DE102017206055B4 - Method and device for regulating dampers in a vehicle - Google Patents

Abstract

Method for damper control in a vehicle, with damping of movements of the vehicle about the vertical, longitudinal and transverse axes based on a determination of information about the movement of the vehicle body as well as information about vertical relative movements between the vehicle body and wheels, wherein the determination of the information about vertical relative movements between the vehicle body and wheels takes place on the basis of measurements with at least two height sensors, which are assigned to the wheels of a front axle of the vehicle, characterized in that exactly two height sensors on the wheels of the front axle and none on the wheels of the rear axle Height sensors are provided, and that the determination of information about vertical relative movements between the vehicle body and wheels for the wheels assigned to the rear axle of the vehicle takes place with the aid of a wheelbase-based forecast estimate, in which the vertical trigger Reductions of the wheels of the rear axle are estimated based on the vertical deflection of the wheels of the front axle as well as on the basis of the wheelbase and the longitudinal speed of the vehicle, with the vertical relative movements between the vehicle body and the wheels for the rear axle being estimated based on the fact that after a certain period of time (Δt) move the rear wheels over the same road profile as the front wheels, this time span (Δt) being given as the quotient of the wheelbase length L and the vehicle speed (V).

Description

The invention relates to a method and a device for regulating dampers in a vehicle. In particular, the invention relates to a method and a device for damper control according to the preamble of claims 1 and 6, respectively.

The electronic damper control (CCD = "Continuously Controlled Damping") is a system or method for electronic chassis adjustment with the aim of reducing movements around the vertical, longitudinal and transverse axes (i.e. lateral inclination and pitching movements). The implementation of such a damper control requires a lot of information about the movements of the vehicle body (i.e. vertical, pitching and rolling movement) and the vehicle wheels (i.e. vertical movement). In particular, four height sensors (two per axle) are conventionally used to measure the vertical relative movements between the body and vehicle wheels. Furthermore, a sensor arrangement (“sensor cluster / inertial sensors”) is used in combination with an estimation algorithm for measuring or estimating the body movements.

In practice, the problem arises that installation space requirements and the costs of the sensors in question contribute significantly to the complexity and costs of the overall system.

Out DE 100 12 131 A1 Among other things, a chassis control system for vehicles is known in which it is used that the disturbances detected directly on the right and left front wheel can be felt on the right and left rear wheel after a time delay depending on the vehicle dimensions and the speed being driven. Because of this time delay between the front axle and the rear axle, a desired normal force is determined at a known vehicle speed and set on the rear wheels with the help of a roll stabilization system.

Out DE 196 05 504 A1 is known, inter alia, a suspension control or regulation system for a motor vehicle, wherein shock absorbers are arranged between the sprung and unsprung masses of the vehicle at the front and rear wheel-side support positions in order to change the damping characteristics. First of all, the vehicle conditions are recorded at the support positions on the front wheel. A predetermined transfer function is then used in order to determine, as a second step, the states of the vehicle at the support positions on the rear wheel based on the vehicle states that were detected first. However, the use of vertical body acceleration sensors positioned on the two front body corners to control the damping characteristics of the shock absorbers attached to the support positions on the front or rear wheel side results in a relatively complex control method and, due to the body-based control, is only used in accordance with this approach Displacements in the low frequency range (typically for frequencies below 4 Hz) are effective.

From the generic DE 10 2010 048 260 A1 It is known to determine the compression travel of the two wheels of a vehicle on a twist beam axle with the help of a single displacement sensor arranged on the twist beam axle and with the aid of the path-dependent signal history of two displacement sensors on an axle of the vehicle in front of it in the direction of travel, with the compression displacement determined in this way the twist beam axle can be used in particular for online chassis fault diagnosis in the vehicle.

It is an object of the present invention to provide a method and a device for damper control which enable the damping of movements of the vehicle about the vertical, longitudinal and transverse axes with comparatively little complexity.

This object is achieved by the method according to the features of independent patent claim 1 and the device according to the features of independent patent claim 6.

