Vehicle stability system, its control unit and method

Abstract

A stability system for a vehicle, its control unit and method are provided. The control unit (21) includes: an acquisition module (31) configured to acquire the distance between the front suspension and the vehicle's center of mass and the distance between the rear suspension and the vehicle's center of mass; a processing module (32) configured to calculate the optimized height of the front suspension based on the static vertical load and the maximum vertical load of the front suspension and the actual friction coefficient, and calculate the optimized height of the rear suspension based on the static vertical load and the maximum vertical load of the rear suspension and the actual friction coefficient; and a generation module (33) configured to generate a first height control signal according to the optimized height of the front suspension; and generate a second height control signal according to the optimized height of the rear suspension.

Description

Technical Field

[0001] The present invention relates to a stability system for a vehicle, its control unit and method. Background Art

[0002] The stability system of a vehicle can improve the handling performance of the vehicle and effectively prevent the vehicle from losing control when it reaches its dynamic limit. Therefore, the stability system of the vehicle can improve the safety and handling of the vehicle. The stability system of the vehicle can play an active safety improvement function in a variety of scenarios. For example, during automatic emergency braking (AEB), the stability system of the vehicle can improve safety and handling by controlling the suspension system.

[0003] The suspension system of a vehicle is used to transmit forces and torques between the wheels and the axles, and suppress vibrations during vehicle driving to ensure smooth driving of the vehicle. Unstable phenomena such as pitching motion will occur during vehicle braking, which has a negative impact on both the stability and braking effect of the vehicle. Although there are already solutions in the prior art to control the suspension system through the stability system of the vehicle to reduce vehicle vibrations, the existing solutions still cannot achieve an ideal shock absorption effect during vehicle braking. Summary of the Invention

[0004] In view of the above problems in the prior art, the present invention aims to provide a stability system for a vehicle, its control unit and method, which can reduce vibrations during automatic emergency braking of the vehicle and improve braking efficiency.

[0005] To this end, according to one aspect of the present invention, a control unit for a stability system of a vehicle is provided, including: an acquisition module configured to acquire the distance between the front suspension and the vehicle's center of mass and the distance between the rear suspension and the vehicle's center of mass; a processing module configured to calculate the static vertical load of the front suspension based on the distance between the front suspension and the vehicle's center of mass, and calculate the static vertical load of the rear suspension based on the distance between the rear suspension and the vehicle's center of mass; determine the maximum vertical load of the front suspension and the maximum vertical load of the rear suspension based on the actual friction coefficient of the road surface; and calculate the optimized height of the front suspension based on the static vertical load and the maximum vertical load of the front suspension and the actual friction coefficient, and calculate the optimized height of the rear suspension based on the static vertical load and the maximum vertical load of the rear suspension and the actual friction coefficient; and a generation module configured to generate a first height control signal according to the optimized height of the front suspension for adjusting the height of the front suspension during automatic emergency braking of the vehicle; and generate a second height control signal according to the optimized height of the rear suspension for adjusting the height of the rear suspension during automatic emergency braking of the vehicle.

[0006] According to a feasible implementation manner, the obtaining module further obtains the actual gas quantity in the first air spring connected to the front suspension of the vehicle and the actual gas quantity in the second air spring connected to the rear suspension; the processing module is further configured to calculate the gas quantity required for the first air spring to reach its optimized height based on the optimized height of the front suspension, and calculate the gas quantity required for the second air spring to reach its optimized height based on the optimized height of the rear suspension; the generating module generates a first gas quantity control signal based on the actual gas quantity in the first air spring and the required gas quantity, for adjusting the gas quantity in the first air spring during the automatic emergency braking of the vehicle; and generates a second gas quantity control signal based on the actual gas quantity in the second air spring and the required gas quantity, for adjusting the gas quantity in the second air spring during the automatic emergency braking of the vehicle.

[0007] According to a feasible implementation manner, the actual friction coefficient is obtained in the following way: the obtaining module further obtains the road surface friction coefficient defaulted by the stability system and the actual acceleration of the vehicle in the running direction, and the processing module calculates the predicted acceleration of the vehicle in the moving direction based on the defaulted road surface friction coefficient; and calculates the actual friction coefficient based on the predicted acceleration and the actual acceleration.

[0008] According to a feasible implementation manner, the processing module calculates the predicted acceleration based on the following formula:

[0009] a(request) = c(default) * g

[0010] where a(request) is the predicted acceleration, c(default) is the default road surface friction coefficient, and g is the gravitational acceleration.

[0011] The processing module calculates the actual friction coefficient based on the following formula:

[0012] c(actual) = c(default) * a(actual) / a(request)

[0013] where a(actual) is the actual acceleration of the vehicle in the moving direction, and c(actual) is the actual friction coefficient of the road surface.

