EP1347884A1

EP1347884A1 - System and method for monitoring the vehicle dynamics of a vehicle

Info

Publication number: EP1347884A1
Application number: EP01991680A
Authority: EP
Inventors: Ulrich Hessmert; Norbert Polzin; Helmut Wandel; Thomas Sauter; Jost Brachert
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: WO2002053397A1; US20040148074A1; JP2004517278A

Abstract

The invention relates to a system for monitoring the vehicle dynamics of a vehicle with a sensor (10) measuring the wheel force, for determining a wheel force on at least one wheel (12) of the vehicle and means (14, 16), for processing the determined wheel force, whereby a state of the damper for the wheel (12) may determined from the result of the processing. The invention further relates to a method for monitoring the vehicle dynamics 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 measuring the wheel force for determining 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 connection 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 the 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 sensors are preferably attached to the body at two or more points that are different in the direction of rotation and also have 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 are detected in the circumferential direction. The wheel speed can be calculated, for example, from the scope of the roll 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 microswitch 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.

Advantages of the invention

The invention is based on the generic system in that a state of a shock absorber assigned to the wheel can be determined from a result of the processing. In motor vehicles with non-functional shock absorbers, critical driving situations can occur in the event of strong decelerations, in particular on simple routes or even during normal driving, for example when cornering. Cornering on poor road surfaces can be particularly critical. The critical situations arise because, for example, the chassis vibrates due to an interference force is offset and this vibration can not be brought to decay by the shock absorbers. An interference force can be generated, for example, by uneven driving or an initiated braking torque. In these cases, the frictional connection between the tire and the road can be lost, which can result in critical driving situations. By determining a state of a shock absorber assigned to the wheel from the measured wheel forces according to the invention, the loss of a damper function can be recognized at an early stage, which ultimately increases driving safety. A sensor system that measures the wheel force is suitable for the purpose of monitoring the chassis damping, since it can be used to measure the wheel contact force. If there are vibrations of the chassis influenced by a disturbing torque, the vertical chassis movement and thus the measured contact force are modulated.

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 is considered to be particularly advantageous record that a wide variety of sensors that measure wheel forces can be modified in the sense of the present invention.

The system according to the invention shows its particular advantages in that the force amplitude of an interference force can be determined by determining the wheel force, whereby a shock absorber is set in motion by the interference force, and that vibration damping can be determined by determining at least one subsequent amplitude of the vibration Vibration damping can be evaluated and that the state of the shock absorber can be determined depending on the evaluation. The initiation of a disturbing torque, for example when a vehicle brakes heavily or due to road surface disturbances, causes the vehicle to vibrate. An intact damper unit quickly subsides the vibration. If damping is disturbed in its function, the vibration persists over a period of time that is not justifiable in connection with driving safety. If an interference force is now introduced from the outside and the measurement of the force amplitude generated by the interference force is measured, for example on the basis of the change in the wheel contact force, a characteristic value for the vibration damping can be determined and evaluated by measuring at least one following amplitude. It is also conceivable that the primary force amplitude, which is generated by the interference force, is not used as the starting value for the comparison of the force amplitudes. Rather, any successive force amplitudes can be used as a measure of the damping. The invention is developed in a particularly preferred manner in that the vibration damping is assessed by comparison with a predetermined critical vibration damping. Such predetermined critical vibration damping is generally vehicle-specific and can be represented by a "critical damping constant". From the evaluation of the vibration damping, for example, a current damping constant can be determined and compared with the vehicle-specific critical damping constant. From this comparison, insufficient damping can then be recognized if necessary, namely if the current damping constant is smaller than the critical damping constant.

However, it is also possible for the vibration damping to be assessed by measuring the temporal change in successive vibration amplitudes. This percentage decrease can also be a measure of sufficient or insufficient damping, so that countermeasures can ultimately be taken.

The system according to the invention is developed in a particularly advantageous manner in that a display can be triggered depending on the determined state of the shock absorber. Such a display can be implemented in a passenger car, for example, via a display in the interior, so that the driver is informed in good time about inadequate damping and thus about impending critical driving situations. In a likewise particularly preferred development of the system according to the invention, provision is made for a starting prevention to be activated depending on the determined state of the shock absorber.

