Commercial vehicle ramp start auxiliary control method based on EBS system

Abstract

The present application relates to the commercial vehicle ramp starting technology, in order to solve the problems of greater danger, high vehicle maintenance cost and short service life when the existing commercial vehicle ramps start, and proposes a commercial vehicle ramp starting auxiliary control method based on EBS system, comprising the following steps: building a ramp starting auxiliary system based on EBS system; when the vehicle stops on the ramp waiting to start, the driver steps on the first trigger ramp starting auxiliary button; the signal processing module calculates the current ramp slope; according to the current ramp slope, the parking state information, the brake pedal information and the vehicle speed information, it is confirmed whether the ramp starting auxiliary system is activated; the ramp starting auxiliary system adjusts the anti-slip target air pressure according to the basic target air pressure, so that the vehicle speed is always kept at 0, and the passive anti-slip of the vehicle is realized; according to the brake pedal information and the throttle pedal information, the ramp starting auxiliary system is closed in time, and the anti-slip target air pressure is gradually released until it drops to 0, so that the vehicle starts smoothly.

Description

Technical Field

[0001] This invention relates to hill start technology for commercial vehicles, specifically to a hill start assist control method for commercial vehicles based on an EBS system. Background Technology

[0002] Commercial vehicles are heavy, especially when heavily loaded. If they are parked on a steep slope, restarting them can be difficult. Starting on a slope requires a high level of skill from the driver. If not handled properly, the vehicle can easily roll backward and collide with other vehicles, pedestrians, or obstacles, causing serious property damage and personal injury. Such situations put immense psychological pressure on the driver, increasing the risk of errors due to panic. Furthermore, improper operation during a slope start can cause severe mechanical impacts to related components, accelerating wear and tear, increasing repair costs, and significantly shortening the vehicle's lifespan.

[0003] Chinese patent application number CN202311534333.8, entitled "A Hill Start Assist Control System and Method," discloses a hill start assist control achieved through a signal receiving module and a hill start assist module to ensure a smooth start for the vehicle and solve the problem of how to achieve a smooth start without rolling back on a small slope. However, this method is not applicable to hill starts for commercial vehicles with a large curb weight. Therefore, in order to reduce the danger of starting commercial vehicles on steep slopes, reduce driver operation risks, reduce frequent use of the handbrake, reduce mechanical wear, and extend the service life of related components, it is of practical significance to develop a hill start assist function, enabling commercial vehicles to achieve a smooth start on slopes within a controllable rolling distance. Summary of the Invention

[0004] The purpose of this invention is to address the technical problems of high risk, significant driver operational risks, and severe wear and tear on related components in existing commercial vehicles when starting on an incline, resulting in high vehicle maintenance costs and significantly shortened vehicle lifespan. Therefore, this invention proposes an auxiliary control method for starting commercial vehicles on an incline based on an EBS system.

[0005] To achieve the above objectives, the technical solution proposed by this invention is as follows:

[0006] The hill start assist control method for commercial vehicles based on the EBS system is unique in that it includes the following steps:

[0007] S1. A hill start assist system is built based on the EBS system. The hill start assist system includes a hill start assist button and a signal processing module connected to the EBS system.

[0008] When the vehicle is stopped on a slope and waiting to start, the driver presses the brake pedal, releases the parking brake, and triggers the hill start assist button for the first time.

[0009] S2. The signal processing module collects the vehicle's current speed information and calculates the current slope gradient.

[0010] S3. Based on the current slope gradient in step S2, as well as the parking status information, brake pedal information, and vehicle speed information of the EBS system, confirm whether to activate the hill start assist system. If the hill start assist system is confirmed to be activated, proceed to step S4; otherwise, the vehicle starts normally.

[0011] S4. Obtain the base target air pressure locked by the EBS system brake pedal when the hill start assist system is activated. The hill start assist system adjusts the anti-roll target air pressure according to the base target air pressure to keep the vehicle speed at 0, thereby achieving passive anti-roll of the vehicle.

[0012] S5. The signal processing module monitors the brake pedal and accelerator pedal information in real time. When the longitudinal driving force of the EBS system is greater than the downward force, the hill start assist system is turned off, and the anti-roll target air pressure is gradually released until it drops to 0, thereby achieving a smooth start for the vehicle.

