DE102005028787A1 - Carriage stabilization system for e.g. personal motor vehicle, has vehicle steering designed as servo steering, with steering aid, and mechanism for detecting critical trailer oscillations - Google Patents

Abstract

The system has a vehicle steering (1) designed as a servo steering, with a steering aid and a mechanism for detecting critical trailer oscillations. A temporary contact takes place in the steering for carriage stabilization, on detection of the oscillation. The reinforcement of the steering in the direction which is opposite to steering movement at a steering wheel (6), is lessened during the temporary contact.

Description

The This invention relates to a trailer stabilization system, especially for passenger cars and light commercial vehicles with trailer is suitable.

At the leaders of motor vehicles with trailers can between the towing vehicle and the towed vehicle speed-dependent vibrations around the vertical axes occur that affect the driving stability.

Currently common approaches for team stabilization aim at the team as possible rapidly decelerating below a so-called critical speed. In principle, the driver can already do this by actuating the Achieve vehicle braking.

automated Systems recognize, for example, critical tension oscillations Help a sensor implemented in the towing vehicle and suitable Detection algorithms in the ESP control unit and initiate an automatic corresponding activation of the wheel brakes.

At the Braking of the team occurs due to the temporary emergence of the trailer the towing vehicle usually first to a reinforcement the vibration before the vibration subsides. Especially at medium and low road friction values, the sounding up the vibration to critical driving conditions and in the worst case lead to a buckling of the team.

Especially critical driving conditions can also then arise when an untrained Driver tries to turn the steering wheel movements to the unstable team stabilize.

Of the Invention is therefore the object of the driving safety to increase of teams.

These The object is achieved by a system according to claim 1, which a vehicle steering with handlebar support and a device for detecting critical trailer vibrations and is characterized in that when detecting a critical trailer fishtailing a temporary one Engaged in the vehicle steering for trailer stabilization takes place.

By the inclusion of steering in a trailer stabilization system let yourself critical to stability Driving situations that result from vibrations around the Hochachsen, counteract better. Steering movements can namely stabilize a Harnessed when these are in the correct phase position to the stability critical Vibration performed become. With the invention can be by the temporary intervention in the steering cause such a corrective steering movement or unfavorable Avoid steering movements.

For the procedure in the steering different concepts are conceivable. So the procedure can be passive, d. H. without one from the driver intended steering movement. Corresponding concepts are based above all on the consideration, faulty steering movement for To complicate the driver or to this a steering recommendation to shake hands, whose compliance is at the discretion of the driver is.

Is possible However, also an active intervention in the steering in the sense of an actual Steering movement.

advantageous Embodiments of the invention are specified in the claims.

following 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 in Ver equal 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 steering 1 independent of an actuation of the wheel brakes 5 to induce.

According to a first advantageous embodiment of the invention, the vehicle steering is designed as a power steering. During tandem stabilization the reinforcement of the steering becomes 1 reduced. This prevents a counterproductive intervention of the driver via the steering wheel 6 , because for this due to the reduced steering assistance the steering 1 harder or heavier. The lowering of the reinforcement is preferably maintained until the team comes to rest again. An essential advantage of this concept lies in its particularly simple realization.

Furthermore, it is possible the steering 1 temporarily only one-sided hardening. This also leads to a counterproductive intervention by the driver via the steering wheel 6 counteracted. At the same time in the opposite direction in which a steering wheel movement is useful for stabilizing the team, the normal state of the steering is maintained. As a result, the driver, if this is the steering wheel 6 operated, supported in a correct action, but inhibited in the wrong action. In a situation critical to stability, under the above-mentioned recognition algorithms, the direction in which small steering movements are conducive to the stabilization of the team can vary from one side to the other side. This can be considered by an alternately hardening of the steering in each case on the one and the other side.

The hardening can be achieved by changing the gain of the steering. Practically, you will be during the temporary intervention for team stabilization, the reinforcement of the steering 1 temporarily reduce only in that direction, which stabilizes the team steering a steering movement on the steering wheel 6 is opposite.

In addition, the gain can be temporarily increased in the direction in which on the steering wheel 6 to make a stabilize the team steering movement.

However, a temporary hardening of the steering can also by other measures, for example by the temporary increase in friction in the steering 1 or on the steering wheel 6 will be realized.

According to a further advantageous embodiment of the invention is during the temporary engagement in the steering 1 in the same a Überlagerungslenkmomenterzeugt over the driver a steering recommendation for stabilizing the team on the steering wheel 6 is displayed haptically. A corresponding steering was explained in the German patent application no. 10 2004 041 413.0 of the applicant. 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 ,

In the above-mentioned system configurations, the engagement with the steering remains 1 passive, that is, as long as the driver does not himself a steering movement on the steering wheel 6 caused, in a stability-critical situation, either only a wrong steering behavior difficult, or the driver a hitched right wheel movement displayed.