The invention builds on the generic method in that a state of a shock absorber assigned to the wheel is determined from a result of the processing. By determining a state of a shock absorber assigned to the wheel from the measured wheel forces according to the invention, the loss of a damper function can be recognized at an early stage, which ultimately increases driving safety. A sensor system that measures the wheel force is suitable for the purpose of monitoring the chassis damping, since it can be used to measure the wheel contact force. If there are vibrations of the chassis influenced by a disturbing torque, the vertical chassis movement and thus the measured contact force are modulated.

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. With such wheel bearing sensors, for example, wheel riot forces are measured, so that the method according to the invention can also be implemented in this way.

The method according to the invention shows its particular advantages in that the force amplitude of a disturbing force is determined by determining the wheel force, a shock absorber being set in vibration by the disturbing force, that a vibration damping is determined by determining at least one subsequent amplitude of the vibration, that the vibration damping is evaluated and that the state of the shock absorber is determined as a function of the evaluation. The initiation of a disturbing torque, for example when a vehicle brakes heavily or due to road surface disturbances, causes the vehicle to vibrate. An intact damper unit quickly subsides the vibration. If damping is disturbed in its function, the vibration persists over a period of time that is not justifiable in connection with driving safety. If an interference force is now introduced from the outside and the measurement of the force amplitude generated by the interference force is measured, for example on the basis of the change in the wheel contact force, a characteristic value for the vibration damping can be determined and evaluated by measuring at least one subsequent amplitude. It is also conceivable that the primary force amplitude, which is generated by the interference force, is not used as the starting value for the comparison of the force amplitudes. Rather, any successive force amplitudes can be used as a measure of the damping. The invention is developed in a particularly preferred manner in that the vibration damping is assessed by comparison with a predetermined critical vibration damping. Such a predetermined critical vibration damping is generally vehicle-specific and can be represented by a "critical damping constant". From the evaluation of the vibration damping, for example, a current damping constant can be determined and compared with the vehicle-specific critical damping constant. From this comparison, insufficient damping can then be recognized if necessary, namely if the current damping constant is smaller than the critical damping constant.

The method according to the invention is developed in a particularly advantageous manner in that a display can be triggered as a function of the determined state of the shock absorber. Such a display can be implemented in a passenger car, for example, via a display in the interior, so that the driver is informed in good time about inadequate damping and thus about impending critical driving situations. In a further particularly preferred development of the method according to the invention, it is provided that a start prevention can be activated depending on the determined state of the shock absorber.

The invention is based on the knowledge that the damper monitoring based on the wheel force makes it possible to determine defects or worn dampers at an early stage and to reduce dangerous driving situations. It is conceivable that the system according to the invention carries out continuous monitoring. Also, the system can be ^'designed so that it is activated only by introducing a relatively large disturbance force, disgust, for example, a pothole or a Schachtde- because of large disturbing forces particularly reliable measurement results can be achieved.

drawings

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

It shows:

FIG. 1 shows a block diagram of a system according to the invention, *

FIG. 2 shows a flow diagram of a method according to the invention; FIG. 3 shows a 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

Figure 1 shows a block diagram of a system according to the invention. Wheel forces of a wheel 12 are determined by means of a sensor system 10 measuring the wheel force. The wheel 12 shown is representative of several wheels of a vehicle, in particular a motor vehicle. The sensor system 10 measuring the wheel force is connected to a device 14 for determining vibration damping. The device 14 for determining the vibration damping is coupled to a device IS for evaluating the vibration damping. The device 16 for evaluating the vibration damping is connected to a display device 18.

The sensor system 10 measuring the wheel force can be part of a side wall sensor, for example. It can also be provided that the sensor system 10 is designed as a wheel bearing sensor system. Among other things, the sensor system 10 measures the tire's contact force. The vibration damping is determined in the unit 14 from the signals output by the sensor system 10 to the device 14. This determination can be made, for example, by measuring successive vibration amplitudes after the conduct an interference force. The vibration damping thus determined in the device 14 is fed to the device 16 for evaluating the vibration damping. The vibration damping can be evaluated, for example, by comparing a determined damping constant with a critical damping constant specific to the vehicle. It is also conceivable that the percentage decrease in successive amplitudes is evaluated. Depending on the result of the evaluation, a display device 18 is then activated. This can be provided, for example, in the interior of a vehicle and emit a warning if the vibration damping determined is less than a critical vibration damping value and was therefore rated as a critical value in the device 16. As an alternative or in addition to the alarm device 18, a start prevention can also be provided, which prevents the vehicle from starting in the case of critical vibration damping values.

