CN116653523A

CN116653523A - Whole vehicle semi-active suspension control method, system, vehicle and storage medium

Info

Publication number: CN116653523A
Application number: CN202310629946.3A
Authority: CN
Inventors: 梁志华; 唐倬; 禹慧丽; 曾庆强
Original assignee: Chongqing Changan Automobile Co Ltd
Current assignee: Chongqing Changan Automobile Co Ltd
Priority date: 2023-05-30
Filing date: 2023-05-30
Publication date: 2023-08-29

Abstract

The application relates to a method and a system for controlling a semi-active suspension of a whole vehicle, a vehicle and a storage medium, and belongs to the field of vehicle suspension control. The method comprises the following steps: acquiring and analyzing a vehicle signal to obtain a vehicle control parameter; judging the roll control state of the current vehicle 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 vehicle control parameters; if the current vehicle belongs to the transient roll control state, determining whether the current vehicle is in the limit ground grabbing control state according to the vehicle control parameters; if the current vehicle is not in the limit ground grabbing control state, determining a transient roll control damping force according to the vehicle control parameters; if the current vehicle is in the limit ground grabbing control state, determining a limit ground grabbing 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 and the road surface characteristic.

Description

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

Technical Field

The application relates to the field of vehicle suspension control, in particular to a whole vehicle semi-active suspension control method, a whole vehicle semi-active suspension control system, a vehicle and a computer readable storage medium.

Background

The semi-active suspension control is mostly based on the research of vertical vibration control of 1/4 suspension, wherein the traditional control method comprises shyhook canopy control, groun hook canopy control, ADD acceleration control and shyhook-Add control, and meanwhile, the sliding film control, optimal control, fuzzy control and a frequency division control method based on invariant points are also derived. The method is based on vertical vibration control to develop and optimize semi-active suspension algorithm, and comfort can be improved to a certain extent.

For example, the application patent 'frequency domain control method of an automobile semi-active suspension system' (application number: 201310111507.X, publication date: 2013.07.17) is mainly based on the non-variable point characteristic of the semi-active suspension, so as to conduct suspension characteristic research of different frequencies, and conduct damping selection based on different frequency ranges. The control method has a heuristic effect on vertical vibration control, but the semi-active suspension control also needs to consider the control of some special scenes such as whole vehicle roll control under the stable operation condition. Naturally, the canopy and the ground canopy are also subjected to mixed control to control the ground grabbing force of the vehicle and balance the comfort and the stability of the vehicle, but the effect is not obvious.

With the application of semi-active suspensions, more and more control methods are realized that under special scenes, the control algorithm based on the vertical direction can not meet the requirements, so that the control method integrating multiple working conditions is gradually developed and applied. For example, the invention patent 'automobile electric control semi-active suspension system control method' (application number: 202110480180.8, publication date: 2021.07.23) can select a special scene and a main algorithm according to the working condition identification and driving style, and can also perform hybrid control according to the selection weight coefficient. The special scene and the basic working condition are effectively fused, the stability of the vehicle is improved, but the control method is still not fine enough, the side tilting control method is not used for dividing the scene, and a more comprehensive and detailed strategy is provided.

In another embodiment, the invention patent (application number: 201910979224.4, publication date: 2021.04.16) discloses a control method and control method for a semi-active suspension of a vehicle, which also considers steering and pitching conditions. And judging whether the roll trend and the pitching trend exist or not according to the working conditions such as the lateral acceleration or the steering wheel rotation angle and the longitudinal acceleration, and performing damping force control. However, the detailed scene division is not performed for the specific roll control of the vehicle body, and the full-scale detailed control strategy formulation is performed.

Disclosure of Invention

The application aims to provide a semi-active suspension control method of a whole vehicle, which can solve the problem that the semi-active suspension control process of the vehicle in the prior art is not subjected to detailed scene division, so that detailed control strategy customization cannot be provided; secondly, a semi-active suspension control system of the whole vehicle is provided; a third object is to provide a vehicle.

In order to achieve the above purpose, the technical scheme adopted by the application is as follows:

a vehicle semi-active suspension control method, the method comprising:

acquiring and analyzing a vehicle signal to obtain a vehicle control parameter;

judging the roll control state of the current vehicle 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 the transient roll control state, determining whether the current vehicle is in the limit ground grabbing control state according to the vehicle control parameters;

if the current vehicle is not in the limit ground grabbing control state, determining a transient roll control damping force according to the vehicle control parameters;

If the current vehicle is in the limit ground grabbing control state, determining a limit ground grabbing 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 and the road surface characteristic.

According to the technical means, the roll control state of the current vehicle is judged according to the acquired vehicle control parameters, the roll control state is divided into the steady roll control state, the transient roll control state and the limit ground grabbing control state in more detail, and different control damping forces are determined according to different control states, so that the control target current of the shock absorber is obtained, the control scene is richer, and the applicability is higher.

In an embodiment of the present application, the vehicle control parameters include: vehicle operating parameters, suspension state parameters, vehicle intrinsic parameters, and vehicle state parameters;

the vehicle operating parameters include: vehicle speed, lateral acceleration, longitudinal acceleration, steering wheel angle and steering wheel angular velocity;

the suspension state parameters include: at least three of a front left acceleration of the vehicle body, a front right acceleration of the vehicle body, a rear left acceleration of the vehicle body, a rear right acceleration of the vehicle body, a front left altitude sensor parameter, a front right altitude sensor parameter, a rear left altitude sensor parameter, and a rear right altitude sensor parameter;

The vehicle-inherent parameters include: vehicle preparation mass, wheelbase, centroid height, front axle roll stiffness and rear axle roll stiffness;

the vehicle state parameters include: vehicle roll angle, shock absorber speed, unsprung acceleration, and vehicle pitch angle. The vehicle running parameters represent the running state of the vehicle, the suspension state parameters represent the state of the current suspension, the suspension control basis is provided, and the vehicle inherent parameters are required to be used for assisting in determining the control state and the control damping force of the suspension, and the vehicle state parameters reflect the current posture of the vehicle.

