. This method is costly, complex, increases maintenance difficulty, and is difficult to scale up on existing vehicle platforms. Some solutions attempt to identify the center of gravity online using complex vehicle dynamics models and expensive sensors, but these methods involve large computational loads, are highly dependent on sensor accuracy and model accuracy, and have reliability and real-time issues in actual vehicle control. Therefore, a control method is needed that can estimate the trailer's center of gravity position in real time with low cost and high reliability, and can proactively improve vehicle steering stability based on this estimation result. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a steering control method, device, terminal, and medium for tractor-trailer combined vehicles. By utilizing existing ECAS system static axle load data and mechanical models, it achieves low-cost, high-reliability estimation of the trailer's center of gravity position. Based on this, it intelligently assesses steering stability risks and then executes adaptive steering assistance control to improve vehicle handling stability and safety.

[0005] The present invention provides a steering control method, device, terminal, and medium for a tractor-trailer combination vehicle. The method includes the following steps: In response to the fulfillment of preset conditions, the longitudinal position of the trailer's center of gravity is determined based on the vehicle's static axle load measurement value through a pre-built mechanical model; Based on the determined longitudinal position of the center of gravity, the stability risk category of the vehicle under steering conditions is assessed; the stability risk category includes at least the first type of risk caused by the rearward shift of the center of gravity and the second type of risk caused by the forward shift of the center of gravity. Based on the assessed stability risk category, the preset steering assist control strategy corresponding to that category is invoked and executed to make compensatory adjustments to the vehicle's steering control parameters.

[0006] As can be seen from the above technical solutions, this application has the following advantages: (1) By utilizing the axle load data measured by the existing electronically controlled air suspension (ECAS) system of the vehicle under static and level road conditions, and combining it with the pre-built simplified mechanical model for calculation, there is no need to install an expensive sensor network on the trailer, which greatly reduces the system cost and complexity and has the prospect of large-scale mass production application. (2) By intelligently associating the estimated centroid position with the stability risk category, control from perception to decision-making is realized, and risks can be predicted in advance; (3) Based on different risk categories, the preset and differentiated steering assist control strategies are invoked and executed to make targeted compensatory adjustments to the steering control parameters, so that the vehicle's steering characteristics can be adaptively optimized according to the actual load state, effectively suppressing instability phenomena such as roll, fishtailing, and understeer caused by improper center of gravity position, and improving handling stability and safety. Attached Figure Description

[0007] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic flowchart of a steering control method for a tractor-trailer combination vehicle provided in an embodiment of the present invention.

[0009] Figure 2 This is a schematic diagram of the dynamic model of the tractor.

[0010] Figure 3 This is a schematic diagram of the dynamic model of a trailer.

[0011] Figure 4 This is a schematic block diagram of a steering control device for a tractor-trailer combination vehicle provided in an embodiment of the present invention.

[0012] Figure 5 This is a schematic diagram of the structure of a terminal provided in an embodiment of the present invention. Detailed Implementation

[0013] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this application and in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0015] Figure 1 This is a schematic flowchart illustrating a steering control method for a tractor-trailer combination vehicle provided in an embodiment of the present invention. Figure 1 The executing entity can be a tractor-trailer combined vehicle steering control device. The tractor-trailer combined vehicle steering control method provided in this embodiment of the invention is executed by computer equipment, and correspondingly, the tractor-trailer combined vehicle steering control device operates within the computer equipment. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0016] like Figure 1 As shown, the method includes the following steps.

[0017] S1, in response to the fulfillment of preset conditions, determines the longitudinal position of the trailer's center of gravity based on the vehicle's static axle load measurement value through a pre-built mechanical model.

[0018] S2, based on the determined longitudinal position of the center of gravity, assess the stability risk category of the vehicle under steering conditions; the stability risk category includes at least a first type of risk caused by the rearward shift of the center of gravity and a second type of risk caused by the forward shift of the center of gravity.

[0019] S3, based on the assessed stability risk category, invokes and executes the preset steering assist control strategy corresponding to that category to make compensatory adjustments to the vehicle's steering control parameters.

[0020] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process of this embodiment, another embodiment of the steering control method for a tractor-trailer combination vehicle is provided, which includes the following steps.

[0021] S100, establish a mechanical model to determine the longitudinal position of the trailer's center of gravity.

[0022] The mechanical model is based on the force and torque balance conditions of the tractor-trailer combination vehicle when it is static on a horizontal road surface. The model treats the rear axle of the tractor as a single axle system and uses the static axle load of the rear axle of the tractor, measured by the electronically controlled air suspension (ECAS) system, as the input parameter.