In a method according to the invention for regulating dampers in a vehicle, movements of the vehicle about the vertical, longitudinal and transverse axes are damped on the basis of a determination of both information about the movement of the vehicle body and information about vertical relative movements between the vehicle body and wheels, wherein the determination of the information about vertical relative movements between the vehicle body and the wheels takes place on the basis of measurements with at least two height sensors which are assigned to the wheels of a front axle of the vehicle.

The method is characterized in that exactly two height sensors are provided on the wheels of the front axle and no height sensors are provided on the wheels of the rear axle, and the determination of information about vertical relative movements between the vehicle body and wheels for the wheels assigned to a rear axle of the vehicle with the help of a wheelbase-based forecast estimate takes place, the vertical deflections of the wheels of the rear axle being estimated on the basis of the vertical deflection of the wheels of the front axle as well as on the basis of the wheelbase of the vehicle, with the vertical relative movements between the vehicle body and the wheels for the rear axle being estimated based thereon, that after a certain period of time Δt the rear wheels move over the same road profile as the front wheels, this period of time Δt being given as the quotient of the wheelbase length L and the vehicle speed V.

The present invention is based, in particular, on the concept of reducing the number of height sensors required in a method or a device for damper control by replacing height sensors on the rear axle in that, to this extent, vertical relative movements between the vehicle body and wheels by way of a wheelbase-based forecast Estimation can be determined.

Both interlinked sensor information (“sensor fusion”) and wheelbase information are used. The sensor fusion is based on the metrologically determined signals for the body condition and the measured vertical relative movements between the front wheels and the body. The wheelbase information or wheelbase-based prediction is based on the fact that after a certain period of time Δt the rear wheels move over the same road profile as the front wheels, this period of time being given as the quotient of the wheelbase length L and the vehicle speed V.

As a result, the method according to the invention can significantly reduce the complexity and costs of damper control.

According to one embodiment, only vertical deflections with a frequency above a predetermined threshold value are taken into account using a high-pass filter. This threshold value can in particular be 10 Hz.

The invention also includes, in particular, the concept of transferring relative deflections or movements between the vehicle body and the wheels assigned to the front axle of the vehicle to the rear axle on the basis of a forecast assessment. As a result, only two height sensors on the front axle can be used to estimate the absolute movements of the rear wheels, which in turn is required to control or regulate a semi-active suspension system in the high-frequency range with deflections of up to 10 Hz and thereby improve the handling and safety behavior of the vehicle .

The method according to the invention differs from conventional approaches in particular in that neither acceleration nor laser or camera sensors are used for damper control, since according to the invention only a control based on (vertical) wheel deflections is implemented.

In particular, a high-pass filter can be used in the damper control according to the invention or in the estimation of the vertical deflections of the wheels of the rear axle, with the result that only deflections with a frequency above a threshold value are taken into account. In embodiments of the invention this threshold value may e.g. B. 10Hz.

In other words, preferably, e.g. B. by using a 10 Hz high-pass filter, according to the invention only the - driving safety-relevant - higher-frequency deflections or disturbances are taken into account, but not the low-frequency fluctuations (which can be corrected by the "normal" vehicle dynamics control).

According to one embodiment, the information about vertical relative movements between the vehicle body and the wheels is determined on the basis of a measurement with precisely two height sensors.

According to one embodiment, the damper control takes place without the use of acceleration sensors or camera-based sensors.

The invention further relates to a device which is configured to carry out a method having the features described above. For advantages and preferred configurations of the device, reference is made to the above statements in connection with the method according to the invention.

Further refinements of the invention can be found in the description and in the subclaims.

The invention is explained in more detail below on the basis of an exemplary embodiment with reference to the accompanying drawings.

• 1 ein Blockdiagramm zur Erläuterung wesentlicher Komponenten bei der Durchführung des erfindungsgemäßen Verfahrens; und
• 2a-b Diagramme zum Vergleich von gemäß der Erfindung erhaltenen Resultaten mit Ergebnissen einer modellbasierten Simulation.

