CN117183641A - Control method of semi-active suspension system - Google Patents
Control method of semi-active suspension system Download PDFInfo
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Abstract
The application provides a control method of a semi-active suspension system, which comprises the following steps: determining the real-time frequency of road disturbance according to the telescopic speed signal of a damper in a semi-active suspension system of the vehicle; according to the driving mode of the vehicle at the current moment and the real-time frequency of road disturbance, determining control gain parameters which are adopted by a control module of the semi-active suspension system at the current moment by searching a control gain scheduling table constructed in advance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments; and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters. Therefore, the damper control parameters can be determined according to the driving mode and the real-time frequency of road disturbance, so that the semi-active suspension system can keep good performance under the full road input frequency band.
Description
Technical Field
The application relates to the technical field of automotive suspensions, in particular to a control method of a semi-active suspension system.
Background
The main source of disturbance in the semi-active suspension system is the excitation of the wheel by the uneven road, and the performance of the control module in the semi-active suspension system is obviously changed along with the change of the road surface input frequency due to the characteristics of the suspension system.
However, the control performance of the existing semi-active suspension system is highly dependent on a given fixed control parameter, and the robustness is poor, and the given fixed control parameter can usually only exert the optimal performance in a specific road disturbance frequency band, but the optimal frequency band cannot cover the frequency band where the full road disturbance may occur, so that the performance limitation of the control method of the existing semi-active suspension system is caused.
Disclosure of Invention
In view of the above, the present application aims to provide a control method of a semi-active suspension system, which can determine a damper control parameter according to a driving mode and a real-time frequency of road disturbance, so that the semi-active suspension system can maintain good performance in an all-road input frequency band.
The embodiment of the application provides a control method of a semi-active suspension system, which comprises the following steps:
determining the real-time frequency of road disturbance according to the telescopic speed signal of a damper in a semi-active suspension system of the vehicle;
according to the driving mode of the vehicle at the current moment and the real-time frequency of road disturbance, determining control gain parameters which are adopted by a control module of the semi-active suspension system at the current moment by searching a control gain scheduling table constructed in advance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments;
and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters.
Further, the determining the real-time frequency of the road disturbance according to the telescopic speed signal of the damper in the semi-active suspension system of the vehicle comprises the following steps:
continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes;
when absolute values of the expansion speeds of two adjacent time nodes are all larger than a preset speed threshold, and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes;
when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment;
and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
Further, the determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period includes:
judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not;
if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance;
and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
Further, the control gain schedule is constructed by:
the state quantity and the control quantity of the vehicle are selected, and a dynamics equation of the semi-active suspension system is converted into a state space equation;
constructing a cost function according to the state space equation by using a bilinear quadratic regulator;
solving a Richa lifting equation corresponding to the cost function to obtain optimal control gain parameters under different driving modes and different road surface disturbance frequency intervals;
and constructing the control gain scheduling table according to the corresponding relation among the driving mode, the road disturbance frequency interval and the optimal control gain parameter.
Further, the system model includes: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the control gain parameters include: a single wheel vertical gain parameter and a half vehicle roll gain parameter; the control module comprises a single-wheel suspension control unit and a roll suspension control unit; and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters, and the method comprises the following steps:
generating a damping force and a damping coefficient of the vertical control of the damper based on the single-wheel vertical semi-active suspension model by taking the single-wheel vertical gain parameter as a linear state feedback value;
generating a damping force and a damping coefficient of roll control of the damper based on the semi-vehicle roll semi-active suspension model by taking the semi-vehicle roll gain parameter as a linear state feedback value;
the damper is controlled by the single wheel suspension control unit in accordance with the damping force and damping coefficient of the vertical control, and by the roll suspension control unit in accordance with the damping force and damping coefficient of the roll control.
The embodiment of the application also provides a control device of the semi-active suspension system, which comprises:
the frequency identification module is used for determining the real-time frequency of road disturbance according to the telescopic speed signal of the damper in the semi-active suspension system of the vehicle;
the gain scheduling module is used for determining control gain parameters which are adopted by the control module of the semi-active suspension system at the current moment by searching a pre-constructed control gain scheduling table according to the driving mode of the vehicle at the current moment and the real-time frequency of road surface disturbance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments;
and the generation module is used for generating the control parameters of the damper according to the control gain parameters and the system model of the semi-active suspension system so that the control module controls the damper according to the control parameters.
