DE102005028787B4 - System for trailer stabilization - Google Patents

Abstract

A system for trailer stabilization, comprising the following system components: - a vehicle steering system (1) with handlebar support, - a device (2) for detecting critical trailer vibrations, and - a controller (7), with the trailer oscillations on the steering wheel angle or the steering torque are actively regulated, wherein upon detection of a critical trailer vibration, a temporary intervention in the vehicle steering for trailer stabilization takes place, wherein the trailer oscillations are adjusted depending on the yaw rate and the yaw acceleration of the vehicle, characterized in that the steering wheel angle is set active according to the following relationship: Θ = K1 · (-K2 · VG - K3 · aG), where Θ the steering wheel angle, vG the yaw rate, aG the yaw acceleration, and K1, K2, K3 are predetermined factors.

Description

The invention relates to a system for stabilizing the trailer according to the preamble of claim 1 and also to system for stabilizing the trailer according to the preamble of claim 2, which are particularly suitable for passenger cars and light commercial vehicles with trailer.

When driving motor vehicles with trailers can occur between the towing vehicle and the towed vehicle speed-dependent vibrations around the vertical axes, which affect the driving stability.

Currently used approaches to stabilize the trailer aim to slow down the combination as quickly as possible under a so-called critical speed. In principle, the driver can already achieve this by actuating the vehicle brakes.

Automated systems detect critical vehicle vibrations, for example with the aid of a sensor system implemented in the towing vehicle, as well as suitable detection algorithms in the ESP control unit, and automatically initiate a corresponding activation of the wheel brakes.

When braking the team, it is due to the temporary emergence of the trailer on the towing vehicle usually initially to an amplification of the vibration before the vibration subsides then. Especially with medium and low road friction coefficients, the opening of the vibration can lead to critical driving conditions and in the worst case to a collapse of the team.

Particularly critical driving conditions can also arise when an untrained driver tries to stabilize the unstable team by steering wheel movements.

A system for trailer stabilization according to the preamble of claim 1 is made DE 100 32 230 C2 known. A system for trailer stabilization according to the preamble of claim 2 is made DE 198 43 826 A1 known.

In DE 198 43 826 A1 It is proposed to compare the actual yaw rate of the towing vehicle with a target yaw rate and to change the steering angle of the steered vehicle wheels of the towing vehicle in order to reduce this difference.

DE 100 32 230 C2 follows a strategy which is based on the determination of a main vibration frequency of the yawing and / or rolling movement of the towing vehicle in a predetermined frequency range and the vibration amplitudes in order to induce an in-phase steering and / or braking intervention. DE 100 34 222 A1 suggests in this context further to use the yaw rate for vibration analysis.

DE 103 42 865 A1 teaches how DE 198 43 826 A1 a strategy that compares an actual yaw rate with a desired yaw rate. If this difference can not be reduced by a steering intervention, a supplementary braking intervention is proposed.

In WO 2004/041613 A1 It is proposed to generate a counter-torque, which is calculated from the yaw acceleration and a gain factor.

Against this background, the invention is based on the object to show alternative strategies for vehicle stabilization.

This object is achieved by a system according to claim 1 and by a system according to claim 2. Advantageous embodiments of the invention are the subject of further claims.

By including the steering in a system for stabilizing the trailer, stability-critical driving situations resulting from vibrations around the vertical axes can be counteracted. Steering movements can indeed be used to stabilize a team if they are performed in the correct phase to the stability-critical vibration. With the invention can be caused by the temporary active engagement in the steering corrective steering movement.

The invention will be explained in more detail with reference to preferred embodiments.

1 shows an example of the construction of a system for vehicle stabilization according to the invention.

2 shows a first example of a control loop for an active steering intervention,

3 shows the course of the steering wheel angle, the lateral acceleration and the yaw rate when compensating a trailer vibration (solid lines) compared to a system without controller (broken lines),

4 shows a second example of a control loop for an active steering intervention,

5 shows the course of the steering wheel angle, the lateral acceleration and the yaw rate when compensating a trailer vibration with a controller 4 compared to a system without regulator, and

6 shows the course of the steering wheel angle, the lateral acceleration and the yaw rate when balancing a trailer vibration with one opposite 4 modified controller compared to a system without controller.

According to the invention, in a system for vehicle stabilization, at least the following system components are present, namely a vehicle steering system 1 with handlebar support and a facility 2 for detecting critical trailer vibrations. The vehicle steering 1 can be configured either as a power steering, in which a Stützungslenkmoment is generated either electrically or hydraulically, or as superposition steering, in which an adjusted steering angle by the driver, an additional steering angle is superimposed. Such steering systems are well known to those skilled in the art and therefore need not be explained in detail here.