[0023] Specifically, the mechanical model is constructed based on two physical assumptions to ensure its rationality and simplification: the static equilibrium assumption and system decoupling and equivalent simplification. The static equilibrium assumption states that the vehicle is on a level road surface and completely stationary. In this state, the net external force and net torque on the vehicle system are zero, and the dynamic equations can be simplified to static equilibrium equations. System decoupling and equivalent simplification involve decoupling the complex tractor-trailer multi-body system into two independent rigid body models through force analysis at the saddle connection point. Simultaneously, to simplify calculations, the tractor's dual rear axles (or triple rear axles) are equivalent to a single axle system located in the middle. The vertical force on this equivalent bearing is the static axle load of the tractor's rear axle. This, together with the front axle of the tractor, forms a simplified two-axle model. This simplification avoids introducing significant errors and reduces the complexity and difficulty of solving the model.

[0024] Based on the above assumptions, force analysis was performed on the tractor and trailer respectively, and equilibrium equations were derived.

[0025] 1) Stress analysis of the tractor and trailer.

[0026] Figure 2 This is a schematic diagram of the dynamic model of the tractor unit. Figure 3 This is a schematic diagram of the dynamic model of the trailer, based on... Figure 2 and Figure 3 The force equations for the tractor and trailer can be drawn up.

[0027] Longitudinal force equation: (1) (2) Vertical force equation: (3) (4) Take torque balance on the front axle of the tractor (center of the front wheel contact mark): (5) To achieve torque balance at the trailer-saddle engagement point: (6) Here we assume that the braking deceleration of all shafts is Z, and that: (7) At the same time, under ideal conditions, the ratio of longitudinal to vertical forces at the saddle is also... .

[0028] 2) Calculation of vertical load From equations (6) and (7), we can obtain : (8) From equations (4) and (8), we can obtain : (9) From equations (5) and (7) and considering It can be solved : (10) From equations (3) and (10), we can obtain : (11) Equations (8) to (11) represent the vertical loads on each shaft, including the saddle. Further simplification of these equations yields the static and braking loads. The expression.

[0029] 3) Calculation of static axle load Simplifying equation (8), we get: (12) when The time is the static axle load of the vehicle. (13) Similarly, this can be organized. and : (14) in: ; ; .

[0030] when The time is the static axle load of the vehicle. (15) Similarly and

[0031] (16) in: ; ; .

[0032] (17) 4) Calculation of the distance from the trailer's center of gravity to the draw pin When the vehicle is stationary, it can be seen from equation (15) that its axle load and sprung mass can be measured by the pressure sensor on the ECAS system. This allows us to determine the distance from the trailer's center of gravity to the lead pin. .

[0033] (18) Table 1 below shows the model parameter details.

[0034] Table 1: Model Parameter Details

[0035] S200, when the preset conditions are met, calculate the longitudinal position of the centroid.

[0036] This step involves determining the longitudinal position of the trailer's center of gravity using a pre-built mechanical model based on the vehicle's static axle load measurement. Specifically, it includes the following sub-steps.

[0037] S201, Real-time monitoring to see if the triggering condition is met, wherein the triggering condition is any one of the following events: power-on initialization event, loading / unloading event, or periodic update event.

[0038] Event A (Power-On Initialization): This event is triggered when the vehicle's power status changes from OFF to ON (i.e., the ignition switch or start button is activated) and the vehicle's parking brake status signal is "activated". This event ensures that the vehicle can obtain the initial center of gravity position under the current load before each transportation task begins.

[0039] Event B (Post-Loading / Unloading): This event is triggered when the system sends a "Loading / Unloading Complete" signal via the CAN message from the on-board weighing system or when the driver manually confirms the signal through the human-machine interface. This event directly addresses the most critical operating condition that causes a change in the trailer's center of gravity.

[0040] Event C (Periodic Update): The system maintains a centroid calculation timer. This event is triggered if the timer reaches a preset period after the last successful centroid calculation and update. This event serves as a redundancy and long-term monitoring mechanism to detect slow load changes not caused by loading / unloading or as a periodic self-check of the system status.

[0041] S202, if the triggering condition is met, read the vehicle level sensor data to determine whether the vehicle is on a level road surface; if the absolute values ​​of both the pitch angle and roll angle are less than the first threshold, it is determined to be on a level road surface, and proceed to the next step.