In the embodiment of the application, the vehicle signal is acquired and analyzed to obtain the vehicle control parameters, which comprises the following steps:

acquiring a CAN signal and converting the CAN signal into vehicle operation parameters;

acquiring a suspension sensor signal as a suspension state parameter;

acquiring intrinsic parameters of a vehicle;

the vehicle state parameter is estimated based on the suspension state parameter and the vehicle intrinsic parameter.

The vehicle control parameters can be obtained from different approaches through the technical means, and needed calculation data is provided for semi-active suspension control.

In an embodiment of the present application, estimating a vehicle state parameter from a suspension state parameter and a vehicle intrinsic parameter includes:

Estimating damper speed:

according to the height sensor parameter of the current position, looking up a table to obtain the suspension displacement corresponding to the current position;

differentiating according to the suspension displacement corresponding to the current position to obtain the suspension relative speed corresponding to the current position;

multiplying the relative speed of the suspension corresponding to the current position by the lever ratio of the shock absorber to obtain the estimated speed of the shock absorber;

estimating a vehicle roll angle:

respectively integrating the front two accelerations or the rear two accelerations of the vehicle body twice;

calculating the difference between two integrals of the front row of the vehicle body or the difference between two integrals of the rear row of the vehicle body to obtain the left and right vehicle body displacement difference;

estimating the roll angle of the vehicle according to the displacement difference of the left and right vehicle bodies and the corresponding wheel track of the front row or the rear row;

estimating unsprung acceleration:

performing twice differentiation according to the suspension displacement corresponding to the current position to obtain the suspension relative acceleration corresponding to the current position;

subtracting the relative acceleration of the suspension corresponding to the current position from the vehicle body acceleration corresponding to the current position to obtain the unsprung acceleration corresponding to the current position;

estimating a pitch angle of the vehicle:

respectively integrating two accelerations at the left side or two accelerations at the right side of the vehicle body twice;

Calculating the difference between two acceleration integrals at the left side of the vehicle body or the difference between two acceleration integrals at the right side of the vehicle body to obtain the displacement difference between the front vehicle body and the rear vehicle body;

and estimating the pitch angle of the vehicle according to the displacement difference of the front vehicle body and the rear vehicle body and the wheelbase.

Through the technical means, the suspension displacement is obtained through the table lookup of the suspension state parameters acquired by the sensor, and the speed and the unsprung acceleration of the shock absorber can be estimated according to the suspension displacement. The displacement difference of two points in the same row of the vehicle represents the roll attitude of the vehicle, the displacement difference of the left and right vehicle bodies can be obtained through the displacement difference integrated by two times of two accelerations in any row of the vehicle, and the roll angle of the vehicle is obtained by combining the wheel track calculation; the displacement difference of two points on the same side of the vehicle reflects the pitching attitude of the vehicle, the displacement difference of the front and rear vehicle bodies can be obtained through the displacement difference integrated by two times of two accelerations on any side of the vehicle, the pitch angle of the vehicle is obtained through combination with wheelbase calculation, and the current attitude of the vehicle is fully reflected.

In an embodiment of the present application, determining, according to the vehicle control parameter, a roll control state to which the current vehicle belongs includes:

comparing the current steering wheel angular speed and the lateral acceleration with corresponding preset thresholds;

If the current steering wheel angular speed is not greater than the first steering wheel angular speed threshold value and the lateral acceleration is not greater than the first lateral acceleration threshold value, judging that the current vehicle belongs to a steady-state roll control state;

and if the current steering wheel angular speed is greater than the first steering wheel angular speed threshold value and the lateral acceleration is greater than the first lateral acceleration threshold value, judging that the current vehicle belongs to the transient roll control state.

According to the technical scheme, the rolling control state of the vehicle can be determined through the steering wheel angular speed and the lateral acceleration, and a dividing standard is provided for finer rolling control.

In an embodiment of the application, determining a steady-state roll control damping force from the vehicle control parameter comprises:

and performing a table look-up of the damping force of the steady-state shock absorber according to the lateral acceleration to obtain a steady-state roll control damping force.

By the technical means, the steady-state roll control damping force can be rapidly confirmed, the influence of scenes such as crosswind and the like is considered, and the semi-automatic suspension control of the vehicle is realized by performing table lookup output of the damping force of the shock absorber through lateral acceleration.

In an embodiment of the present application, determining whether the vehicle is currently in a limited grip control state according to the vehicle control parameter includes:

Estimating tire vertical force according to vehicle control parameters;

and under the condition that the current lateral acceleration is larger than a second lateral acceleration threshold value, the minimum value of the tire vertical forces is smaller than a preset tire vertical force threshold value, and the duration time that the minimum value of the lateral acceleration is larger than the second lateral acceleration threshold value and the tire vertical forces is smaller than the preset tire vertical force threshold value is larger than a preset time threshold value, judging that the current vehicle belongs to the limit ground grabbing control state.

Through the technical means, when the overbending speed is high, the phenomenon of insufficient ground grabbing force can occur when the vehicle is in a limit state, the damping requirement is opposite to the large damping of the transient roll control, and whether the limit ground grabbing control is needed at present can be determined through the technical means, so that the full lateral acceleration range management and control are facilitated.

In an embodiment of the present application, estimating tire vertical force based on vehicle control parameters includes:

estimating lateral load transfer based on vehicle control parameters;

estimating longitudinal load transfer based on the vehicle control parameters;

estimating a mass distribution amount according to the vehicle control parameters;

and calculating the vertical force of each tire according to the mass distribution amount, the transverse load transfer and the longitudinal load transfer.

By the technical means, the tire vertical force can be obtained through calculation according to the vehicle control parameters, and data support is provided for judging the limit ground grabbing control state.

