WO2004050395A1 - Method for roadway-dependent signal generation in a motor vehicle - Google Patents

Abstract

Signal generation is provided in a motor vehicle according to road conditions. A reflection signal (FS) emanating from the roadway is picked up by a sensor (1); the sensor (1) transmits an input signal (ES) relating to the state of the roadway to an evaluation unit (2). The input signal (ES) is compared to a reference signal (RS) in the evaluation unit (2). A signal generator (3) generates an output signal (AS1, AS2) provided that the deviation between the input signal and the reference signal (RS) is above a certain threshold (S, S1, S2, S3); the height of the threshold (S, S1, S2, S3) varies according to the degree of deviation between a plurality of input signals (ES) during a given time period (I1,...,I6) and the reference signal (RS). The output signal (AS1, AS2) is, for example, a warning signal (AS1) or a chassis adjustment signal (AS2).

Description

description

Method for signal generation dependent on the roadway in a motor vehicle

The invention relates to a method and a device for signal generation in a motor vehicle depending on the nature of the road.

A device for detecting the state of a road surface in the area of a road vehicle is known for example from DE 43 47 015 C2. With the aid of this device it should be possible to predict the uneven condition of a road surface with any indented or bulged surface areas in front of the moving vehicle in order to influence the control of a suspension or another mechanism in the vehicle.

A method and a device for preventing collisions, in particular for motor vehicles in road traffic, is for example known from US Pat

DE 36 37 165 AI known. Detection of moving or unmoving objects in the area of the roadway and detection of the condition of the road surface are provided. A sensor, which signals the condition of the road, is attached to the side of the vehicle and does not allow predictive vehicle interference.

The invention has for its object to further develop a system for predictive detection of the road condition in a motor vehicle. This object is achieved according to the invention by a method for signal generation in a motor vehicle as a function of the road surface with the features of claim 1 and by a device with the features of claim 8. In a motor vehicle there is a sensor for recording a reflection signal originating from the road intended. The reflection signal can be, for example, a radar signal or an optical signal, a transmitter serving to generate the reflection signal, in particular a radar transmitter or an optical transmitter, preferably being arranged on board the vehicle. The sensor forwards an input signal relating to the condition of the road to an evaluation unit also arranged in the vehicle. In the evaluation unit, the input signal is compared with a reference signal, in the simplest case a comparison value. If the deviation between the input signal and the reference signal is above a threshold, an output signal is generated by a signal generator on board the motor vehicle. The level of the threshold is variable depending on the degree of deviation between a plurality of input signals recorded within a time interval on the one hand and the reference signal on the other hand. As a result, the response behavior of the signal generator depends on the nature of sections of the route that have already been covered.

The signal generator outputs, for example, a warning signal perceptible in the vehicle and / or a chassis control signal as the output signal. The height of the threshold is preferably also dependent on the vehicle speed.

The signal generator offers the possibility to react proactively to a change in the condition of the road. Such a by means of the sensor te change in the road surface is, for example, the transition from dry to wet road or from a smooth road surface to a relatively rough road surface, for example pavement. With the aid of the sensor, several individual measurements are carried out in a time interval, for example a few seconds or just a fraction of a second, which provide information about the condition of the road. The input signal for the evaluation unit generated with the aid of the sensor can be, for example, a single scalar which, for example, provides a reference value for the roughness of the road surface. Likewise, however, the input signal can also be a multidimensional data field, for example generated by the recording of optical reflection signals. Analogously, the reference signal can also be formed from a single value or any number of individual values.

When the signal generator responds, ie as soon as the difference between the input signal and the reference signal is above the threshold, the shock absorber setting in the vehicle is changed, for example, in the case of monitoring the road surface roughness. The sensitivity of the signal generator, ie the threshold, should be set in such a way that an unnecessarily frequent response is avoided. This is ensured by comparing a plurality of input signals within a time interval, preferably a plurality of immediately following input signals, with the reference signal. The comparison can relate, for example, to the sum of the deviations of the input signals from the reference signal within the time interval. Likewise, determined maximum deviations of individual input signals within the time interval can also be taken into account. In any case, it is ensured that the threshold only changes after a time interval • in which several input signals have been recorded. The setting of the threshold that determines the sensitivity of the signal generator is therefore associated with at least a slight inertia.

If the motor vehicle is equipped with a chassis control system, for example a system for adjusting the damper detection, this system is preferably coupled with the signal generation depending on the condition of the road surface. With the help of such a coupling, the sensitivity of the signal generation, e.g. H. the threshold of the signal generator to be lowered when the vehicle shock absorbers are set to strong damping. Furthermore, the strength of the control signal to be output by the signal generator, for example chassis control signal, may depend on the chassis configuration. With the help of such an adjustment of the control signal to the respective chassis setting, a particularly targeted automatic reaction to changes in the roadway detected in front of the vehicle or discontinuities in the roadway condition is made possible.