[0042] S203: Read the wheel speed sensor data, determine whether the speed of all wheels is zero, and confirm that the parking brake has been activated; if all conditions are met, determine that the vehicle is in a reliable stationary state and proceed to the next step.

[0043] The system reads signals from the four wheel speed sensors of the ABS / ESC system to confirm that the instantaneous speed of all wheels is zero. Simultaneously, it reconfirms that the parking brake system's status signal is "activated." When both conditions—"all wheel speeds are zero" and "parking brake activated"—are met, the system ultimately determines that the vehicle is reliably stationary, eliminating any possible minor creep and ensuring the accuracy and stability of axle load measurements.

[0044] S204 collects target vehicle parameters via the vehicle's CAN bus and the electronically controlled air suspension ECAS system.

[0045] The following target vehicle parameters are collected via the vehicle CAN bus according to preset message identifiers: tractor gross vehicle weight. Total weight of trailer .

[0046] The static axle load of the tractor's rear axle is directly read from the controller of the Electronically Controlled Air Suspension (ECAS) system, which is calculated or measured. .

[0047] Simultaneously, pre-stored vehicle inherent geometric parameters, including the tractor wheelbase, are read from the vehicle's non-volatile memory (EEPROM). Distance from the center of gravity of the tractor to the front axle Distance from saddle pin hole to the rear axle of the tractor Distance from trailer tow pin to trailer rear axle .

[0048] S205, input the target vehicle parameters into the pre-built mechanical model to determine the longitudinal position of the trailer's center of gravity.

[0049] All valid target vehicle parameters collected and verified in step S204 are substituted into the pre-built mechanical model. The controller executes the calculation of the formula and finally calculates the longitudinal distance from the trailer's center of gravity to the drawbar. .

[0050] In one optional implementation, if the triggering condition is met, but the horizontal road surface or stationary state is not determined, the following steps are performed.

[0051] S206, set the centroid calculation status flag to "waiting for conditions to be met", and output prompt information to the driver through the human-machine interface. The prompt information includes at least "the vehicle is not level and the load cannot be calculated" or "the vehicle is not completely stationary and the load cannot be calculated".

[0052] When the system determines that the vehicle is not on a level surface or reliably stationary, it first updates the internal centroid calculation status flag from "Ready" to "Waiting for conditions to be met." Simultaneously, the system outputs clear prompts to the driver through the human-machine interface. If the level surface condition is not met, the system prompts: "Please park the vehicle on a level surface for load calculation." If the stationary condition is not met, the system prompts: "Please ensure the vehicle is completely stopped and the handbrake is engaged for load calculation." S207, Start the timer. During the timer period, continuously monitor the horizontal road surface conditions and the stationary vehicle conditions. If the monitored conditions are met before the timeout, clear the prompt message and continue to collect target vehicle parameters and subsequent steps. If the monitored conditions are not met after the timer expires, stop the current calculation process and set the centroid calculation status flag to "Calculation Failure".

[0053] The system initiates a configurable first timer, the period of which defines the maximum time window during which the system waits for driver intervention and condition improvement. During the operation of this timer, the system continuously monitors the "level road conditions" and "vehicle stationary conditions" defined in S202 and S203 in the background at fixed intervals.

[0054] If the system detects that all conditions have been met before the timer expires, it immediately clears the prompt message displayed to the driver, exits the waiting loop, and jumps to S204 to continue the normal calculation process.

[0055] If the necessary calculation conditions are not met after the first timer expires, the system determines that this active attempt has failed. At this time, the current calculation process is stopped, and the centroid calculation status flag is updated to "calculation failed".

[0056] S208, in the "calculation failed" state, use the default or the last valid centroid longitudinal position data for steering assistance control, and record the calculation failure event.

[0057] In the "calculation failure" state, to ensure the continuity of vehicle steering assist control, the system activates a degradation strategy. The system retrieves backup centroid longitudinal position data from non-volatile memory, with the following priority: the last successfully calculated and stored valid data; if no historical data is available, a preset, safer default centroid position parameter is used. The control system will use this backup data to continue subsequent risk assessment and steering assist control.

[0058] S300 assesses stability risk categories.

[0059] This step assesses the vehicle's stability risk category under steering conditions based on the determined longitudinal position of the center of gravity, and includes the following sub-steps.

[0060] S301, the calculated longitudinal distance from the trailer's center of gravity to the towing pin is compared with the distance from the trailer's towing pin to the trailer's rear axle to obtain the relative ratio of the center of gravity positions.

