Anti-folding braking system and control method

Abstract

An anti-folding braking system comprises a sensing unit used for obtaining motion state information of an articulated vehicle in real time; the ECU is in signal connection with the sensing unit and used for calculating a folding risk index based on the motion state information and synchronously generating a braking control instruction and an active steering control instruction when the folding risk index exceeds a first threshold value; and the execution unit comprises an active steering system and an electronic braking system and is used for executing the braking control instruction and the active steering control instruction so as to realize cooperative inhibition of the folding trend of the vehicle. The invention further discloses a folding control method applied to the braking system. The folding risk is predicted in advance by monitoring the dynamic state of the vehicle in real time, and the braking system and the active steering system of the tractor are cooperatively controlled, so that the folding phenomenon is actively prevented and inhibited.

Description

Technical Field

[0001] This application relates to the field of active safety technology for vehicles, and in particular to a braking system and control method for articulated vehicles, such as truck-semi-trailer combinations, to prevent the trailer from jackknifing during emergency braking. Background Technology

[0002] Articulated vehicles, such as combinations of tractor-trailers and semi-trailers, have inherent instability risks during high-speed emergency braking due to their unique articulated structure. The most common dangerous situation is the "folding" phenomenon, where the trailer, due to inertia, forms a sharp angle between its longitudinal axis and the tractor's longitudinal axis, ultimately leading to loss of control, fishtailing, or even rollover.

[0003] In existing technologies, anti-lock braking systems (ABS) and electronic stability programs (ESP) are widely used to improve vehicle braking stability. ABS maintains directional controllability during braking by preventing wheel lock-up; ESP corrects understeer or oversteer by monitoring vehicle status and braking individual wheels. However, these systems primarily operate on the braking system itself, and their intervention capabilities for the folding problem unique to articulated vehicles are limited, especially on low-friction surfaces (such as wet, slippery, icy, or snowy roads), where their effectiveness is poor.

[0004] Another existing technology involves detecting the articulation angle between the tractor and trailer. When this angle exceeds a safety threshold, the system attempts to "straighten" the vehicle by braking the rear wheels of the tractor. This method suffers from response lag because by the time the system detects an excessively large articulation angle, a folding tendency has often already formed. Correcting the braking force distribution at this point has limited effectiveness and may even exacerbate instability.

[0005] Therefore, there is an urgent need in the field for a system that can predict and actively suppress folding trends in advance, thereby fundamentally improving the braking stability of articulated vehicles. Summary of the Invention

[0006] In view of this, this application provides an anti-folding braking system based on inertial measurement and active steering. This system monitors the vehicle's dynamic state in real time, predicts folding risks in advance, and coordinates the braking system with the active steering system of the tractor to actively prevent and suppress folding phenomena.

[0007] The technical solution adopted in this application is as follows: An anti-folding braking system, comprising: The sensing unit, used to acquire the motion state information of the articulated vehicle in real time, includes: An inertial measurement unit (IMU) installed on the tractor unit is used to measure the yaw rate, longitudinal acceleration, and lateral acceleration of the tractor unit. An articulation angle sensor installed between the tractor and trailer is used to measure the real-time articulation angle; and The vehicle bus interface is used to acquire wheel speed, steering wheel angle, and brake master cylinder pressure signals. Also includes: Electronic control unit (ECU), which is signal-connected to the sensing unit, includes, The state estimation module, based on signals from the sensor units, calculates or estimates the vehicle's dynamic state parameters in real time, including the lateral velocity of the tractor and trailer, the sideslip angle, and the rate of change of the articulation angle; and The stability determination module calculates a comprehensive folding risk index based on the dynamic state parameters. When the index exceeds a preset first threshold, the vehicle is determined to have a folding risk. When a risk of folding is detected, the cooperative controller simultaneously generates braking control commands and active steering control commands. Also includes: The execution unit, including the vehicle's active steering system and electronic braking system, is used to receive and execute braking control commands and active steering control commands issued by the cooperative controller to achieve cooperative suppression of the vehicle's folding tendency.

[0008] This application also includes an anti-folding control method applied to the anti-folding braking system, comprising the following steps: The anti-folding braking system acquires real-time motion status information of the vehicle, including the yaw rate and acceleration of the tractor and the articulation angle between the tractor and the trailer. The anti-folding braking system calculates a comprehensive folding risk index based on the motion state information. The anti-folding braking system determines whether the folding risk index exceeds a preset threshold. If so, then perform the following operations simultaneously: (a) Control the active steering system to generate an additional front wheel steering angle superimposed on the driver input to stabilize the vehicle attitude; (b) Control the electronic braking system and adjust the braking force distribution to help suppress the folding tendency; If not, the system will exit the intervention.