Further, the frequency identification module is used for determining the real-time frequency of road disturbance according to the telescopic speed signal of the damper in the semi-active suspension system of the vehicle, and the frequency identification module is used for:
continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes;
when absolute values of the expansion speeds of two adjacent time nodes are all larger than a preset speed threshold, and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes;
when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment;
and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
Further, when the frequency identification module is used for equivalently determining the real-time frequency of the road surface disturbance according to the frequency of the telescopic speed signal in the current period, the frequency identification module is used for:
judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not;
if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance;
and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
According to the control method of the semi-active suspension system, provided by the embodiment of the application, the damper control parameters are determined according to the driving mode and the road disturbance real-time frequency, so that the semi-active suspension system can keep good performance under the whole road input frequency band.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
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In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart illustrating a method of controlling a semi-active suspension system according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a method for determining a real-time frequency of a road disturbance according to a telescopic speed signal of a damper according to an embodiment of the present application;
FIG. 3 is a logic flow diagram of a method for determining a real-time frequency of a road disturbance based on a telescopic speed signal of a damper according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a single wheel vertical semi-active suspension system according to an embodiment of the present application;
FIG. 5 illustrates a schematic structural diagram of a semi-vehicle roll semi-active suspension system provided by an embodiment of the present application;
FIG. 6 is a schematic diagram of a control gain schedule provided by an embodiment of the present application;
fig. 7 is a schematic structural diagram of a control device of a semi-active suspension system according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. The components of the embodiments of the present application generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the application, as presented in the figures, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, every other embodiment obtained by a person skilled in the art without making any inventive effort falls within the scope of protection of the present application.
It is found that the disturbance in the semi-active suspension system is mainly caused by the excitation of the uneven road to the wheels, and the performance of the control module in the semi-active suspension system is obviously changed along with the change of the road surface input frequency due to the characteristics of the suspension system.
However, the control performance of the existing semi-active suspension system is highly dependent on a given fixed control parameter, and the robustness is poor, and the given fixed control parameter can usually only exert the optimal performance in a specific road disturbance frequency band, but the optimal frequency band cannot cover the frequency band where the full road disturbance may occur, so that the performance limitation of the control method of the existing semi-active suspension system is caused.
Based on the above, the embodiment of the application provides a control method of a semi-active suspension system, which can determine the control parameters of a damper according to the driving mode and the real-time frequency of road disturbance, so that the semi-active suspension system can maintain good performance under the full road input frequency band.
Referring to fig. 1, fig. 1 is a flowchart of a control method of a semi-active suspension system according to an embodiment of the application. As shown in fig. 1, a control method provided by an embodiment of the present application includes:
s101, determining the real-time frequency of road disturbance according to the telescopic speed signal of a damper in a semi-active suspension system of the vehicle.
In the step, firstly, the telescopic speed signal of the damper is sampled, and then the real-time frequency of road surface disturbance is accurately determined by combining a zero crossing method and a filtering algorithm.
In one possible implementation, step S101 may include: continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes; when absolute values of the expansion speeds of two adjacent time nodes are all larger than a preset speed threshold, and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes; when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment; and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
Referring now to fig. 2, fig. 2 is a schematic diagram illustrating a method for determining a real-time frequency of a road disturbance according to a telescopic speed signal of a damper according to an embodiment of the present application. As shown in fig. 2, the telescopic speed signal of the damper is sampled, and the sampling period is Δt; in the figure, a curve 1 represents a telescopic speed signal, an arrow represents a time axis, scales on the time axis represent sampling time nodes, and T 1 、T 2 The dots represent zero-penetration time and the expansion speed S corresponding to different sampling time nodes k (k=0, 1,2,3, … …) is used to detect zero-crossings. The method provided by the embodiment of the application is based on a zero penetration method, and the real-time frequency of road surface disturbance can be estimated by detecting three continuous zero penetration, and the formula is expressed as follows:
in the precise zero-penetration time T 1 、T 2 Can be obtained by sampling a time node (S 0 ，S 1 ) Sum (S) 2 ，S 3 ) Linear interpolation.