Show it:

• 1 a block diagram to explain essential components when performing the method according to the invention; and
• 2a-b Diagrams for comparing results obtained according to the invention with results of a model-based simulation.

1 first shows a block diagram to explain essential components when carrying out the method according to the invention.

According to 1 takes place in a method according to the invention for damper control in a with " 20th "Designated function block an estimation of the body and wheel states on the basis of information both about relative movements between the vehicle body and wheels as well as information concerning the movement of the vehicle body, whereby signals of a sensor cluster (" inertial sensors ") 10 , Signals from height sensors 11 and 12 , which are assigned to the wheels of the front axle of the vehicle, as well as CAN signals 13 be used.

Based on this in the function block 20th The actual electronic damper control ("CCD control", CCD = "Continuously Controlled Damping") takes place in the function block after the assessment of the body and wheel conditions 30th , whereby to reduce movements of the vehicle about the vertical, longitudinal or transverse axis (ie of lateral inclination and pitching movements) the corresponding dampers on the wheels of the vehicle are controlled accordingly. In 1 is the damper of the left front wheel (= VL) with " 41 ", The damper of the right front wheel (= VR) with" 42 ", The damper of the left rear wheel (= HL) with" 43 "And the damper of the right rear wheel (= HR) with" 44 " designated.

As already from 1 As can be seen, in the method and device according to the invention for damper control, apart from the two height sensors 11 and 12 No further height sensors are required on the front axle of the vehicle, since the information about the vertical relative movement between the vehicle body and these wheels, which is also required for damper control, is determined for the wheels of the rear axle with the help of a wheelbase-based forecast estimate explained below.

In the following, the variables measured at the center of gravity of the vehicle or the body are designated as follows: The vertical deflection of the body is designated with Z _b , the roll angle with ψ _b and the pitch angle with φ _b . The distances from the front and rear axles to the center of gravity and the wheel track have been designated with I _f I _r and b. $$\left[\begin{array}{c}{Z}_{b_{fl}}\\ Z_{b_{fr}}\\ Z_{b_{rl}}\\ Z_{b_{rr}}\end{array}\right]=\left[\begin{array}{c}{Z}_b\\ {\psi }_b\\ {\phi }_b\end{array}\right]\cdot \left[\begin{array}{l}\hfill \\ 1\hfill \\ 1\hfill \\ 1\hfill \\ 1\hfill \\ \hfill \end{array}\begin{array}{c}\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.\\ -\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.\\ \raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.\\ -\raisebox{1ex}{$b$}\!\left/ \!\raisebox{-1ex}{$2$}\right.\end{array}\begin{array}{l}\hfill \\ l_f\hfill \\ l_f\hfill \\ -l_r\hfill \\ -l_r\hfill \\ \hfill \end{array}\right]$$

This results in the vertical deflections of the body at the four corners of the vehicle, which are referred to below as Z _{b fl} (front left), Z _{b fr} (front right), Z _{b rl} (back left) and Z _{b rr} (back right). The measurements on the two height sensors on the front axle show the relative movement or Vertical deflection between the body and the respective wheel at ΔZ _fl and ΔZ _fr . The respective vertical deflections of the wheels on the front axle Z _{w fl} (front left) and Z _{w fr} (front right) can be determined.

The respective vertical deflections of the wheels on the rear axle Z _w are therefore still unknown _rl (back left) and Z _{w rr} (back right). In this respect, a wheelbase-based forecast is now made on the basis of the consideration that after a period of time Δt the rear wheels move over the same road profile as the front wheels, this period of time Δt being given as the quotient of wheelbase length L and vehicle speed V, ie: $$\mathrm{\Delta }t=\frac{\mathrm{L.}}{V}$$

In the following, the respective equations of motion of the front and rear wheels are solved using this fact.

