EP1347905A1

EP1347905A1 - System and method for monitoring the driving state of a vehicle

Info

Publication number: EP1347905A1
Application number: EP01991682A
Authority: EP
Inventors: Jost Brachert; Ulrich Hessmert; Norbert Polzin; Thomas Sauter; Helmut Wandel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-12-30
Filing date: 2001-12-22
Publication date: 2003-10-01
Also published as: US20030109968A1; JP2004516985A; WO2002053434A1

Abstract

The invention relates to a system for monitoring the handling characteristics of a vehicle. Said system comprises a sensor mechanism (10), which measures the wheel force and which is provided for determining a wheel force on at least one wheel (12) of the vehicle, and comprises means (14) for processing the determined wheel force, whereby a state of the roadway is discerned from the result of the processing. The invention also relates to a method for monitoring the handling characteristics of a vehicle.

Description

System and method for monitoring the driving condition of a vehicle

The invention relates to a system for monitoring the driving state of a vehicle with a sensor system that measures the wheel force to determine a wheel force on at least one wheel of the vehicle and means for processing the determined wheel force. The invention further relates to a method for monitoring the driving state of a vehicle, comprising the steps of: determining a wheel force on at least one wheel of the vehicle by means of a sensor system measuring the wheel force and processing the determined wheel force.

State of the art

The generic system and the generic method are used in the context of vehicle dynamics controls. For example, they are used in conjunction with anti-lock braking systems (ABS), traction control systems (ASR) and the electronic stability program (ESP). It is known to detect the wheel speeds of the individual wheels of a motor vehicle via sensors and the detected wheel speeds. in the control and / or regulation of the driving behavior of the Motor vehicle to be considered. Although good results have already been achieved with the known methods and systems, there is an interest, particularly with regard to traffic safety, in further improving the generic methods and systems.

In connection with the sensors provided in this category, it is also known that various tire manufacturers are planning the future use of so-called intelligent tires. New sensors and evaluation circuits can be attached directly to the tire. The use of such tires allows additional functions, such as, for example, measuring the torque occurring on the tire transversely and longitudinally to the direction of travel, the tire pressure or the tire temperature. In this context, for example, tires can be provided in which magnetized surfaces or strips are incorporated into each tire, preferably with field lines running in the circumferential direction. For example, the magnetization always takes place in sections in the same direction, but with opposite orientation, that is to say with alternating polarity. The magnetized stripes preferably run near the rim flange and near the mountain. The sensors therefore rotate at wheel speed. Corresponding measured value recorders are preferably attached to the body at two or more points which are different in the direction of rotation and are also at a different radial distance from the axis of rotation. As a result, an inner measurement signal and an outer measurement signal can be obtained. A rotation of the tire can then via the changing polarity of the measurement signal or of the measurement signals in the circumferential direction are recognized. The wheel speed can be calculated, for example, from the rolling range and the change over time of the inner measurement signal and the outer measurement signal.

It has also already been proposed to arrange sensors in the wheel bearing, this arrangement being able to take place both in the rotating and in the static part of the wheel bearing. For example, the sensors can be implemented as micro sensors in the form of micro switch arrays. For example, forces and accelerations and the speed of a wheel are measured by the sensors arranged on the movable part of the wheel bearing. This data is compared with electronically stored basic patterns or with data from a similar or similar microsensor that is attached to the fixed part of the wheel bearing.

In the context of the known control systems mentioned above, it is also known to draw conclusions about the condition of the roadway by evaluating certain measured variables. For this purpose, wheel speeds and wheel accelerations are currently measured, for example. Furthermore, the brake pressure on a wheel is estimated, for example, using vehicle models.

Advantages of the invention

The invention is based on the generic system in that a state of the roadway is recognized from a result of the processing. The state of driving track is thus determined directly from the wheel forces determined by the sensors. This enables a more reliable detection of the condition of the road, which can be used advantageously in the known control systems.

The system according to the invention is particularly disadvantageous in that the conditions of poor road, μ-grit, gravel, wetness, icy conditions and / or deep snow can be recognized. Under all these circumstances, vehicles show different driving behavior, which also depends on the current driving condition. Knowledge of the state of the road can thus be advantageously used to influence the state of the road.