[0014] According to a feasible implementation manner, the obtaining module further obtains vehicle parameters, where the vehicle parameters include vehicle mass, the actual acceleration of the vehicle in the moving direction, and the distance between the front suspension and the rear suspension; the processing module is configured to calculate the optimized height of the front suspension in the following manner: calculate the difference between the maximum vertical load and the static vertical load of the front suspension to obtain the vertical load transfer amount of the front suspension; and calculate the optimized height of the front suspension according to the vertical load transfer amount of the front suspension, the actual friction coefficient, and the vehicle parameters; and the processing module is configured to calculate the optimized height of the rear suspension in the following manner: calculate the difference between the maximum vertical load and the static vertical load of the rear suspension to obtain the vertical load transfer amount of the rear suspension; and calculate the optimized height of the rear suspension according to the vertical load transfer amount of the rear suspension, the actual friction coefficient, and the vehicle parameters.

[0015] According to a feasible implementation manner, the processing module calculates the optimized height of the front suspension through the following formula:

[0016] h(front,optimal)=[F(front,max)-F(front,static)]*L(total) / [m*c(actual)*a(brake)]

[0017] The processing module calculates the optimized height of the rear suspension through the following formula:

[0018] h(rear,optimal)=[F(rear,max)-F(rear,static)]*L(total) / [m*c(actual)*a(brake)]

[0019] Where, F(front,max) is the maximum vertical load of the front suspension, F(front,static) is the static vertical load of the front suspension, F(rear,max) is the maximum vertical load of the rear suspension, F(rear,static) is the static vertical load of the rear suspension, a(brake) is the actual acceleration of the vehicle in the moving direction, c(actual) is the actual friction coefficient, m is the vehicle mass, and L(total) is the distance between the front and rear suspensions.

[0020] According to a feasible implementation manner, the processing module calculates the static vertical load of the front suspension through the following formula:

[0021] F(front,static)=m*g*L(front) / L(total)

[0022] The processing module calculates the static vertical load of the rear suspension through the following formula:

[0023] F(rear, static) = m * g * L(rear) / L(total)

[0024] Wherein, m is the vehicle mass, g is the acceleration due to gravity, L(front) is the distance between the front suspension and the vehicle's center of mass, L(rear) is the distance between the rear suspension and the vehicle's center of mass, and L(total) is the distance between the front and rear suspensions.

[0025] According to a feasible implementation manner, the obtaining unit further obtains the tire pressure of the front wheels connected to the front suspension, the tire pressure of the rear wheels connected to the rear suspension, and environmental parameters, and the environmental parameters at least include environmental temperature and road surface humidity; the processing module determines the maximum vertical load of the front suspension based on the tire pressure of the front wheels, the environmental parameters, and the actual friction coefficient; and the processing module determines the maximum vertical load of the rear suspension based on the tire pressure of the rear wheels, the environmental parameters, and the actual friction coefficient.

[0026] According to a feasible implementation manner, the processing module is further configured to: calculate a first target braking force for the front wheels connected to the front suspension based on the optimized height and static vertical load of the front suspension and the actual friction coefficient; and calculate a second target braking force for the rear wheels connected to the rear suspension based on the optimized height and static vertical load of the rear suspension and the actual friction coefficient.

[0027] According to a feasible implementation manner, the processing module calculates the first target braking force according to the following formula:

[0028] Fbf = F(front, static) + c(actual) * m * a(brake) * h(front, optimal) / L(total)

[0029] The processing module calculates the second target braking force according to the following formula:

[0030] Fbr = F(rear, static) - c(actual) * m * a(brake) * h(rear, optimal) / L(total)

[0031] Wherein, Fbf is the first target braking force, F(front, static) is the static vertical load of the front suspension, Fbr is the second target braking force, F(rear, static) is the static vertical load of the rear suspension, a(brake) is the actual acceleration of the vehicle in the moving direction, c(actual) is the actual friction coefficient, m is the vehicle mass, and L(total) is the distance between the front and rear suspensions.

[0032] According to another aspect of the present invention, there is provided a stability system for a vehicle, comprising: a sensor unit for detecting a relative distance between the vehicle itself and a potential collision object; a controller coupled to the sensor unit, the controller including the control unit as described above, the controller being configured to enable the control unit as described above when it is determined that the vehicle enters automatic emergency braking based on the relative distance; and a suspension system coupled to the controller, the suspension system including a front suspension and a first air spring connected thereto, a rear suspension and a second air spring connected thereto, and a suspension controller, wherein the suspension controller is configured to control the amount of gas in the first air spring under the control of a first height control signal so that the height of the front suspension is adjusted to be consistent with its optimized height, and control the amount of gas in the second air spring under the control of a second height control signal so that the height of the rear suspension is adjusted to be consistent with its optimized height.

[0033] According to a feasible embodiment, the suspension controller is further configured to: detect a height change amount of the front suspension and a height change amount of the rear suspension; generate a stop instruction when it is detected that the height change amounts of the front suspension and the rear suspension are equal; and send the stop instruction to the controller to stop the operation of the control unit.