The device 2 to detect critical trailer vibrations preferably uses already existing sensors on the towing vehicle 3 to determine any stability-critical driving situations. In particular, the yaw rate of the towing vehicle can be taken into account. However, it is also conceivable to include sensors on the towed vehicle in the determination of stability-critical driving situations. Suitable detection algorithms for determining critical vehicle oscillations are preferably in an ESP control unit 4 implemented. About the ESP control unit 4 can with a detected critical trailer vibration on the one hand, an activation of selected or even all wheel brakes 5 take place and at the same time or with a time delay, a temporary intervention in the steering 1 be initiated for trailer stabilization. However, it is also possible to interfere with the vehicle's steering system 1 independent of an actuation of the wheel brakes 5 to induce.

During a temporary intervention in the vehicle steering 1 a superimposed steering torque is generated in the same over which the driver a steering recommendation for stabilizing the team on the steering wheel 6 is displayed haptically. An appropriate steering was in the German Patent Application No. 10 2004 041 413.0 the applicant explains. The content of said patent application is incorporated in the present application with respect to the generation of the superimposed steering torque. The corresponding signal input takes place, for example, via the ESP control unit 4 ,

According to the invention, in a stability-critical driving situation, independent of the driver and possibly assisted by an automatic brake intervention, automatically initiate a corrective steering movement that stabilizes the vehicle.

According to a corresponding embodiment, this can be done with a trained as superposition steering vehicle steering 1 in which an additional steering angle can be superimposed on a steering angle set by the driver during the temporary intervention in the vehicle steering 1 an additional steering angle stabilizing the combination is generated. By means of an in-phase steering angle specification, trailer vibrations can be damped in a controlled manner via the above-mentioned detection algorithms without the assistance of the driver.

About the automatic braking intervention, it is also possible to generate a towing vehicle stabilizing moment about the vertical axis by the brake pressures at the individual wheel brakes are controlled individually. An existing ESP in the vehicle can accomplish this without much additional effort. Furthermore, it is conceivable to individually control the individual wheel brakes in braked trailers in a way stabilizing the team. In combination with a driver-side or automatic steering correction, a particularly effective system for vehicle stabilization can be realized.

As already indicated above, the driver can also be assisted by an active steering intervention when trailer vibrations occur, which is understood here to mean those measures which are reflected in a change in the steering angle to the vehicle wheels, regardless of whether the driver himself specifies a steering command or not.

For this purpose, suitable control strategies are presented, which are in the above-mentioned device 2 are implemented to detect critical trailer vibrations. All control strategies are based on already existing information on the vehicle, so that no further sensors are needed.

In a first variant, the trailer vibrations are actively regulated as a function of the yaw rate v _G and the yaw acceleration a _{G of} the vehicle via the steering wheel angle or the steering wheel torque. 2 shows the corresponding control loop using the example of the steering wheel angle Θ.

The yaw rate v _G is usually available via a corresponding sensor on the vehicle. In contrast, the yaw acceleration a _{G is} preferably obtained from the yaw rate v _G by derivation.

With these parameters, the steering wheel angle can be actively set according to the following relationship: Θ = K ₁ · (-K ₂ · v _G - K ₃ · a _G )

In this case, Θ the steering wheel angle, v _G the yaw rate, a _G the yaw acceleration, and K ₁ , K ₂ , K ₃ vehicle and / or steering specific predefinable factors with which can easily perform a vote for trailer stabilization.

By means of the factor K ₁ , the overall gain can be adjusted, while with the factor K ₃ the phase position is regulated. The latter is a measure of how far you can hold in the steering with the steering wheel angle time. In addition, the inertia of the steering wheel and the steering gear can be taken into account via the factor K ₃ , so as to produce a steering command for damping trailer vibrations in the correct phase.

In 2 Θ represents the steering wheel angle needed to balance the trailer vibrations. Introduced by the driver's steering movements F Θ _F are also included in the system. The reaction of the vehicle 8th is returned to the steering wheel angle über via the yaw rate v _G and the yaw acceleration a _G.

3 shows by way of example the reaction to a trailer noise impulse for the steering wheel angle Θ, the lateral acceleration a _Q and the yaw rate v _G at a travel speed of 90 km / h. In broken lines, the situation is shown without a controller, which is juxtaposed with the situation with controller in solid lines. From the course of the steering wheel angle Θ the active system intervention is clearly visible. By this a trailer oscillation is calmed within a few seconds, which would build up more and more without the controller, as the course of the lateral acceleration a _Q and the yaw rate v _G shows.

In order to avoid violent steering wheel reactions in response to a glitch, the control torque of the vehicle steering 1 limited to a maximum value.

In a second variant, the trailer vibrations are actively regulated as a function of the yaw rate v _G and the float angle velocity v _{S of} the vehicle via the steering wheel angle or the steering wheel torque. A corresponding control circuit is in 4 shown.

For this purpose, the steering wheel angle Θ is set active according to the following relationship: Θ = K ₁ · v _S , where Θ the steering wheel angle, v _S, the float angle velocity v _S and K _{1 are} a predetermined factor.

