VEHICLE WITH A CURVE TILTING FUNCTION

Abstract

A vehicle having an active chassis system with curve tilting function, comprises a control unit, which when negotiating a curve determines a vehicle tilting angle on the basis of a current vehicle transverse acceleration or a correlated driving operation parameter, by which the vehicle transverse acceleration can be reduced, wherein the control unit uses the vehicle tilting angle so determined to trigger actuators of a suspension/shock absorbing system in order to adjust the vehicle tilting angle. The curve tilting function incorporates a prediction unit which provides the curve negotiation data for an upcoming curve. The vehicle tilting angle is set in consideration of the curve negotiation data.

Claims

1. A vehicle having an active chassis system with curve tilting function, comprising: a control unit, which when negotiating a curve determines a vehicle tilting angle on the basis of a current vehicle transverse acceleration or a correlated driving operation parameter, by which the vehicle transverse acceleration can be reduced, wherein the control unit uses the vehicle tilting angle so determined to trigger actuators of a suspension/shock absorbing system in order to adjust the vehicle tilting angle, wherein the curve tilting function incorporates a prediction unit which provides curve negotiation data for an upcoming curve, and the vehicle tilting angle is set in consideration of the curve negotiation data.

2. The vehicle according to claim 1, wherein the control unit is connected upstream in the signal flow direction to a low pass filter, which generates from the detected current vehicle transverse acceleration a modified transverse acceleration signal by signal filtering, and with the aid of this the control unit determines the vehicle tilting angle.

3. The vehicle according to claim 2 wherein the signal filter behavior of the low pass filter depends on its corner frequency, that is, a low corner frequency results in a smooth transverse acceleration signal with little signal noise, but great latency, corresponding to the delay time resulting from the signal filtering, and/or a high corner frequency results in a transverse acceleration signal with large signal noise, but small latency.

4. The vehicle according to claim 2, wherein the curve tilting function comprises an adapter unit, which adapts the signal filter behavior of the low pass filter.

5. The vehicle according to claim 4 wherein the adapter unit adjusts a corner frequency of the low pass filter on the basis of the curve negotiation data.

6. The vehicle according to claim 5, wherein the prediction unit provides a counting-down duration up to the instant of entering the curve, and the adapter unit comprises a comparator, which compares the lead-up time to a threshold value, and if the lead-up time is greater than the threshold value the adapter unit sets the corner frequency at a low value, and/or the adapter unit sets the corner frequency at a high value as soon as the lead-up time falls below the threshold value to a high set time.

7. The vehicle according to claim 5, wherein the prediction unit provides a curve negotiating time, which lies between the instant of entering the curve and an instant of exiting the curve.

8. The vehicle according to claim 7 wherein the curve negotiating time is divided up into a curve entry time, an average curve travel time, and a curve exit time.

9. The vehicle according to claim 7, wherein the adapter unit maintains the corner frequency at the high value in a time interval between the high set time and the expiration of the curve entry time, and the adapter unit maintains the corner frequency at the low value after expiration of the curve entry time, that is, during the average curve travel time and/or during the curve exit time, and/or during a straight stretch of road.

10. The vehicle according to claim 1, wherein the curve tilting function is associated with a deactivation unit having a comparator, which compares the curve negotiating time with a threshold value, and the deactivation unit generates a blocking signal for the deactivation of the curve tilting function once the curve negotiating time is less than the threshold value.

11. The vehicle according to claim 1, wherein the prediction unit generates a model for the time variation of the vehicle tilting angle calculated for the upcoming curve, and the prediction unit uses this to provide the curve negotiation data regarding the upcoming curve for the adapter unit, that is, the lead-up time, the curve negotiating time, the curve entry time, the average curve travel time, and the curve exit time.

12. The vehicle according to claim 4, wherein the prediction unit determines the instant at which a predefined threshold value is exceeded in the model of the vehicle tilting angle to be the instant of entering the curve.

13. The vehicle according to claim 4, wherein the prediction unit determines the instant at which a predefined threshold value is decreased in the model of the vehicle tilting angle to be the instant of exiting the curve.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0034] In the following, an embodiment shall be described with the aid of the accompanying figures.

[0035] FIG. 1 is a circuit block diagram illustrating a curve tilting function of a vehicle.

[0036] FIGS. 2 to 4 are respective views illustrating the mode of operation of the curve tilting function while traveling different curves.

DETAILED DESCRIPTION

[0037] The circuit block diagram of FIG. 1 describes a curve tilting function 10 which is integrated in an active chassis system of a vehicle. The curve tilting function 10 comprises a sensor device 1, by means of which the current transverse acceleration a.sub.ist can be detected. The sensor device 1 is connected downstream in the signal flow direction from a low pass filter 3 and a control unit 5 connected to it. The control unit 5 is composed of a calculator 7 and a signal generator 9. This is in signal connection with actuators 11 of a suspension/shock absorbing system of the vehicle. The low pass filter 3 generates from the current vehicle transverse acceleration a.sub.ist by signal filtering a modified transverse acceleration signal a.sub.mod, which is presented at the signal input of the calculator 7 of the control unit 5. Using the modified transverse acceleration signal a.sub.mod, the calculator 7 determines a vehicle tilting angle α. On this basis, control signals for the actuators 11 of the suspension/shock absorbing system of the vehicle are determined in the signal generator 9, with which the actuators 11 are controlled to adjust the vehicle tilting angle α while negotiating a curve.