[0034] According to a feasible embodiment, the controller is further configured to send the first target braking force and the second target braking force to a hydraulic actuator of the vehicle, so that the actuator performs braking control of the front wheels connected to the front suspension based on the first target braking force and performs braking control of the rear wheels connected to the rear suspension based on the second target braking force.

[0035] According to yet another aspect of the present invention, there is also provided a control method for a stability system of a vehicle, optionally implemented by means of the control unit as described above and / or the stability system as described above. The method includes: obtaining a distance between the front suspension and the vehicle's center of mass and a distance between the rear suspension and the vehicle's center of mass; calculating a static vertical load of the front suspension based on the distance between the front suspension and the vehicle's center of mass, and calculating a static vertical load of the rear suspension based on the distance between the rear suspension and the vehicle's center of mass; determining a maximum vertical load of the front suspension and a maximum vertical load of the rear suspension based on the actual friction coefficient of the road surface; calculating an optimized height of the front suspension based on the static vertical load and the maximum vertical load of the front suspension and the actual friction coefficient, and calculating an optimized height of the rear suspension based on the static vertical load and the maximum vertical load of the rear suspension and the actual friction coefficient; and generating a first height control signal according to the optimized height of the front suspension for adjusting the height of the front suspension during the automatic emergency braking of the vehicle; and generating a second height control signal according to the optimized height of the rear suspension for adjusting the height of the rear suspension during the automatic emergency braking of the vehicle.

[0036] It can be seen that, according to the technical solution of the present invention, by providing the optimized height of the front suspension and the optimized height of the rear suspension during the automatic emergency process, the smoothness of the vehicle body during the automatic emergency braking process is maintained, thereby improving the stability and safety of the vehicle. Moreover, according to the technical solution of the present invention, a target braking force can also be provided, thereby improving the braking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 FIG. shows a schematic block diagram of a stability system for a vehicle according to a feasible embodiment of the present invention.

[0038] Figure 2 FIG. shows Figure 1 a schematic block diagram of the control unit of the stability system in

[0039] Figure 3 FIG. shows Figure 1 a schematic structural diagram of the suspension system of the stability system in

[0040] Figure 4 FIG. shows a partial schematic structural diagram of the suspension system according to a feasible embodiment of the present invention Figure 3 in

[0041] Figure 5 FIG. shows a schematic diagram of the pitching motion of the vehicle during the automatic emergency braking process.

[0042] Figure 6 FIG. shows a flowchart of a control method for a stability system for a vehicle according to a feasible embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The technical solution of the present invention calculates the optimized heights of the front suspension and the rear suspension respectively during the automatic emergency braking process of the vehicle, and adjusts the heights of the front suspension and the rear suspension simultaneously according to the calculated optimized heights until the height change amounts of the two are the same, thereby realizing the mitigation or suppression of the pitching motion of the vehicle during the automatic emergency braking process. Moreover, the technical solution of the present invention also provides a target braking force for the vehicle during the automatic emergency braking process, thereby improving the braking efficiency.

[0044] The following describes the embodiments of the present invention with reference to the accompanying drawings.

[0045] Figure 1 FIG. shows a stability system 100 for a vehicle according to a feasible embodiment of the present invention, which mainly includes a sensor unit 10, a controller 20, a hydraulic actuator 40, and a suspension system 50.

[0046] The sensor unit 10 may include a variety of sensors for detecting different parameters. For example, the sensor unit 10 may include a radar sensor and a displacement sensor mounted on the vehicle. The radar sensor is used to detect the relative distance between the vehicle and a potential collision object, such as the relative distance between the host vehicle and the vehicle in front or an obstacle. The sensor unit 10 may also include other types of sensors for assisting in sensing information around the vehicle, such as GPS, a photographing device, etc. The displacement sensor is used to detect the displacement of the vehicle in the vertical direction. For example, there may be multiple displacement sensors, which respectively detect the displacements of the front suspension and the rear suspension of the suspension system 50 in the vertical direction.

[0047] The sensor unit 10 may also include an acceleration sensor for sensing the acceleration of the vehicle in the moving direction (e.g., braking deceleration). The sensor unit 10 may include an environment sensor for sensing the environment around the vehicle. For example, the environment sensor may include a temperature sensor for sensing the ambient temperature around the vehicle and a humidity sensor for sensing the humidity of the road surface on which the vehicle travels. The sensor unit 10 may also include a pressure sensor for sensing the tire pressure of the wheels.

