Whole vehicle semi-active suspension control method, system, vehicle and storage medium

Abstract

The application relates to a whole vehicle semi-active suspension control method, system, vehicle and storage medium, and belongs to the vehicle suspension control field. The method comprises the following steps: acquiring vehicle signals and analyzing the vehicle signals to obtain vehicle control parameters; determining a current vehicle roll control state according to the vehicle control parameters; if the current vehicle belongs to a steady-state roll control state, determining a steady-state roll control damping force according to the vehicle control parameters; if the current vehicle belongs to a transient roll control state, determining whether the current vehicle is in a limit grip control state according to the vehicle control parameters; if the current vehicle is not in the limit grip control state, determining a transient roll control damping force according to the vehicle control parameters; if the current vehicle is in the limit grip control state, determining a limit grip control damping force according to the vehicle control parameters; and determining a shock absorber control target current according to the steady-state roll control damping force, the limit grip control damping force or the transient roll control damping force in combination with road surface characteristics.

Description

Technical Field

[0001] This application relates to the field of vehicle suspension control, specifically to a semi-active suspension control method for a vehicle, a semi-active suspension control system for a vehicle, a vehicle, and a computer-readable storage medium. Background Technology

[0002] Semi-active suspension control research is mostly based on vertical vibration control of quarter-suspension systems. Traditional control methods include shyhook ceiling control, groundhook floor control, ADD acceleration control, and shyhook-Add control. Other derivative methods include slicker control, optimal control, fuzzy control, and frequency division multiplexing based on invariant points. All of these methods are based on the development and optimization of semi-active suspension algorithms using vertical vibration control, which can improve comfort to a certain extent.

[0003] For example, the invention patent "Frequency Domain Control Method for Automotive Semi-Active Suspension System" (Application No.: 201310111507.X, Publication Date: 2013.07.17) mainly studies the suspension characteristics at different frequencies based on the invariant point characteristics of semi-active suspension, and selects damping based on different frequency ranges. This has an enlightening effect on vertical vibration control, but semi-active suspension control also needs to consider control in some special scenarios, such as vehicle roll control under stable handling conditions. Of course, there are also methods that combine control of the roof and floor to control vehicle grip and balance vehicle comfort and handling performance, but the effect is not significant.

[0004] With the application of semi-active suspension, more and more control methods have realized that vertical-based control algorithms are no longer sufficient for certain scenarios. Therefore, multi-condition integrated control methods have gradually developed and are being applied. For example, the invention patent "Control Method for Automotive Electronic Control Semi-Active Suspension System" (application number: 202110480180.8, publication date: 2021.07.23) selects special scenarios and main algorithms based on operating condition identification and driving style, and can also perform hybrid control based on selected weight coefficients. This patent effectively integrates special scenarios and basic operating conditions, which is beneficial to improving vehicle handling and stability characteristics. However, the control method itself is still not refined enough, and it does not differentiate between scenarios for roll control methods, nor does it propose a more comprehensive and detailed strategy.

[0005] For example, the invention patent "An Integrated Control Method and Control for Semi-Active Suspension of a Vehicle" (Application No.: 201910979224.4, Publication Date: 2021.04.16) also proposes a control method that considers steering and pitch conditions. It determines whether there is a tendency for roll or pitch based on lateral acceleration or steering wheel angle, and controls the damping force accordingly. However, it does not provide detailed scenario divisions for specific vehicle roll control, nor does it formulate a comprehensive and detailed control strategy. Summary of the Invention

[0006] One objective of this application is to provide a semi-active suspension control method for a vehicle, which can solve the problem that the semi-active suspension control process of vehicles in the prior art does not have detailed scenario division, thus making it impossible to provide detailed control strategy customization; the second objective is to provide a semi-active suspension control system for a vehicle; and the third objective is to provide a vehicle.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0008] A semi-active suspension control method for a vehicle, the method comprising:

[0009] The vehicle signals are acquired and analyzed to obtain the vehicle control parameters;

[0010] The current roll control state of the vehicle is determined based on the vehicle control parameters.

[0011] If the vehicle is currently in a steady-state roll control state, the steady-state roll control damping force is determined based on the vehicle control parameters.

[0012] If the current vehicle is in a transient roll control state, then determine whether the current vehicle is in an extreme grip control state based on the vehicle control parameters.

[0013] If the vehicle is not currently in a state of extreme grip control, then the transient roll control damping force is determined based on the vehicle control parameters.

[0014] If the vehicle is currently in extreme grip control state, the extreme grip control damping force is determined based on the vehicle control parameters.

[0015] Based on the steady-state roll control damping force, ultimate grip control damping force, or transient roll control damping force, and in conjunction with road surface characteristics, determine the target control current for the shock absorber.

[0016] Based on the aforementioned technical means, the current roll control state of the vehicle is determined by the acquired vehicle control parameters. These technical means further divide the roll control state into steady-state roll control state, transient roll control state, and extreme grip control state. Different control damping forces are determined according to different control states, thereby obtaining the target current for shock absorber control. This results in a wider range of control scenarios and greater applicability.

[0017] In this embodiment of the application, the vehicle control parameters include: vehicle operating parameters, suspension state parameters, vehicle inherent parameters, and vehicle state parameters;

[0018] The vehicle operating parameters include: vehicle speed, lateral acceleration, longitudinal acceleration, steering wheel angle, and steering wheel angular velocity;

[0019] The suspension state parameters include at least three of the following: front left acceleration of the vehicle body, front right acceleration of the vehicle body, rear left acceleration of the vehicle body, and rear right acceleration of the vehicle body, as well as front left height sensor parameters, front right height sensor parameters, rear left height sensor parameters, and rear right height sensor parameters.

[0020] The inherent parameters of the vehicle include: vehicle curb weight, wheelbase, track width, center of gravity height, front axle roll stiffness, and rear axle roll stiffness.

[0021] The vehicle state parameters include: vehicle roll angle, shock absorber speed, unsprung acceleration, and vehicle pitch angle. Vehicle operating parameters reflect the vehicle's operating state, while suspension state parameters reflect the current state of the suspension and are the basis for suspension control. Vehicle inherent parameters are used to assist in determining the suspension's control state and control damping force. Vehicle state parameters reflect the vehicle's current attitude.

[0022] In this embodiment of the application, vehicle signals are acquired and parsed to obtain vehicle control parameters, including:

[0023] Acquire CAN signals and convert them into vehicle operating parameters;

[0024] Acquire suspension sensor signals as suspension state parameters;

[0025] Obtain the vehicle's inherent parameters;

[0026] Vehicle state parameters are estimated based on suspension state parameters and inherent vehicle parameters.

[0027] The aforementioned technical means can be used to obtain vehicle control parameters through different channels, providing the necessary calculation data for semi-active suspension control.

[0028] In this embodiment of the application, estimating vehicle state parameters based on suspension state parameters and inherent vehicle parameters includes:

[0029] Estimate the shock absorber speed:

[0030] The suspension displacement corresponding to the current position is obtained by looking up the table based on the height sensor parameters at the current position.

[0031] The relative velocity of the suspension at the current position is obtained by differentiating the suspension displacement at the current position.

[0032] Multiply the relative suspension speed at the current position by the shock absorber lever ratio to obtain the estimated shock absorber speed;

[0033] Estimate vehicle roll angle:

[0034] The two accelerations of the front row or the two accelerations of the rear row of the vehicle are integrated twice, respectively.

[0035] Calculate the difference between the two integrals of the front row of the vehicle body or the difference between the two integrals of the rear row to obtain the displacement difference between the left and right sides of the vehicle body;

[0036] Estimate the vehicle roll angle based on the difference in displacement between the left and right sides of the vehicle body and the corresponding wheelbase of the front or rear rows;

[0037] Estimate unsprung acceleration:

[0038] The suspension displacement corresponding to the current position is obtained by looking up the table based on the height sensor parameters at the current position.