[0061] The control unit first determines the longitudinal position of the center of mass. Quantification was performed, taking into account the wheelbase of different trailers. Unlike other methods, directly using absolute distance for evaluation lacks universality. Therefore, the relative ratio of the centroid positions is first calculated. The ratio It can universally characterize the relative position of the center of mass in the longitudinal direction of the trailer. The larger the value, the further back the centroid is.

[0062] S302 compares the relative ratio with the pre-stored risk threshold range.

[0063] The control unit will ratio It was compared with several pre-calibrated risk thresholds, which were determined based on vehicle dynamics simulation and real vehicle test data.

[0064] S303 If the relative ratio is greater than the first risk threshold, the stability risk category is assessed as Category I risk, which is the tilt risk caused by the center of mass shifting backward.

[0065] This situation is classified as high-risk, indicating a risk of tilting and folding due to the rearward shift of the center of gravity. In this state, the excessive load at the rear of the trailer will significantly increase the centrifugal force generated during turning, leading to lateral load transfer and potentially causing the trailer to overturn or a "jack-knifing" phenomenon between the tractor and trailer.

[0066] S304. If the relative ratio is less than the second risk threshold, the stability risk category is assessed as the second type of risk, namely the turning inertia risk caused by the forward shift of the center of mass; the second risk threshold is not greater than the first risk threshold.

[0067] This situation is classified as medium risk, a steering inertia risk caused by the center of gravity being shifted forward. In this state, excessive mass is concentrated near the saddle, causing the trailer to respond too slowly to the steering actions of the tractor, resulting in an increased tendency for understeer. At the same time, during emergency turns, the trailer's huge inertia will strongly interfere with the tractor's posture through the saddle, posing a risk of understeer or instability.

[0068] S305. If the relative ratio is between the first risk threshold and the second risk threshold, the stability risk category is assessed as the third type of risk, that is, the centroid position is in the safe range.

[0069] This situation is considered low-risk, with the center of gravity located within a safe range. Under these conditions, the vehicle's dynamic response characteristics tend to be balanced, and steering stability is optimal.

[0070] S400 invokes and executes the steering assist control strategy.

[0071] This step, based on the assessed stability risk category, invokes and executes the preset steering assist control strategy corresponding to that category to make compensatory adjustments to the vehicle's steering control parameters. Specifically, if the stability risk category is the first type of risk, the first steering assist control strategy is invoked and executed; if the stability risk category is the second type of risk, the second steering assist control strategy is invoked and executed.

[0072] The first steering assist control strategy is configured to achieve the following adjustment control.

[0073] a1) Adaptive speed management.

[0074] Based on the relative ratio of the center of gravity positions, the maximum permissible vehicle speed under steering conditions is dynamically set by querying a first preset mapping table. Specifically, this is based on real-time calculations... The value is dynamically set to a maximum steering speed lower than the current road speed limit by querying a calibrated "λ-speed limit" mapping table. For example, when When the value increases from 0.7 to 0.9, The speed will linearly decrease from 60 km / h to 40 km / h. When the steering wheel angle is predicted or detected to be greater than a certain threshold, the system will reduce engine torque or apply active braking to ensure the vehicle speed does not exceed [a certain threshold]. .

[0075] b1) Control of turning radius convergence.

[0076] When the vehicle is turning, a basic braking torque is determined by querying a third preset mapping table based on the relative ratio of the center of gravity position and the steering wheel angular velocity. Then, the basic braking torque is corrected based on the current vehicle speed and the vehicle's lateral acceleration to obtain the final target braking torque. The target braking torque is then sent to the electronic stability control system, which adjusts the braking pressure on the designated inner rear wheel.

[0077] Turning radius convergence is used when the vehicle is turning and in a high-risk state with its center of gravity shifted aft. It actively generates a yaw moment that reduces the turning radius to counteract the oversteer tendency and roll risk caused by the aft center of gravity, thereby improving the vehicle's turning stability. This control process is achieved in conjunction with the vehicle's integrated controller and the Electronic Stability Control (ESC) system.

[0078] Specifically, the controller uses the relative ratio of the centroid position. and steering wheel angular velocity As the core input parameter, a pre-calibrated third preset mapping table is queried to determine a basic expected yaw moment. .

[0079] A larger value indicates a smaller stability margin, and therefore a larger required foundation stabilizing moment. Follow The value increases monotonically as it increases. The larger the absolute value, the more abrupt the steering maneuver, and the higher the risk of transient vehicle instability. Therefore, Follow The absolute value increases monotonically.

[0080] The above output It is the basic control quantity required to maintain stability, based on the driver's operating intentions and the prediction of potential vehicle risks.