[0048] The suspension system 50 may be a component (e.g., a subsystem) of the stability system 100 for mitigating the impact transmitted from an uneven road surface to the vehicle. Refer to Figure 3 , the suspension system 50 may be implemented as an air suspension system, which mainly includes a front suspension 56, a rear suspension 57, air springs 52 - 55, and a suspension controller 58. Both the front suspension 56 and the rear suspension 57 are connected to the vehicle body 1. The front suspension 56 is connected to the wheels 2 and 3. The rear suspension 57 is connected to the wheels 4 and 5. The air springs 52 - 55 are respectively assigned to one of the wheels 2 - 5. The air spring 52 is connected to the front suspension 56 and the wheel 2. The air spring 53 is connected to the front suspension 56 and the wheel 3. That is to say, the air springs 52 and 53 are connected to the front suspension and the front wheels. For the sake of convenient description, the air springs 52 and 53 are referred to as the first air springs. The air spring 54 is connected to the rear suspension 57 and the wheel 4. The air spring 55 is connected to the rear suspension 57 and the wheel 5. That is to say, the air springs 54 and 55 are connected to the rear suspension and the rear wheels. For the sake of convenient description, the air springs 54 and 55 are referred to as the second air springs.

[0049] It should be understood that the suspension controller 58 may be separately provided in the vehicle, may be integrated with the controller 20 of the stability system 100, or may be centralized in the controller of other systems of the vehicle.

[0050] Hereinafter, refer to Figure 4 , taking an air spring 55 of the suspension system 50 as an example, to describe the working principle of the suspension system of the present invention.

[0051] Figure 4 Schematically shows an air spring 55 of a suspension system 50 and its associated components according to a feasible embodiment of the present invention. As Figure 4 shown, the air spring 55 is coupled to a damper 61, and the damper 61 is coupled to the hub 5' of the wheel 5. The piston position of the damper 61 is adjusted by adjusting the amount of gas in the air spring 55, thereby adjusting the height of the centroid of the wheel 5 (e.g., the hub 5') from the ground. The air spring 55 is fluidly connected to an air storage chamber 67, and a compressor 63 is connected to the pipeline between the air spring 55 and the air storage chamber 67. The compressor 63 is connected to an electric motor 65 to be driven by the electric motor 65 to adjust the amount of gas in the air spring 55.

[0052] The suspension controller 58 acts as a secondary controller in the stability system 100, and under the control of the control signal from the controller 20 of the stability system 100, controls the adjustment of the amount of gas in the air spring. For example, by adjusting the amount of gas in the air spring, the height of the suspension is adjusted, so that the shock applied to the suspension by the wheel can be dampened and the vehicle body can be kept stable.

[0053] It should be understood that Figure 3 and Figure 4 only schematically shows the structure of the suspension system and its air spring, and the suspension system and its air spring according to the present invention can also be implemented as other combinations of elements or other arrangements.

[0054] The controller 20 is coupled to the sensor unit 10 to receive the relative distance between the vehicle and a potential collision object from the sensor unit 10. The controller 20 includes a control unit 30 that can be enabled in the automatic emergency braking of the vehicle. When the controller 20 determines that the vehicle needs to enter automatic emergency braking according to the relative distance, the controller 20 enables the control unit 30 to execute a control strategy for reducing the vehicle vibration and improving the braking efficiency during automatic emergency braking.

[0055] After the vehicle enters automatic emergency braking, the control unit 30 can calculate the optimized height of the front suspension and the optimized height of the rear suspension for adjusting the heights of the front suspension and the rear suspension respectively. The control unit 30 can further calculate the required amount of gas in the first air spring for the optimized height of the front suspension and the required amount of gas in the second air spring for the optimized height of the rear suspension to achieve the optimized height of the suspension based on the required amount of gas.

[0056] The control unit 30 can calculate a first target braking force for the front wheels and a second target braking force for the rear wheels for the hydraulic actuator 40 to perform braking control.

[0057] The control unit 30 can also determine a first braking torque request based on the measured relative distance, the vehicle speed and acceleration in the moving direction, and in combination with the first target braking force, so that the hydraulic actuator 40 performs a braking operation on the front wheels connected to the front suspension based on the first braking torque request. The control unit 30 determines a second braking torque request according to the measured relative distance, the vehicle speed and acceleration in the moving direction, and in combination with the second target braking force, so that the hydraulic actuator 40 performs a braking operation on the rear wheels connected to the rear suspension based on the second braking torque request.

[0058] See Figure 5 , when the vehicle enters automatic emergency braking, the wheels are displaced in the vertical direction, thereby causing the vehicle to produce a pitching motion similar to "nodding". The control unit 30 can provide a control strategy for suppressing the pitching motion. See Figure 2 , the control unit 30 mainly includes an acquisition module 31, a processing module 32, and a generation module 33. The following specifically introduces each module of the control unit 30 and its working principle.

[0059] The acquisition module 31 acquires various parameters for subsequent calculations. The parameters include the front suspension displacement and the rear suspension displacement, the vehicle mass, the distance between the front suspension and the vehicle center of mass, the distance between the rear suspension and the vehicle center of mass, the distance between the front and rear suspensions, the system default road surface friction coefficient, the vehicle speed and acceleration in the moving direction.

[0060] In the present invention, the front suspension displacement refers to the displacement of the front suspension in the vertical direction, that is, the height change amount of the front suspension, which can be measured by a displacement sensor close to or coupled to the front suspension. The rear suspension displacement refers to the displacement of the rear suspension in the vertical direction, that is, the change amount in the height direction of the rear suspension, which can be measured by a displacement sensor close to or coupled to the rear suspension. The vehicle mass can be understood as the mass of the vehicle body.