[0013] Furthermore, step S2 specifically includes:

[0014] The signal processing module calculates the current slope based on the observations from the longitudinal accelerometer of the EBS system's vehicle attitude sensor and the current vehicle speed, satisfying the following formula:

[0015]

[0016] in, The current slope of the ramp. These are observations from the longitudinal accelerometer of the EBS vehicle attitude sensor. Let g be the differential of the vehicle speed, and g be the gravitational acceleration constant.

[0017] Furthermore, step S3 specifically includes:

[0018] S3.1 The signal processing module determines whether to activate the ramp start assist system based on the current ramp gradient in step S2;

[0019] If the current slope is less than 2%, the hill start assist system will not be activated.

[0020] If the current slope is ≥2%, the signal processing module collects parking status information;

[0021] S3.2 Determine whether the parking status has been released;

[0022] If the parking status is not released, the hill start assist system will not be activated;

[0023] If the parking state has been released, the signal processing module collects brake pedal information;

[0024] S3.3 Determine whether the brake pedal is depressed;

[0025] Hill Start Assist will not be activated if the brake pedal is not depressed.

[0026] If the brake pedal is depressed, the signal processing module collects vehicle speed information;

[0027] S3.4 Determine if the vehicle speed is 0;

[0028] If the vehicle speed is not 0, the hill start assist system will not be activated, and the vehicle will start normally.

[0029] If the vehicle speed is 0, the hill start assist system is activated, and step S4 is executed.

[0030] Furthermore, step S4 specifically includes:

[0031] S4.1 Obtain the base target air pressure locked by the EBS system brake pedal when the hill start assist system is activated;

[0032] S4.2. The vehicle speed information is collected in real time through the signal processing module, and the air pressure of the anti-rollover target is adjusted in real time according to the vehicle speed information;

[0033] If the vehicle speed is greater than 0, the hill start assist system will adjust the anti-roll target air pressure to ensure that the anti-roll target air pressure is not less than the base target air pressure, thereby ensuring that the vehicle speed is always kept at 0, thus achieving passive anti-roll of the vehicle.

[0034] If the vehicle speed is 0, the hill start assist system will maintain the target air pressure to prevent rollback.

[0035] Furthermore, step S5 specifically includes:

[0036] S5.1 During the activation of the hill start assist system, the timing starts each time the brake pedal is released, and the brake pedal information and accelerator pedal information are monitored in real time through the signal processing module with a time period of 2 seconds.

[0037] If the brake pedal is pressed during the time period, proceed to step S5.2;

[0038] If the accelerator pedal is pressed during the time period, proceed to step S5.3;

[0039] S5.2 The brake pedal information is monitored in real time through the signal processing module;

[0040] If the brake pedal is not pressed within the time period, the hill start assist system will maintain the target air pressure to prevent slippage.

[0041] If the brake pedal is pressed within the time period, the corresponding air pressure of the brake pedal opening is collected in real time through the signal processing module.

[0042] The decision target pressure of the ramp start assist system is determined based on the real-time collected opening pressure and the anti-slip target pressure in step S4.2.

[0043] The decision target air pressure is the maximum value between the opening air pressure collected within 2 seconds and the anti-slip target air pressure, and step S5.3 is executed with this decision target air pressure;

[0044] S5.3, Real-time monitoring of accelerator pedal information via signal processing module;

[0045] When the accelerator pedal is pressed, if the longitudinal driving force of the EBS system is less than or equal to the descent force, the hill start assist system maintains the target air pressure to prevent the vehicle from rolling backward until the longitudinal driving force of the EBS system is greater than the descent force.

[0046] If the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system will be turned off, and the target air pressure will be gradually released until it drops to 0, thereby achieving a smooth start for the vehicle.

[0047] Further, in step S5.3, the formula for calculating the longitudinal driving force of the EBS system is as follows:

[0048]

[0049] in: This is the current output torque of the engine. Main reducer speed ratio, For transmission efficiency, Let be the wheel rolling radius constant. This represents the current reduction ratio of the transmission.

[0050] Further, in step S5.3, the formula for calculating the sliding force is as follows:

[0051]

[0052] in: For downward force, This refers to the vehicle's weight.