[0039] The relative acceleration of the suspension at the current position is obtained by performing two differentials on the suspension displacement at the current position.

[0040] Subtract the relative acceleration of the suspension at the current position from the vehicle body acceleration at the current position to obtain the unsprung acceleration at the current position.

[0041] Estimate vehicle pitch angle:

[0042] Integrate the two accelerations on the left side of the vehicle body or the two accelerations on the right side twice, respectively;

[0043] Calculate the difference between the integrals of the two accelerations on the left side of the vehicle body or the difference between the integrals of the two accelerations on the right side to obtain the displacement difference between the front and rear of the vehicle body;

[0044] The vehicle pitch angle is estimated based on the difference in displacement between the front and rear vehicle bodies and the wheelbase.

[0045] Using the aforementioned techniques, suspension displacement is obtained by looking up suspension state parameters collected by sensors in a table. Based on the suspension displacement, the shock absorber speed and unsprung acceleration can be estimated. The displacement difference between two points on the same side of the vehicle reflects the vehicle's roll attitude. The displacement difference between the left and right sides of the vehicle can be obtained by integrating the two accelerations twice on any side of the vehicle, and the vehicle roll angle can be calculated by combining this with the wheelbase. Similarly, the displacement difference between two points on the same side of the vehicle reflects the vehicle's pitch attitude. The displacement difference between the front and rear sides of the vehicle can be obtained by integrating the two accelerations twice on any side of the vehicle, and the vehicle pitch angle can be calculated by combining this with the wheelbase, thus fully reflecting the vehicle's current attitude.

[0046] In this embodiment of the application, determining the current roll control state of the vehicle based on the vehicle control parameters includes:

[0047] Compare the current steering wheel angular velocity and lateral acceleration with the corresponding preset thresholds;

[0048] If the current steering wheel angular velocity is not greater than the first steering wheel angular velocity threshold and the lateral acceleration is not greater than the first lateral acceleration threshold, then the vehicle is determined to be in a steady-state roll control state.

[0049] If the current steering wheel angular velocity is greater than the first steering wheel angular velocity threshold and the lateral acceleration is greater than the first lateral acceleration threshold, then the vehicle is determined to be in a transient roll control state.

[0050] The above technical solution can determine the vehicle's roll control state by measuring the steering wheel angular velocity and lateral acceleration, providing a standard for more refined roll control.

[0051] In this embodiment of the application, determining the steady-state roll control damping force based on the vehicle control parameters includes:

[0052] The steady-state roll control damping force is obtained by looking up the table based on the lateral acceleration.

[0053] The above-mentioned technical means can quickly confirm the steady-state roll control damping force. Considering the influence of crosswinds and other scenarios, the damper damping force can be output by looking up a table through lateral acceleration to achieve semi-automatic suspension control of the vehicle.

[0054] In this embodiment of the application, determining whether the vehicle is currently in a state of extreme grip control based on the vehicle control parameters includes:

[0055] Estimate the vertical force of the tires based on the vehicle control parameters;

[0056] If the current lateral acceleration is greater than the second lateral acceleration threshold, the minimum value of the tire vertical force is less than the preset tire vertical force threshold, and the duration of the lateral acceleration being greater than the second lateral acceleration threshold and the minimum value of the tire vertical force being less than the preset tire vertical force threshold is greater than the preset time threshold, then the current vehicle is determined to be in extreme grip control state.

[0057] Using the above-mentioned technical means, when the cornering speed is high and the vehicle is in a limit state, there may be insufficient grip force. The damping requirement is the opposite of the large damping required for transient roll control. The above-mentioned technical means can determine whether limit grip control is needed at the moment, which is beneficial for the control of the entire lateral acceleration range.

[0058] In this embodiment of the application, estimating the vertical force of the tires based on vehicle control parameters includes:

[0059] Estimate lateral load transfer based on vehicle control parameters;

[0060] Estimate longitudinal load transfer based on vehicle control parameters;

[0061] Estimate the mass distribution based on vehicle control parameters;

[0062] The vertical force of each tire is calculated based on the mass distribution, lateral load transfer, and longitudinal load transfer.

[0063] The above-mentioned technical means can be used to calculate the vertical force of the tires based on the vehicle control parameters, providing data support for judging the ultimate grip control state.

[0064] In this embodiment, the lateral load transfer is estimated using the following formula:

[0065] ;

[0066] in, m For vehicle curb weight; a y It is lateral acceleration; h The height of the center of mass; The vehicle's roll angle; Front axle roll stiffness; Rear axle roll stiffness; Track is the wheelbase. g It is the acceleration due to gravity;

[0067] The longitudinal load transfer is estimated using the following formula:

[0068] ;

[0069] in, a x It is longitudinal acceleration; θ WB is the vehicle pitch angle; WB is the vehicle wheelbase.

[0070] The mass distribution amount is estimated using the following formula:

[0071] ;

[0072] Where b is the distance from the center of mass to the center of the rear axle;

[0073] The vertical force of each tire is calculated using the following formula:

[0074] ;

[0075] ;

[0076] ;

[0077] ;

[0078] in, F zfL The vertical force on the front left tire; F zfR The vertical force is applied to the front right tire. F zrL The vertical force on the rear left tire; F zrRThis is the vertical force of the rear right tire.

[0079] The aforementioned techniques can be used to calculate longitudinal load transfer, lateral load transfer, mass distribution, and vertical force on each tire. The calculation parameters are based on current vehicle parameters and are highly accurate.

[0080] In this embodiment of the application, determining the ultimate grip control damping force based on the vehicle control parameters includes:

[0081] Calculate the difference between the vertical force of each tire and the preset vertical force threshold of the tire;

[0082] The damping force discount factor is obtained by looking up the table based on the difference.

[0083] The transient roll control damping force is determined based on the vehicle control parameters.

[0084] The product of the transient roll control damping force and the damping force discount factor is calculated as the ultimate grip control damping force.

[0085] The extreme grip control damping force can be calculated using the above-mentioned technical means. The damping force discount factor is obtained through calibration, avoiding iterative calculations of complex algorithms and resulting in a fast response speed.

[0086] In this embodiment of the application, determining the transient roll control damping force based on the vehicle control parameters includes:

[0087] Determine the transient steering base damping force by referring to a table based on lateral acceleration or by referring to a table based on steering wheel angle and vehicle speed;

[0088] Determine the transient steering dynamic damping force by referring to a table based on vehicle speed and steering wheel angular velocity;

[0089] The transient roll control damping force is calculated based on the transient steering base damping force and the transient steering dynamic damping force.

[0090] Considering that the lateral acceleration response is slower than the steering wheel angle in cornering and exiting scenarios, transient roll control is achieved using both steering wheel angle and steering wheel angular velocity. The transient roll control damping force is determined based on the transient steering base damping force based on lateral acceleration and the transient steering dynamic damping force based on vehicle speed and steering wheel angular velocity. This approach integrates lateral acceleration for transient roll control, avoiding the impact of overly sensitive steering wheel on steady-state characteristics.

[0091] In this embodiment of the application, determining the transient steering dynamic damping force based on vehicle speed and steering wheel angular velocity includes:

[0092] Dynamic robustness processing is applied to the steering wheel angular velocity to obtain the dynamic steering wheel angular velocity;

[0093] Determine whether the dynamic steering wheel angular velocity and the steering wheel rotation angle are in phase;

[0094] If they are in the same phase, it is determined that the steering wheel angular velocity is on an upward trend;

[0095] Based on the vehicle speed and steering wheel angular velocity, the rising edge damping force is looked up in a table to determine the transient steering dynamic damping force;

[0096] If they are not the same, it is determined that the steering wheel angular velocity is in a decreasing trend;

[0097] The transient steering dynamic damping force is determined by looking up the table based on the vehicle speed and steering wheel angular velocity to calculate the falling edge damping force.