[0061] The processing module 32 calculates the vertical load transfer amount ΔF f of the front suspension and the vertical load transfer amount ΔF r of the rear suspension by using the parameters acquired by the acquisition module 31. The vertical load transfer amount ΔF f of the front suspension is obtained by the difference between the maximum vertical load F(front,max) of the front suspension and the static vertical load F(front,static), where the static vertical load F(front,static) of the front suspension is obtained by the following formula ①. The vertical load transfer amount ΔF r of the rear suspension is obtained by the difference between the maximum vertical load F(rear,max) of the rear suspension and the static vertical load F(rear,static), where the static vertical load F(rear,static) of the rear suspension is obtained by the following formula ②.

[0062] F(front, static) = m * g * L(front) / L(total) ①

[0063] F(rear, static) = m * g * L(rear) / L(total) ②

[0064] Among them, m is the vehicle mass, g is the acceleration due to gravity, L(front) is the distance between the front suspension and the vehicle's center of mass, L(rear) is the distance between the rear suspension and the vehicle's center of mass, and L(total) is the distance between the front and rear suspensions.

[0065] The maximum vertical load F(front, max) of the front suspension can be obtained by looking up a table based on the actual friction coefficient of the road surface on which the vehicle travels, the tire pressure of the front wheels, the ambient temperature, and the road surface humidity. The maximum vertical load F(rear, max) of the rear suspension can be obtained by looking up a table based on the actual friction coefficient of the road surface on which the vehicle travels, the tire pressure of the rear wheels, the ambient temperature, and the road surface humidity. It should be understood that the table for finding the actual friction coefficient can be obtained with the help of a tire model provided by the tire supplier. Hereinafter, the process by which the processing module 32 calculates the actual friction coefficient will be described.

[0066] The processing module 32 determines the requested value (predicted value) of the vehicle's acceleration in the moving direction based on the system default road surface friction coefficient, that is, predicts the acceleration that the vehicle can currently obtain according to the vehicle's overall motion model and the parameters set by the system default. For example, the processing module 32 calculates the requested value of the acceleration according to the following formula ③. Then, the processing module 32 determines the actual friction coefficient of the current road surface based on the predicted value and the measured value of the acceleration. For example, the processing module 32 calculates the actual friction coefficient according to the following formula ④.

[0067] a(request) = c(default) * g ③

[0068] c(actual) = c(default) * a(actual) / a(request) ④

[0069] Among them, a(request) is the requested value of the vehicle's acceleration in the moving direction, a(actual) is the measured value of the vehicle's acceleration in the moving direction, g is the acceleration due to gravity, c(default) is the default value of the road surface friction coefficient, and c(actual) is the actual value of the road surface friction coefficient.

[0070] After the processing module 32 calculates the vertical load transfer amount ΔF of the front suspension f and the vertical load transfer amount ΔF of the rear suspension r then, according to the vertical load transfer amount ΔF of the front suspension fBased on the actual friction coefficient between the road surface, the optimized height h(front, optimal) of the front suspension is calculated, and based on the vertical load transfer ΔF of the rear suspension r and the actual friction coefficient between the road surface, the optimized height h(rear, optimal) of the rear suspension is calculated. For example, the processing module calculates the optimized height h(front, optimal) of the front suspension according to Formula ⑤ below, and calculates the optimized height h(rear, optimal) of the rear suspension according to Formula ⑥ below.

[0071] h(front,optimal)=ΔF f *L(total) / [m*c(actual)*a(brake)]=[F(front,max)-F(front,static)]*L(total) / [m*c(actual)*a(brake)] ⑤

[0072] h(rear,optimal)=ΔF r *L(total) / [m*c(actual)*a(brake)]=[F(rear,max)-F(rear,static)]*L(total) / [m*c(actual)*a(brake)] ⑥

[0073] Wherein, a(brake) is the braking deceleration, that is, the actual acceleration of the vehicle in the moving direction, c(actual) is the actual value of the road surface friction coefficient, m is the vehicle mass, and L(total) is the distance between the front and rear suspensions.

[0074] After the processing module 32 calculates the optimized height of the front suspension and the optimized height of the rear suspension, the generation module 33 generates a first height control signal based on the optimized height of the front suspension and generates a second height control signal based on the optimized height of the rear suspension.

[0075] Then, the suspension controller 58 controls the adjustment of the front and rear suspension heights in response to the first height control signal and the second height control signal. For example, the suspension controller 58 controls the adjustment of the gas volume in the first air springs 52 and 53 according to the first height control signal to adjust the height of the front suspension 56 to its optimized height and monitors the height change amount of the front suspension 56. The suspension controller 58 controls the adjustment of the gas volume in the second air springs 54 and 55 according to the second height control signal to adjust the height of the rear suspension 57 to its optimized height and monitors the height change amount of the rear suspension 57.