[0081] To ensure the control input more accurately matches the current vehicle dynamics, the baseline expected yaw moment is corrected in real time. The controller acquires the current vehicle speed. Lateral acceleration of the vehicle ,according to The dynamic correction coefficient is calculated using a built-in correction algorithm, which can be a two-dimensional lookup table or a transfer function. The basic expected yaw moment is then calculated. Multiplying by the correction factor yields the final target yaw moment used for control. The correction factor takes into account the following factors: the higher the vehicle speed, the greater the energy required to stabilize the vehicle, and the correction factor may be greater than 1; when the lateral acceleration is already high, the correction factor may be less than 1 in order to avoid over-control.

[0082] To achieve The defined yaw moment with convergent turning radius is used to preferentially apply braking force to the inner rear wheel of the tractor. Based on the vehicle dynamics model, the target yaw moment is... Converted into a target braking torque acting on a specified wheel, a simplified calculation formula is:

[0083] In the formula, The effective radius of the wheel, The track width corresponds to the wheelbase of the axle. This is the allocation coefficient. The controller will calculate the target braking torque. This information is converted into specific braking pressure commands and sent to the Electronic Stability Control (ESC) system via the CAN bus. Upon receiving the commands, the ESC's hydraulic modulator precisely adjusts the braking pressure of the designated inner rear wheel of the tractor.

[0084] c1) Control of driving force suppression.

[0085] Based on the relative ratio of the center of mass positions, a driving torque limiting coefficient is determined by querying the fourth preset mapping table. The driving torque requested by the engine control unit or drive motor controller is multiplied by the driving torque limiting coefficient to obtain the limited allowable driving torque.

[0086] This step, upon identifying a rearward shift of the trailer's center of gravity, limits the torque output to the drive wheels to prevent excessive driving force from compromising the vehicle's lateral stability, especially during cornering and on low-traction surfaces. Specifically, it queries a pre-calibrated fourth preset mapping table and determines the relative ratio of the current center of gravity position. and vehicle speed Directly determine a driving torque limiting coefficient ,in, .

[0087] This coefficient The value of is negatively correlated with stability risk. A larger value indicates a more aft center of gravity, a higher risk of roll, and therefore a more stringent limitation on the driving force required by the system. Value follows The value increases and then monotonically decreases. For example, when When the safety threshold is increased from 0.6 to the high-risk threshold of 0.9, The value can linearly decrease from 1.0 (unrestricted) to 0.4 (only 40% of the torque is allowed). In the same... At higher speeds, vehicle stability becomes more sensitive to changes in driving force. The value decreases further as vehicle speed increases.

[0088] The vehicle integrated controller receives drive torque request values ​​in real time from the engine control unit (ECU) or drive motor controller (MCU). The controller then compares this request value with a queried limiting factor. Multiply the values ​​to calculate the final permissible drive torque, and instruct the powertrain to execute that torque value.

[0089] Preferably, considering that the start and return-to-center phases of steering are the most stability-sensitive transient conditions, deeper torque suppression is implemented during these phases. Specifically, at the start of steering, when the steering wheel angle acceleration exceeds a first preset threshold, the system determines that the driver is making a sharp steering input. At this time, within a certain time window, the torque is suppressed at the original coefficient. Based on this, a smaller, enhanced suppression factor is temporarily superimposed for deep torque suppression to counteract the severe lateral load transfer that may be caused by acceleration during cornering. During the steering return phase, when the system detects that the driver is quickly returning the steering wheel to center, it predicts that the trailer's huge lateral inertia may cause a swaying impact on the tractor. To prevent this impact from being superimposed on the driving force and causing the drive wheels to slip, the system commands to temporarily reduce the drive torque to zero, or even apply slight engine braking or negative torque from the electric motor, to actively dampen and stabilize the vehicle's attitude.

[0090] The second steering assist control strategy is configured to achieve the following adjustment control.

[0091] a2) Parametric adjustment of steering assist characteristics.

[0092] Based on the degree of deviation between the relative ratio of the center of gravity position and the second risk threshold, the assist gain coefficient is determined by querying the second preset mapping table, and the assist gain of the electric power steering system is adjusted down according to the system.

[0093] This control provides a direct tactile warning to the driver by altering the steering assist characteristics, making the driver aware that the vehicle is currently in a state of forward center of gravity and high inertia, thereby avoiding sudden and aggressive steering maneuvers.