According to a preferred development, the level of the threshold of the signal generator and / or the level of the output signals generated by the signal generator is dependent on data from the chassis control system recorded during a plurality of time intervals. Compared to a single time interval - - longer-term data recording beruhender balance between the ^'chassis control system and with which the roadway ahead monitoring sensor-equipped system allows for signal generation in this manner is an on. In particular, the process Ren to signal generation using the chassis control system calibrated, in particular long-term calibrated, and has a learning ability. This means that when a change in the road surface is detected by the sensor, the chassis control system of the motor vehicle is adjusted in accordance with the new road surface condition before the changing road surface is reached, the accuracy of the predictive chassis adjustment increasing over the course of the route.

The advantages and developments mentioned in connection with the method also apply analogously to the device for signal generation in a motor vehicle depending on the condition of the road surface.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Show here:

1 shows schematically in a diagram the data acquisition with a device according to the invention in several successive time intervals,

2 shows schematically in a block diagram the method according to the invention,

3 shows, in a diagram, different variants of adapting the sensitivity of a signal generator in the method according to FIG. 2, and

4 shows in a diagram the interaction of a chassis control system with the method according to FIG. 2.

Corresponding parts or parameters are each provided with the same reference symbols. Figures 1 and 2 illustrate a method for signal generation in a motor vehicle depending on the road surface. The device for carrying out the method is completely installed on board the motor vehicle. A sensor 1 detects a reflection signal FS from a road section in front of the moving motor vehicle. The reflection signal FS is, for example, a radar signal or an optical signal. A corresponding radiation source, for example a radar transmitter or a laser, may also be on board the motor vehicle. The sensor 1 forwards an input signal ES to an evaluation unit 2, in which the input signal ES is compared with a reference signal RS. Insofar as the conditions of signal generation which are explained in more detail below are met, a signal generator 3 connected to the evaluation unit 2 generates an output signal AS 1, AS 2. In the exemplary embodiment, the output signal AS 1 is an audible warning signal which can be perceived in the vehicle, while the Output signal AS 2 on

Undercarriage control signal for influencing the shock absorber detection of the motor vehicle. The acoustic output signal AS 1 is forwarded to a warning device 4; the chassis control signal AS 2 is fed into a chassis control system 5. This in turn is coupled to the evaluation unit 2 via a data connection 6, which transmits data D. Several or all of the components sensor 1, evaluation unit 2, signal generator 3, warning device 4 and chassis control system 5 can be combined in one structural unit.

The diagram of Fig. 1 illustrates the distance covered with different road surfaces. An amplitude A is recorded, which is measured with the aid of sensor 1 is measured and represents a measure of the roughness of the road surface. In each time interval I, a certain number, in the illustration four, of measurements of the road surface, in each case in front of the vehicle, is carried out. In a first time interval Ii, the motor vehicle moves on an asphalt road with very good road quality. The amplitudes A measured with the aid of the sensor 1 are all below a first threshold Si, which determines the sensitivity of the signal generator 3. This means that an output signal AS would be generated by the signal generator 3 even if the surface irregularities were detected to be relatively small. Such an output signal AS could warn the driver, for example, of stones on the road, potholes, a gravel road or a level crossing. Likewise, the driver of the motor vehicle could be warned acoustically and / or optically, for example, of bumps, bumps in the area of a construction site or a zebra crossing. As an alternative or in addition, if the threshold Si is exceeded, the chassis setting could be changed or, in extreme cases, a brake intervention could also be triggered.

At the beginning of the second time interval I, an input signal ES is recorded which clearly exceeds the threshold S1. In the exemplary embodiment, this symbolizes the start of a cobbled street. The driver of the motor vehicle is warned in good time before reaching this section of the route which has reduced grip. As the road continues to be paved with cobblestone, the threshold Si is practically permanently exceeded. A constant further warning of the driver would not be appropriate to the situation. The same applies to the chassis setting. A possibly Changing the chassis setting once is sufficient. Further interventions in the chassis while covering the paved route are not necessary. For this reason, raising the threshold S makes sense. However, the threshold S should not already be adjusted in the case of a single unevenness in the floor. Therefore, during the second time interval I _2, the input signals ES supplied by the sensor 1 are initially recorded and compared overall with the reference signal RS. Since, in the present case, the input signals ES are permanently significantly above the first threshold Si within the second time interval I ₂ , the threshold S is raised to the value S ₃ from the third time interval I ₃ . The vehicle continues to drive on paved roads during the third and fourth time intervals I ₃ , I ₄

Road. From the fifth time interval I ₅ , the roadway again has an asphalt surface, but with a lower quality than the roadway section which the vehicle traveled in the first time interval Ii. The change in the condition of the road is recognized in the evaluation unit 2, so that the threshold S is reset from the time interval I ₆ to the value S ₂ , which is somewhat above the threshold Si set in the first two time intervals I 1, I 1.