In a preferred embodiment of the system according to the invention, this is further developed in that the sensor system measuring the wheel force has tire sensors. The tire sensors described in connection with the prior art are particularly suitable for measuring, for example, the wheel contact force, so that driving safety can be improved to a great extent.

However, it can also be useful for the sensor system that measures the wheel force to have wheel bearing sensors. For example, wheel contact forces can also be measured with such wheel bearing sensors, so that the system according to the invention can also be implemented in this way. In this context, it can be seen as particularly advantageous that a wide variety of sensor systems which measure wheel forces can be modified in the sense of the present invention. In a further preferred embodiment of the system according to the invention, this is further developed in that the circumferential force of the tire can be determined using a characteristic between deformation in the tangential direction and circumferential force from the measurement of the deformation in the tangential direction by means of a tire sensor and that a braking pressure can be determined from the circumferential force , The tire's contact forces and circumferential forces change depending on the road surface. Since the tire deforms depending on these forces, the forces can ultimately be determined from the signals from the sensors measuring the wheel force. The circumferential force of the respective tire is determined by measuring the deformation in the tangential direction of the tire equipped with a tire sensor. This is done by a characteristic curve stored in a storage unit, which describes the relationship between deformation and circumferential force. The brake pressure can then be determined from this.

It can advantageously be provided that when using a traction control system (ASR) with unilateral regulation and a brake pressure difference between the regulated side and the unregulated side of more than 40 bar on _/ ..- split is recognized. Such a pressure difference in a rear-wheel drive vehicle, provided that only one brake control memory of the braking torque control is set, can be used as a criterion that is detected precisely on μ-split. It can also be provided within the framework of the system according to the invention that the dynamics of changing wheel contact forces and simultaneous consideration of wheel speed and wheel acceleration can be used to detect exactly in a bad way. A bad road detection or a threshold roadway can thus be determined with an approximately constant engine torque.

In a particularly preferred development of the system according to the invention, it is designed in such a way that the recognized state of the road is converted into a roadway state signal and that the roadway state signal is used by a control and / or a regulation to influence the driving behavior of the vehicle , In this way, the algorithms of ASR or ABS can be improved, for example. This can be achieved, for example, by specifically activating certain program parts in the algorithm, such as, for example, pressure maintenance functions in the case of ASR on a bad road, or by pressure build-up in phase opposition or pressure reduction for vibration damping on a bad road.

• The invention builds on the generic method in that a state of the roadway is recognized from a result of the processing. The state of the road is thus determined directly from the wheel forces determined by the sensor system. This enables a more reliable detection of the condition of the road, which can be used advantageously in the known control systems. The method according to the invention is particularly advantageous in that the conditions of poor road, μ-grit, gravel, wetness, icy conditions and / or deep snow are recognized. Under all these circumstances, vehicles show different driving behavior, which also depends on the current driving condition. Knowledge of the state of the road can thus be advantageously used to influence the state of the road.

In a preferred embodiment of the method according to the invention, this is further developed in that the sensor system measuring the wheel force uses tire sensors. The tire sensors described in connection with the prior art are particularly suitable for measuring, for example, the wheel contact force, so that driving safety can be improved to a great extent.

However, it can also be useful that the sensor system measuring the wheel force uses wheel bearing sensors. For example, wheel contact forces can also be measured with such wheel bearing sensors, so that the method according to the invention can also be implemented in this way. In this context, it can be seen as particularly advantageous that a wide variety of sensor systems which measure wheel forces can be modified in the sense of the present invention.

In a further preferred embodiment of the method according to the invention, this is further developed in that the circumferential force of the tire using a characteristic curve between deformation in the tangential direction tion and circumferential force from the measurement of the deformation in the tangential direction is determined by means of a tire sensor and that a braking pressure is determined from the circumferential force. The tire's contact forces and circumferential forces change depending on the road surface. Since deformed in accordance with the tire in response to these forces, _ι can ultimately the forces from the signals of the wheel force measuring sensor determine. The circumferential force of the respective tire is determined by measuring the deformation of the tire equipped with a tire sensor in the tangential direction. This is done by means of a characteristic curve stored in a ^" storage unit, which describes the relationship between deformation and circumferential force. From this, the brake pressure can then be determined.