In an embodiment of the present application, the lateral load transfer is estimated using the following formula:

wherein m is the vehicle preparation quality; a, a _y Is the lateral acceleration; h is the centroid height;is the roll angle of the vehicle; />The roll angle rigidity of the front axle; />Is the back shaft roll angle stiffness; track is Track, g is gravitational acceleration;

the longitudinal load transfer is estimated using the following formula:

wherein a is _x Is the longitudinal acceleration; θ is the pitch angle of the vehicle; WB is the vehicle wheelbase;

the mass distribution amount is estimated by the following formula:

wherein b is the center distance of the centroid from the rear axle;

the vertical force of each tire was calculated using the following formula:

F _zfL ＝F _{z_m} -F _{z_lon} -F _{z_lat} ；

F _zfR ＝F _{z_m} -F _{z_lon} +F _{z_lat} ；

F _zrL ＝F _{z_m} +F _{z_lon} -F _{z_lat} ；

F _zrR ＝F _{z_m} +F _{z_lon} +F _{z_lat} ；

wherein F is _zfL Is the vertical force of the front left tire; f (F) _zfR Is the vertical force of the front right tire; f (F) _zrL Is the vertical force of the rear left tire; f (F) _zrR Is the vertical force of the rear right tire.

By the technical means, the longitudinal load transfer, the transverse load transfer, the mass distribution amount and the vertical force of each tire can be calculated, the calculated parameters are based on the current vehicle parameters, and the accuracy is high.

In an embodiment of the application, determining a limit grip control damping force according to the vehicle control parameter comprises:

Calculating the difference value between each tire vertical force and a preset tire vertical force threshold value;

according to the difference value, table lookup is carried out to obtain a damping force discount coefficient;

determining a transient roll control damping force according to the vehicle control parameter;

and calculating the product of the transient roll control damping force and the damping force discount coefficient as a limit grip control damping force.

The limit ground grabbing control damping force can be calculated through the technical means, the damping force discount coefficient is obtained through calibration, iterative calculation of a complex algorithm is avoided, and the response speed is high.

In an embodiment of the application, determining a transient roll control damping force according to the vehicle control parameter comprises:

determining transient steering basic damping force according to a table look-up of lateral acceleration or a table look-up of steering wheel rotation angle and vehicle speed;

determining transient steering dynamic damping force according to the table look-up of the vehicle speed and the steering wheel angular velocity;

and calculating a transient roll control damping force according to the transient steering base damping force and the transient steering dynamic damping force.

Considering that the response of the lateral acceleration is slower than the steering wheel corner in the over-bending and out-bending scene, the steering wheel corner and the steering wheel angular velocity are adopted to carry out transient roll control, the transient roll control damping force is determined according to the transient steering basic damping force based on the lateral acceleration and the transient steering dynamic damping force based on the vehicle speed and the steering wheel angular velocity, the transient roll control is carried out by fusing the lateral acceleration, and the influence of the steering wheel on the steady state characteristic due to oversensitivity is avoided.

In an embodiment of the application, determining a transient steering dynamic damping force based on a vehicle speed and a steering wheel angular velocity includes:

carrying out dynamic robustness processing on the steering wheel angular velocity to obtain the dynamic steering wheel angular velocity;

judging whether the dynamic steering wheel angular speed is in phase with the steering wheel angle;

if the steering wheel angular speeds are in the same phase, judging that the steering wheel angular speeds are in an ascending trend;

performing rising edge damping force table lookup according to the vehicle speed and the steering wheel angular speed to determine transient steering dynamic damping force;

if the angular speeds are different, judging that the angular speeds of the steering wheels are in a descending trend;

and (5) performing falling edge damping force table lookup according to the vehicle speed and the steering wheel angular speed to determine the transient steering dynamic damping force.

By the technical means, dynamic robustness is considered in transient steering, and the defect that the damping force is found to shake continuously and the robustness is poor due to abrupt change of the angular velocity of the steering wheel is overcome by keeping for a certain time when the angular velocity of the steering wheel gradually increases to the maximum value through dynamic robustness processing. Meanwhile, the rising edge and the falling edge are respectively calibrated aiming at the increase or decrease of the angular speed of the steering wheel, so that the damping force is closer to the actual demands of users.

In an embodiment of the present application, calculating a transient roll control damping force from the transient steering base damping force and the transient steering dynamic damping force includes:

Superposing the transient steering basic damping force and the transient steering dynamic damping force to obtain a transient roll control damping force; or alternatively

And acquiring the maximum value of the transient steering base damping force and the transient steering dynamic damping force as a transient roll control damping force.

The transient roll control damping force determined by the technical means fuses the steering wheel angular speed and the lateral acceleration to control, and is more practical.

In an embodiment of the present application, determining a shock absorber control target current from 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 includes:

determining a current road surface grade according to the current vehicle speed and the unsprung acceleration;

according to the grade of the current road surface and the current vehicle speed, determining a gain coefficient by looking up a table;

multiplying the steady-state roll control damping force, the limit grip control damping force or the transient roll control damping force by a gain coefficient to obtain a target output damping force;

and determining a shock absorber control target current by combining the target output damping force with a shock absorber speed table.

Through the technical means, the influence of the road surface characteristic is fully considered when the control target current of the shock absorber is finally determined, the output damping force is more fit with the actual scene, and the user experience is improved. On the other hand, the road surface characteristics are calibrated in a grading way, and the gain coefficient is searched in combination with the vehicle speed, so that the response speed is high.

The second aspect of the application provides a vehicle semi-active suspension control system, which comprises:

the signal processing unit is used for acquiring and analyzing the vehicle signals to obtain vehicle control parameters;

a roll control state determining unit configured to determine a roll control state to which the current vehicle belongs according to the vehicle control parameter;

a steady-state roll control damping force determination unit configured to determine a steady-state roll control damping force according to the vehicle control parameter when a current vehicle belongs to a steady-state roll control state;

the limit ground grabbing control state judging unit is used for determining whether the current vehicle is in a limit ground grabbing control state or not according to the vehicle control parameters when the current vehicle is in a transient roll control state;

a transient roll control damping force determining unit configured to determine a transient roll control damping force according to the vehicle control parameter when a current vehicle belongs to a transient roll control state and is not in a limit grip control state;

a limit grip control damping force determination unit configured to determine a limit grip control damping force according to the vehicle control parameter when a current vehicle is in a limit grip control state;

and a target current determining unit for determining a damper 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.