[0038] In some embodiments, a prediction unit 13 is incorporated in the curve tilting function 10, which provides curve negotiation data D on an upcoming curve. The setting of the tilting angle α is done in consideration of these curve negotiation data D. In FIG. 1, the curve negotiation data D generated in the prediction unit 13 are read out in an adapter unit 15. The adapter unit 15 uses the curve negotiation data D to adapt a corner frequency f of the low pass filter 3, with which the signal filter behavior of the low pass filter 3 can be changed. That is, a low corner frequency f.sub.niedrig results in a smooth transverse acceleration signal a.sub.mod with low signal noise, but with large latency. The latency indicates the delay time due to the signal filtering occurring in the low pass filter. Conversely, a high corner frequency f.sub.hoch results in a transverse acceleration signal a.sub.mod with large signal noise, but slight latency.

[0039] In the prediction unit 13, a model is created for the time variation α(t) of the vehicle tilting angle α calculated for the upcoming curve negotiation on the basis of the curve trend of the upcoming road curve, on the basis of the current vehicle speed v, and on the basis of the current vehicle position P in a road map stored in the prediction unit 13. The prediction unit 13 uses the time variation α(t) to determine the relevant curve negotiation data D for the upcoming curve negotiation. These data are the remaining lead-up time Δtv until the instant of entering the curve t.sub.KE and the curve negotiation time Δt.sub.k, extending from the instant of entering the curve t.sub.KE to the instant of exiting the curve t.sub.KA. Furthermore, in the model of the prediction unit 13 shown in FIG. 1, the curve negotiating time Δt.sub.K is divided into a curve entry time Δt.sub.KE, an average curve travel time Δt.sub.KDF, and a curve exit time Δt.sub.KA.

[0040] The adapter unit 15 comprises a comparator, which compares the lead-up time Δt.sub.v to a threshold value Δt.sub.vs. If the lead-up time Δt.sub.v is greater than the threshold value Δt.sub.vs, the adapter unit 15 sets the corner frequency f at a low value f.sub.niedrig. On the other hand, the adapter unit 15 sets the corner frequency f at a high value f.sub.hoch once the lead-up time Δt.sub.v falls below the threshold value Δt.sub.vs. This occurs in the model of the prediction unit 13 at a high set time t.sub.start.

[0041] Furthermore, the adapter unit 15 maintains the corner frequency f at the high value f.sub.hoch in a time interval between the high set time t.sub.start and the expiration t.sub.ende of the curve entry time Δt.sub.KE. On the other hand, the adapter unit 15 resets the corner frequency f at the low value f.sub.niedrig after expiration t.sub.ende of the curve entry time Δt.sub.KE, that is, during the average curve travel time Δt.sub.KDF and the curve exit time Δt.sub.KA.

[0042] As further emerges from FIG. 1, the curve tilting function 10 is associated with a deactivation unit 19 having a comparator 21 and with a signal generating unit 23. The comparator 21 compares the curve negotiating time Δt.sub.K with a threshold value Δt.sub.KS. If the curve negotiating time Δt.sub.K is less than the threshold value Δt.sub.KS, the signal generating unit 23 generates a blocking signal S, with which the curve tilting function 10 can be deactivated.

[0043] The prediction unit 13 defines the instant at which the vehicle tilting angle α in the model exceeds a predefined threshold value as the instant of entering the curve t.sub.KE. Furthermore, the prediction unit 13 defines the instant at which the vehicle tilting angle α in the model falls below a predefined threshold value as the instant of exiting the curve t.sub.KA.

[0044] In FIG. 2 is shown a time sequence t.sub.1 to t.sub.4 of the tilting angle α of a vehicle 25 (indicated roughly from the rear) as set by a curve tilting function 10 during the negotiating of a road curve 27. The setting of the tilting angle α is performed in FIG. 2 by a comparison curve tilting function known in the prior art with no prediction (that is, without a prediction unit 13 and without an adapter unit 15) and by a curve tilting function 10 with prediction (that is, with a prediction unit 13 and with an adapter unit 15). As can be seen from FIG. 2 in combination with FIG. 1, upon reaching the high set time t.sub.start the corner frequency f is set by the adapter unit 15 at a high value f.sub.hoch. In this way, the tilting angle α can be established already at an early time t.sub.2 during the negotiating of the curve. By contrast with this, in the comparison curve tilting function without prediction the establishing of the tilting angle α occurs only at a time t.sub.3 with a delay time Δt after the time t.sub.2.

[0045] FIG. 3 shows the negotiating of a curve on a road curve 27 consisting of two alternating curves in immediate succession. In the curve tilting function 10 with prediction, the curve negotiating time Δt.sub.K is determined in the prediction unit 13 at which the curve tilting function 10 can presumably be activated. In the scenario shown in FIG. 3, for example, the curve negotiating time Δt.sub.K determined in the prediction unit 13 is less than a threshold value Δt.sub.KS stored in the deactivation unit 19. Accordingly, the curve tilting function 10 remains deactivated during the curve negotiation. By contrast with this, the comparison curve tilting function without prediction known in the prior art remains active. The vehicle passengers therefore experience a continual establishing and removing of the tilting angle α when moving through the alternating curves in immediate succession, resulting in a loss of comfort.

[0046] FIG. 4 shows another negotiating of a curve with a long curve trend. Due to the long curve trend, short compensatory steering movements of the driver occur, for example to remain in the driving lane. In this case, it is desirable for the curve tilting function 10 to respond with less sensitivity to changes in the transverse acceleration produced by driver input after the curve entry time Δt.sub.KE, that is, during the average curve travel time Δt.sub.KDF and during the curve exit time Δt.sub.KA. This is achieved with the aid of the adapter unit 13, which sets the corner frequency f at a low value f.sub.niedrig during the average curve travel time Δt.sub.KDF and during the curve exit time Δt.sub.KA.

[0047] German patent application no. 10 2021 123306.2, filed Sep. 9, 2021, to which this application claims priority, is hereby incorporated herein by reference, in its entirety. Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.