[0098] By employing the aforementioned technical methods, dynamic robustness is considered during transient steering. Through dynamic robustness processing, the steering wheel angular velocity is gradually increased to its maximum value and then maintained for a certain period of time. This avoids the shortcomings of poor robustness caused by continuous oscillations in damping force due to sudden changes in steering wheel angular velocity. Furthermore, the damping force is calibrated separately for the rising and falling edges of the steering wheel angular velocity increase or decrease, more closely reflecting actual user needs.

[0099] In this embodiment of the application, the calculation of the transient roll control damping force based on the transient steering base damping force and the transient steering dynamic damping force includes:

[0100] The transient steering base damping force is superimposed with the transient steering dynamic damping force to obtain the transient roll control damping force; or

[0101] The maximum value of the transient steering base damping force and the transient steering dynamic damping force is obtained as the transient roll control damping force.

[0102] The transient roll control damping force determined by the above-mentioned technical means integrates the steering wheel angular velocity and lateral acceleration for control, which is more in line with reality.

[0103] In this embodiment of the application, the target control current of the shock absorber is determined based on the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force combined with road surface characteristics, including:

[0104] Determine the current road surface grade based on the current vehicle speed and unsprung acceleration;

[0105] Determine the gain coefficient by referring to the table based on the current road surface grade and current vehicle speed;

[0106] The target output damping force is obtained by multiplying the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force by the gain coefficient.

[0107] The target output damping force is combined with the shock absorber speed to determine the target control current of the shock absorber by referring to a table.

[0108] By employing the aforementioned technical methods, the influence of road surface characteristics is fully considered when determining the target current for shock absorber control, resulting in an output damping force that better reflects actual scenarios and improves user experience. Furthermore, by classifying and calibrating road surface characteristics and combining this with vehicle speed to find the gain coefficient, a fast response time is achieved.

[0109] A second aspect of this application provides a semi-active vehicle suspension control system, the system comprising:

[0110] The signal processing unit is used to acquire and analyze vehicle signals to obtain vehicle control parameters.

[0111] A roll control state determination unit is used to determine the current roll control state of the vehicle based on the vehicle control parameters.

[0112] The steady-state roll control damping force determination unit is used to determine the steady-state roll control damping force based on the vehicle control parameters when the vehicle is in a steady-state roll control state.

[0113] The extreme grip control state determination unit is used to determine whether the vehicle is currently in an extreme grip control state based on the vehicle control parameters when the vehicle is in a transient roll control state.

[0114] The transient roll control damping force determination unit is used to determine the transient roll control damping force based on the vehicle control parameters when the current vehicle is in a transient roll control state and not in a limit grip control state.

[0115] The ultimate grip control damping force determination unit is used to determine the ultimate grip control damping force based on the vehicle control parameters when the vehicle is currently in the ultimate grip control state.

[0116] The target current determination unit is used to determine the target control current of the shock absorber based on the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force combined with road surface characteristics.

[0117] Through the above technical means, the system can determine the current roll control state of the vehicle based on the acquired vehicle control parameters during operation. During the control process, the roll control state is further divided into steady-state roll control state, transient roll control state, and extreme grip control state. Different control damping forces are determined according to different control states, thereby obtaining the target current for shock absorber control. The control scenarios are richer and the applicability is higher.

[0118] A third aspect of this application provides a vehicle in which the aforementioned semi-active suspension control method is used to calculate the target current for shock absorber control.

[0119] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned semi-active vehicle suspension control method.

[0120] The beneficial effects of this application are:

[0121] (1) This application designs detailed control methods for vehicle roll control in different scenarios, including steady-state roll control, transient steering control and extreme grip control, which are more applicable to actual roll control scenarios.

[0122] (2) In transient roll control, this application considers dynamic robustness in transient steering. Through dynamic robustness processing, it achieves a certain time holding when the steering wheel angular velocity gradually increases to the maximum value, avoiding the shortcomings of poor robustness caused by the constant oscillation of damping force search due to sudden changes in steering wheel angular velocity.

[0123] (3) In transient roll control, this application separately calibrates the damping force at the rising and falling edges for the increase or decrease of steering wheel angular velocity, which is closer to the actual needs of users;

[0124] (4) The method of this application addresses the phenomenon of insufficient grip force when the vehicle is in extreme condition at high cornering speeds. It proposes extreme grip control for the state where the damping demand is opposite to the large damping of transient roll control, which is beneficial for the control of the entire lateral acceleration range.

[0125] (5) When determining the target current for the shock absorber control, the influence of road surface characteristics is fully considered, and the output damping force is more in line with the actual scenario, improving the user experience. Attached Figure Description

[0126] Figure 1 A flowchart of a semi-active suspension control method for a vehicle provided in one embodiment of this application;

[0127] Figure 2 This application provides a schematic diagram of the vehicle roll control working area.

[0128] Figure 3 This is a diagram of the vehicle roll control sensor architecture in the embodiments of this application;

[0129] Figure 4 This is a diagram illustrating the dynamic robustness effect in the embodiments of this application;

[0130] Figure 5 This is a table showing the pavement characteristic gain coefficient in the embodiments of this application;

[0131] Figure 6 This is a block diagram illustrating the vehicle roll control principle in the embodiments of this application;

[0132] Figure 7 This is a block diagram illustrating the transient roll control principle in an embodiment of this application.

[0133] Figure 8 This is a block diagram of the vehicle semi-active suspension control system in the embodiments of this application.

[0134] Among them, M70 is the signal processing module, M701 is the sensor signal processing module, M702 is the CAN signal conversion module, M703 is the signal filtering and processing module, and M704 is the vehicle status signal estimation module;

[0135] M90 - Main Control Method Module, M901 - Steady-State Roll Control Module, M902 - Transient Roll Control Module, M903 - Ultimate Grip Control Module, M904 - Road Surface Characteristic Influence Factor Estimation Module, M905 - Damping Force Current Conversion Module, M902-1 - Transient Steering Basic Damping Force Calculation Module, M902-2 - Transient Steering Dynamic Damping Force Fsb Calculation Module;

[0136] 11-Front left height sensor, 12-Front left acceleration sensor, 21-Front right height sensor, 22-Front right acceleration sensor, 31-Rear left height sensor, 32-Rear left acceleration sensor, 41-Rear right height sensor, 60-Control module, 13-Steering wheel angle sensor;

[0137] S11 - Front left height sensor signal, S12 - Front left acceleration sensor signal, S21 - Front right height sensor signal, S22 - Front right acceleration sensor signal, S31 - Rear left height sensor signal, S32 - Rear left acceleration sensor signal, S33 - Lateral acceleration signal, S41 - Rear right height sensor signal, S43 - Longitudinal acceleration signal, S53 - Steering wheel speed signal, S63 - Lateral acceleration signal. Detailed Implementation

[0138] The embodiments of this application will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be understood that the preferred embodiments are only for illustrating this application and are not intended to limit the scope of protection of this application.

[0139] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. Therefore, the illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0140] This application provides a method for controlling a semi-active suspension of a vehicle, such as... Figure 1 As shown, the method includes:

[0141] The vehicle signals are acquired and analyzed to obtain the vehicle control parameters.

[0142] The current roll control state of the vehicle is determined based on the vehicle control parameters.

[0143] If the vehicle is currently in a steady-state roll control state, the steady-state roll control damping force is determined based on the vehicle control parameters.

[0144] If the current vehicle is in a transient roll control state, then determine whether the current vehicle is in an extreme grip control state based on the vehicle control parameters.

[0145] If the vehicle is not currently in a state of extreme grip control, then the transient roll control damping force is determined based on the vehicle control parameters.

[0146] If the vehicle is currently in extreme grip control state, the extreme grip control damping force is determined based on the vehicle control parameters.

[0147] Based on the steady-state roll control damping force, ultimate grip control damping force, or transient roll control damping force, and in conjunction with road surface characteristics, determine the target control current for the shock absorber.