Through the technical means, the system can judge the roll control state of the current vehicle according to the acquired vehicle control parameters when in operation, the roll control state is divided into the steady roll control state, the transient roll control state and the limit ground grabbing control state in more detail in the control process, and different control damping forces are determined according to different control states, so that the control target current of the shock absorber is obtained, the control scene is richer, and the applicability is higher.

The third aspect of the application provides a vehicle, which adopts the whole vehicle semi-active suspension control method to calculate the control target current of the shock absorber.

The application also provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the vehicle semi-active suspension control method.

The application has the beneficial effects that:

(1) The application designs a detailed control method for dividing the rolling control of the whole vehicle into steady rolling control, transient steering control and limit ground grabbing control, has more abundant application scenes and is more suitable for the actual rolling control scenes;

(2) In the transient roll control, the dynamic robustness is considered in transient steering, and the defect that the damping force is searched for and continuously oscillated and the robustness is poor due to abrupt change of the angular velocity of the steering wheel is avoided by keeping for a certain time when the angular velocity of the steering wheel gradually increases to reach the maximum value through dynamic robustness processing;

(3) In the transient roll control, the rising edge and the falling edge are respectively calibrated aiming at the increase or decrease of the angular velocity of the steering wheel, so that the damping force is closer to the actual requirement of a user;

(4) Aiming at the situation that when the over-bending speed is high, the grip performance is possibly insufficient when the vehicle is in a limit state, the method provides limit grip control for the state that the damping requirement is opposite to the transient roll control large damping, and is beneficial to the full lateral acceleration range management and control;

(5) When the control target current of the shock absorber is finally determined, the influence of the road surface characteristic is fully considered, the output damping force is more fit with the actual scene, and the user experience is improved.

Drawings

FIG. 1 is a flowchart of a method for controlling a semi-active suspension of a whole vehicle according to an embodiment of the present application;

fig. 2 is a schematic diagram of a roll control operating area of the whole vehicle provided by the application;

FIG. 3 is a schematic diagram of a roll control sensor architecture for an entire vehicle in accordance with an embodiment of the present application;

FIG. 4 is a diagram of dynamic robustness effects in an embodiment of the present application;

FIG. 5 is a table of road surface gain factor look-up in an embodiment of the present application;

FIG. 6 is a schematic block diagram of roll control for the whole vehicle in an embodiment of the application;

FIG. 7 is a schematic block diagram of transient roll control in an embodiment of the present application;

FIG. 8 is a block diagram of a semi-active suspension control system for a whole vehicle in accordance with an embodiment of the present application.

The system comprises an M70-signal processing module, an M701-sensor signal processing module, an M702-CAN signal conversion module, an M703-signal filtering processing module and an M704-vehicle state signal estimation module;

the system comprises an M90-main control method module, an M901-steady-state roll control module, an M902-transient roll control module, an M903-limit ground grabbing control module, an M904-road surface characteristic influence factor estimation module, an M905-damping force current conversion module, an M902-1-transient steering basic damping force calculation module and an M902-2-transient steering dynamic damping force Fsb calculation module;

11-front left altitude sensor, 12-front left acceleration sensor, 21-front right altitude sensor, 22-front right acceleration sensor, 31-rear left altitude sensor, 32-rear left acceleration sensor, 41-rear right altitude sensor, 60-control module, 13-steering wheel angle sensor;

s11-front left altitude sensor signal, S12-front left acceleration sensor signal, S21-front right altitude sensor signal, S22-front right acceleration sensor signal, S31-rear left altitude sensor signal, S32-rear left acceleration sensor signal, S33-lateral acceleration signal, S41-rear right altitude sensor signal, S43-longitudinal acceleration signal, S53-steering wheel rotational speed signal, S63-lateral acceleration signal.

Detailed Description

Further advantages and effects of the present application will become readily apparent to those skilled in the art from the disclosure herein, by referring to the accompanying drawings and the preferred embodiments. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be understood that the preferred embodiments are presented by way of illustration only and not by way of limitation.

It should be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the illustrations, not according to the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

The embodiment of the application provides a method for controlling a semi-active suspension of a whole vehicle, as shown in fig. 1, comprising the following steps:

and acquiring and analyzing the vehicle signals to obtain vehicle control parameters.

In the method, the whole vehicle roll control is mainly based on a whole vehicle roll control working area schematic diagram shown in fig. 2, and an area where the steering wheel angular speed SwaRate is lower than a certain threshold value and the lateral acceleration Ay is lower than a certain threshold value in an actual overcurved scene is a steady roll control area (for example, the steering wheel is slowly driven at the steering wheel angular speed lower than 5deg/s to carry out left turning running); in addition, for example, when the vehicle overtakes during daily lane changing, the steering wheel has larger angular velocity, and the area is in a transient roll control area; when the lateral acceleration is greater than the limit determination threshold and the duration is greater than the time threshold, then the limit grip control region is in. The threshold value in the judging condition can be calibrated according to the actual requirement of the vehicle in the specific vehicle type. When the vehicle is in different control areas, the corresponding roll control targets of the whole vehicle are inconsistent, and the requirements on damping force of the shock absorber are inconsistent, for example, the steady-state roll angle of the vehicle is improved mainly by increasing the damping force in a steady-state roll control area; the vehicle roll angle speed is improved mainly through damping force quick response in a transient roll control area; the vehicle load transfer is improved in the limit grip control region mainly by reducing the left-right damping force difference, thereby improving the vehicle limit grip.