[0094] The controller uses the calculated relative ratio of the centroid positions. Query the pre-calibrated second preset mapping table to determine a boost gain coefficient. This coefficient defines the ratio of the target assist level to the standard assist level. . The smaller the value, the further forward the center of gravity is, and the higher the risk of turning inertia. Therefore, the assist gain coefficient... Follow The value decreases and monotonically decreases. For example, when When the safety threshold is reduced from 0.5 to the high-risk threshold of 0.3, The value may decrease linearly from 0.9 to 0.6.

[0095] The controller will calculate The value is sent to the Electric Power Steering (EPS) system. Based on this coefficient, the EPS system adjusts its assist mapping curve in real time. Specifically, to obtain the same steering effort, the assist force provided by the motor is reduced proportionally, resulting in a significant increase in the steering wheel torque felt by the driver, and a more damped steering feel.

[0096] b2) Adaptation of steering gear ratio.

[0097] If the vehicle is equipped with a variable steering ratio system, the transmission ratio from the steering wheel angle to the wheel angle is increased by consulting the fifth preset mapping table based on the relative ratio of the center of gravity positions.

[0098] This control reduces the angular transmission gain of the steering system to dull the steering response, filter out sudden steering commands that the driver may input, and leave more reaction time for the control system to prevent the trailer's inertia from causing a severe impact on the tractor's attitude.

[0099] Specifically, this control is activated only when the vehicle is equipped with a variable steering ratio system. The controller adjusts the ratio based on the relative position of the center of gravity. Query the pre-calibrated fifth preset mapping table to determine an increased target steering ratio. Steering ratio Defined as steering wheel angle With the turning angle of the wheel The ratio, i.e. The higher the risk of steering inertia, the more "sluggish" the steering response the system needs. Therefore, the target gear ratio... Follow The value decreases and increases monotonically. For example, the standard transmission ratio. The ratio is 16:1, but under high risk, It can be increased to 20:1.

[0100] The controller will The signal is sent to the variable steering ratio system. The system's actuators adjust the transmission so that the driver needs to turn the steering wheel a greater angle to achieve the same steering angle change in the wheels. This effectively reduces steering sensitivity and enhances high-speed straight-line stability.

[0101] c2) Control of front axle load compensation Based on the relative ratio of the center of gravity positions, the target height increase is determined by querying the sixth preset mapping table, and the front axle suspension height of the tractor is raised to the sum of the standard height and the target height increase by the electronically controlled air suspension system.

[0102] This control system actively adjusts the front suspension height and changes the front wheel alignment parameters to simulate the effect of increasing the front axle load, thereby physically improving the steering wheel centering feel and self-centering feedback, helping the driver to more accurately perceive and control the vehicle's direction.

[0103] Specifically, the controller uses the relative ratio of the centroid positions. Query the pre-calibrated sixth preset mapping table to determine a target height increase. . It is a non-negative value, and the unit is millimeters (mm). The smaller the value, the further forward the center of mass is, and the greater the physical stability compensation required by the steering system. Therefore, the target height increase... Follow The value decreases and monotonically increases. For example, when When it decreases from 0.5 to 0.3, It may be increased from 15mm to 35mm.

[0104] The controller sends a command to the Electronically Controlled Air Suspension (ECAS) system, with the goal of raising the suspension height of the tractor's front axle from the standard height. Upgraded to The ECAS system stabilizes the front of the vehicle at a target height by inflating the front axle air springs and using a height sensor for closed-loop control. Increasing the front axle height causes positioning parameters such as the caster angle of the front wheel kingpin to change in a greater direction, generating a larger stabilizing torque.

[0105] The foregoing has described in detail an embodiment of a steering control method for a tractor-trailer combination vehicle. Based on the steering control method for a tractor-trailer combination vehicle described in the above embodiment, this invention also provides a steering control device for a tractor-trailer combination vehicle corresponding to the method.

[0106] Figure 4 This is a schematic block diagram of a tractor-trailer combined vehicle steering control device provided in an embodiment of the present invention. In this embodiment, the tractor-trailer combined vehicle steering control device 400 can be divided into multiple functional modules according to the functions it performs, such as... Figure 4 As shown. The module referred to in this invention is a series of computer program segments that can be executed by at least one processor and perform a fixed function, and which are stored in memory.

[0107] The longitudinal position determination module 410 is used to determine the longitudinal position of the trailer's center of gravity based on the vehicle's static axle load measurement value and a pre-built mechanical model in response to the fulfillment of preset conditions.

[0108] The risk category determination module 420 is used to assess the stability risk category of the vehicle under steering conditions based on the determined longitudinal position of the center of gravity; the stability risk category includes at least a first type of risk caused by the rearward shift of the center of gravity and a second type of risk caused by the forward shift of the center of gravity.