[0148] In this method, the overall vehicle roll control is mainly based on Figure 2The diagram illustrates the vehicle roll control working area principle. In actual cornering scenarios, the steady-state roll control area is defined as the region where the steering wheel angular velocity (SwaRate) and lateral acceleration (Ay) are both below a certain threshold (e.g., when gently turning the steering wheel at a speed below 5 deg / s for a left turn). Similarly, during routine lane changes and overtaking, when the steering wheel angular velocity is higher, this area falls within the transient roll control area. When the lateral acceleration exceeds the limit threshold and its duration exceeds the time threshold, the vehicle is in the extreme grip control area. The thresholds in these criteria can be calibrated according to the specific vehicle model and its actual requirements. When the vehicle is in different control areas, the corresponding vehicle roll control objectives and damper damping force requirements differ. In the steady-state roll control area, increasing damping force primarily improves the vehicle's steady-state roll angle; in the transient roll control area, rapid damping force response improves the vehicle's roll angular velocity; and in the extreme grip control area, reducing the difference in damping force between the left and right sides improves load transfer, thereby improving the vehicle's extreme grip.

[0149] Based on the aforementioned technical means, the current roll control state of the vehicle is determined by the acquired vehicle control parameters. These technical means further divide the roll control state into steady-state roll control state, transient roll control state, and extreme grip control state. Different control damping forces are determined according to different control states, thereby obtaining the target current for shock absorber control. This results in a wider range of control scenarios and greater applicability.

[0150] In this embodiment, the vehicle control parameters include: vehicle operating parameters, suspension state parameters, vehicle inherent parameters, and vehicle state parameters. Vehicle operating parameters reflect the vehicle's operating state; suspension state parameters reflect the current suspension state and are the basis for suspension control; vehicle inherent parameters are used to assist in determining the suspension's control state and control damping force; and vehicle state parameters reflect the vehicle's current attitude.

[0151] In this embodiment of the application, vehicle signals are acquired and parsed to obtain vehicle control parameters, including:

[0152] The CAN signal is acquired and converted into vehicle operating parameters. In this embodiment, the vehicle operating parameters include vehicle speed, lateral acceleration, longitudinal acceleration, steering wheel angle, and steering wheel angular velocity. These parameters can be converted based on offsets, amplification factors, or limits in the DBC parameter table of the vehicle dynamic body control system. The acquired lateral acceleration, longitudinal acceleration, and other signals need to be low-pass filtered to ensure that vehicle roll control mainly focuses on low-frequency handling stability control, filtering out ride comfort-related vehicle roll attitude control.

[0153] Suspension sensor signals are acquired as suspension state parameters. In this embodiment, the suspension state parameters include at least three of the following: front left acceleration, front right acceleration, rear left acceleration, and rear right acceleration, as well as front left height sensor parameters, front right height sensor parameters, rear left height sensor parameters, and rear right height sensor parameters. Vehicle body acceleration is mainly used to calculate the vehicle's pitch and roll angles. The roll angle needs to be calculated based on the accelerations of two vehicles in the same row, while the pitch angle needs to be calculated based on the accelerations of two vehicles on the same side. Therefore, by collecting any three of the front left, front right, rear left, and rear right accelerations, the vehicle's pitch and roll angles can be calculated. In one embodiment of this application, three sprung acceleration sensors are used to collect vehicle body acceleration: a front left acceleration sensor, a front right acceleration sensor, and a rear left acceleration sensor. After acquiring the suspension sensor signals, noise reduction processing is performed on the sensor signals to improve data accuracy.

[0154] like Figure 3 As shown in the figure, the sensors arranged in this embodiment are illustrated. In the figure, 10 represents the vehicle chassis. A front left height sensor 11 and a front left acceleration sensor 12 are arranged on the left front wheel of the vehicle; a front right height sensor 21 and a front right acceleration sensor 22 are arranged on the right front wheel of the vehicle; a rear left height sensor 31 and a rear left acceleration sensor 32 are arranged on the left rear wheel of the vehicle; and a rear right height sensor 41 is arranged on the rear right wheel of the vehicle. The front left height sensor 11 collects the front left height sensor signal S11 and transmits it to the control module 60. The front right height sensor 21 collects the front right height sensor signal S11. Signal S21 is collected and transmitted to control module 60; rear left height sensor 31 collects rear left height sensor signal S31 and transmits it to control module 60; rear right height sensor 41 collects rear right height sensor signal S41 and transmits it to control module 60; front left acceleration sensor 12 collects front left acceleration sensor signal S12 and transmits it to control module 60; front right acceleration sensor 22 collects front right acceleration sensor signal S22 and transmits it to control module 60; rear left acceleration sensor 32 collects rear left acceleration sensor signal S32 and transmits it to control module 60. The figure also shows steering wheel angle sensor 13, which in this application obtains the steering wheel angle signal S13 from the CAN signal. It should be noted that the control module 60 in this application can be the vehicle's original controller.

[0155] Obtaining vehicle inherent parameters. In this embodiment, the vehicle inherent parameters include: vehicle curb weight, wheelbase, track width, center of gravity height, front axle roll stiffness, and rear axle roll stiffness. These parameters can be stored in a storage device on the vehicle and obtained by calling them, or they can be directly assigned values ​​to the semi-active suspension control method of this application.

[0156] Vehicle state parameters are estimated based on suspension state parameters and inherent vehicle parameters. In this embodiment, the vehicle state parameters include: vehicle roll angle, shock absorber speed, unsprung acceleration, and vehicle pitch angle.

[0157] In this embodiment of the application, the vehicle state parameters are estimated based on the suspension state parameters and the vehicle's inherent parameters, including: estimating the shock absorber speed, estimating the vehicle roll angle, estimating the unsprung acceleration, and estimating the vehicle pitch angle.

[0158] The estimation of shock absorber speed includes:

[0159] The suspension displacement Ds corresponding to the current position is obtained by looking up the table based on the height sensor parameters at the current position.

[0160] The relative speed of the suspension at the current position is obtained by differentiating the suspension displacement Ds at the current position.

[0161] Multiply the relative suspension velocity Vs at the current position by the shock absorber lever ratio i to obtain the estimated shock absorber velocity Vd, where Vd = Vs * i. The shock absorber lever ratio i is an inherent parameter of the vehicle. The suspension displacement is obtained by looking up the suspension state parameters collected by sensors in a table, and the shock absorber velocity can be estimated based on the suspension displacement.

[0162] Estimating unsprung acceleration includes:

[0163] The suspension displacement Ds corresponding to the current position is obtained by looking up the table based on the height sensor parameters at the current position.

[0164] The relative acceleration As of the suspension at the current position is obtained by performing two differentials on the suspension displacement at the current position.

[0165] Subtracting the relative acceleration of the suspension at the current position, Ab, from the vehicle body acceleration at the current position, As, yields the unsprung acceleration Aw = Ab - As. The suspension displacement is obtained by looking up the suspension state parameters collected by sensors in a table, and the unsprung acceleration can be estimated based on the suspension displacement.

[0166] Estimating vehicle roll angle includes:

[0167] The two accelerations of the front row or the two accelerations of the rear row of the vehicle are integrated twice, respectively.

[0168] Calculate the difference between the two integrals of the front row of the vehicle body or the difference between the two integrals of the rear row to obtain the displacement difference between the left and right sides of the vehicle body;

[0169] The vehicle roll angle is estimated based on the difference in displacement between the left and right sides of the vehicle body and the corresponding track width of the front or rear rows.

[0170] Estimating the vehicle pitch angle includes:

[0171] Integrate the two accelerations on the left side of the vehicle body or the two accelerations on the right side twice, respectively;

[0172] Calculate the difference between the integrals of the two accelerations on the left side of the vehicle body or the difference between the integrals of the two accelerations on the right side to obtain the displacement difference between the front and rear of the vehicle body;

[0173] The vehicle pitch angle is estimated based on the difference in displacement between the front and rear vehicle bodies and the wheelbase.