In an embodiment of the present application, the vehicle control parameters include: vehicle operating parameters, suspension state parameters, vehicle intrinsic parameters, and vehicle state parameters. The vehicle running parameters represent the running state of the vehicle, the suspension state parameters represent the state of the current suspension, the suspension control basis is provided, and the vehicle inherent parameters are required to be used for assisting in determining the control state and the control damping force of the suspension, and the vehicle state parameters reflect the current posture of the vehicle.

and acquiring a CAN signal and converting the CAN signal into vehicle operation parameters. In an embodiment of the present application, the vehicle operation parameters include: vehicle speed, lateral acceleration, longitudinal acceleration, steering wheel angle and steering wheel angular velocity, which may be converted according to offsets, amplification factors or limits in the vehicle dynamic body control system DBC parameter table. The obtained signals such as lateral acceleration, longitudinal acceleration and the like need to be subjected to low-pass filtering processing, so that the vehicle roll control is mainly concentrated on low-frequency operation stability control, and the signals are filtered to the vehicle roll attitude control related to smoothness.

Suspension sensor signals are acquired as suspension state parameters. In an embodiment of the present application, the suspension state parameters include: at least three of a vehicle body front left acceleration, a vehicle body front right acceleration, a vehicle body rear left acceleration, a vehicle body rear right acceleration, and a front left height sensor parameter, a front right height sensor parameter, a rear left height sensor parameter, and a rear right height sensor parameter. The vehicle body acceleration is mainly used for calculating the pitch angle and the roll angle of the vehicle, the roll angle of the vehicle needs to be calculated according to two vehicle body accelerations of the same row, the pitch angle of the vehicle needs to be calculated according to two vehicle body accelerations of the same side, and based on the vehicle body acceleration, the pitch angle and the roll angle of the vehicle can be calculated by randomly collecting three of the vehicle body front left acceleration, the vehicle body front right acceleration, the vehicle body rear left acceleration and the vehicle body rear right acceleration. In one embodiment of the present application, three sprung acceleration sensors are employed to collect vehicle body acceleration, a front left acceleration sensor, a front right acceleration sensor, and a rear left acceleration sensor, respectively. After the suspension sensor signal is obtained, noise reduction processing is carried out on the sensor signal, and the data accuracy is improved.

As shown in fig. 3, the sensors arranged in the present embodiment are shown, in the figure, 10 is a vehicle chassis, a front left-height sensor 11 and a front left acceleration sensor 12 are arranged on a left front wheel of the vehicle, a front right-height sensor 21 and a front right acceleration sensor 22 are arranged on a right front wheel of the vehicle, a rear left-height sensor 31 and a rear left acceleration sensor 32 are arranged on a left rear wheel of the vehicle, a rear right-height sensor 41 is arranged on a rear right wheel of the vehicle, the front left-height sensor 11 acquires a front left-height sensor signal S11 and transmits to the control module 60, and the front right-height sensor 21 acquires a front right-height sensor signal S21 and transmits to the control module 60; the rear left height sensor 31 collects a rear left height sensor signal S31 and transmits the signal to the control module 60; the rear right height sensor 41 collects a rear right height sensor signal S41 and transmits it to the control module 60; the front left acceleration sensor 12 collects a front left acceleration sensor signal S12 and transmits it to the control module 60; the front right acceleration sensor 22 collects a front right acceleration sensor signal S22 and transmits it to the control module 60; the rear left acceleration sensor 32 collects a rear left acceleration sensor signal S32 and transmits it to the control module 60. Also shown is a steering wheel angle sensor 13, in the present application, a steering wheel angle signal S13 is derived from the CAN signal. It should be noted that, the control module 60 in the present application may be an original controller of the vehicle.

The intrinsic parameters of the vehicle are acquired. In an embodiment of the present application, the intrinsic parameters of the vehicle include: vehicle preparation mass, wheelbase, centroid height, front axle roll stiffness, and rear axle roll stiffness. The parameters can be stored in a storage device on the vehicle, obtained through a calling mode, or can be directly provided for the semi-active suspension control method of the whole vehicle through an assignment mode.

The vehicle state parameter is estimated based on the suspension state parameter and the vehicle intrinsic parameter. In an embodiment of the present application, the vehicle state parameter includes: vehicle roll angle, shock absorber speed, unsprung acceleration, and vehicle pitch angle.

In an embodiment of the present application, estimating a vehicle state parameter from a suspension state parameter and a vehicle intrinsic parameter includes: estimating shock absorber speed, estimating vehicle roll angle, estimating unsprung acceleration, and estimating vehicle pitch angle.

Wherein estimating the damper speed comprises:

according to the height sensor parameter of the current position, looking up a table to obtain a suspension displacement Ds corresponding to the current position;

differentiating according to the suspension displacement Ds corresponding to the current position to obtain a suspension relative speed Vs corresponding to the current position;

The suspension relative speed Vs corresponding to the current position is multiplied by the damper lever ratio i to obtain an estimated damper speed Vd, vd=vs. Wherein the damper lever ratio i is a vehicle-specific parameter. The suspension displacement is obtained through the table lookup of suspension state parameters acquired by the sensor, and the speed of the shock absorber can be estimated according to the suspension displacement.

Estimating the unsprung acceleration includes:

performing twice differentiation according to the suspension displacement corresponding to the current position to obtain a suspension relative acceleration As corresponding to the current position;

subtracting the suspension relative acceleration As corresponding to the current position from the vehicle body acceleration Ab corresponding to the current position to obtain unsprung acceleration aw=ab-As corresponding to the current position. Suspension displacement is obtained through the table lookup of suspension state parameters acquired by the sensor, and unsprung acceleration can be estimated according to the suspension displacement.

Estimating the vehicle roll angle includes:

And estimating the roll angle of the vehicle according to the left and right vehicle body displacement difference and the corresponding wheel track of the front row or the rear row.

Estimating the pitch angle of the vehicle includes:

The displacement difference of two points in the same row of the vehicle reflects the roll attitude of the vehicle, the displacement difference of the left and right vehicle bodies can be obtained through the displacement difference integrated by two times of acceleration of any row of the vehicle, and the roll angle of the vehicle is obtained by combining the wheel track calculation; the displacement difference of two points on the same side of the vehicle reflects the pitching attitude of the vehicle, the displacement difference of the front and rear vehicle bodies can be obtained through the displacement difference integrated by two times of two accelerations on any side of the vehicle, the pitch angle of the vehicle is obtained through combination with wheelbase calculation, and the current attitude of the vehicle is fully reflected.

