DE102006053102A1 - Improvement of steering comfort when traveling on inclined surfaces - Google Patents

Abstract

The invention relates to a method for improving the steering comfort in transverse driving on inclined surfaces. In order to make it easier for the driver to steer on inclined surfaces, it is proposed to detect driving on an inclination by means of a sensor and, if this condition was detected, to actuate an actuator of a vehicle system so that the steering torque to be exerted on the steering wheel (3) ( M <SUB> H </ SUB>) is reduced.

Description

State of the art

The The invention relates to a method for improving the steering comfort when traveling on inclined surfaces according to the generic term of claim 1, and a corresponding device according to the preamble of claim 8.

at Transverse travel on inclined surfaces, such as. embankments, or journeys on sideways rising or falling lanes, acts on the vehicle a downgrade force, which causes that the vehicle during the ride drifts slightly downhill. The driver must therefore steer uphill to the vehicle at a constant height to keep and continue to drive straight out. For longer embankment rides, such as. in terrain, is this for the driver relatively exhausting.

Disclosure of the invention

It is therefore the object of the present invention, the steering comfort at oblique journeys on transversely inclined surfaces to improve.

Is solved this task according to the invention by those specified in the patent claim 1 and in claim 8 Characteristics. Further embodiments of the invention are the subject of dependent claims.

One An essential aspect of the invention is the driving state "lateral travel on a sloping surface "sensory record and, if such a condition has been detected, an actuator of a Vehicle system, e.g. a steering actuator, so to control that the Steering forces acting on the steering wheel be reduced. The steering wheel forces can with it - similarly as when driving straight ahead in the plane - in extreme cases except for the Value zero can be reduced. This has the significant advantage that also longer crossings on a sloping surface substantially less fatigue carried out can be.

at the said "crossing on a sloping surface "it may be in the Principle to act every ride on a sloping surface in any one Angle transverse to the slope, such as. to a cross drive up Hang or embankments in terrain, but also to rides on sideways sloping or rising Roadways.

• – das Vorliegen einer Fahrzeugbewegung auf einer bezüglich der Fahrtrichtung quergeneigten Fläche detektiert und
• – im Falles eines Vorliegens einer Fahrzeugbewegung auf einer bezüglich der Fahrtrichtung quergeneigten Fläche ein Aktuator derart betätigt, dass sich das vom Fahrer insbesondere zur Sicherstellung einer Geradeausfahrt auszuübende Lenkradmoment verringert.

This is by the invention

• - detects the presence of a vehicle movement on a transversely inclined surface with respect to the direction of travel, and
• - In the case of a presence of a vehicle movement on a transverse inclined surface with respect to the direction of travel, an actuator is actuated in such a way that the steering wheel torque to be exerted by the driver, in particular to ensure straight-ahead driving, is reduced.

According to one first embodiment The invention is the supportive Vehicle system, a power steering system (power steering). In this Case is the steering actuator, usually an electric motor, of electronics so controlled that this one additional support moment exerts on the steering. Thereby Reduce the steering forces acting on the steering wheel. The amount of additional support torque is preferably dependent from the angle of inclination and possibly also from the ground (coefficient of friction) and / or the driving speed.

According to one second embodiment is the supporting one Vehicle system, for example, an active additional steering (electrical Steering). In such a steering, which continues to be a mechanical Pass-through between the steering wheel and wheels is a steering wheel according to a predetermined steering characteristic (characteristic) or driven according to a Control strategy regulated. When traveling on inclined surfaces can by means of the steering actuator (eg electric or hydraulic) additional Steering angles are applied to the steering. This reduces the steering angle to be set by the driver. The same principle can also be used with active rear-wheel steering.

alternative the invention can also be applied to a purely electric steering (Steer by wire), in which no mechanical penetration between steering wheel and wheels consists.

According to the invention can also be a regulation in which the vehicle is e.g. on compliance with a specific Height (at Crossing) or a certain trajectory is regulated, as long as the driver does not interfere with the steering. The desired by the driver trajectory results e.g. from the steering wheel position, and the actual trajectory of the vehicle can e.g. above Position data (e.g., GPS). With the help of electronics the actual movement path can be regulated to the desired movement path.

According to one third embodiment The invention is the supportive Vehicle system an active braking system, such. ESP. In this case is carried out on at least one wheel, a braking intervention, the generates a yaw moment about the vertical axis of the vehicle, which in the direction upslope is directed and thus to a decrease acting on the steering wheel personnel leads.

The mentioned vehicle systems can of course also simultaneously in any combination be operated.

The Height of automatic control intervention is preferably dependent on Tilt angle. According to one preferred embodiment The invention is the inclination angle or a proportional thereto Size, like e.g. the slope force, sensory determined and the automatic Control intervention in dependence designed for it.

Of the automatic control intervention is preferably only in a driving state fires in which the vehicle is either transverse to the inclination or in one upslope directed angle to the inclination.

A inventive device for improving the steering comfort when traveling on inclines a sensor for detecting the driving state "cross travel on a tilted Area ", a control unit with a Algorithm that evaluates the sensor signals, and at least one Actuator of a vehicle system, which is controlled by the control unit when the vehicle is moving on an inclined surface. The vehicle system may, as described above, for example, a power steering system, an active front or Rear axle steering or an active braking system, such as a vehicle dynamics control system, act.