[0174] The displacement difference between two points on the same side of the vehicle reflects the vehicle's roll attitude. The displacement difference between the left and right sides of the vehicle can be obtained by integrating the two accelerations twice on any side of the vehicle, and the vehicle roll angle can be calculated by combining the wheelbase. The displacement difference between two points on the same side of the vehicle reflects the vehicle's pitch attitude. The displacement difference between the front and rear sides of the vehicle can be obtained by integrating the two accelerations twice on any side of the vehicle, and the vehicle pitch angle can be calculated by combining the wheelbase, which fully reflects the current attitude of the vehicle.

[0175] In one embodiment of this application, the vehicle body acceleration collected by the sprung acceleration sensor includes: the front left acceleration, the front right acceleration, and the rear left acceleration. Therefore, when calculating the vehicle roll angle, the front left acceleration, the front right acceleration, and the front axle track are used; the formula for calculating the vehicle roll angle is as follows:

[0176] ;

[0177] in, The vehicle roll angle, A bfL The acceleration is the front left side of the vehicle body. A bfR is the front right acceleration of the vehicle body, Track is the front axle track, and 57.3 is the inherent parameter for converting radians to angles.

[0178] When calculating the vehicle pitch angle, the front left acceleration, the rear left acceleration, and the wheelbase are used; the formula for calculating the vehicle pitch angle is as follows:

[0179]

[0180] in, The vehicle's pitch angle, A brLWB represents the left rear acceleration of the vehicle body, and WB represents the wheelbase.

[0181] The aforementioned technical means can be used to obtain vehicle control parameters through different channels, providing the necessary calculation data for semi-active suspension control.

[0182] In this embodiment of the application, determining the current roll control state of the vehicle based on the vehicle control parameters includes:

[0183] Compare the current steering wheel angular velocity and lateral acceleration with the corresponding preset thresholds;

[0184] If the current steering wheel angular velocity is not greater than the first steering wheel angular velocity threshold and the lateral acceleration is not greater than the first lateral acceleration threshold, then the vehicle is determined to be in a steady-state roll control state. The main control objective of the steady-state roll control state is the steady-state roll angle, which has a higher requirement for stability and a relatively lower requirement for speed.

[0185] If the current steering wheel angular velocity is greater than the first steering wheel angular velocity threshold, and the lateral acceleration is greater than the first lateral acceleration threshold, then the vehicle is determined to be in a transient roll control state. The primary control objective in the transient roll control state is the roll angular velocity, and the requirement for stability is relatively smaller than the requirement for rapid response.

[0186] The above technical solution allows for the determination of a vehicle's roll control state using steering wheel angular velocity and lateral acceleration, providing a standard for more refined roll control. In this embodiment, the first steering wheel angular velocity threshold and the first lateral acceleration threshold are calibrated based on the vehicle.

[0187] In this embodiment of the application, determining the steady-state roll control damping force based on the vehicle control parameters includes:

[0188] Based on the lateral acceleration, the steady-state damping force of the shock absorber is obtained by looking up a table, and a steady-state roll control damping force is determined for each shock absorber.

[0189] The above-mentioned technical means can quickly confirm the steady-state roll control damping force. Considering the influence of crosswinds and other scenarios, the damper damping force is output by looking up a table through lateral acceleration to realize the semi-automatic suspension control of the vehicle, avoiding fluctuations caused by steering wheel angle as input.

[0190] Considering the phenomenon that lateral acceleration may not have been established or reduced when a vehicle is cornering or exiting a corner, while the driver has already increased or decreased the steering wheel angle input, calibrating the damping force based on lateral acceleration could easily lead to a response slower than the driver expects. Therefore, when the transient roll control state conditions are met, i.e., the transient steering basic damping force is calculated using steering wheel angle and vehicle speed, and considering the triggering of transient roll control when the steering wheel angular velocity is large, the transient steering dynamic damping force is calculated using steering wheel angular velocity and vehicle speed, and the transient steering basic damping force and transient steering dynamic damping force are superimposed and output.

[0191] In this embodiment of the application, determining the transient roll control damping force based on the vehicle control parameters includes:

[0192] The transient steering damping force can be determined by looking up a table based on lateral acceleration or by looking up a table based on steering wheel angle and vehicle speed. In the embodiments of this application, the damping force can be looked up in a one-dimensional table based on lateral acceleration, or in a two-dimensional table based on steering wheel angle and vehicle speed.

[0193] The transient steering dynamic damping force is determined by referring to a table based on vehicle speed and steering wheel angular velocity, specifically including:

[0194] Dynamic robustness processing is applied to the steering wheel angular velocity to obtain the dynamic steering wheel angular velocity. Considering that when the vehicle's steering wheel angular velocity reaches its peak, it may decrease in the next instant, the dynamic robustness processing maintains the steering wheel angular velocity at its peak for a certain period. This avoids the feeling of sudden pressure relief caused by fluctuations, preventing abrupt changes in the vehicle's lateral movement and avoiding continuous oscillations in the damping force caused by sudden changes in steering wheel angular velocity, which results in poor robustness. Figure 4 As shown in the figure, the processed steering wheel angular velocity is the dynamic steering wheel angular velocity DynSwaRat, and the unprocessed steering wheel angular velocity is SwaRat. It can be seen from the figure that after dynamic robustness processing, the dynamic steering wheel angular velocity will maintain the peak value for a certain period of time when it decreases after the peak value.

[0195] The damping force requirements are calibrated to consider the different requirements at the rising and falling edges. When the steering wheel angular velocity and steering wheel angle are in the same direction and are constantly increasing (i.e., the rising edge), a larger damping force is required. Conversely, the damping force should be appropriately reduced. Therefore, when determining the dynamic damping force for transient steering, it is necessary to first determine whether the dynamic steering wheel angular velocity and steering wheel angle are in phase.

[0196] If they are in the same phase, it is determined that the steering wheel angular velocity is on an upward trend;

[0197] Based on the vehicle speed and steering wheel angular velocity, the rising edge damping force is looked up in a table to determine the transient steering dynamic damping force;

[0198] If they are not the same, it is determined that the steering wheel angular velocity is in a decreasing trend;

[0199] The transient steering dynamic damping force is determined by looking up the table based on the vehicle speed and steering wheel angular velocity to calculate the falling edge damping force.

[0200] By employing the aforementioned technical methods, dynamic robustness is considered during transient steering. Through dynamic robustness processing, the steering wheel angular velocity is gradually increased to its maximum value and then maintained for a certain period of time. This avoids the shortcomings of poor robustness caused by continuous oscillations in damping force due to sudden changes in steering wheel angular velocity. Furthermore, the damping force is calibrated separately for the rising and falling edges of the steering wheel angular velocity increase or decrease, more closely reflecting actual user needs.

[0201] The transient roll control damping force is calculated based on the transient steering base damping force and the transient steering dynamic damping force.

[0202] Considering that the lateral acceleration response is slower than the steering wheel angle in cornering and exiting scenarios, transient roll control is achieved using both steering wheel angle and steering wheel angular velocity. The transient roll control damping force is determined based on the transient steering base damping force based on lateral acceleration and the transient steering dynamic damping force based on vehicle speed and steering wheel angular velocity. This approach integrates lateral acceleration for transient roll control, avoiding the impact of overly sensitive steering wheel on steady-state characteristics.

[0203] In this embodiment of the application, the calculation of the transient roll control damping force based on the transient steering base damping force and the transient steering dynamic damping force includes:

[0204] The transient steering base damping force is superimposed with the transient steering dynamic damping force to obtain the transient roll control damping force:

[0205] ;

[0206] Among them, F s For transient roll control damping force, F sb For transient steering, the basic damping force, F ss This is the dynamic damping force for transient steering.