In one embodiment of the present application, the vehicle body acceleration acquired by the sprung acceleration sensor is: vehicle body front left acceleration, vehicle body front right acceleration, and vehicle body rear left acceleration. Therefore, when the roll angle of the vehicle is calculated, the front left acceleration of the vehicle body, the front right acceleration of the vehicle body and the wheel tread of a front axle are adopted; the roll angle calculation formula of the vehicle is as follows:

Wherein, the liquid crystal display device comprises a liquid crystal display device,for vehicle roll angle, A _bfL For the front left acceleration of the car body, A _bfR The Track is the Track of the front axle, and 57.3 is the inherent parameter of radian and angle conversion.

When the pitch angle of the vehicle is calculated, adopting the front left acceleration of the vehicle body, the rear left acceleration of the vehicle body and the wheelbase; the calculation formula of the pitch angle of the vehicle is as follows:

wherein θ is the pitch angle of the vehicle, A _brL The vehicle body rear left acceleration and WB is the wheelbase.

if the current steering wheel angular speed is not greater than the first steering wheel angular speed threshold value and the lateral acceleration is not greater than the first lateral acceleration threshold value, judging that the current vehicle belongs to a steady-state roll control state, wherein a main control target of the steady-state roll control state is a steady-state roll angle, the requirement on stability is higher, and the requirement on the corresponding speed is relatively smaller.

And if the current steering wheel angular speed is greater than the first steering wheel angular speed threshold value and the lateral acceleration is greater than the first lateral acceleration threshold value, judging that the current vehicle belongs to the transient roll control state. The main control objective of the transient roll control state is roll angle speed, which is relatively less responsive to stability demands.

According to the technical scheme, the rolling control state of the vehicle can be determined through the steering wheel angular speed and the lateral acceleration, and a dividing standard is provided for finer rolling control. In the embodiment of the application, the first steering wheel angular speed threshold and the first lateral acceleration threshold are calibrated according to the vehicle.

and performing steady-state vibration damper damping force table lookup according to the lateral acceleration to obtain steady-state rolling control damping force, wherein each vibration damper determines to obtain one steady-state rolling control damping force.

By the aid of the technical means, steady-state roll control damping force can be rapidly confirmed, influences of scenes such as crosswind are considered, the vehicle semiautomatic suspension control is realized by looking up table output of damping force of the shock absorber through lateral acceleration, and fluctuation of steering wheel rotation angle serving as input is avoided.

Considering that when the vehicle is over-bent and out-bent, the lateral acceleration is not established or reduced, and the steering wheel angle is increased or the steering wheel angle input is reduced by the driver, if the damping force is calibrated based on the lateral acceleration, the response is slower than the expected response of the driver. When the transient roll control state condition is met, the transient steering basic damping force is calculated through the steering wheel angle and the vehicle speed, the transient roll control trigger is considered when the steering wheel angle speed is large, the transient steering dynamic damping force is calculated through the steering wheel angle speed and the vehicle speed, and the transient steering basic damping force and the transient steering dynamic damping force are output through superposition calculation.

and determining the transient steering basic damping force according to a table look-up of the lateral acceleration or a table look-up of the steering wheel angle and the vehicle speed. In the embodiment of the application, damping force one-dimensional table lookup can be performed according to lateral acceleration, or two-dimensional table lookup can be performed according to steering wheel rotation angle and vehicle speed.

The method for determining the transient steering dynamic damping force by looking up a table according to the vehicle speed and the steering wheel angular velocity specifically comprises the following steps:

and carrying out dynamic robustness processing on the steering wheel angular velocity to obtain the dynamic steering wheel angular velocity. When the angular velocity of the steering wheel of the vehicle reaches a peak value, the phenomenon of reduction exists at the next moment, and the angular velocity of the steering wheel is kept at the peak value for a certain time when reaching the peak value through dynamic robustness processing, so that the instant pressure relief feeling caused by fluctuation is avoided, the feeling of transverse abrupt change of the vehicle is avoided, the abrupt change of the angular velocity of the steering wheel is avoided, the continuous vibration of the damping force searching is avoided, and the robustness is poor. As shown in fig. 4, the processed steering wheel angular velocity is a dynamic steering wheel angular velocity dynswaray, and the steering wheel angular velocity before processing is swaray, and it can be seen from the figure that the dynamic steering wheel angular velocity is kept at a peak value for a certain time when being reduced after the peak value through dynamic robustness processing.

Calibrating different requirements of damping force when considering rising edge and falling edge; when the angular speed of the steering wheel is in the same direction as the steering wheel angle and is continuously increased, the steering wheel rises, and the damping force is required to be larger; otherwise, the damping force is properly reduced, so that when the transient steering dynamic damping force is determined, whether the angular speed of the dynamic steering wheel is in phase with the steering wheel angle is firstly judged;

superposing the transient steering basic damping force and the transient steering dynamic damping force to obtain a transient roll control damping force:

F _s ＝F _sb +F _ss ；

wherein F is _s Controlling damping force for transient roll, F _sb F for transient steering base damping force _ss Is a transient steering dynamic damping force.

Or obtaining the maximum value of the transient steering base damping force and the transient steering dynamic damping force as a transient roll control damping force:

F _s ＝Max(F _sb ，F _ss )。

The transient roll control damping force determined by the technical means fuses the steering wheel angular speed and the lateral acceleration to control, and is more practical. In order to avoid too strong transient effects, which may lead to poor late and ride performance combinations, it is recommended to use a superposition-mode calculated transient roll control damping force. Each shock absorber calculates a transient roll control damping force.

estimating tire vertical force according to vehicle control parameters;

The tire vertical force estimation mainly comprises three parts, namely transverse load transfer, longitudinal load transfer and mass distribution amount calculation, and in the embodiment of the application, the tire vertical force estimation according to the vehicle control parameters comprises the following steps:

lateral load transfer is estimated based on vehicle control parameters. The transverse load transfer mainly refers to load transfer caused by centrifugal force of a vehicle and load transfer caused by gravity of the vehicle, and the calculation formula is as follows:

wherein m is the vehicle preparation quality; a, a _y Is the lateral acceleration; h is the centroid height;is the roll angle of the vehicle; />The roll angle rigidity of the front axle; />Is the back shaft roll angle stiffness; track is Track, g is gravitational acceleration.