[0076] The control unit 30 continuously calculates the optimized heights of the front and rear suspensions based on the parameters sensed in real time by the sensor unit 10. The suspension system 50 dynamically adjusts the heights of the front and rear suspensions in response to the first height control signal and the second height control signal until the change in height of the front suspension is the same as the change in height of the rear suspension. For example, when the suspension controller 58 monitors that the change in height of the front suspension is the same as the change in height of the rear suspension, a stop command is generated, and the control unit 30 stops calculating the optimized heights of the front and rear suspensions in response to this stop command.

[0077] It should be understood that when the change in height of the front and rear suspensions is the same, it can be understood that the change in the vehicle's center of gravity caused by the forces and height changes of the front and rear suspensions is the same.

[0078] In one embodiment, the processing module 32 can also calculate the amount of gas required for the first air spring to make the front suspension reach its optimized height and the amount of gas required for the second air spring to make the rear suspension reach its optimized height after calculating the optimized heights of the front and rear suspensions. Moreover, the generating unit 33 determines the amount of gas that the first air spring needs to be adjusted (inflow or outflow) based on the actual gas amount and the required gas amount in the first air spring to generate a first gas amount control signal. The generating unit 33 determines the amount of gas that the second air spring needs to be adjusted (inflow or outflow) based on the actual gas amount and the required gas amount in the second air spring to generate a second gas amount control signal.

[0079] The suspension controller 58 controls the adjustment of the gas amount in the first air spring in response to the first gas amount control signal and controls the adjustment of the gas amount in the second air spring in response to the second gas amount control signal. When the gas amount in the first air spring reaches its required gas amount, the front suspension is adjusted to its optimized height. When the gas amount in the second air spring reaches its required gas amount, the rear suspension is adjusted to its optimized height.

[0080] According to this embodiment, the front and rear suspensions can be quickly adjusted to the corresponding optimized heights because this embodiment can directly adjust the suspension height to the target height through the calculated gas adjustment amount, omitting the process of detecting whether the optimized height is reached while adjusting.

[0081] Next, the processing module 32 calculates a first target braking force Fbf for the front wheel connected to the front suspension based on the optimized height of the front suspension, the static vertical load, and the actual friction coefficient. For example, the processing module 32 calculates the first target braking force Fbf according to the following formula ⑦. The processing module 32 calculates a second target braking force Fbr for the rear wheel connected to the rear suspension based on the optimized height of the rear suspension, the static vertical load, and the actual friction coefficient. For example, the processing module 32 calculates the second target braking force Fbr according to the following formula ⑧.

[0082] Fbf = F(front, static) + c(actual) * m * a(brake) * h(front, optimal) / L(total) ⑦

[0083] Fbr = F(rear, static) - c(actual) * m * a(brake) * h(rear, optimal) / L(total) ⑧

[0084] Among them, h(front, optimal) is the final value of the optimized height of the front suspension, that is, the value when the height change of the front and rear suspensions is the same; h(rear, optimal) is the final value of the optimized height of the rear suspension, that is, the value when the height change of the front and rear suspensions is the same.

[0085] It can be seen that the present invention can provide optimized heights for the front suspension and the rear suspension respectively, and calculate the target braking forces for the front and rear wheels of the vehicle based on the optimized heights of the front and rear suspensions and the actual road surface friction coefficient. In view of the fact that the pitching motion that occurs during the braking process of the vehicle will have a negative impact on the vehicle stability, according to the technical solution of the present invention, the strategy of optimizing the front and rear suspensions respectively is extremely beneficial. Therefore, according to the technical solution of the present invention, the stability of the vehicle during the automatic emergency braking process can be improved, and the application and distribution of the braking force are made more reasonable, thereby improving the braking efficiency.

[0086] The present invention also provides a method 600 for controlling the vehicle body stability during automatic emergency braking. Figure 6 The flowchart of the method 600 according to a feasible implementation manner of the present invention is shown. Optionally, the method 600 can be implemented by the above control unit 30, and the method 600 can also be implemented by the above stability system 100. Therefore, the above related descriptions also apply here.

[0087] See Figure 6 , in step S602, the acquisition module 31 acquires the parameters for subsequent calculation.

[0088] In step S604, the processing module 32 calculates the static vertical loads of the front suspension and the rear suspension.

[0089] In step S606, the processing module 32 calculates the actual friction coefficient of the road surface.

[0090] In step S608, the processing module 32 determines the maximum vertical loads of the front and rear suspensions.

[0091] In step S610, the processing module 32 calculates the vertical load transfer amounts of the front and rear suspensions.

[0092] In step S612, the processing module 32 calculates the optimized heights of the front and rear suspensions.

[0093] In step S614, the generating module 33 generates a first height control signal and a second height control signal.

[0094] In step S616, the processing module 32 calculates the required gas amounts in the first air spring and the second air spring.