In order to improve the robustness of the frequency determination method, the embodiment of the application combines a filtering algorithm while using a zero crossing method, specifically, when the absolute value of the expansion speed corresponding to two adjacent time nodes at zero-crossing time is too close to zero, namely, the absolute value is smaller than or equal to a preset speed threshold sigma, the expansion speed signal between the two adjacent time nodes is considered to be zero-crossing at the moment, namely, zero-crossing time does not exist once, at the moment, the real-time frequency of road surface disturbance identified in the last period is kept, and the subsequent zero-crossing time is continuously detected. Therefore, fine high-frequency vibration of the vehicle on the rough road surface with small amplitude can be filtered, and the real-time frequency of road surface disturbance can be accurately determined.
Further, the determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period may include: judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not; if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance; and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
Here, after detecting that there are three continuous zero-crossing times, determining the frequency f (k) of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing time and two adjacent time nodes with the last zero-crossing time, and judging whether the difference between the frequency f (k) of the current period and the frequency f (k-1) of the previous period is greater than a preset difference threshold; if the frequency of the current period is larger than the current period, determining that distortion occurs, discarding the determined frequency of the telescopic speed signal in the current period, and keeping the identification result of the previous period, namely, re-determining the frequency of the telescopic speed signal in the previous period as the frequency of the telescopic speed signal in the current period, and equivalently determining the frequency of the telescopic speed signal in the previous period as the real-time frequency of road surface disturbance; if the speed signal is not greater than the current period, the frequency of the determined telescopic speed signal in the current period can be reserved, and the equivalent frequency is determined as the real-time frequency of the road surface disturbance.
In this way, the method for determining the real-time frequency of the road disturbance provided by the embodiment of the application takes the zero crossing method as a main body, the calculation amount and the memory amount which are required to be occupied in the operation process are very small, the defects of long calculation time, overlarge occupied memory and the like of the existing frequency estimation algorithm are overcome, and the cost can be effectively saved; meanwhile, the distortion points are removed through filtering after the estimated frequency is obtained, and the accuracy and the robustness of the frequency determining method can be improved.
Referring now to fig. 3, fig. 3 is a logic flow diagram illustrating a method for determining a real-time frequency of a road disturbance according to a telescopic speed signal of a damper according to an embodiment of the present application. As shown in FIG. 3, where n z For recording the current zero-crossing times, N represents the number of sampling points separated among three zero-crossings, N s The current sampling period is recorded.
Firstly, inputting a telescoping speed S corresponding to a current k sampling time node k If S is satisfied k S k-1 <0 and |S k |>σ，|S k-1 |>Sigma is regarded as S k And S is equal to k-1 There is one zero-crossing between the two times of zero-crossing n z Adding 1; if not, then describe S k And S is equal to k-1 Zero penetration does not exist between the sampling time nodes, the sampling time nodes are increased by 1, and the real-time frequency of the road surface disturbance determined in the previous period is kept unchanged, namely f (k) =f (k-1).
Thereafter, if n z =1, i.e. the first zero-crossing occurs, the current sampling period is recorded, and the first zero-crossing time T is calculated by interpolation 1 The method comprises the steps of carrying out a first treatment on the surface of the If n z Increasing the sampling time node by 1 when the frequency of the road disturbance determined in the previous period is not changed, namely f (k) =f (k-1); if n z =3, at which time the presence has been detectedCalculating the last zero-crossing time T by interpolation at three continuous zero-crossing times 2 And calculates the frequency of the telescoping speed signal at the current period, i.e., f (k).
Finally, judging whether the difference value between the frequency f (k) of the current period and the frequency f (k-1) of the previous period is larger than a preset difference value threshold Max or not; if the frequency of the current period is greater than the current period, determining that distortion occurs, and discarding the frequency of the determined telescopic speed signal in the current period, and keeping the identification result of the previous period, namely f (k) =f (k-1); if the frequency of the determined telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, namely the frequency f (k) of the current period is output, the frequency of the determined telescopic speed signal in the current period can be reserved, and the equivalent of the frequency is determined as the real-time frequency of the road surface disturbance.