It can advantageously be provided that when using a traction control system (ASR) with unilateral control and a brake pressure difference between the regulated side and unregulated side of more than 40 bar on μ-split is recognized. Such a pressure difference in a rear-wheel-drive vehicle, provided that only one brake control memory of the braking torque control is set, can be used as a criterion that is detected precisely on μ-split.

It can also be provided within the scope of the method according to the invention that the dynamics of changing wheel contact forces and simultaneous consideration of wheel speed and wheel acceleration are used to detect exactly in a bad way. A bad road detection or a threshold trajectory can thus be determined with an approximately constant engine torque.

In a particularly preferred development of the method according to the invention, it is designed in such a way that the recognized state of the roadway is converted into a roadway state signal and that the roadway state signal is used by a control and / or a regulation to influence the driving behavior of the vehicle , In this way, the algorithms of ASR or ABS can be improved, for example. This can be achieved, for example, by specifically activating certain program parts in the algorithm, such as, for example, pressure maintenance functions in the case of ASR on a bad road, or by pressure build-up in phase opposition or pressure reduction for vibration damping on a bad road.

The invention is based on the knowledge that it is possible, based on the measurement of wheel forces, to obtain reliable information about the currently existing roadway. Known control systems, such as ABS, ASR and ESP, can advantageously improve their control on the basis of this information.

drawings

The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments. It shows:

Figure 1 is a block diagram of a system according to the invention;

FIG. 2 shows a flow diagram of a method according to the invention;

Figure 3 shows part of a tire equipped with a tire sidewall sensor; and

FIG. 4 shows exemplary signal profiles of the tire side wall sensor shown in FIG. 3.

Description of the embodiments

FIG. 1 shows a block diagram of a system according to the invention. A sensor system 10 is assigned to a wheel 12, the wheel 12 shown being shown as representative of the wheels of a vehicle. The sensor system 10 is connected to a device 14 for processing signals. The device 14 is connected to a controller 16. This control 16 is in turn assigned to the wheel 12.

The sensor system 10 measures the wheel force of the wheel 12. The measurement results resulting therefrom are transmitted to the device 14 for processing the measurement results. For example, a circumferential force is determined in the device 14 from a measured deformation in the tangential direction. This can be done by using a characteristic curve stored in a storage unit. The brake pressure can also be determined from the circumferential force. A signal can then be generated further in the device 14, which represents a specific state of the roadway that is dependent on the measured values. This signal can then be transferred to a controller 16, so that the wheel 12 can be influenced as a function of the signal.

FIG. 2 shows a flowchart of a method in the context of the present invention, in particular showing a μ-slip detection. First, the meaning of the individual steps is given:

SOI: measurement of a deformation in the tangential direction of a tire. S02: Determine a peripheral force of the tire. S03: Determination of a brake pressure assigned to the tire.

S04: Brake pressure difference between the regulated vehicle side and unregulated vehicle side> 40 bar? S05: Detect on μ-grit.

The method sequence shown in FIG. 2 can be carried out in this or a similar manner in a rear-wheel drive vehicle, the detection on μ-split taking place in the case when there is a one-sided control, that is to say only one brake control memory of the braking torque control is set. A deformation of a tire in the tangential direction is measured in step SOI.

A circumferential force is determined from this deformation in step S02. This is done by means of a characteristic curve stored in a storage unit, which indicates the relationship between the deformation in the tangential direction and the circumferential force.

The brake pressure is determined from this in step S03.

Step S04 now checks whether the brake pressure difference between the regulated side of the motor vehicle and the unregulated side of the motor vehicle is greater than 40 bar. If this is not the case, then μ-split is not recognized.

However, if the minimum value of the brake pressure difference checked in step S04 is present, then μ-split is recognized in step SO5.