[0207] Alternatively, the maximum value of the transient steering base damping force and the transient steering dynamic damping force can be obtained as the transient roll control damping force:

[0208] .

[0209] The transient roll control damping force determined using the aforementioned techniques integrates steering wheel angular velocity and lateral acceleration for control, resulting in a more realistic effect. To avoid excessively strong transient action that could negatively impact ride comfort later on, it is recommended to use a superposition method to calculate the transient roll control damping force. One transient roll control damping force is calculated for each shock absorber.

[0210] In this embodiment of the application, determining whether the vehicle is currently in a state of extreme grip control based on the vehicle control parameters includes:

[0211] Estimate the vertical force of the tires based on the vehicle control parameters;

[0212] If the current lateral acceleration is greater than the second lateral acceleration threshold, the minimum value of the tire vertical force is less than the preset tire vertical force threshold, and the duration of the lateral acceleration being greater than the second lateral acceleration threshold and the minimum value of the tire vertical force being less than the preset tire vertical force threshold is greater than the preset time threshold, then the current vehicle is determined to be in extreme grip control state.

[0213] Using the above-mentioned technical means, when the cornering speed is high and the vehicle is in a limit state, there may be insufficient grip force. The damping requirement is the opposite of the large damping required for transient roll control. The above-mentioned technical means can determine whether limit grip control is needed at the moment, which is beneficial for the control of the entire lateral acceleration range.

[0214] Tire vertical force estimation mainly includes three parts: lateral load transfer, longitudinal load transfer, and mass distribution calculation. In this embodiment, the tire vertical force is estimated based on vehicle control parameters, including:

[0215] Lateral load transfer is estimated based on vehicle control parameters. Lateral load transfer mainly refers to load transfer caused by vehicle centrifugal force and load transfer caused by vehicle gravity. The calculation formula is as follows:

[0216] ;

[0217] in, m For vehicle curb weight; a y It is lateral acceleration; h The height of the center of mass; The vehicle's roll angle; Front axle roll stiffness; Rear axle roll stiffness; Track is the wheelbase. g This is the acceleration due to gravity.

[0218] Longitudinal load transfer is estimated based on vehicle control parameters. Longitudinal load transfer mainly refers to load transfer caused by vehicle longitudinal acceleration and load transfer caused by vehicle gravity. The calculation formula is as follows:

[0219] ;

[0220] in, a x It is longitudinal acceleration; θ WB is the vehicle pitch angle; WB is the vehicle wheelbase.

[0221] The mass distribution is estimated based on vehicle control parameters. Mass distribution primarily refers to the distribution of the vehicle's own weight, and the calculation formula is as follows:

[0222] ;

[0223] Where b is the distance from the center of mass to the rear axle center.

[0224] The vertical force of each tire is calculated based on the mass distribution, lateral load transfer, and longitudinal load transfer. The vertical force of each tire is calculated using the following formula:

[0225] ;

[0226] ;

[0227] ;

[0228] ;

[0229] in, F zfL The vertical force on the front left tire; F zfR The vertical force is applied to the front right tire. F zrL The vertical force on the rear left tire; F zrR This is the vertical force of the rear right tire.

[0230] Substituting the mass distribution, lateral load transfer, and longitudinal load transfer into the above formulas, the formulas for calculating the vertical force of each tire are as follows:

[0231] ;

[0232] ;

[0233] ;

[0234] ;

[0235] The aforementioned techniques can be used to calculate longitudinal load transfer, lateral load transfer, mass distribution, and vertical forces on each tire. The calculation parameters are based on current vehicle parameters, ensuring high accuracy. These techniques can also be used to calculate tire vertical forces based on vehicle control parameters, providing data support for determining the ultimate grip control state.

[0236] In this embodiment of the application, determining the ultimate grip control damping force based on the vehicle control parameters includes:

[0237] Calculate the difference between the vertical force of each tire and the preset vertical force threshold of the tire; it should be noted that the preset vertical force threshold of the tire used to calculate the difference is the same as the preset vertical force threshold of the tire used to determine the ultimate grip control state.

[0238] The damping force discount coefficient is obtained by looking up the table based on the difference. The damping force discount coefficient is calibrated based on the difference between the tire vertical force and the preset tire vertical force threshold. The larger the difference, the larger the damping force discount coefficient.

[0239] The transient roll control damping force is determined based on the vehicle control parameters. The method for determining the transient roll control damping force is the same as described above.

[0240] Calculate the product of the transient roll control damping force and the damping force discount factor as the ultimate grip control damping force:

[0241] ;

[0242] in, To control damping force for ultimate grip, This is the damping force discount factor. F z This represents the vertical force on the tire corresponding to the current shock absorber. The tire vertical force and the preset tire vertical force threshold F nom1 The difference and The results are obtained from a one-dimensional lookup table. Each shock absorber is calculated to have an ultimate grip control damping force.

[0243] The extreme grip control damping force can be calculated using the above-mentioned technical means. The damping force discount factor is obtained through calibration, avoiding iterative calculations of complex algorithms and resulting in a fast response speed.

[0244] In this embodiment of the application, the target control current of the shock absorber is determined based on the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force combined with road surface characteristics, including:

[0245] The current road surface grade is determined based on the current vehicle speed and unsprung acceleration. In this embodiment, the road surface grade is customized according to the specific vehicle performance requirements. In the process of customizing the road surface grade, different road surface datasets are first established, such as rural roads, damaged roads, smooth asphalt roads, and rough cement roads. The appropriate road surface dataset can be selected based on the specific vehicle requirements. Then, the road surface grade is customized by combining unsprung acceleration on different road surfaces and at different vehicle speeds.

[0246] The gain coefficient is determined by referring to a table based on the current road surface grade and current vehicle speed. A two-dimensional table of vehicle speed, road surface grade, and gain coefficient is created based on actual vehicle calibration. An example table is shown below. Figure 5As shown in the table. During actual vehicle use, the gain coefficient is determined according to this table. For example... Figure 5 As shown in the two-dimensional table, the columns represent road surface grades, and the rows represent vehicle speeds. When the road surface grade is 1 and the current vehicle speed is vspd1, the gain is G11. Other road surface grades and vehicle speeds are determined by looking up the table accordingly.

[0247] The target output damping force is obtained by multiplying the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force by the gain coefficient.

[0248] The target output damping force is combined with the shock absorber speed to determine the target control current of the shock absorber by referring to a table.

[0249] By employing the aforementioned technical methods, the influence of road surface characteristics is fully considered when determining the target current for shock absorber control, resulting in an output damping force that better reflects actual scenarios and improves user experience. Furthermore, by classifying and calibrating road surface characteristics and combining this with vehicle speed to find the gain coefficient, a fast response time is achieved.

[0250] like Figure 6 The diagram shown is a block diagram illustrating the vehicle roll control principle provided in the application embodiment. The semi-active suspension control in this application is mainly divided into two modules: a signal processing module M70 and a main control method module M90. The main control method module M90 ​​is also suitable for other sensor architectures not shown in this application (such as...). Figure 3 The signal processing methods can be flexibly applied to other sensor architectures and signal processing methods.