S102, according to the driving mode of the vehicle at the current moment and the real-time frequency of the road disturbance, determining control gain parameters which are adopted by a control module of the semi-active suspension system at the current moment by searching a pre-constructed control gain scheduling table.
The control module refers to a software control algorithm running in the semi-active suspension system and is used for controlling the damper; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through simulation experiments and/or real vehicle experiments. The driving mode may include a comfort mode, a sport mode, and the like; the road disturbance frequency interval is divided into a low frequency band, a high frequency band and the like according to the self characteristics of the semi-active suspension system, such as first-order and second-order natural frequencies.
In the step, after the real-time frequency of road surface disturbance is determined, the control gain parameters which should be adopted by the control module at the current moment can be searched in the control gain scheduling table in a table look-up mode by combining the driving mode set by the user.
In one possible implementation, the control gain schedule may be constructed by:
and step 1, selecting the state quantity and the control quantity of the vehicle, and converting the dynamic equation of the semi-active suspension system into a state space equation.
Referring to fig. 4 and 5, fig. 4 is a schematic structural diagram of a single-wheel vertical semi-active suspension system according to an embodiment of the present application; fig. 5 shows a schematic structural diagram of a semi-vehicle roll semi-active suspension system according to an embodiment of the present application. As shown in fig. 4 and 5, 6 denotes a controllable damper, 7 denotes a sprung mass of the vehicle, 8 denotes a suspension spring, 9 denotes an uncontrollable damper, 10 denotes a wheel mass, 11 denotes a wheel equivalent spring, and 12 denotes an equivalent stabilizer bar.
Accordingly, the system model comprises: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the construction process of the control gain schedule is described below by taking a single-wheel vertical semi-active suspension model as an example.
The dynamic equation of the constructed semi-active suspension system can be expressed as follows in combination with the vehicle dynamics principle:
the state quantity of the selected vehicle is as follows:wherein z is b Representing sprung mass displacement, z t Representing the unsprung mass displacement, at this point, the state space equation for the semi-active suspension system can be expressed as:
y＝Cx+Du
where u is a control amount, and w is a road disturbance, and represents a damping force of a damper (controllable damper 6) in the semi-active suspension system.
Design method based on bilinear quadratic regulator, in bilinear system, control input is regarded asDamping coefficient u c Thus, the state space equation can be further expressed as:
wherein x is * Indicating the expansion and contraction speed of the damper.
And 2, constructing a cost function according to the state space equation by using a bilinear quadratic regulator.
Here, when the input is irregular, since the state quantity is a random variable, the construction cost function from the control quantity and the control quantity in the state space equation of the vehicle can be expressed as:
and step 3, solving the Richa lifting equation corresponding to the cost function to obtain the optimal control gain parameters under different driving modes and different road surface disturbance frequency intervals.
In the step, the Richa lifting equation corresponding to the cost function is solved, and the gain parameters are optimally controlled under different driving modes and different road surface disturbance frequency intervals. For example, parameters of a Q, R matrix are adjusted by means of computer simulation and expert adjustment, and optimal control gain parameters corresponding to different road surface disturbance frequency intervals in a driving mode are obtained aiming at comfort performance (vehicle vertical acceleration) and steering performance (tire force) of a semi-active suspension system.
The method for obtaining the optimal control gain parameter of the semi-vehicle roll semi-active suspension model is the same as the above steps of the single-wheel vertical semi-active suspension model, and the difference point is only that the dynamic equations of the two are different, and the detailed description is omitted.
And 4, constructing the control gain scheduling table according to the corresponding relation among the driving mode, the road disturbance frequency interval and the optimal control gain parameter.
Referring now to fig. 6, fig. 6 is a schematic diagram illustrating a control gain schedule according to an embodiment of the present application. As shown in fig. 6, the control gain schedule shows the single wheel vertical gain parameters and the half roll gain parameters corresponding to the single wheel vertical half active suspension model and the half roll half active suspension model, respectively, under different driving modes and different road surface disturbance frequency intervals.