It but it is also possible in a stability critical Driving situation independent from the driver and possibly supported by an automatic Brake intervention automatically to initiate a corrective steering movement that stabilizes the team.

According to a corresponding, further advantageous 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 temporary intervention in the 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.

On the automatic braking intervention, it is still possible, a towing vehicle stabilizing moment to create the vertical axis by the brake pressures be individually controlled at the individual wheel brakes. About one in the vehicle existing ESP leaves this without big Accomplish additional effort. Furthermore, it is conceivable to be braked followers the individual wheel brakes in a way stabilizing the team individually to steer. In combination with a driver side or automatic steering correction can be a particularly effective Realize system for trailer stabilization.

As already indicated above, the driver can occur when trailer vibrations also be supported by an active steering intervention, including here such measures be understood, resulting in a change in the steering angle the vehicle wheels knock down, 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 a tuning for the trailer stabilization can be carried out very easily.

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. Through this a trailer oscillation is assured within a few seconds that would get progressively more and more without controller, as shown in the course of the transverse acceleration a _Q and yaw rate v _G.

In order to avoid violent steering wheel reactions in response to a glitch, the control torque of the 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 is the steering wheel angle, v _{S is} the slip angle speed v _S and K _{1 are} a given 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 - there G where a _{Q is} the 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 The invention has been explained in more detail above with reference to preferred embodiments. she but is not limited to these, but rather includes all by the claims defined embodiments. In all cases, the driving safety while guiding increased by teams.

1

steering

2

Facility 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

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

from Driver applied steering wheel angle

Θ _ges

on the steering total acting steering wheel angle

Claims (19)

System for trailer stabilization, comprising the following system components: - a vehicle steering system ( 1 ) with handlebar support, and - a facility ( 2 ) for the detection of critical trailer vibrations, characterized in that upon detection of a critical trailer vibration, a temporary intervention in the vehicle steering for trailer stabilization takes place. System for trailer stabilization according to claim 1, characterized in that the vehicle steering is designed as a power steering and during the temporary engagement for the vehicle stabilization, the gain of the steering ( 1 ) is reduced. System for trailer stabilization according to claim 1 or 2, characterized in that the steering ( 1 ) is temporarily hardened on one side. System for trailer stabilization according to claim 1, characterized in that the vehicle steering is designed as a power steering and during the temporary engagement for the vehicle stabilization, the gain of the steering ( 1 ) is temporarily reduced only in that direction, the one of the team stabilizing the steering wheel steering ( 6 ) is directed opposite. System for trailer stabilization according to claim 4, characterized in that the ampl kung is temporarily increased in the direction in which the steering wheel ( 1 ) is to make a team stabilizing the steering movement. Track stabilization system according to one of claims 1 to 5, characterized in that during the temporary engagement in the steering ( 1 ) is generated in the same a Überlagerungslenkmomenter over which the driver a steering recommendation for stabilizing the combination on the steering wheel ( 6 ) is displayed haptically. System for vehicle stabilization according to claim 1, characterized in that the vehicle steering is designed as a superposition steering, in which a driver's steering angle set an additional steering angle is superimposed, and that during the temporary engagement in the steering ( 1 ) an additional steering angle stabilizing the combination is generated. System for trailer stabilization according to one of claims 1 to 7, characterized in that before or during the intervention in the steering ( 1 ) the towing vehicle of the team is automatically braked. A vehicle stabilization system according to any one of claims 1 to 8, 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. System for trailer stabilization according to claim 1, characterized in that a controller ( 7 ) is provided with the trailer vibrations on the steering wheel angle or the steering torque are actively compensated. A system for trailer stabilization according to claim 10, characterized in that the trailer vibrations in dependence the yaw rate and the yaw acceleration of the vehicle regulated become. System for vehicle stabilization according to claim 11, characterized in that the 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. A system for trailer stabilization according to claim 10, characterized in that the trailer vibrations in dependence yaw rate and float velocity of the vehicle be corrected. System for trailer stabilization according to claim 13, 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 14, 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 - there G where a _{Q is} the 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 the claims 10 to 15, characterized in that the yaw rate is measured. System for trailer stabilization according to one of the claims 10 to 16, characterized in that the yaw acceleration by Derivation from the yaw rate is obtained. System for vehicle stabilization according to one of claims 10 to 17, characterized in that before or during the intervention in the steering ( 1 ) the towing vehicle of the team is automatically braked. Track stabilization system according to any one of claims 10 to 18, characterized in that before or during the intervention in the steering ( 1 ) via the brake system a stabilizing Moment is generated automatically around the vertical axis of the towing vehicle and / or the trailer.