The slip angle velocity v _S is obtained from the lateral acceleration a _Q , the vehicle speed v _F and the yaw rate v _G as follows: v _S = a _Q / v _F - v _G ,

Both the vehicle speed v _S and the measured lateral acceleration a _Q are quantities available on the vehicle.

Since the float angle amplitudes in the region of the vehicle clutch or the engine output shaft are generally greater than at the usual installation location of a lateral acceleration sensor, the float angle velocity can be referred to the position of the clutch as follows in the context of an extended Schwimmwinkelgeschwindigkeitsreglers as follows: a _Q * = a _Qsensor - d · a _G where a _Q * is the modified lateral acceleration at the vehicle _clutch , a _{Qsensor is} the lateral acceleration actually measured at a lateral acceleration _sensor , d is the distance of the lateral acceleration sensor from the vehicle clutch, and a _{G is} the yaw acceleration.

A comparison of 5 and 6 shows in the latter case tends to stronger steering wheel angle engagement associated with a slightly greater damping of the trailer vibrations.

The control approaches explained above are based on a steering wheel angle control, the controller 7 still must be downstream. However, trailer stabilization can also be realized solely with the aid of steering wheel torques, in which case phase position and amplitude are likewise identified. A corresponding controller is configured so that the additional steering torque to the driver the steering wheel angle in the correct phase as set as it would set the above-described controller.

The invention has been explained in more detail above with reference to preferred embodiments. However, it is not limited to these, but rather encompasses all embodiments defined by the claims. In all cases, the driving safety is increased when driving teams.

LIST OF REFERENCE NUMBERS

1

steering

2

Device for detecting critical trailer vibrations

3

sensors

4

ESP control unit

5

wheel brakes

6

steering wheel

7

regulator

8th

vehicle

a _G

yaw acceleration

a _Q

lateral acceleration

_aQ *

modified lateral acceleration at the vehicle clutch

d

Distance clutch - lateral acceleration sensor

v _F

driving speed

v _G

yaw rate

F

driver

S

glitch

Θ

Steering wheel angle for compensating trailer vibrations

Θ _F

the steering wheel angle applied by the driver

Θ _ges

total steering wheel angle acting on the steering

Claims (8)

System for trailer stabilization, comprising the following system components: - a vehicle steering system ( 1 ) with handlebar support, - a device ( 2 ) for detecting critical trailer vibrations, and - a controller ( 7 ), with the trailer oscillations on the steering wheel angle or the steering torque are actively ausgeregelbar, wherein upon detection of critical trailer vibration, a temporary intervention in the vehicle steering for trailer stabilization takes place, the trailer oscillations are adjusted depending on the yaw rate and the yaw acceleration of the vehicle, characterized in that Steering wheel angle is set active according to the following relationship: Θ = K ₁ · (-K ₂ · v _G - K ₃ · a _G ), where Θ the steering wheel angle, v _G yaw rate, a _G yaw acceleration, and K ₁ , K ₂ , K _{3 are} predetermined factors. System for trailer stabilization, comprising the following system components: - a vehicle steering system ( 1 ) with handlebar support, - a device ( 2 ) for detecting critical trailer vibrations, and - a controller ( 7 ), with the trailer oscillations on the steering wheel angle or the steering torque are actively controlled, the trailer oscillations depending on he yaw rate of the vehicle are compensated, and wherein upon detection of a critical trailer vibration, a temporary intervention in the vehicle steering for trailer stabilization takes place, characterized in that the trailer vibrations can also be adjusted depending on the Schwimmwinkelgeschwindigkeit of the vehicle. System for vehicle stabilization according to claim 2, characterized in that the steering wheel angle is set active according to the following relationship: Θ = K ₁ · v _S , and v _S = a _Q / v _F - v _G , where Θ is the steering wheel angle, v _{S is} the slip angle velocity, a _{Q is} the lateral acceleration, v _{F is} the vehicle speed, v _{G is} the yaw rate, and K _{1 is} a predetermined factor. System for vehicle stabilization according to claim 3, characterized in that the lateral acceleration is referred to as a modified lateral acceleration on the position of the vehicle clutch and is determined as follows: a _Q * = a _Qsensor - d · a _G where a _Q * is the modified lateral acceleration at the vehicle _clutch , a _{Qsensor is} the lateral acceleration actually measured at a lateral acceleration _sensor , d is the distance of the lateral acceleration sensor from the vehicle clutch, and a _{G is} the yaw acceleration. System for trailer stabilization according to one of claims 1 to 4, characterized in that the yaw rate is measured. System for trailer stabilization according to one of claims 1 to 5, characterized in that the yaw acceleration is obtained by derivation from the yaw rate. System for trailer stabilization according to one of claims 1 to 6, characterized in that before or during the intervention in the steering ( 1 ) the towing vehicle of the team is automatically braked. System for trailer stabilization according to one of claims 1 to 7, characterized in that before or during the intervention in the steering ( 1 ) via the brake system, a stabilizing moment about the vertical axis of the towing vehicle and / or the trailer is automatically generated.

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