[0095] In step S618, the generating module 33 generates a first gas amount adjustment signal and a second gas amount adjustment signal.

[0096] In step S620, the processing module 32 determines a first braking torque request and a second braking torque request.

[0097] It should be understood that the steps in the above method 600 can be executed in other orders or in parallel, as long as the corresponding functions of each module can be achieved.

[0098] Although some embodiments have been described above, these embodiments are given by way of example only and are not intended to limit the scope of the present invention. The appended claims and their equivalents are intended to cover all modifications, substitutions, and changes made within the scope and spirit of the present invention.

Claims

1. A control unit (30) for a stability system (100) of a vehicle, comprising: An acquisition module (31) configured to acquire the distance between the front suspension and the vehicle's center of mass and the distance between the rear suspension and the vehicle's center of mass; A processing module (32) configured to calculate the static vertical load of the front suspension based on the distance between the front suspension and the vehicle's center of mass, and calculate the static vertical load of the rear suspension based on the distance between the rear suspension and the vehicle's center of mass; Determine the maximum vertical load of the front suspension and the maximum vertical load of the rear suspension based on the actual friction coefficient of the road surface; and calculate the optimized height of the front suspension based on the static vertical load and the maximum vertical load of the front suspension and the actual friction coefficient, and calculate the optimized height of the rear suspension based on the static vertical load and the maximum vertical load of the rear suspension and the actual friction coefficient; And A generation module (33) configured to generate a first height control signal according to the optimized height of the front suspension for adjusting the height of the front suspension during the automatic emergency braking of the vehicle; and generate a second height control signal according to the optimized height of the rear suspension for adjusting the height of the rear suspension during the automatic emergency braking of the vehicle, wherein, the processing module is further configured to: Calculate a first target braking force for the front wheel connected to the front suspension based on the optimized height, static vertical load and actual friction coefficient of the front suspension; and calculate a second target braking force for the rear wheel connected to the rear suspension based on the optimized height, static vertical load and actual friction coefficient of the rear suspension, wherein, the processing module calculates the first target braking force according to the following formula: Fbf = F(front,static) + c(actual) * m * a(brake) * h(front,optimal) / L(total); The processing module calculates the second target braking force according to the following formula: Fbr = F(rear,static) - c(actual) * m * a(brake) * h(rear,optimal) / L(total); where, Fbf is the first target braking force, F(front,static) is the static vertical load of the front suspension, Fbr is the second target braking force, F(rear,static) is the static vertical load of the rear suspension, a(brake) is the actual acceleration of the vehicle in the moving direction, c(actual) is the actual friction coefficient, m is the vehicle mass, L(total) is the distance between the front and rear suspensions, h(front,optimal) is the optimized height of the front suspension, h(rear,optimal) is the optimized height of the rear suspension.

2. The control unit (30) according to claim 1, wherein, The acquisition module further acquires the actual gas volume in the first air spring connected to the front suspension of the vehicle and the actual gas volume in the second air spring connected to the rear suspension; The processing module is further configured to calculate the gas volume required for the first air spring to make the front suspension reach its optimized height based on the optimized height of the front suspension, and calculate the gas volume required for the second air spring to make the rear suspension reach its optimized height based on the optimized height of the rear suspension; The generating module generates a first gas quantity control signal based on the actual gas quantity and the required gas quantity in the first air spring, for adjusting the gas quantity in the first air spring during the automatic emergency braking of the vehicle; and generates a second gas quantity control signal based on the actual gas quantity and the required gas quantity in the second air spring, for adjusting the gas quantity in the second air spring during the automatic emergency braking of the vehicle.

3. The control unit (30) according to claim 1 or 2, wherein, The actual friction coefficient is obtained in the following manner: The obtaining module further obtains the road surface friction coefficient defaulted by the stability system and the actual acceleration of the vehicle in the running direction, and The processing module calculates the predicted acceleration of the vehicle in the moving direction based on the default road surface friction coefficient; and calculates the actual friction coefficient based on the predicted acceleration and the actual acceleration.

4. The control unit (30) according to claim 3, wherein, The processing module calculates the predicted acceleration based on the following formula: a(request) = c(default) * g Wherein, a(request) is the predicted acceleration, c(default) is the default road surface friction coefficient, and g is the gravitational acceleration. The processing module calculates the actual friction coefficient based on the following formula: c(actual) = c(default) * a(actual) / a(request) Wherein, a(actual) is the actual acceleration of the vehicle in the moving direction, and c(actual) is the actual road surface friction coefficient.

5. The control unit (30) according to claim 1 or 2, wherein, The obtaining module further obtains vehicle parameters, and the vehicle parameters include vehicle mass, the actual acceleration of the vehicle in the moving direction, and the distance between the front suspension and the rear suspension. The processing module is configured to calculate the optimized height of the front suspension in the following manner: calculating the difference between the maximum vertical load and the static vertical load of the front suspension to obtain the vertical load transfer amount of the front suspension; and calculating the optimized height of the front suspension according to the vertical load transfer amount of the front suspension, the actual friction coefficient, and the vehicle parameters; and The processing module is configured to calculate the optimized height of the rear suspension in the following manner: calculating the difference between the maximum vertical load and the static vertical load of the rear suspension to obtain the vertical load transfer amount of the rear suspension; and calculating the optimized height of the rear suspension according to the vertical load transfer amount of the rear suspension, the actual friction coefficient, and the vehicle parameters.