In the specific implementation, the frequency estimation method for determining the real-time frequency of the road surface disturbance by the telescopic speed signal is used for searching the road surface disturbance frequency interval obtained by segmenting the frequency in advance, so that whether the road surface disturbance frequency interval to which the current road surface disturbance real-time frequency belongs is a low frequency band or a high frequency band can be determined; the hysteresis interval is used for preventing frequent switching of frequency estimation results (high/low frequency), and the frequency of switching is reduced by designing a hysteresis algorithm;
meanwhile, the current driving mode can be determined to be a comfortable mode or a motion mode through the manual instruction received by the vehicle;
according to the current road disturbance frequency interval and driving mode, the control gain parameters which the control module of the semi-active suspension system should adopt at the current moment can be determined by looking up the control gain scheduling table shown in fig. 6.
Therefore, the control gain scheduling table provided by the embodiment of the application can divide the frequency into a plurality of road surface disturbance frequency intervals for gain scheduling according to the characteristics of the suspension system, is more in line with the vibration characteristics of the suspension, and can overcome the defect that the traditional control method cannot cover in the full frequency range. The optimal gain parameters generated in the control gain schedule are generated based on the BLQR control algorithm, and compared with the traditional optimal control algorithm, the control performance of optimal control can be further improved. In addition, the control gain schedule is combined with a driving mode, so that more personalized setting space can be provided for a user.
And S103, generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters.
As previously described, the system model includes: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the control gain parameters include: a single wheel vertical gain parameter and a half vehicle roll gain parameter; the control module comprises a single-wheel suspension control unit and a roll suspension control unit; step S103 may include:
generating a damping force and a damping coefficient of the vertical control of the damper based on the single-wheel vertical semi-active suspension model by taking the single-wheel vertical gain parameter as a linear state feedback value; generating a damping force and a damping coefficient of roll control of the damper based on the semi-vehicle roll semi-active suspension model by taking the semi-vehicle roll gain parameter as a linear state feedback value; the damper is controlled by the single wheel suspension control unit in accordance with the damping force and damping coefficient of the vertical control, and by the roll suspension control unit in accordance with the damping force and damping coefficient of the roll control.
The damping force and the damping coefficient of the roll control are required to be fused with those of the vertical control, and a set of final control parameters are generated to jointly control the damper. The specific fusion mode can refer to the related mode in the prior art, and the application is not repeated here.
The control method of the semi-active suspension system provided by the embodiment of the application comprises the following steps: determining the real-time frequency of road disturbance according to the telescopic speed signal of a damper in a semi-active suspension system of the vehicle; according to the driving mode of the vehicle at the current moment and the real-time frequency of road disturbance, determining control gain parameters which are adopted by a control module of the semi-active suspension system at the current moment by searching a control gain scheduling table constructed in advance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments; and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters.
Therefore, the damper control parameters can be determined according to the driving mode and the real-time frequency of road disturbance, so that the semi-active suspension system can keep good performance under the full road input frequency band.
Referring to fig. 7, fig. 7 is a schematic structural diagram of a control device of a semi-active suspension system according to an embodiment of the application. As shown in fig. 7, the control device 600 includes:
the frequency identification module 610 is used for determining the real-time frequency of road disturbance according to the telescopic speed signal of the damper in the semi-active suspension system of the vehicle;
the gain scheduling module 620 is configured to determine, according to a driving mode of the vehicle at a current time and the real-time frequency of the road disturbance, a control gain parameter to be adopted by a control module of the semi-active suspension system at the current time by searching a control gain schedule constructed in advance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments;
and the generating module 630 is configured to generate a control parameter of the damper according to the control gain parameter and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameter.
The frequency identification module 610 is configured to, when determining a real-time frequency of a road disturbance according to a telescopic speed signal of a damper in a semi-active suspension system of a vehicle, the frequency identification module 610 is configured to:
continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes;
when absolute values of the expansion speeds of two adjacent time nodes are all larger than a preset speed threshold, and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes;
when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment;
and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
The frequency identification module 610 is configured to, when configured to determine the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period, the frequency identification module 610 is configured to:
judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not;
if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance;
and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
Further, the control device 600 further includes a construction module; the construction module is configured to construct the control gain schedule by:
the state quantity and the control quantity of the vehicle are selected, and a dynamics equation of the semi-active suspension system is converted into a state space equation;
constructing a cost function according to the state space equation by using a bilinear quadratic regulator;
solving a Richa lifting equation corresponding to the cost function to obtain optimal control gain parameters under different driving modes and different road surface disturbance frequency intervals;
and constructing the control gain scheduling table according to the corresponding relation among the driving mode, the road disturbance frequency interval and the optimal control gain parameter.