$$K_{s_f}\left(Z_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)+C_{s_f}\left({\dot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\dot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)=M_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}$$

$$M_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}=-K_{t_f}\left(Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-Z_{o_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)+M_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}$$

For example, the equations of motion for the left front wheel are: $$\begin{array}{c}{\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{f\left(t-\mathrm{\Delta }t\right)}}=-K_{t_f}\left(Z_{w_{f\left(t-\mathrm{\Delta }t\right)}}-Z_{O_{f\left(t-\mathrm{\Delta }t\right)}}\right)+K_{s_f}\left(Z_{b_{f_{f\left(t-\mathrm{\Delta }t\right)}}}-Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)\\ +{\mathrm{C.}}_{s_f}\left({\dot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\dot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)\end{array}$$

$$K_{s_f}\left(Z_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)+{\mathrm{C.}}_{s_f}\left({\dot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\dot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)={\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}$$

$${\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}=-K_{t_f}\left(Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-Z_{O_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}\right)+{\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}$$

Here and in the following, “M” denotes the respective masses and “Z” denotes the respective vertical deflections of the wheels (index “w”) or the body (index “b”). "K" denotes the respective stiffnesses and "C" denotes the respective damping of the chassis (index "s") or the tires (index "t") the rear wheels are indexed with a subscript “r”. In the case of a second subscript, the corresponding size for a left wheel is indicated with “l” and for a right wheel with “r”.

Since after a period of time Δt the rear wheels move over the same road profile as the front wheels, the following applies after the period of time Δt. $$Z_{O_{r\left(t\right)}}=Z_{O_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}$$

$$M_{w_r}{\ddot{Z}}_{w_{r\left(t\right)}}=-K_{t_r}\left(Z_{w_{{}_{r\left(t\right)}}}-Z_{o_{{}_{r\left(t\right)}}}\right)+M_{b_r}{\dot{Z}}_{b_{{}_{r\left(t\right)}}}$$

The equations of motion of the rear wheels are: $$\begin{array}{l}{\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{r\left(t\right)}}=-K_{t_r}\left(Z_{w_{r\left(t\right)}}-Z_{O_{r\left(t\right)}}\right)+K_{s_r}\left(Z_{b_{r\left(t\right)}}-Z_{w_{r\left(t\right)}}\right)+{\mathrm{C.}}_{s_r}\left({\dot{Z}}_{b_{r\left(t\right)}}-{\dot{Z}}_{w_{r\left(t\right)}}\right)\left(\mathrm{7th}\right)\\ K_{s_r}\left(Z_{b_{r\left(t\right)}}-Z_{w_{r\left(t\right)}}\right)+{\mathrm{C.}}_{s_r}\left(Z_{b_{r\left(t\right)}}-{\dot{Z}}_{w_{r\left(t\right)}}\right)={\mathrm{M.}}_{b_r}{\ddot{Z}}_{b_{r\left(t\right)}}\left(\mathrm{8th}\right)\end{array}$$

$${\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{r\left(t\right)}}=-K_{t_r}\left(Z_{w_{{}_{r\left(t\right)}}}-Z_{O_{{}_{r\left(t\right)}}}\right)+{\mathrm{M.}}_{b_r}{\dot{Z}}_{b_{{}_{r\left(t\right)}}}$$

Out ( 5 ) and ( 9 ) follows $${\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{{}_{r\left(t\right)}}}=-K_{t_f}{Z}_w{}_{{}_{f\left(t-\mathrm{\Delta }t\right)}}+K_{t_r}{Z}_w{}_{{}_{{}_{r\left(t\right)}}}+{\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\mathrm{M.}}_{b_r}{\ddot{Z}}_{b_{{}_{r\left(t\right)}}}$$