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

wherein a is _x Is the longitudinal acceleration; θ is the pitch angle of the vehicle; WB is the vehicle wheelbase.

The mass distribution amount is estimated based on the vehicle control parameters. The mass distribution amount mainly refers to the distribution of the self gravity of the vehicle, and the calculation formula is as follows:

wherein b is the distance between the center of mass and the center of the rear axle.

And calculating the vertical force of each tire according to the mass distribution amount, the transverse load transfer and the longitudinal load transfer. The vertical force of each tire is calculated using the following formula:

F _zfL ＝F _{z_m} -F _{z_lon} -F _{z_lat} ；

F _zfR ＝F _{z_m} -F _{z_lon} +F _{z_lat} ；

F _zrL ＝F _{z_m} +F _{z_lon} -F _{z_lat} ；

F _zrR ＝F _{z_m} +F _{z_lon} +F _{z_lat} ；

After substituting the mass distribution amount, the lateral load transfer and the longitudinal load transfer into the above formulas, each tire vertical force calculation formula is expressed as:

by the technical means, the longitudinal load transfer, the transverse load transfer, the mass distribution amount and the vertical force of each tire can be calculated, the calculated parameters are based on the current vehicle parameters, and the accuracy is high. By the technical means, the tire vertical force can be obtained through calculation according to the vehicle control parameters, and data support is provided for judging the limit ground grabbing control state.

calculating the difference value between each tire vertical force and a preset tire vertical force threshold value; the preset tire vertical force threshold value for calculating the difference value is the same value as the preset tire vertical force threshold value for determining the limit grip control state.

And looking up a table according to the difference value to obtain a damping force discount coefficient, calibrating the damping force discount coefficient according to the difference value between the tire vertical force and a preset tire vertical force threshold value, and increasing the damping force discount coefficient when the difference value is larger.

And determining a transient roll control damping force according to the vehicle control parameter. The transient roll control damping force determination is consistent with the foregoing.

Calculating a product of the transient roll control damping force and the damping force discount coefficient as a limit grip control damping force:

F _sf ＝F _s *G _lim (Table(abs(F _z -F _noml )))；

wherein F is _sf For controlling damping force to limit grip _lim F for damping force discount coefficient _z The vertical force of the tire corresponding to the current shock absorber; table (abs (F) _z -F _noml ) For tire normal force and preset tire normal force threshold F) _nom1 Is the difference between G and G _lim Is a one-dimensional table look-up result. Each shock absorber calculates a limit grip control damping force.

and determining the current road surface grade according to the current vehicle speed and the unsprung acceleration. In the embodiment of the application, the grading of the road surface grade is customized according to the performance requirements of specific vehicle types. In the process of customizing the road surface grade grading, different road surface data sets are firstly established, such as rural roads, broken roads, smooth asphalt roads, rough cement roads and the like, the road surface sets can be selected and formulated according to the requirements of specific vehicle types, and then the road surface grade is graded and customized on different road surfaces and at different vehicle speeds by combining unsprung acceleration.

And determining a gain coefficient by looking up a table according to the grade of the current road surface and the current vehicle speed. A two-dimensional table of vehicle speed, road surface level and gain factor is established according to the actual vehicle calibration, and the table is shown in fig. 5. During use of the real vehicle, the gain coefficient is determined according to the table. As shown in fig. 5, in the two-dimensional table, road surface levels are indicated, and the rows indicate vehicle speeds. When the road surface grade is 1 grade and the current vehicle speed is vspd1, the gain is G11, and other road surface grades and vehicle speeds are checked according to the table.

Multiplying the steady-state roll control damping force, the limit ground grabbing control damping force or the transient roll control damping force by a gain coefficient to obtain a target output damping force;

As shown in fig. 6, a schematic block diagram of the roll control of the entire vehicle is provided in the application embodiment. The semi-active suspension control of the whole vehicle is mainly divided into two large modules: the signal processing module M70 and the main control method module M90, wherein the main control method module M90 is also suitable for other sensor architectures (such as fig. 3) and signal processing methods not shown in the present application, and can be flexibly applied to other sensor architectures and signal processing methods.

The signal processing module M70 mainly includes sub-modules: the system comprises a sensor signal processing module M701, a CAN signal conversion module M702, a signal filtering processing module M703 and a vehicle state signal estimation module M704. The sensor signals in this embodiment mainly include 4 height sensor signals, a front left height sensor signal S11, a front right height sensor signal S21, a rear left height sensor signal S31, a rear right height sensor signal S41, and 3 acceleration sensor signals, a front left acceleration sensor signal S12, a front right acceleration sensor signal S22, and a rear left acceleration sensor signal S32. The sensor signal processing mainly comprises the steps of judging the effectiveness of a sensor and adopting low-pass filtering with adjustable cut-off frequency to perform noise reduction processing. The CAN signal conversion module M702 mainly includes CAN signal validity determination such as a steering wheel rotation angle signal S13, a vehicle speed signal S23, a lateral acceleration signal S33, a longitudinal acceleration signal S43, a steering wheel rotation speed signal S53, a lateral acceleration signal S63, and the like, and performs conversion according to a DBC parameter table (offset, amplification factor, limit value) of the vehicle dynamic body control system. When the reading of the sensor signal and the CAN signal is completed, a signal filtering processing module M703 is needed according to the requirement, and the filtering processing of the module mainly focuses on the improvement of the vehicle operation stability, so that the module mainly covers a low frequency band and adopts a low cut-off frequency to carry out low-pass filtering processing, thereby realizing the design of a high-middle-low frequency division control method. The vehicle state signal estimation module M704 mainly includes a damper speed estimation, an unsprung acceleration estimation, a vehicle roll angle estimation, a vehicle pitch angle estimation, a vehicle parameter assignment, and the like.