[0053] Furthermore, step S5 also includes:

[0054] During the start-up process, the parking status information of the EBS system is collected in real time through the signal processing module;

[0055] If you park again, the hill start assist system will be deactivated, and the vehicle will stop moving.

[0056] Furthermore, step S5 also includes:

[0057] During the start-up process, the signal processing module determines whether the hill start assist button is triggered a second time.

[0058] If present, it is determined that the driver actively deactivated the hill start assist system, and the vehicle started normally.

[0059] Furthermore, in step S5.3, when the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system is turned off, and the target air pressure is gradually released until it drops to 0.

[0060] Among them, the target air pressure of the vehicle's non-driving wheels can drop directly to 0; the target air pressure of the vehicle's driving wheels can drop at a rate not exceeding 3 Bar / s until it drops to 0.

[0061] The beneficial effects of this invention are:

[0062] [1] The commercial vehicle hill start assist control method based on EBS system of the present invention has a simple operation process, is easy to implement, has low assembly cost, and saves vehicle hardware cost. It has active hill start assist function and passive anti-rollover function. It can respond to the brake pedal status of EBS system in real time and adjust the anti-rollover target air pressure of the system to ensure that the vehicle speed on the slope is always kept at 0. It effectively avoids the rollover hazards caused by the vehicle rolling over during the hill start of commercial vehicles. At the same time, it also effectively reduces the wear and damage of related components and extends the service life of the vehicle.

[0063] [2] By real-time compensation of the anti-roll-off target air pressure, the present invention can make an effective decision on the exit mechanism of the system in a precise, fast and reliable manner based on the longitudinal driving force of the EBS system, which can effectively avoid the simultaneous operation of the vehicle braking and driving systems, reduce vehicle functional losses, and ensure smooth vehicle start-up.

[0064] [3] The present invention uses the longitudinal accelerometer of the vehicle posture sensor of the EBS system to judge the actual environmental state of the vehicle, avoiding the function triggering caused by the driver's misoperation. Furthermore, it uses the parking status information, brake pedal information, vehicle speed information, and current slope information of the EBS system to make effective judgments under various working conditions, ensuring that the hill start assist system can effectively intervene or withdraw under various complex working conditions or operating conditions, thereby achieving passive anti-rollback and smooth start of the vehicle. Attached Figure Description

[0065] Figure 1 This is a flowchart of an embodiment of the commercial vehicle hill start assist control method based on the EBS system of the present invention;

[0066] Figure 2 This is a flowchart of step S5 in an embodiment of the present invention. Detailed Implementation

[0067] like Figure 1 As shown, a hill start assist control method for commercial vehicles based on the EBS system is presented. This method can realize active hill start assist function and passive anti-rollback function. The hill start assist system receives brake pedal information, parking status information, accelerator pedal information, vehicle speed information and longitudinal accelerator information from the EBS system vehicle posture sensor, etc., performs calculation and decision output, and releases brake air pressure at an appropriate time to realize hill start assist function.

[0068] Specifically, the following steps are included:

[0069] S1. A hill start assist system is built based on the EBS system. The hill start assist system includes a hill start assist button and a signal processing module connected to the EBS system.

[0070] When the vehicle is stopped on a slope and waiting to start, the driver presses the brake pedal, releases the parking brake, and the vehicle comes to a stop. The driver then triggers the hill start assist button for the first time.

[0071] S2. The signal processing module collects the vehicle's current speed information and calculates the current slope gradient.

[0072] The signal processing module calculates the current slope gradient based on the observations from the longitudinal accelerometer of the EBS system's vehicle attitude sensor and the current vehicle speed. The observations from the longitudinal accelerometer of the EBS system's vehicle attitude sensor are the coupling values ​​of the actual motion acceleration and the gravitational acceleration components. Therefore, by analyzing the forces acting on the vehicle on the slope, the current vehicle slope can be calculated, which satisfies the following formula:

[0073]

[0074] in, The current slope of the ramp. These are observations from the longitudinal accelerometer of the EBS vehicle attitude sensor. Let g be the differential of the vehicle speed, and g be the gravitational acceleration constant.

[0075] S3. Based on the current slope gradient in step S2, as well as the parking status information, brake pedal information, and vehicle speed information of the EBS system, confirm whether to activate the hill start assist system. If the hill start assist system is confirmed to be activated, proceed to step S4; otherwise, the vehicle starts normally.