[0009] The beneficial effects of this application are as follows: 1) Forward prediction: By integrating IMU data and vehicle models, the system can identify potential folding trends earlier than by simply relying on hinge angle detection, thus gaining valuable time for intervention.

[0010] 2) Active intervention: Active steering is introduced as a control method, which can generate a stable yaw moment by finely adjusting the front wheel angle in the early stage of the folding trend, suppressing folding from the kinematic root, which is smoother and more efficient than simply relying on braking.

[0011] 3) Coordinated Control: The coordinated operation of braking and steering provides dual protection. In low-risk situations, active steering can be finely adjusted independently; in high-risk situations, the braking system intervenes to provide stronger stabilizing torque. The synergy between the two results in a control effect superior to that of a single system.

[0012] 4) Wide adaptability: The system does not rely on high-precision road surface recognition, but is controlled based on the vehicle's own dynamic response, so it is suitable for various complex road conditions. Attached Figure Description

[0013] Figure 1 This is a block diagram of the overall architecture of the anti-folding braking system in this application; Figure 2 This is a control flowchart of the anti-folding control method in this application; In the diagram: 100-Sensing unit, 101-Inertial measurement unit (IMU), 102-Articulation angle sensor, 103-Vehicle bus interface, 200-Electronic control unit (ECU), 201-State estimation module, 202-Stability judgment module, 203-Cooperation controller, 300-Actuation unit, 301-Active steering system, 302-Electronic braking system. Detailed Implementation

[0014] To make the above-mentioned features and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0015] See Figure 1 An anti-folding braking system mainly consists of a sensing unit 100, an electronic control unit (ECU) 200, and an execution unit 300. The sensing unit 100 includes an inertial measurement unit (IMU) 101, an articulation angle sensor 102, and a vehicle bus interface 103. The ECU 200 is the core of the system, containing a state estimation module 201, a stability determination module 202, and a cooperative controller 203. The execution unit 300 includes an active steering system 301 and an electronic braking system 302.

[0016] The sensing unit 100 is used to acquire the motion state information of the articulated vehicle in real time, and includes, The inertial measurement unit (IMU101) installed on the tractor is used to measure the yaw rate, longitudinal acceleration and lateral acceleration of the tractor. The articulation angle sensor 102, installed between the tractor and the trailer, is used to measure the real-time articulation angle θ. The vehicle bus interface 103 is used to acquire wheel speed, steering wheel angle and brake master cylinder pressure signals.

[0017] The electronic control unit ECU200 is signal-connected to the sensing unit 100, and includes, The state estimation module 201 calculates or estimates the dynamic state parameters of the vehicle in real time based on the signals from the sensing unit 100, including the lateral velocity of the tractor and trailer, the sideslip angle of the center of gravity, and the rate of change of the articulation angle dθ / dt. The stability determination module 202 calculates a comprehensive folding risk index based on the dynamic state parameters. When the index exceeds a preset first threshold, it determines that the vehicle has a folding risk. The folding risk index R is a function of the hinge angle θ, the hinge angle change rate dθ / dt, and the relative yaw motion between the tractor and the trailer. When a folding risk is detected, the cooperative controller 203 simultaneously generates braking control commands and active steering control commands. The active steering control command is an additional front wheel steering angle δ_add superimposed on the driver's steering wheel input, with the control objective of generating a yaw moment for the tractor unit opposite to the folding trend. The calculation of the additional front wheel steering angle δ_add is negatively correlated with the real-time measured hinge angle θ and the hinge angle change rate dθ / dt. The braking control command is used to dynamically correct the target slip ratio or braking torque of the onboard anti-lock braking system (ABS) or electronic stability program (ESP), prioritizing the braking stability of the tractor unit's rear axle. When the folding risk index exceeds a second threshold higher than the first threshold, the braking control command generated by the cooperative controller 203 includes independent braking control of one or more wheels of the tractor unit to generate additional corrective yaw moments. The execution unit 300 includes the vehicle's active steering system 301 and electronic braking system 302, and is used to receive and execute braking control commands and active steering control commands issued by the cooperative controller 203 to achieve cooperative suppression of the vehicle's folding tendency.

[0018] Under normal operating conditions, the ECU 200 continuously acquires data through the sensing unit 100. The state estimation module 201 uses algorithms such as the Kalman filter to fuse the yaw rate, acceleration signals, and wheel speed signals from the IMU 101 to estimate key states of the tractor unit that are difficult to measure directly, such as the sideslip angle. Meanwhile, the articulation angle sensor 102 provides a precise articulation angle θ and its rate of change dθ / dt.