Further, the system model includes: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the control gain parameters include: a single wheel vertical gain parameter and a half vehicle roll gain parameter; the control module comprises a single-wheel suspension control unit and a roll suspension control unit; the generating module 630 is configured to, when configured to generate the control parameter of the damper according to the control gain parameter and the system model of the semi-active suspension system, so that the control module controls the damper according to the control parameter, the generating module 630 is configured to:
generating a damping force and a damping coefficient of the vertical control of the damper based on the single-wheel vertical semi-active suspension model by taking the single-wheel vertical gain parameter as a linear state feedback value;
generating a damping force and a damping coefficient of roll control of the damper based on the semi-vehicle roll semi-active suspension model by taking the semi-vehicle roll gain parameter as a linear state feedback value;
the damper is controlled by the single wheel suspension control unit in accordance with the damping force and damping coefficient of the vertical control, and by the roll suspension control unit in accordance with the damping force and damping coefficient of the roll control.
It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.
In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in the embodiments of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.
Finally, it should be noted that: the above examples are only specific embodiments of the present application, and are not intended to limit the scope of the present application, but it should be understood by those skilled in the art that the present application is not limited thereto, and that the present application is described in detail with reference to the foregoing examples: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.
Claims (10)
1. A control method of a semi-active suspension system, the control method comprising:
determining the real-time frequency of road disturbance according to the telescopic speed signal of a damper in a semi-active suspension system of the vehicle;
according to the driving mode of the vehicle at the current moment and the real-time frequency of road disturbance, determining control gain parameters which are adopted by a control module of the semi-active suspension system at the current moment by searching a control gain scheduling table constructed in advance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments;
and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters.
2. The control method according to claim 1, wherein the determining the road disturbance real-time frequency from the telescopic speed signal of the damper in the semi-active suspension system of the vehicle includes:
continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes;
when absolute values of the expansion speeds of two adjacent time nodes are all larger than a preset speed threshold, and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes;
when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment;
and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
3. The control method according to claim 2, wherein the equivalently determining the real-time frequency of the road surface disturbance according to the frequency of the telescopic speed signal in the current period includes:
judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not;
if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance;
and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
4. The control method according to claim 1, characterized in that the control gain schedule is constructed by:
the state quantity and the control quantity of the vehicle are selected, and a dynamics equation of the semi-active suspension system is converted into a state space equation;
constructing a cost function according to the state space equation by using a bilinear quadratic regulator;
solving a Richa lifting equation corresponding to the cost function to obtain optimal control gain parameters under different driving modes and different road surface disturbance frequency intervals;
and constructing the control gain scheduling table according to the corresponding relation among the driving mode, the road disturbance frequency interval and the optimal control gain parameter.
5. The control method according to claim 1, characterized in that the system model includes: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the control gain parameters include: a single wheel vertical gain parameter and a half vehicle roll gain parameter; the control module comprises a single-wheel suspension control unit and a roll suspension control unit; and generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters, and the method comprises the following steps:
generating a damping force and a damping coefficient of the vertical control of the damper based on the single-wheel vertical semi-active suspension model by taking the single-wheel vertical gain parameter as a linear state feedback value;
generating a damping force and a damping coefficient of roll control of the damper based on the semi-vehicle roll semi-active suspension model by taking the semi-vehicle roll gain parameter as a linear state feedback value;
the damper is controlled by the single wheel suspension control unit in accordance with the damping force and damping coefficient of the vertical control, and by the roll suspension control unit in accordance with the damping force and damping coefficient of the roll control.