FIG. 2 shows a flow diagram of a method according to the invention. First, the meaning of the individual process steps is given:

SOI measure a wheel force. S02 Determine a circuit damping. S03 Vibration damping greater than predetermined vibration damping? S04: alarm.

A wheel force is measured in step S01, for example the contact force of a wheel. In step S02, vibration damping is determined from the results of step SOI. This can be done by comparing successive wheel force amplitudes.

In step S03, the vibration damping determined is compared with a predetermined vibration damping. ACTUAL: If the vibration damping determined is greater than a predetermined vibration damping, this is classified as unproblematic and the process sequence can continue with the normal monitoring operation.

If the vibration damping is less than the predetermined vibration damping, an alarm is output, for example, in step S04. It is also possible to activate a start prevention.

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 sidewall of the tire 32 is provided with a plurality of sensors 24, 26, 28, 30, which have alternating magnetic polarity.

FIG. 4 shows the signal profiles S. and S _{a of} the sensor 20 arranged on the inside according to FIG. 3 and of the sensor 22 arranged outside according to FIG. 3. A rotation of the Tires are recognized by the changing polarity of the measurement signals. The wheel speed, for example _, can be calculated therefrom from the rolling range of the temporal change in the signals S. 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 the manner according to 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 condition 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, 16) for processing the determined wheel force,

characterized in that a state of a shock absorber assigned to the wheel (12) can be determined from a result of the processing.

2. System according to claim 1, characterized in that the wheel force measuring sensor system has tire sensors (20, 22, 24, 26, 28, 30).

3. System according to claim 1 or 2, characterized in that the sensor measuring the wheel force has wheel bearing sensors.

4. System according to one of the preceding claims, characterized in that that the force amplitude of an interference force can be determined by determining the wheel force, a shock absorber being set in motion by the interference force,

that vibration damping can be determined by determining at least one subsequent amplitude of the vibration,

- That the vibration damping can be assessed and

that the state of the shock absorber can be determined depending on the evaluation.

5. System according to any one of the preceding claims, characterized in that the vibration damping is assessed by comparison with a predetermined critical vibration damping.

6. System according to one of the preceding claims, characterized in that the evaluation of the vibration damping is carried out by measuring the change over time of successive Schwingungsarr.plituden.

7. System according to any one of the preceding claims, characterized in that a display (18) can be controlled depending on the determined state of the shock absorber.

8. System according to one of the preceding claims, characterized in that depending on the determined tεn state of the shock absorber a start prevention can be activated.

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

Determining a wheel force on at least one wheel (12) of the vehicle using a sensor system that measures the wheel force and

Processing of the determined wheel force,

10. The method according to claim 9, characterized in that the wheel force measuring sensors tire sensors

(20, 22, 24, 26, 28, 30) is used.

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

12. The method according to any one of claims 9 to 11, characterized in

that the force amplitude of an interference force is determined by determining the wheel force, a shock absorber being set in motion by the interference force, that vibration damping is determined by determining at least one subsequent amplitude of the vibration,

- that the vibration damping is assessed and

that the state of the shock absorber is determined as a function of the evaluation.

13. The method according to any one of claims 9 to 12, characterized in that the vibration damping is assessed by comparison with a predetermined critical vibration damping.

14. The method according to any one of claims 9 to 13, characterized in that the vibration damping is assessed by measuring the change over time of successive vibration amplitudes.

15. The method according to any one of claims 9 to 14, characterized in that depending on the determined

State of the shock absorber a display (18) can be controlled.

16. The method according to any one of claims 9 to 15, characterized in that a starting prevention can be activated depending on the determined state of the shock absorber.

17. System for generating a state signal representing the state of a motor vehicle shock absorber, at least one tire and / or one wheel being provided is and a force sensor is mounted in the tire and / or the wheel, in particular on the wheel bearing, and the status signal is generated depending on the output signals of the force sensor.