FIG. 3 shows various possibilities for changing the threshold S as a function of the detected deviation between the input signals ES and the reference signal RS. The setting of the threshold S depends on the number z of changes in the characteristics of the reflection signals FS within the last time period I to be evaluated. Four setting curves kl-k4 are shown. As can be seen from the illustration, the variation of the threshold S can be done both in discrete steps (k3) and continuously (kl, k2, k4). With continuous adaptation of the threshold S, various linear (k2) and progressive (k4) or degressive (kl) setting curves can be selected. The choice of the setting curve kl-k4 is dependent on data D of the chassis control system 5 transmitted to the evaluation unit 2.

FIG. 4 illustrates the interaction of the method for signal generation with the chassis control system 5. Depending on the time t, the relative shock absorber setting DE is shown, which allows a statement about the actual shock absorber setting of the motor vehicle in comparison to the optimal shock absorber setting corresponding to the road conditions. The motor vehicle is equipped with an adaptive damping control system, with a target damper setting D _s for each road surface, which has the value 3 in the example. The damper settings made are shown at three different times t each time the road surface changes. In any case, it is assumed that the device for signal generation first detects the lane change with the aid of the sensor 1, which looks ahead and senses the lane. In the first case, at time t = 1, the damper detection Di of the chassis control system 5 is set too hard when the changing track roughness is detected. As soon as the motor vehicle actually reaches the changed road surface, the damping is therefore reduced to the damper target setting D _s . A correct damper setting by the chassis control system 5 is assumed here.

In the second case, at time t = n + 1, an insufficient damper detection D _{2 is} compared to the damper setpoint due to input signals ES recorded by sensor 1. Setting D _s selected. The damping must therefore be increased when the motor vehicle reaches the new road surface.

j Both the data D of the chassis control system 5 and the data of the evaluation unit 2 are used for long-term calibration of the anticipatory method for signal generation. At the time t = m + 1, the signal generator 3 takes immediately, i. H. even before

) the vehicle reaches the modified road surface, with the damper detection D ₃ , which corresponds to the damper target setting D _s , the optimal setting of the suspension control system 5. Overall, this makes a learning system for predictive signal generation in a motor vehicle

; given stuff.

LIST OF REFERENCE NUMBERS

1 sensor. 2 evaluation unit

3 signal generator

4 warning device

5 suspension control system

6 data connection

A amplitude

AS1, AS2 output signal

D data

DE relative damper setting Dι, D ₂ , D ₃ damper setting

D _Ξ damper target setting

ES input signal

FS reflection signal

I, Ii ... I ₆ time interval kl, k2, k3, k4 setting curve

RS reference signal

S, Sι, S ₂ , S ₃ threshold t time z number

Claims

Claims: 1. Method for signal generation in a motor vehicle depending on the condition of the road, wherein a reflection signal (FS) emanating from the roadway is recorded by a sensor (1), - the sensor (1) sends an input signal (ES) to an evaluation unit (2) relating to the road condition, - In the evaluation unit (2) the input signal (ES) is compared with a reference signal (RS), a signal generator (3) generates an output signal (AS1, AS2), provided the deviation between the input signal (ES) and the reference signal ( RS) lies above a threshold (S, Sι, S ₂ , S ₃ ), - The height of the threshold (S, Sι, S ₂ , S ₃ ) is varied depending on the degree of deviation between a plurality of input signals (ES) within a time interval (Iι, ..., I ₆ ) and the reference signal (RS) , 2. The method according to claim 1, characterized in that the signal generator (3) generates a warning signal as the output signal (ASl). 3. The method according to claim 1 or 2, characterized in that the signal generator (3) generates a chassis control signal as an output signal (AS2). 4. The method according to any one of claims 1 to 3, characterized gekennz ei chnet, that the height of the threshold (S, Sχ, S ₂ , S ₃ ) depends on the speed of the motor vehicle. 5. The method according to any one of claims 1 to 4, characterized gekennz ei chnet that the height of the threshold (S, Sι, S ₂ , S ₃ ) is dependent on the setting of a chassis control system (5) of the motor vehicle. 6. The method according to claim 5, characterized in that the height of the threshold (S, Sι, S ₂ , S ₃ ) is dependent on data (D) of the chassis control system recorded during a plurality of time intervals {Iχ, ..., 1s) (5). 7. The method according to claim 5 or 6, characterized in that the level of the output signal (ASl, AS2) is dependent on data (D) of the chassis control system (5.) Recorded during a plurality of time intervals (Iι, ..., I ₆ ) ). 8. Device for signal generation in a motor vehicle as a function of the condition of the road, with a sensor (1) which detects a reflection signal (FS) emanating from the road and which is provided for providing an input signal (ES) relating to the condition of the road, - with an evaluation unit (2) for comparing the input signal (ES) with a reference signal (RS), - With a signal generator (3), which is provided for generating an output signal (AS1, AS2), provided the deviation between the input signal (ES) and the reference signal (RS) lies above a threshold (S, S _α , S ₂ , S ₃ ), the height of the threshold (S, Sι, S ₂ , S ₃ ) being dependent on the degree of deviation between one A plurality of input signals (ES) within a time interval (Ii, ..., I ₆ ) and the reference signal (RS).