6. A control device for a semi-active suspension system, the control device comprising:
the frequency identification module is used for determining the real-time frequency of road disturbance according to the telescopic speed signal of the damper in the semi-active suspension system of the vehicle;
the gain scheduling module is used for determining control gain parameters which are adopted by the control module of the semi-active suspension system at the current moment by searching a pre-constructed control gain scheduling table according to the driving mode of the vehicle at the current moment and the real-time frequency of road surface disturbance; the control gain schedule comprises control gain parameters under different driving modes and different road surface disturbance frequency intervals, which are calibrated in advance through experiments;
and the generation module is used for generating the control parameters of the damper according to the control gain parameters and the system model of the semi-active suspension system so that the control module controls the damper according to the control parameters.
7. The control device of claim 6, wherein the frequency identification module is configured to, when configured to determine the real-time frequency of the road disturbance based on a telescopic speed signal of a damper in a semi-active suspension system of the vehicle:
continuously sampling the telescopic speed signal of the damper to obtain telescopic speeds of the damper at a plurality of sampling time nodes;
when the expansion speed of two adjacent time nodes is larger than a preset speed threshold value and the product of the expansion speeds of the two adjacent time nodes is smaller than zero, determining that zero-penetration time exists in an expansion speed signal between the two adjacent time nodes;
when detecting that continuous three zero-crossing moments exist, determining the frequency of the telescopic speed signal in the current period according to two adjacent time nodes with the first zero-crossing moment and two adjacent time nodes with the last zero-crossing moment;
and determining the real-time frequency of the road disturbance according to the frequency equivalent of the telescopic speed signal in the current period.
8. The control device according to claim 7, wherein the frequency identification module, when configured to determine the road disturbance real-time frequency based on the frequency equivalent of the telescopic speed signal at the current period, is configured to:
judging whether the difference value between the frequency of the telescopic speed signal in the current period and the frequency of the telescopic speed signal in the previous period is larger than a preset difference value threshold value or not;
if the frequency of the telescopic speed signal is larger than the frequency of the current period, the frequency of the telescopic speed signal in the previous period is redetermined as the frequency of the telescopic speed signal in the current period, and the frequency of the telescopic speed signal in the previous period is equivalently determined as the real-time frequency of the road disturbance;
and if the frequency of the telescopic speed signal in the current period is not greater than the real-time frequency of the road surface disturbance, equivalently determining the frequency of the telescopic speed signal in the current period as the real-time frequency of the road surface disturbance.
9. The control device of claim 6, further comprising a build module; the construction module is configured to construct the control gain schedule by:
the state quantity and the control quantity of the vehicle are selected, and a dynamics equation of the semi-active suspension system is converted into a state space equation;
constructing a cost function according to the state space equation by using a bilinear quadratic regulator;
solving a Richa lifting equation corresponding to the cost function to obtain optimal control gain parameters under different driving modes and different road surface disturbance frequency intervals;
and constructing the control gain scheduling table according to the corresponding relation among the driving mode, the road disturbance frequency interval and the optimal control gain parameter.
10. The control device of claim 6, wherein the system model comprises: a single wheel vertical semi-active suspension model and a semi-vehicle side-tipping semi-active suspension model; the control gain parameters include: a single wheel vertical gain parameter and a half vehicle roll gain parameter; the control module comprises a single-wheel suspension control unit and a roll suspension control unit; the generation module is used for generating control parameters of the damper according to the control gain parameters and a system model of the semi-active suspension system, so that the control module controls the damper according to the control parameters, and the generation module is used for:
generating a damping force and a damping coefficient of the vertical control of the damper based on the single-wheel vertical semi-active suspension model by taking the single-wheel vertical gain parameter as a linear state feedback value;
generating a damping force and a damping coefficient of roll control of the damper based on the semi-vehicle roll semi-active suspension model by taking the semi-vehicle roll gain parameter as a linear state feedback value;
the damper is controlled by the single wheel suspension control unit in accordance with the damping force and damping coefficient of the vertical control, and by the roll suspension control unit in accordance with the damping force and damping coefficient of the roll control.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311008746.2A CN117183641A (en) | 2023-08-11 | 2023-08-11 | Control method of semi-active suspension system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311008746.2A CN117183641A (en) | 2023-08-11 | 2023-08-11 | Control method of semi-active suspension system |
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