[0251] The signal processing module M70 mainly includes the following sub-modules: sensor signal processing module M701, CAN signal conversion module M702, signal filtering module M703, and vehicle status signal estimation module M704. In this embodiment, the sensor signals mainly include four height sensor signals: front left height sensor signal S11, front right height sensor signal S21, rear left height sensor signal S31, and rear right height sensor signal S41; and three acceleration sensor signals: front left acceleration sensor signal S12, front right acceleration sensor signal S22, and rear left acceleration sensor signal S32. Sensor signal processing mainly involves sensor validity determination and noise reduction using low-pass filtering with adjustable cutoff frequency. The CAN signal conversion module M702 mainly includes the determination of the validity of CAN signals such as steering wheel angle signal S13, vehicle speed signal S23, lateral acceleration signal S33, longitudinal acceleration signal S43, steering wheel speed signal S53, and lateral acceleration signal S63, and conversion based on the vehicle dynamic body control system DBC parameter table (offset, amplification factor, limit). Once the sensor and CAN signals are read, the signal filtering module M703 is required. This filtering is primarily for improving vehicle handling and stability, as this application focuses on enhancing these aspects. Therefore, it mainly covers the low-frequency band, employing a low-cutoff frequency for low-pass filtering to achieve the high-mid-low frequency division control design. The vehicle state signal estimation module M704 mainly includes damper speed estimation, unsprung acceleration estimation, vehicle roll angle estimation, vehicle pitch angle estimation, and vehicle parameter assignment.

[0252] The relevant signals are processed by the signal processing module M70 and then transmitted to the main control method module M90. The main control method module M90 ​​mainly includes: a steady-state roll control module M901, a transient roll control module M902, a limit grip control module M903, a road surface characteristic influence factor estimation module M904, and a damping force-current conversion module M905. The steady-state roll control module M901 is used to determine the steady-state roll control damping force; the transient roll control module M902 is used to determine the transient roll control damping force; the limit grip control module M903 is used to determine the limit grip control damping force; the road surface characteristic influence factor estimation module M904 is used to determine the target output damping force after considering the road surface characteristic influence factor; and the damping force-current conversion module M905 is used to look up the output current value based on the damper's inverse model or the damper's external characteristic curve.

[0253] Among them, such as Figure 7As shown, the transient roll control module M902 includes a transient steering basic damping force calculation module M902-1 and a transient steering dynamic damping force Fsb calculation module M902-2. In this embodiment, the transient steering basic damping force calculation module M902-1 performs a two-dimensional lookup table calculation of Fsb based on the steering wheel angle and vehicle speed to obtain the transient steering basic damping force. The transient steering dynamic damping force Fsb calculation module M902-2 includes methods for improving dynamic robustness and separating the rising and falling edges. After dynamic robustness processing, the dynamic steering wheel angular velocity DynSwaRat is obtained. When the dynamic steering wheel angular velocity DynSwaRat is in the same direction as the steering wheel angle, it is determined that the steering wheel angular velocity is on an upward trend. Then, the rising edge damping force Fsu is searched with reference to the vehicle speed and the steering wheel angular velocity. When DynSwaRat is in the opposite direction to the steering wheel angle, it is determined that the steering wheel angular velocity is on a downward trend. Then, the falling edge damping force Fsd is searched with reference to the vehicle speed and the steering wheel angular velocity. Finally, Fsu or Fsd is output as the transient steering dynamic damping force Fss.

[0254] Finally, the transient steering base damping force Fsb and the transient steering dynamic damping force Fss are superimposed to obtain the transient roll control damping force Fs.

[0255] The second aspect of this application provides a semi-active suspension control system for a vehicle, such as... Figure 8 As shown, the system includes:

[0256] The signal processing unit is used to acquire and analyze vehicle signals to obtain vehicle control parameters.

[0257] A roll control state determination unit is used to determine the current roll control state of the vehicle based on the vehicle control parameters.

[0258] The steady-state roll control damping force determination unit is used to determine the steady-state roll control damping force based on the vehicle control parameters when the vehicle is in a steady-state roll control state.

[0259] The extreme grip control state determination unit is used to determine whether the vehicle is currently in an extreme grip control state based on the vehicle control parameters when the vehicle is in a transient roll control state.

[0260] The transient roll control damping force determination unit is used to determine the transient roll control damping force based on the vehicle control parameters when the current vehicle is in a transient roll control state and not in a limit grip control state.

[0261] The ultimate grip control damping force determination unit is used to determine the ultimate grip control damping force based on the vehicle control parameters when the vehicle is currently in the ultimate grip control state.

[0262] The target current determination unit is used to determine the target control current of the shock absorber based on the steady-state roll control damping force, the ultimate grip control damping force, or the transient roll control damping force combined with road surface characteristics.

[0263] Through the above technical means, the system can determine the current roll control state of the vehicle based on the acquired vehicle control parameters during operation. During the control process, the roll control state is further divided into steady-state roll control state, transient roll control state, and extreme grip control state. Different control damping forces are determined according to different control states, thereby obtaining the target current for shock absorber control. The control scenarios are richer and the applicability is higher.

[0264] A third aspect of this application provides a vehicle in which the aforementioned semi-active suspension control method is used to calculate the target current for shock absorber control.

[0265] This application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned semi-active vehicle suspension control method.

[0266] While this application has been described in detail with reference to a limited number of examples, it should be readily understood that this application is not limited to these disclosed embodiments. Rather, this application can be modified to incorporate any number of variations, alterations, substitutions, or equivalent methods not previously described, but which remain consistent with the spirit and scope of this application. Furthermore, although multiple embodiments of this application have been described, it should be understood that various aspects of this application may include only some of the described embodiments. Moreover, this application should not be construed as being limited by the foregoing description.

Claims

1. A method of controlling a vehicle's semi-active suspension, characterized by, The method comprises: acquiring vehicle signals and analyzing the same to obtain vehicle control parameters; judging a current vehicle's belonging to a roll control state according to the vehicle control parameters; if the current vehicle belongs to a steady roll control state, determining a steady roll control damping force according to the vehicle control parameters; if the current vehicle belongs to a transient roll control state, determining whether the current vehicle is in a limit grip control state according to the vehicle control parameters; if the current vehicle is not in the limit grip control state, determining a transient roll control damping force according to the vehicle control parameters; if the current vehicle is in the limit grip control state, determining a limit grip control damping force according to the vehicle control parameters; determining a shock absorber control target current according to the steady roll control damping force, the limit grip control damping force or the transient roll control damping force in combination with road surface characteristics; determining whether the current vehicle is in the limit grip control state according to the vehicle control parameters comprises: estimating a tire vertical force according to the vehicle control parameters; determining that the current vehicle belongs to the limit grip control state when a current lateral acceleration is greater than a second lateral acceleration threshold, a minimum value in the tire vertical force is less than a preset tire vertical force threshold, and a duration that the lateral acceleration is greater than the second lateral acceleration threshold and the minimum value in the tire vertical force is less than the preset tire vertical force threshold is greater than a preset time threshold.

2. The vehicle-integrated semi-active suspension control method according to claim 1, characterized by, The vehicle control parameters comprise vehicle operating parameters, suspension state parameters, vehicle inherent parameters and vehicle state parameters; the vehicle operating parameters comprise vehicle speed, lateral acceleration, longitudinal acceleration, steering wheel angle and steering wheel angular velocity; the suspension state parameters comprise at least three of front left body acceleration, front right body acceleration, rear left body acceleration and rear right body acceleration, and front left height sensor parameter, front right height sensor parameter, rear left height sensor parameter and rear right height sensor parameter; the vehicle inherent parameters comprise vehicle kerb mass, wheelbase, track, center of mass height, front axle roll angle stiffness and rear axle roll angle stiffness; the vehicle state parameters comprise vehicle roll angle, shock absorber speed, sprung mass acceleration and vehicle pitch angle.

3. The vehicle-integrated semi-active suspension control method according to claim 2, characterized by, acquiring vehicle signals and analyzing the same to obtain vehicle control parameters comprises: acquiring CAN signals and converting the same into vehicle operating parameters; acquiring suspension sensor signals as suspension state parameters; acquiring vehicle inherent parameters; estimating vehicle state parameters according to the suspension state parameters and the vehicle inherent parameters.