FIG. 3 shows a section of a tire 32 with a tire / side wall sensor system 20, 22, 24, 26, 28, 30. This comprises two sensors 20, 22, which are attached to the body at two different points in the direction of rotation. Furthermore, the sensors 20, 22 have different radial distances from the axis of rotation of the wheel. The side wall of the tire 32 is provided with a large number of sensors 24, 26, 28, 30, these having alternating magnetic polarity. FIG. 4 shows the signal curves S and S _{ε of} the inside sensor 20 according to FIG. 3 and of the outside sensor 22 according to FIG. 3. Rotation of the tire is recognized by the changing polarity of the measuring signals. The wheel speed, for example _, can be calculated therefrom from the rolling range of the change over time of the signals Si and S _a . Torsions of the tire can be determined by means of phase shifts between the signals and thus, for example, wheel forces can be measured directly. In the context of the present invention, it is particularly advantageous if the contact force of the tire 32 on the road 34 according to FIG. 3 can be determined, since the contact force of the shock absorbers can be deduced from this contact force in accordance with the invention.

The preceding description of the exemplary embodiments according to the present invention is only for illustrative purposes and not for the purpose of restricting the invention. Various changes and modifications are possible within the scope of the invention without leaving the scope of the invention and its equivalents.

Claims

Expectations

1. System for monitoring the driving behavior of a vehicle with

- A sensor system (10) measuring the wheel force for determining a wheel force on at least one wheel (12) of the vehicle and

Means (14) for processing the determined wheel force,

characterized in that a state of the road is recognized from a result of the processing.

2. System according to claim 1, characterized in that the conditions bad road, μ-grit, gravel, wet, ice and / or deep snow are recognizable.

3. System according to claim 1 or 2, characterized in that the sensor system (10) measuring the wheel force has tire sensors.

4. System according to one of the preceding claims, characterized in that the wheel force measuring sensor system (10) has wheel bearing sensors.

5. System according to any one of the preceding claims, characterized in

that the circumferential force of the tire can be determined using a characteristic curve between deformation in the tangential direction and circumferential force from the measurement of the deformation in the tangential direction by means of a tire sensor and

- That a braking pressure can be determined from the circumferential force.

6. System according to one of the preceding claims, characterized in that when using a traction control system (ASR) with one-sided control and a brake pressure difference between the regulated side and unregulated side of more than about 40 bar on μ-split is recognized.

7. System according to any one of the preceding claims, characterized in that at substantially constant engine torque from the dynamics of changing wheel standing forces and simultaneous consideration of wheel speed and wheel acceleration is recognized exactly on bad road.

8. System according to any one of the preceding claims, characterized in that

- that the recognized state of the road is converted into a lane.toBtan.dssignal and that the roadway state signal is used by a control and / or a regulation (16) to influence the driving behavior of the vehicle.

9. Method for monitoring the driving behavior of a vehicle with the steps:

Determining a wheel force on at least one wheel (12) of the vehicle by means of a sensor system and measuring the wheel force

Processing of the determined wheel force,

characterized in that a state of the roadway is recognized from a result of the processing.

10. The method according to claim 9, characterized in that the conditions bad road, μ-grit, crushed stone, wet, ice and / or deep snow are recognized.

11. The method according to claim 9 or 10, characterized in that the wheel force measuring sensor system (10) uses tire sensors.

12. The method according to any one of claims 9 to 11, characterized in that the wheel force measuring sensor system (10) uses wheel position sensors.

13. The method according to any one of claims 9 to 12, characterized in that that the circumferential force of the tire is determined using a characteristic curve between deformation in the tangential direction and circumferential force from the measurement of the deformation in the tangential direction by means of a tire sensor and

that a braking pressure is determined from the circumferential force.

14. The method according to any one of claims 9 to 13, characterized in that when using a traction control system (ASR) with one-sided control and a brake pressure difference between the regulated side and unregulated side of more than about 40 bar on μ-split is detected.

15. The method according to any one of claims 9 to 14, characterized in that with substantially constant engine torque from the dynamics of changing wheel contact forces and simultaneous consideration of wheel speed and wheel acceleration is recognized exactly on bad road.

16. The method according to any one of claims 9 to 15, characterized in

that the recognized state of the roadway is converted into a roadway state signal and

- That the roadway condition signal is used by a control and / or a regulation to influence the driving behavior of the vehicle.

17. System for controlling and / or regulating the driving behavior of a motor vehicle with at least one tire and / or one wheel, a force sensor being fitted in the tire and / or on the wheel, in particular on the wheel bearing, and depending on the output signals of the force sensor the roadway condition signal representing the condition of the roadway is determined and this roadway status signal is used to control and / or regulate the driving behavior.