To the Detecting driving on an inclined surface may be e.g. a roll rate sensor and / or a lateral acceleration sensor can be used. Optionally, too the sensors of an active chassis are used, the compression travel measures the wheel suspension on different longitudinal sides of the vehicle and from the difference in the compression travel on the left and right Side of the vehicle a ride on a sloping surface and if necessary, it is also possible to determine the exact inclination angle α. alternative could Also, an inertial sensor can be used to detect an inclined surface. It can Naturally also used several different sensors in combination become.

Brief description of the drawings

The Invention will be exemplified below with reference to the accompanying drawings explained in more detail. It demonstrate:

1 a view of a vehicle that moves on an inclined surface;

2 a view of the vehicle from 1 ; and

3 a block diagram of a system for improving the steering comfort when driving on transversely inclined surfaces.

Embodiments of the invention

1 shows a rear view of a vehicle that moves on a transverse inclined surface. The surface has an inclination angle α. The proportion of gravity attached to a wheel 2 acts, is denoted by F _G. On the vehicle 1 This has the effect of a downhill force F _slope , which the driver must compensate by countersteering if he wants to continue to drive straight ahead.

2 shows a view of the vehicle from 1 , wherein in particular the inclination of the front wheels 2 can be seen. The inclination is required here to keep the vehicle at a constant height. The steering torque to be applied to the steering wheel is designated M _H.

3 shows a schematic block diagram of a vehicle system, by means of which the driver on the steering wheel 3 applied force can be reduced. The influence of the driver on the vehicle is through a block 5 shown.

The vehicle system includes a sensor system 7 for detecting a driving state in which the vehicle is traveling on a transverse inclined surface. The sensors 7 For example, it may include a sensor that measures the compression travel of the wheel suspension on different longitudinal sides of the vehicle and the difference in compression travel on the left and right sides of the vehicle 1 a cross travel on an inclined surface and possibly also the exact inclination angle α can determine. Optionally or additionally, an inertial sensor can also be provided which can determine the position and position of the vehicle. The sensors 7 In addition, in particular also includes speed, yaw rate and lateral acceleration sensors, which are usually provided in a conventional vehicle dynamics control (ESP). The sensor signals of the sensors 7 be from a controller 8th processed, in which a special algorithm for supporting the driver is stored. If the algorithm recognizes the driving state "transverse travel on a gradient" and the vehicle also drives straight ahead - this can be detected, for example, via the steering angle - automatically becomes an actuator 9 controlled, which reduces the steering wheel torque M _H and thus supports the driver while steering. The steering of the vehicle is here schematically by a block 6 shown.

In the vehicle system 7 . 8th . 9 it may be, for example, a power steering system (power steering). The actuator 9 is in this case a servomotor, which in case of a cross travel on one inclined surface generates an additional servo torque. An alternative vehicle system 7 - 9 is for example an active steering. In this case, the actuator would be 9 a steering wheel of the active steering, that of the associated control unit 8th is controlled accordingly. To assist the driver, both active front axle steering and active rear axle steering or both systems can be used simultaneously.

Alternatively, the braking system of the vehicle could be used to assist the driver in steering. In this case, the controller would 8th determine a certain yaw moment, for example, from a brake slip control on individual wheels 2 of the vehicle 1 could be implemented. However, the vehicle would be decelerated by the automatic brake intervention.

The Inventive support of the vehicle when driving across a slope, it is preferable to activate only when the vehicle is in straight-ahead driving. The state "straight ahead" can be transmitted via the Steering or steering wheel angle, the lateral acceleration or GPS data are determined. Thereby In particular, it should be prevented that dynamic driving maneuvers, at which have relatively high lateral forces act, be confused with a ride across a slope.

Claims (9)

Method for improving the steering comfort in cross travels on inclined surfaces, characterized by the following steps: - Monitoring the driving state by means of a sensor system ( 7 ) with respect to driving transversely on an inclined surface, and - actuating an actuator ( 9 ) of a vehicle system ( 7 ), when the driving state "lateral travel on an inclined surface" has been detected, so that the driver's steering wheel torque (M _H ) decreases. A method according to claim 1, characterized in that in a vehicle with power steering a steering actuator ( 9 ) of the power steering system is controlled. A method according to claim 1 or 2, characterized in that in a vehicle with electric steering of the actuator ( 9 ) of the electric steering is controlled, so that the steering angle changes automatically. Method according to claim 3, characterized in that the actuator ( 9 ) is activated an active front and / or rear-wheel steering. Method according to one of the preceding claims, characterized in that in a vehicle with an automatic braking system at least one wheel brake ( 9 ), thereby generating a yawing moment about the vertical axis of the vehicle resulting in a decrease of the steering wheel torque (M _H ). Method according to one of the preceding claims, characterized in that the angle of inclination (α) or a variable proportional thereto is determined, and the extent of the actuation of the actuator ( 9 ) is dependent on the angle of inclination (α). Method according to one of the preceding claims, characterized in that an automatic actuation of the actuator ( 9 ) is executed only when the vehicle is traveling transversely to the incline or in a downhill trajectory. Device for improving the steering comfort in transverse driving on slopes, characterized in that a sensor system ( 7 ) for monitoring the driving condition with respect to driving transversely on an inclined surface, a control unit ( 8th ) and at least one actuator ( 9 ) are provided, which is so controlled that reduces the driver to be exercised steering wheel torque (M _H ) when a driving state "cross travel on a sloping surface" was detected. Control unit ( 8th ) comprising means adapted to perform a method according to any one of claims 1 to 7.