[0076] S3.1 The signal processing module determines whether to activate the ramp start assist system based on the current ramp gradient in step S2;

[0077] If the current slope is less than 2%, the hill start assist system will not be activated.

[0078] If the current slope is ≥2%, the signal processing module collects parking status information;

[0079] S3.2 Determine whether the parking status has been released;

[0080] If the parking status is not released, the hill start assist system will not be activated;

[0081] If the parking state has been released, the signal processing module collects brake pedal information;

[0082] S3.3 Determine whether the brake pedal is depressed;

[0083] Hill Start Assist will not be activated if the brake pedal is not depressed.

[0084] If the brake pedal is depressed, the signal processing module collects vehicle speed information;

[0085] S3.4 Determine if the vehicle speed is 0;

[0086] If the vehicle speed is not 0, the hill start assist system will not be activated, and the vehicle will start normally.

[0087] If the vehicle speed is 0, the hill start assist system is activated, and step S4 is executed.

[0088] S4. Obtain the baseline target air pressure locked by the EBS system brake pedal at the moment the Hill Start Assist system is activated. The hill start assist system is based on the target air pressure. Adjust the air pressure of the anti-slip target ， This keeps the vehicle speed at 0, thus achieving passive anti-rollover protection.

[0089] S4.1. When confirming the hill start assist system is activated, obtain the baseline target air pressure locked by the EBS system brake pedal at the moment the hill start assist system is activated. ;

[0090] S4.2. The vehicle speed information is collected in real time through the signal processing module, and the air pressure of the anti-rollover target is adjusted in real time according to the vehicle speed information;

[0091] If the vehicle begins to roll backward without the driver engaging reverse gear, this is considered unintentional rolling backward, and the hill start assist system interprets the output anti-rollback target air pressure. ， Insufficient to keep the vehicle stationary on the current slope, therefore, the air pressure at the anti-rollover target is gradually increased. ， The passive anti-rollover function is achieved until the vehicle speed reaches 0.

[0092] If the vehicle speed is greater than 0, the hill start assist system will be used to adjust the anti-rollback target air pressure. ， This reduces the air pressure at the target of the escape route. ， Not less than the basic target air pressure This ensures that the vehicle speed remains at 0, thereby achieving passive anti-rollover protection.

[0093] If the vehicle speed is 0, the hill start assist system will maintain the target air pressure to prevent rollback. ， .

[0094] S5, such as Figure 2 As shown, the signal processing module monitors the brake pedal and accelerator pedal information in real time. When the longitudinal driving force of the EBS system is greater than the downward force, the hill start assist system is turned off, and the anti-roll target air pressure is gradually released until it drops to 0, thereby achieving a smooth start for the vehicle.

[0095] Throughout the entire hill start assist system process, the EBS system maintains a locked baseline target air pressure. During the subsequent time of the entire hill start assist system triggering process, its anti-rollback target air pressure is always at the maximum value of the air pressure corresponding to the brake pedal opening, to obtain the final decision target air pressure. This ensures that the decision target air pressure throughout the entire hill start assist system triggering process is not lower than the baseline target air pressure, and the decision target air pressure responds at any time to the air pressure value corresponding to the driver pressing the brake pedal deeper.

[0096] S5.1 During the activation of the hill start assist system, the timing starts each time the brake pedal is released, and the brake pedal information and accelerator pedal information are monitored in real time through the signal processing module with a time period of 2 seconds.

[0097] If the brake pedal is pressed during the time period, proceed to step S5.2;

[0098] If the accelerator pedal is pressed during the time period, proceed to step S5.3;

[0099] S5.2 The brake pedal information is monitored in real time through the signal processing module;

[0100] If the brake pedal is not pressed within the time period, the hill start assist system will maintain the target air pressure to prevent slippage.

[0101] If the brake pedal is pressed within the time period, the corresponding air pressure of the brake pedal opening is collected in real time through the signal processing module.

[0102] The decision target pressure of the ramp start assist system is determined based on the real-time collected opening pressure and the anti-slip target pressure in step S4.2.