[0109] The control strategy execution module 430 is used to call and execute a preset steering assist control strategy corresponding to the assessed stability risk category in order to make compensatory adjustments to the vehicle's steering control parameters.

[0110] The tractor-trailer combination vehicle steering control device of this embodiment is used to implement the aforementioned tractor-trailer combination vehicle steering control method. Therefore, the specific implementation of this device can be found in the embodiment section of the tractor-trailer combination vehicle steering control method above. Thus, its specific implementation can be referred to the description of the corresponding embodiments, and will not be elaborated here.

[0111] Furthermore, since the tractor-trailer combination vehicle steering control device in this embodiment is used to implement the aforementioned tractor-trailer combination vehicle steering control method, its function corresponds to the function of the above method, and will not be described again here.

[0112] Figure 5 This is a schematic diagram of a terminal 500 provided in an embodiment of the present invention, including: a processor 510, a memory 520, and a communication unit 530. The processor 510 is used to implement the flow steps of the above-described embodiment of the tractor-trailer combined vehicle steering control method when implementing the steering control program for the tractor-trailer combined vehicle stored in the memory 520.

[0113] The present invention also provides a computer storage medium, which may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0114] The computer storage medium stores a steering control program for a tractor-trailer combination vehicle. When the tractor-trailer combination vehicle steering control program is executed by the processor, it implements the process steps of the above-described embodiment of the tractor-trailer combination vehicle steering control method.

[0115] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A steering control method for a tractor-trailer combined vehicle, characterized in that, Includes the following steps: In response to the fulfillment of preset conditions, the longitudinal position of the trailer's center of gravity is determined based on the vehicle's static axle load measurement value through a pre-built mechanical model; Based on the determined longitudinal position of the center of gravity, assess the vehicle's stability risk category under steering conditions; The stability risk category includes at least the first type of risk caused by the rearward shift of the centroid and the second type of risk caused by the forward shift of the centroid. Based on the assessed stability risk category, the preset steering assist control strategy corresponding to that category is invoked and executed to make compensatory adjustments to the vehicle's steering control parameters.

2. The steering control method for a tractor-trailer combination vehicle according to claim 1, characterized in that, The mechanical model is based on the force and torque balance conditions of the tractor-trailer combination vehicle when it is static on a horizontal road surface. The model treats the rear axle of the tractor as a single axle system and uses the static axle load of the rear axle of the tractor, measured by the electronically controlled air suspension (ECAS) system, as the input parameter.

3. The steering control method for a tractor-trailer combination vehicle according to claim 2, characterized in that, The mechanical model is represented as follows: In the formula, The total mass of the tractor unit. The total mass of the trailer. This refers to the wheelbase of the tractor unit. This is the distance from the saddle pin hole to the rear axle of the tractor. This is the distance from the trailer tow pin to the trailer rear axle. The distance from the center of gravity of the tractor to the front axle. The longitudinal distance from the trailer's center of gravity to the draw pin. This refers to the static axle load on the rear axle of the tractor.

4. The steering control method for a tractor-trailer combination vehicle according to claim 3, characterized in that, In response to the fulfillment of preset conditions, based on the vehicle's static axle load measurements, the longitudinal position of the trailer's center of gravity is determined using a pre-built mechanical model, specifically including: Real-time monitoring to determine if triggering conditions are met, wherein the triggering conditions are any one of the following events: power-on initialization event, loading / unloading event, or periodic update event; If the triggering conditions are met, read the vehicle level sensor data to determine whether the vehicle is on a level road surface; if the absolute values ​​of both the pitch angle and roll angle are less than the first threshold, the road surface is determined to be level, and proceed to the next step. Read the wheel speed sensor data, determine whether the speed of all wheels is zero, and confirm that the parking brake is activated; if all conditions are met, determine that the vehicle is in a reliably stationary state and proceed to the next step. Parameters of the target vehicle are collected via the vehicle's CAN bus and the electronically controlled air suspension (ECAS) system. The target vehicle parameters are input into the pre-built mechanical model to determine the longitudinal position of the trailer's center of gravity.