6. The control unit (30) according to claim 5, wherein, The processing module calculates the optimized height of the front suspension through the following formula: h(front,optimal) = [F(front,max) - F(front,static)] * L(total) / [m * c(actual) * a(brake)] The processing module calculates the optimized height of the rear suspension through the following formula: h(rear,optimal) = [F(rear,max) - F(rear,static)] * L(total) / [m * c(actual) * a(brake)] Among them, F(front,max) is the maximum vertical load of the front suspension, F(front,static) is the static vertical load of the front suspension, F(rear,max) is the maximum vertical load of the rear suspension, F(rear,static) is the static vertical load of the rear suspension, a(brake) is the actual acceleration of the vehicle in the moving direction, c(actual) is the actual friction coefficient, m is the vehicle mass, and L(total) is the distance between the front and rear suspensions.

7. The control unit (30) according to claim 5, wherein,The processing module calculates the static vertical load of the front suspension through the following formula: F(front,static) = m * g * L(front) / L(total) The processing module calculates the static vertical load of the rear suspension through the following formula: F(rear,static) = m * g * L(rear) / L(total) Among them, m is the vehicle mass, g is the acceleration due to gravity, L(front) is the distance between the front suspension and the vehicle's center of mass, L(rear) is the distance between the rear suspension and the vehicle's center of mass, and L(total) is the distance between the front and rear suspensions.

8. The control unit (30) according to claim 1, wherein, The acquisition unit also acquires the tire pressure of the front wheels connected to the front suspension, the tire pressure of the rear wheels connected to the rear suspension, and environmental parameters, and the environmental parameters at least include environmental temperature and road surface humidity; The processing module determines the maximum vertical load of the front suspension based on the tire pressure of the front wheels, environmental parameters, and the actual friction coefficient; and The processing module determines the maximum vertical load of the rear suspension based on the tire pressure of the rear wheels, environmental parameters, and the actual friction coefficient.

9. A stability system (100) for a vehicle, comprising: The sensor unit (10) is used to detect the relative distance between the vehicle and a potential collision object; The controller (20) is coupled to the sensor unit, and the controller includes the control unit (30) described in any one of claims 1-8, and the controller is configured to enable the control unit (30) described in any one of claims 1-8 when it is determined based on the relative distance that the vehicle enters automatic emergency braking; and The suspension system (50) is coupled to the controller, and the suspension system includes a front suspension (56) and a first air spring connected thereto, a rear suspension (57) and a second air spring connected thereto, and a suspension controller (58), Among them, the suspension controller is configured to control the gas volume in the first air spring under the control of a first height control signal so that the height of the front suspension is adjusted to be consistent with its optimized height, and control the gas volume in the second air spring under the control of a second height control signal so that the height of the rear suspension is adjusted to be consistent with its optimized height.

10. The stability system (100) according to claim 9, wherein, The suspension controller is further configured to: Detect the height change amount of the front suspension and the height change amount of the rear suspension; Generate a stop command when it is detected that the height change amounts of the front suspension and the rear suspension are equal; and Send the stop command to the controller to stop the operation of the control unit.

11. The stability system (100) according to claim 9, wherein, The controller is further configured to send the first target braking force and the second target braking force to a hydraulic actuator of the vehicle, so that the actuator performs braking control of a front wheel connected to a front suspension based on the first target braking force and performs braking control of a rear wheel connected to a rear suspension based on the second target braking force.

12. A control method (600) for a stability system of a vehicle, implemented by means of the control unit according to any one of claims 1-8 and / or the stability system according to any one of claims 9-11, the method comprising: Obtain the distance between the front suspension and the vehicle's center of mass and the distance between the rear suspension and the vehicle's center of mass; Calculate the static vertical load of the front suspension based on the distance between the front suspension and the vehicle's center of mass, and calculate the static vertical load of the rear suspension based on the distance between the rear suspension and the vehicle's center of mass; Determine the maximum vertical load of the front suspension and the maximum vertical load of the rear suspension based on the actual friction coefficient of the road surface; Calculate the optimized height of the front suspension based on the static vertical load and the maximum vertical load of the front suspension and the actual friction coefficient, and calculate the optimized height of the rear suspension based on the static vertical load and the maximum vertical load of the rear suspension and the actual friction coefficient; And Generate a first height control signal according to the optimized height of the front suspension for adjusting the height of the front suspension during the automatic emergency braking of the vehicle; and generate a second height control signal according to the optimized height of the rear suspension for adjusting the height of the rear suspension during the automatic emergency braking of the vehicle.

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