[0019] The stability assessment module 202 calculates the folding risk index R based on the estimated and measured state parameters. An exemplary formula for calculating R is:

[0020] Where α, β, and γ are weighting coefficients, and ω_tractor and ω_trailer are the yaw rates of the tractor and trailer, respectively (the trailer yaw rate can be derived from the rate of change of the articulation angle, etc.). The system is activated when R > R_th1 (the first threshold). After the cooperative controller 203 is activated, it first calculates the active steering command. The goal of calculating the additional front wheel steering angle δ_add is to generate a yaw moment for the tractor to counteract the folding tendency. A simplified control law could be:

[0021] K1 and K2 are the control gains. This command is sent to the active steering system 301, which adds a small steering angle to the driver's steering input.

[0022] Simultaneously, the cooperating controller 203 sends correction commands to the electronic braking system 302. For example, it may moderately increase the target slip ratio of the tractor's rear wheels to bring them into cyclic braking earlier, thereby increasing rear axle stability, or apply a slight braking force to the rear wheel on the side about to fold, generating a stabilizing torque.

[0023] If the folding risk index R increases further and exceeds a higher second threshold R_th2, the co-controller 203 will adopt a more aggressive joint control strategy, such as applying braking to the outer front wheel of the tractor while superimposing the steering angle, to generate a stronger corrective yaw moment.

[0024] The entire control process is a closed loop. The ECU 200 continuously adjusts the control commands based on real-time feedback of the vehicle status until the folding risk index R falls back to a safe range, at which point the system exits intervention.

[0025] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An anti-fold brake system characterized by, The application relates to a control method for a folding prevention braking system of a vehicle, comprising: a sensing unit for acquiring real-time motion state information of the articulated vehicle; an electronic control unit ECU connected with the sensing unit, for calculating a folding risk index based on the motion state information, and synchronously generating a braking control instruction and an active steering control instruction when the folding risk index exceeds a first threshold value; and an execution unit comprising an active steering system and an electronic braking system, for executing the braking control instruction and the active steering control instruction to realize cooperative inhibition of a folding trend of the vehicle. The sensing unit comprises:

2. A non-folding brake system according to claim 1, wherein an inertial measurement unit IMU installed on a tractor, for measuring a yaw angular velocity, a longitudinal acceleration and a lateral acceleration of the tractor; an articulation angle sensor installed between the tractor and a trailer, for measuring a real-time articulation angle; and a vehicle bus interface for acquiring wheel speed, steering wheel angle and brake master cylinder pressure signals. The electronic control unit ECU comprises:

3. A non-folding brake system according to claim 2, wherein a state estimation module for calculating or estimating dynamic state parameters of the vehicle in real time based on signals of the sensing unit, the dynamic state parameters comprising lateral velocities of the tractor and the trailer, a center of mass side slip angle and an articulation angle change rate; a stability determination module for calculating a comprehensive folding risk index based on the dynamic state parameters, and determining that the vehicle has a folding risk when the index exceeds a preset first threshold value; and a cooperative controller for synchronously generating a braking control instruction and an active steering control instruction when it is determined that there is a folding risk. The folding risk index R is a function of the articulation angle theta, the articulation angle change rate dtheta / dt and relative yaw motion of the tractor and the trailer.

4. A non-folding brake system according to claim 3, wherein The active steering control instruction is an additional front wheel steering angle delta_add superimposed on a driver steering wheel input.

5. A non-folding brake system according to claim 3, wherein The additional front wheel steering angle delta_add is negatively related to the real-time measured articulation angle theta and articulation angle change rate dtheta / dt.

6. A non-folding brake system according to claim 5, wherein, The braking control instruction is used for dynamically correcting a target slip ratio or a braking torque of an anti-lock braking system ABS or an electronic stability program ESP on the vehicle.

7. A non-folding brake system according to claim 3, wherein When the folding risk index exceeds a second threshold value higher than the first threshold value, the braking control instruction generated by the cooperative controller comprises independent braking control of single or multiple wheels of the tractor to generate an additional correction yaw moment.

8. A non-folding brake system according to claim 3, wherein The control method is applied to the folding prevention braking system as claimed in any one of claims 4-8, and comprises the following steps:

9. A fold prevention control method characterized by, The folding prevention braking system acquires real-time motion state information of the vehicle, including a yaw angular velocity, an acceleration of the tractor and an articulation angle between the tractor and the trailer; The folding prevention braking system calculates a comprehensive folding risk index based on the motion state information; The folding prevention braking system determines whether the folding risk index exceeds a preset threshold value; If yes, the following operations are synchronously executed: (a) controlling the active steering system to generate an additional front wheel steering angle superimposed on a driver input to stabilize a vehicle posture; (b) controlling the electronic braking system to adjust a braking force distribution to assist in inhibiting a folding trend; If no, the system exits intervention. ​ 10. A method of preventing foldover control according to claim 9, wherein While controlling the active steering system and the electronic brake system, the change of the folding risk index is continuously monitored and the control instructions are dynamically adjusted until the folding risk index falls back below the safe range.

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