5. The steering control method for a tractor-trailer combination vehicle according to claim 4, characterized in that, If the triggering condition is met, but the horizontal road surface or stationary state judgment is not passed, then the following steps are executed: Set the centroid calculation status flag to "waiting for conditions to be met" and output prompt information to the driver through the human-machine interface. The prompt information includes at least "the vehicle is not level and the load cannot be calculated" or "the vehicle is not completely stationary and the load cannot be calculated". Start the timer and continuously monitor the horizontal road surface conditions and the stationary vehicle conditions within the timer period. If the monitored conditions are met before the timeout, clear the prompt message and continue to collect target vehicle parameters and subsequent steps. If the monitored conditions are not met after the timer expires, stop the current calculation process and set the centroid calculation status flag to "calculation failed". In the "calculation failed" state, the default or the last valid centroid longitudinal position data is used for steering assistance control, and the calculation failure event is recorded.

6. The steering control method for a tractor-trailer combination vehicle according to claim 4, characterized in that, Based on the determined longitudinal position of the center of gravity, the stability risk category of the vehicle under steering conditions is assessed, specifically including: The calculated longitudinal distance from the trailer's center of gravity to the lead pin is compared with the distance from the trailer's lead pin to the trailer's rear axle to obtain the relative ratio of the center of gravity positions. The relative ratio is compared with the pre-stored risk threshold range; If the relative ratio is greater than the first risk threshold, the stability risk category is assessed as Category I risk, which is the tilt risk caused by the centroid shifting backward. If the relative ratio is less than the second risk threshold, the stability risk category is assessed as the second type of risk, namely the turning inertia risk caused by the forward shift of the center of mass; the second risk threshold is not greater than the first risk threshold. If the relative ratio is between the first risk threshold and the second risk threshold, the stability risk category is assessed as the third type of risk, meaning the centroid position is within the safe range.

7. The steering control method for a tractor-trailer combination vehicle according to claim 6, characterized in that, Based on the assessed stability risk category, the corresponding preset steering assist control strategy is invoked and executed, specifically including: If the stability risk category is Category 1, then the first steering assist control strategy is invoked and executed, which is configured as follows: Based on the relative ratio of the center of gravity positions, the maximum permissible vehicle speed under steering conditions is dynamically set by querying the first preset mapping table. When the vehicle is turning, a basic braking torque is determined by querying a third preset mapping table based on the relative ratio of the center of gravity position and the steering wheel angular velocity. Then, the basic braking torque is corrected based on the current vehicle speed and the vehicle's lateral acceleration to obtain the final target braking torque. The target braking torque is then sent to the electronic stability control system, which adjusts the braking pressure on the designated inner rear wheel. Based on the relative ratio of the center of mass positions, a driving torque limiting coefficient is determined by querying the fourth preset mapping table. The driving torque requested by the engine control unit or drive motor controller is multiplied by the driving torque limiting coefficient to obtain the limited allowable driving torque. If the stability risk category is Category 2, then the second steering assist control strategy is invoked, which is configured as follows: Based on the degree of deviation between the relative ratio of the center of gravity position and the second risk threshold, the assist gain coefficient is determined by querying the second preset mapping table, and the assist gain of the electric power steering system is reduced according to the system. If the vehicle is equipped with a variable steering ratio system, the transmission ratio from the steering wheel angle to the wheel angle is increased by consulting the fifth preset mapping table based on the relative ratio of the center of gravity positions. Based on the relative ratio of the center of gravity positions, the target height increase is determined by querying the sixth preset mapping table, and the front axle suspension height of the tractor is raised to the sum of the standard height and the target height increase by the electronically controlled air suspension system.

8. A steering control device for a tractor-trailer combined vehicle, characterized in that, include: The longitudinal position determination module is used to determine the longitudinal position of the trailer's center of gravity based on the vehicle's static axle load measurement value and a pre-built mechanical model in response to the fulfillment of preset conditions. The risk category determination module is used to assess the stability risk category of a vehicle under steering conditions based on a determined longitudinal position of the center of gravity. The stability risk category includes at least the first type of risk caused by the rearward shift of the centroid and the second type of risk caused by the forward shift of the centroid. The control strategy execution module is used to call and execute the preset steering assist control strategy corresponding to the assessed stability risk category in order to make compensatory adjustments to the vehicle's steering control parameters.

9. A terminal, characterized in that, include: Memory for storing the steering control program of the tractor-trailer combination vehicle; A processor is configured to implement the steps of the tractor-trailer combination vehicle steering control method as described in any one of claims 1 to 7 when executing the tractor-trailer combination vehicle steering control program.

10. A computer-readable storage medium, characterized in that, The readable storage medium stores a tractor-trailer combination vehicle steering control program, which, when executed by a processor, implements the steps of the tractor-trailer combination vehicle steering control method as described in any one of claims 1 to 7.

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