[0103] The target air pressure for decision is the maximum value between the opening air pressure collected within 2 seconds and the anti-slip target air pressure, and step S5.3 is executed with this target air pressure;

[0104] S5.3, Real-time monitoring of accelerator pedal information via signal processing module;

[0105] When the accelerator pedal is pressed, if the longitudinal driving force of the EBS system is less than or equal to the descent force, the hill start assist system maintains the target air pressure to prevent the vehicle from rolling backward until the longitudinal driving force of the EBS system is greater than the descent force.

[0106] If the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system will be turned off, and the target air pressure will be gradually released until it drops to 0, thereby achieving a smooth start for the vehicle.

[0107] When the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system is turned off, and the target air pressure is gradually released until it drops to 0.

[0108] Among them, the target air pressure of the vehicle's non-drive wheels can drop directly to 0; the target air pressure of the vehicle's drive wheels drops at a rate not exceeding 3 Bar / s until it drops to 0, ensuring a smooth start for the vehicle.

[0109] The formula for calculating the longitudinal driving force of the EBS system is as follows:

[0110]

[0111] in: The current output torque of the engine can be calculated from the current torque percentage and the engine reference torque in CAN1; Main reducer speed ratio, For transmission efficiency, a value of 0.9 is taken. Let be the wheel rolling radius constant. This represents the current reduction ratio of the transmission.

[0112] The formula for calculating the sliding force is as follows:

[0113]

[0114] in: For downward force, This refers to the vehicle's weight.

[0115] During the start-up process, the parking status information of the EBS system is collected in real time through the signal processing module; if parking is resumed, the hill start assist system is turned off and the vehicle stops starting.

[0116] During the start-up process, the signal processing module determines whether the hill start assist button is triggered a second time; if so, it is determined that the driver has actively deactivated the hill start assist system, and the vehicle starts normally.

[0117] The vehicle display device is equipped with function indicator lights that are connected to the hill start assist system and the EBS system to show the activation status of the hill start assist system; the EBS system continuously sends function flag bits to the vehicle through CAN1, and the activation status of the hill start assist system is shown by the illumination status of the function indicator lights.

[0118] When the Hill Start Assist System is activated, the EBS system's function indicator is in position 1, and the function indicator light remains on.

[0119] When the hill start assist system is activated and the time cycle is about to end, the function indicator light of the EBS system at position 2 will flash several times and then turn off.

[0120] When the Hill Start Assist system is not activated, the EBS system's function indicator is at position 0, and the function indicator light is always off. This function allows the driver to intuitively understand the working status of the Hill Start Assist system.

Claims

1. A method for hill start assist control of commercial vehicles based on an EBS system, characterized in that, Includes the following steps: S1. A hill start assist system is built based on the EBS system. The hill start assist system includes a hill start assist button and a signal processing module connected to the EBS system. When the vehicle is stopped on a slope and waiting to start, the driver presses the brake pedal, releases the parking brake, and triggers the hill start assist button for the first time. S2. The signal processing module collects the vehicle's current speed information and calculates the current slope gradient. S3. Based on the current slope gradient in step S2, as well as the parking status information, brake pedal information, and vehicle speed information of the EBS system, confirm whether to activate the hill start assist system. If the hill start assist system is confirmed to be activated, proceed to step S4; otherwise, the vehicle starts normally. S4. Obtain the base target air pressure locked by the EBS system brake pedal when the hill start assist system is activated. The hill start assist system adjusts the anti-roll target air pressure according to the base target air pressure to keep the vehicle speed at 0, thereby achieving passive anti-roll of the vehicle. S4.1 Obtain the base target air pressure locked by the EBS system brake pedal when the hill start assist system is activated; S4.

2. The vehicle speed information is collected in real time through the signal processing module, and the air pressure of the anti-rollover target is adjusted in real time according to the vehicle speed information; If the vehicle speed is greater than 0, the hill start assist system will adjust the anti-roll target air pressure to ensure that the anti-roll target air pressure is not less than the base target air pressure, thereby ensuring that the vehicle speed is always kept at 0, thus achieving passive anti-roll of the vehicle. If the vehicle speed is 0, the hill start assist system will maintain the target air pressure to prevent rollback. S5. The signal processing module monitors the brake pedal and accelerator pedal information in real time. When the longitudinal driving force of the EBS system is greater than the downward force, the hill start assist system is turned off, and the anti-roll target air pressure is gradually released until it drops to 0, thereby achieving a smooth start for the vehicle. S5.1 During the activation of the hill start assist system, the timing starts each time the brake pedal is released, and the brake pedal information and accelerator pedal information are monitored in real time through the signal processing module with a time period of 2 seconds. If the brake pedal is pressed during the time period, proceed to step S5.2; If the accelerator pedal is pressed during the time period, proceed to step S5.3; S5.2 The brake pedal information is monitored in real time through the signal processing module; If the brake pedal is not pressed within the time period, the hill start assist system maintains the target air pressure to prevent slippage. If the brake pedal is pressed within the time period, the corresponding opening pressure of the brake pedal is collected in real time through the signal processing module. The decision target pressure of the hill start assist system is determined based on the real-time collected opening pressure and the anti-roll-off target pressure in step S4.