4. The vehicle overall semi-active suspension control method according to claim 3, characterized by, estimating vehicle state parameters according to the suspension state parameters and the vehicle inherent parameters comprises: estimating shock absorber speed: looking up a table according to a height sensor parameter at a current position to obtain a suspension displacement corresponding to the current position; differencing the suspension displacement corresponding to the current position to obtain a suspension relative speed corresponding to the current position; multiplying the suspension relative speed corresponding to the current position by a shock absorber lever ratio to obtain an estimated shock absorber speed; estimating vehicle roll angle: integrating two accelerations of a front row of a vehicle body or two accelerations of a rear row of the vehicle body twice respectively; calculating a difference between two integrations of the front row of the vehicle body or calculating a difference between two integrations of the rear row of the vehicle body to obtain a left-right vehicle body displacement difference; Estimating vehicle roll angle according to left and right vehicle body displacement difference and corresponding front or rear wheel track; Estimating unsprung acceleration: Looking up current position corresponding suspension displacement according to current position height sensor parameter; Getting current position corresponding suspension relative acceleration by twice differentiating current position corresponding suspension displacement; Subtracting current position corresponding suspension relative acceleration from current position corresponding vehicle body acceleration to get current position corresponding unsprung acceleration; Estimating vehicle pitch angle according to front and rear vehicle body displacement difference and wheel base; Integrating left two vehicle body accelerations or right two vehicle body accelerations twice respectively; Calculating front and rear vehicle body displacement difference by calculating difference of left two vehicle body acceleration integrals or right two vehicle body acceleration integrals; Estimating vehicle pitch angle according to front and rear vehicle body displacement difference and wheel base.

5. The vehicle-integrated semi-active suspension control method according to claim 2, characterized by, Determining current vehicle belonging to which roll control state according to vehicle control parameters, including: Comparing current steering wheel angular velocity and lateral acceleration with corresponding preset threshold values; If current steering wheel angular velocity is not greater than first steering wheel angular velocity threshold value and lateral acceleration is not greater than first lateral acceleration threshold value, then determining that current vehicle belongs to steady state roll control state; If current steering wheel angular velocity is greater than first steering wheel angular velocity threshold value and lateral acceleration is greater than first lateral acceleration threshold value, then determining that current vehicle belongs to transient state roll control state.

6. The vehicle overall semi-active suspension control method according to claim 2, characterized by, Determining steady state roll control damping force according to vehicle control parameters, including: Looking up steady state roll control damping force according to lateral acceleration to get steady state roll control damping force.

7. The vehicle overall semi-active suspension control method according to claim 2, characterized by, Estimating tire vertical force according to vehicle control parameters, including: Estimating lateral load transfer according to vehicle control parameters; Estimating longitudinal load transfer according to vehicle control parameters; Estimating mass distribution amount according to vehicle control parameters; Calculating each tire vertical force according to mass distribution amount, lateral load transfer and longitudinal load transfer.

8. The vehicle-integrated semi-active suspension control method according to claim 7, characterized by, Estimating lateral load transfer by using following formula: ； wherein, m is the vehicle mass; a y is the lateral acceleration; h is the height of the center of mass; is the roll angle of the vehicle; is the roll stiffness of the front axle; is the roll stiffness of the rear axle; Track is the wheel track, g is the acceleration due to gravity; Estimating longitudinal load transfer by using following formula: ； wherein, a x is the longitudinal acceleration; θ is the vehicle pitch angle; and WB is the vehicle wheelbase. Estimating mass distribution amount by using following formula: ； wherein, b is the distance from the center of mass to the rear axle center; Calculating each tire vertical force by using following formula: ； ； ； ； wherein, F zfL is the front left tire vertical force; F zfR is the front right tire vertical force; F zrL is the rear left tire vertical force; F zrR is the rear right tire vertical force.

9. The vehicle overall semi-active suspension control method according to claim 2, characterized by, Determining limit grip control damping force according to vehicle control parameters, including: Calculating difference between each tire vertical force and preset tire vertical force threshold value; Looking up damping force discount coefficient according to the difference to get damping force discount coefficient; Determining transient state roll control damping force according to vehicle control parameters; Calculating product of transient state roll control damping force and damping force discount coefficient as limit grip control damping force.

10. The vehicle semi-active suspension control method according to claim 1, characterized by, Determining transient state roll control damping force according to vehicle control parameters, including: Determining transient state steering base damping force according to lateral acceleration or according to steering wheel angle and vehicle speed; Determining transient state steering dynamic damping force according to vehicle speed and steering wheel angular velocity; Calculating transient state roll control damping force according to transient state steering base damping force and transient state steering dynamic damping force.

11. The vehicle-integrated semi-active suspension control method according to claim 10, characterized by, Determining transient state steering dynamic damping force according to vehicle speed and steering wheel angular velocity, including: Processing dynamic robustness of steering wheel angular velocity to get dynamic steering wheel angular velocity; Determining whether dynamic steering wheel angular velocity and steering wheel angle are in phase; If in phase, then determining that steering wheel angular velocity is in rising trend; According to the vehicle speed and the steering wheel angular velocity, an ascending edge damping force lookup table is performed to determine a transient steering dynamic damping force; If not, it is determined that the steering wheel angular velocity is in a descending trend; According to the vehicle speed and the steering wheel angular velocity, a descending edge damping force lookup table is performed to determine a transient steering dynamic damping force.

12. The vehicle semi-active suspension control method according to claim 10, characterized by, According to the transient steering base damping force and the transient steering dynamic damping force, a transient roll control damping force is calculated, including: The transient steering base damping force and the transient steering dynamic damping force are superimposed to obtain a transient roll control damping force; or The maximum value of the transient steering base damping force and the transient steering dynamic damping force is obtained as a transient roll control damping force.

13. The vehicle overall semi-active suspension control method according to claim 2, characterized by, According to the steady-state roll control damping force, the limit grip control damping force or the transient roll control damping force, in combination with the road surface characteristics, a shock absorber control target current is determined, including: According to the current vehicle speed and the under-spring acceleration, a current road surface grade is determined; According to the grade of the current road surface and the current vehicle speed, a gain coefficient is determined by lookup table; The steady-state roll control damping force, the limit grip control damping force or the transient roll control damping force is multiplied by the gain coefficient to obtain a target output damping force; The target output damping force is combined with a shock absorber speed lookup table to determine a shock absorber control target current.

14. A vehicle integrated semi-active suspension control system, characterized by, The system comprises: A signal processing unit for obtaining and analyzing vehicle signals to obtain vehicle control parameters; A roll control state determination unit for determining the current vehicle's roll control state according to the vehicle control parameters; A steady-state roll control damping force determination unit for determining a steady-state roll control damping force according to the vehicle control parameters when the current vehicle is in a steady-state roll control state; A limit grip control state determination unit for determining whether the current vehicle is in a limit grip control state according to the vehicle control parameters when the current vehicle is in a transient roll control state; A transient roll control damping force determination unit for determining a transient roll control damping force according to the vehicle control parameters when the current vehicle is in a transient roll control state and is not in a limit grip control state; A limit grip control damping force determination unit for determining a limit grip control damping force according to the vehicle control parameters when the current vehicle is in a limit grip control state; A target current determination unit for determining a shock absorber control target current according to the steady-state roll control damping force, the limit grip control damping force or the transient roll control damping force in combination with the road surface characteristics; According to the vehicle control parameters, it is determined whether the current vehicle is in a limit grip control state, including: According to the vehicle control parameters, the tire vertical force is estimated; In the case that the current lateral acceleration is greater than a second lateral acceleration threshold, the minimum value of the tire vertical force is less than a preset tire vertical force threshold, and the lateral acceleration is greater than the second lateral acceleration threshold, the minimum value of the tire vertical force is less than the preset tire vertical force threshold, and the duration is greater than a preset time threshold, it is determined that the current vehicle is in a limit grip control state.

15. A vehicle characterized by comprising: The vehicle adopts the whole vehicle semi-active suspension control method of any one of claims 1-13 to calculate the shock absorber control target current.

16. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the whole vehicle semi-active suspension control method of any one of claims 1-13.

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