It follows from this: $$K_{t_r}{Z}_{w_{{}_{r\left(t\right)}}}=K_{t_f}{Z}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}+{\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}-{\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{{}_{r\left(t\right)}}}+{\mathrm{M.}}_{b_r}{\ddot{Z}}_{b_{{}_{r\left(t\right)}}}$$

und mit K_tf = K_tr= K_t ergibt sich $$Z_{w_{{}_{r\left(t\right)}}}=Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}+\frac{M_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_t}-\frac{M_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_t}-\frac{M_{w_r}{\ddot{Z}}_{w_{{}_{r\left(t\right)}}}}{K_t}+\frac{M_{b_r}{\ddot{Z}}_{b_{{}_{r\left(t\right)}}}}{K_t}$$

It follows: $$Z_{w_{{}_{r\left(t\right)}}}=\frac{K_{t_f}{Z}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_{t_r}}+\frac{{\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_{t_r}}-\frac{{\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_{t_r}}-\frac{{\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{{}_{r\left(t\right)}}}}{K_{t_r}}+\frac{{\mathrm{M.}}_{b_r}{\ddot{Z}}_{b_{{}_{r\left(t\right)}}}}{K_{t_r}}$$

and with K _tf = K _tr = K _t we get $$Z_{w_{{}_{r\left(t\right)}}}=Z_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}+\frac{{\mathrm{M.}}_{w_f}{\ddot{Z}}_{w_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_t}-\frac{{\mathrm{M.}}_{b_f}{\ddot{Z}}_{b_{{}_{f\left(t-\mathrm{\Delta }t\right)}}}}{K_t}-\frac{{\mathrm{M.}}_{w_r}{\ddot{Z}}_{w_{{}_{r\left(t\right)}}}}{K_t}+\frac{{\mathrm{M.}}_{b_r}{\ddot{Z}}_{b_{{}_{r\left(t\right)}}}}{K_t}$$

This equation of motion ( 13 ) in connection with the mentioned high-pass filter (with a cut-off frequency of typically approx. 10 Hz) can be used to determine the absolute vertical deflections for the rear wheels. Chassis control taking these deflections into account can improve the manageability and safety of the vehicle, for example with regard to behavior when driving over larger and / or deeper potholes (“pothole driving events”).

In 2a and 2 B diagrams for comparing results obtained according to the invention with the result of a model-based simulation are plotted for different areas of the time scale. A comparison of the respective curves shows a very good agreement of the results obtained according to the invention with those of the model-based simulation.

Claims (6)

Method for damper control in a vehicle, with damping of movements of the vehicle about the vertical, longitudinal and transverse axes based on a determination of information about the movement of the vehicle body as well as information about vertical relative movements between the vehicle body and wheels, wherein the determination of the information about vertical relative movements between the vehicle body and wheels based on measurements with at least two height sensors, which are assigned to the wheels of a front axle of the vehicle, characterized in that exactly two height sensors on the wheels of the front axle and none on the wheels of the rear axle Height sensors are provided, and that the determination of information about vertical relative movements between the vehicle body and the wheels for the wheels assigned to the rear axle of the vehicle takes place with the aid of a wheelbase-based forecast estimate, in which the vertical out Steering of the wheels of the rear axle can be estimated on the basis of the vertical deflection of the wheels of the front axle as well as on the basis of the wheelbase and the longitudinal speed of the vehicle, with the vertical relative movements between the vehicle body and the wheels for the rear axle being estimated based on that, after a certain period of time (Δt) move the rear wheels over the same road profile as the front wheels, this time span (Δt) being given as the quotient of the wheelbase length L and the vehicle speed (V). Procedure according to Claim 1 , characterized in that when estimating the vertical deflections of the wheels of the rear axle using a high-pass filter, only vertical deflections with a frequency above a predetermined threshold value are taken into account. Procedure according to Claim 2 , characterized in that this threshold value is 10Hz. Method according to one of the Claims 1 to 3 , characterized in that the information about relative movements between the vehicle body and wheels is determined on the basis of a measurement with exactly two height sensors. Method according to one of the preceding claims, characterized in that the damper control takes place without the use of acceleration sensors or camera-based sensors. Device for regulating dampers in a vehicle, characterized in that the device is configured to carry out a method according to one of the preceding claims.

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