2. The decision target air pressure is the maximum value between the opening air pressure collected within 2 seconds and the anti-slip target air pressure, and step S5.3 is executed with this decision target air pressure; S5.3, Real-time monitoring of accelerator pedal information via signal processing module; When the accelerator pedal is pressed, if the longitudinal driving force of the EBS system is less than or equal to the descent force, the hill start assist system maintains the target air pressure to prevent the vehicle from rolling backward until the longitudinal driving force of the EBS system is greater than the descent force. If the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system will be turned off, and the target air pressure will be gradually released until it drops to 0, thereby achieving a smooth start for the vehicle.

2. The commercial vehicle hill start assist control method based on EBS system according to claim 1, characterized in that, Step S2 is as follows: The signal processing module calculates the current slope based on the observations from the longitudinal accelerometer of the EBS system's vehicle attitude sensor and the current vehicle speed, satisfying the following formula: ； in, The current slope of the ramp. These are observations from the longitudinal accelerometer of the EBS vehicle attitude sensor. Let g be the differential of the vehicle speed, and g be the gravitational acceleration constant.

3. The commercial vehicle hill start assist control method based on EBS system according to claim 2, characterized in that, Step S3 is as follows: S3.1 The signal processing module determines whether to activate the ramp start assist system based on the current ramp gradient in step S2; If the current slope is less than 2%, the hill start assist system will not be activated. If the current slope is ≥2%, the signal processing module collects parking status information; S3.2 Determine whether the parking status has been released; If the parking status is not released, the hill start assist system will not be activated; If the parking state has been released, the signal processing module collects brake pedal information; S3.3 Determine whether the brake pedal is depressed; Hill Start Assist will not be activated if the brake pedal is not depressed. If the brake pedal is depressed, the signal processing module collects vehicle speed information; S3.4 Determine if the vehicle speed is 0; If the vehicle speed is not 0, the hill start assist system will not be activated, and the vehicle will start normally. If the vehicle speed is 0, the hill start assist system is activated, and step S4 is executed.

4. The commercial vehicle hill start assist control method based on EBS system according to claim 1, characterized in that: In step S5.3, the formula for calculating the longitudinal driving force of the EBS system is as follows: ； in: This is the current output torque of the engine. Main reducer speed ratio, For transmission efficiency, Let be the wheel rolling radius constant. This represents the current reduction ratio of the transmission.

5. The commercial vehicle hill start assist control method based on EBS system according to claim 4, characterized in that: In step S5.3, the formula for calculating the sliding force is as follows: ； in: For downward force, This refers to the vehicle's weight.

6. The commercial vehicle hill start assist control method based on EBS system according to claim 5, characterized in that, Step 5 also includes: During the start-up process, the parking status information of the EBS system is collected in real time through the signal processing module; If you park again, the hill start assist system will be deactivated, and the vehicle will stop moving.

7. The commercial vehicle hill start assist control method based on EBS system according to claim 6, characterized in that, Step S5 also includes: During the start-up process, the signal processing module determines whether the hill start assist button is triggered a second time. If present, it is determined that the driver actively deactivated the hill start assist system, and the vehicle started normally.

8. The commercial vehicle hill start assist control method based on EBS system according to claim 7, characterized in that: In step S5.3, when the longitudinal driving force of the EBS system is greater than the descent force, the hill start assist system is turned off, and the target air pressure is gradually released until it drops to 0. Among them, the target air pressure of the vehicle's non-driving wheels can drop directly to 0; the target air pressure of the vehicle's driving wheels can drop at a rate not exceeding 3 Bar / s until it drops to 0.

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