The signal processing module M70 performs related signal processing, and transmits the signal 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 for determining a steady-state roll control damping force; the transient roll control module M902 is for determining a transient roll control damping force; the limit grip control module M903 is configured to determine a limit grip control damping force; the road surface characteristic influence factor estimation module M904 is configured to determine a target output damping force taking the road surface characteristic influence factor into consideration; the damping force current conversion module M905 is used for looking up a table to output a current value according to the inverse model of the shock absorber or according to the test external characteristic curve of the shock absorber.

As shown in fig. 7, the transient roll control module M902 includes a transient steering base damping force calculation module M902-1 and a transient steering dynamic damping force Fsb calculation module M902-2. In this embodiment, the transient steering base damping force calculation module M902-1 performs two-dimensional table lookup calculation of Fsb through the steering wheel angle and the vehicle speed to obtain the transient steering base damping force. The transient steering dynamic damping force Fsb calculation module M902-2 includes a method of dynamic robustness improvement and rising and falling edge separation. Obtaining a dynamic steering wheel angular speed DynSwaRat after dynamic robustness processing, when the dynamic steering wheel angular speed DynSwaRat is in the same direction as a steering wheel angle, judging that the steering wheel angular speed is in an ascending trend, and searching an ascending edge damping force Fsu by referring to the vehicle speed and the steering wheel angular speed; when DynSwaRat is opposite to the steering wheel angle, the steering wheel angular velocity is judged to be in a descending trend, the descending-edge damping force Fsd is searched by referring to the vehicle speed and the steering wheel angular velocity, and finally, fsu or Fsd is output as transient steering dynamic damping force Fss.

And finally, carrying out superposition calculation on the transient steering basic damping force Fsb and the transient steering dynamic damping force Fss to obtain the transient roll control damping force Fs.

A second aspect of the present application provides a vehicle semi-active suspension control system, as shown in fig. 8, including:

While the application has been described in detail in connection with a limited number of examples, it should be readily understood that the application is not limited to such disclosed embodiments. Rather, the application can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the application. Further, while various embodiments of the application have been described, it is to be understood that aspects of the application may include only some of the described embodiments. Furthermore, the application is not to be seen as limited by the foregoing description.

Claims

1. The method for controlling the semi-active suspension of the whole vehicle is characterized by comprising the following steps of:

acquiring and analyzing a vehicle signal to obtain a vehicle control parameter;

2. The vehicle semi-active suspension control method of claim 1, wherein the vehicle control parameters include: vehicle operating parameters, suspension state parameters, vehicle intrinsic parameters, and vehicle state parameters;

the vehicle state parameters include: vehicle roll angle, shock absorber speed, unsprung acceleration, and vehicle pitch angle.

3. The method for controlling a semi-active suspension of a whole vehicle according to claim 2, wherein obtaining and analyzing a vehicle signal to obtain a vehicle control parameter comprises:

acquiring a suspension sensor signal as a suspension state parameter;

acquiring intrinsic parameters of a vehicle;

4. The vehicle semi-active suspension control method according to claim 3, wherein estimating the vehicle state parameter from the suspension state parameter and the vehicle intrinsic parameter comprises:

Estimating damper speed:

estimating a vehicle roll angle:

estimating unsprung acceleration:

estimating a pitch angle of the vehicle:

5. The entire vehicle semi-active suspension control method according to claim 2, characterized in that judging the roll control state to which the current vehicle belongs according to the vehicle control parameter includes:

6. The vehicle semi-active suspension control method of claim 2, wherein determining a steady-state roll control damping force from the vehicle control parameter comprises:

7. The vehicle semi-active suspension control method according to claim 2, wherein determining whether the vehicle is currently in a limit grip control state according to the vehicle control parameter includes:

estimating tire vertical force according to vehicle control parameters;

8. The vehicle semi-active suspension control method of claim 7, wherein estimating tire vertical force based on vehicle control parameters comprises:

estimating lateral load transfer based on vehicle control parameters;

estimating longitudinal load transfer based on the vehicle control parameters;

9. The vehicle semi-active suspension control method of claim 8, wherein the lateral load transfer is estimated using the formula:

the longitudinal load transfer is estimated using the following formula:

the mass distribution amount is estimated by the following formula:

wherein b is the center distance of the centroid from the rear axle;

the vertical force of each tire was calculated using the following formula:

F _zfL ＝F _{z_m} -F _{z_lon} -F _{z_lat} ；

F _zfR ＝F _{z_m} -F _{z_lon} +F _{z_lat} ；

F _zrL ＝F _{z_m} +F _{z_lon} -F _{z_lat} ；

F _zrR ＝F _{z_m} +F _{z_lon} +F _{z_lat} ；

10. The vehicle semi-active suspension control method of claim 2, wherein determining a limit grip control damping force based on the vehicle control parameter comprises:

11. The vehicle semi-active suspension control method of claim 1, wherein determining a transient roll control damping force based on the vehicle control parameter comprises:

12. The vehicle semi-active suspension control method of claim 11, wherein determining the transient steering dynamic damping force based on the vehicle speed and the steering wheel angular velocity comprises:

13. The vehicle semi-active suspension control method of claim 11, wherein calculating a transient roll control damping force from the transient steering base damping force and the transient steering dynamic damping force comprises:

14. The entire vehicle semi-active suspension control method according to claim 2, characterized in that determining a shock absorber control target current according to the steady-state roll control damping force, limit grip control damping force, or transient roll control damping force in combination with road surface characteristics includes:

15. A vehicle semi-active suspension control system, the system comprising:

16. A vehicle characterized in that it calculates a damper control target current using the whole vehicle semi-active suspension control method according to any one of claims 1 to 14.

17. A computer-readable storage medium, on which a computer program is stored, characterized in that the program, when executed by a processor, implements the vehicle semi-active suspension control method according to any one of claims 1 to 14.