DE102006044424B4 - Determination of the desired yaw rate by means of an extended single-track model - Google Patents

Abstract

wobei k₁, k₂ zwei zusätzliche Parameter, v die Fahrgeschwindigkeit, δ_H der Lenkradwinkel, I der Radstand, iL die Lenkübersetzung und v_ch die so genannte charakteristische Geschwindigkeit sind.

Method for controlling the driving dynamics of a vehicle (1), in which a desired yaw rate is calculated, wherein the target yaw rate (dψ / dt) is calculated by means of an extended one-track model, which in addition to the state variables and parameters of the linear single-track model at least one additional parameter (k ₁ , k ₂ ),
characterized in that the desired yaw rate (dψ / dt) is calculated according to the following formula: $${\dot{\psi }}_{\text{should}}={\text{k}}_1\cdot \frac{\text{v}}{\text{I}\cdot \left(1+{\text{k}}_2\cdot \frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

where k ₁ , k _{2 are} two additional parameters, v is the vehicle speed, δ _{H is} the steering wheel angle, I is the wheelbase, iL is the steering ratio and v _{ch is} the so-called characteristic speed.

Description

State of the art

The invention relates to a method for regulating the driving dynamics of a vehicle according to the preamble of patent claim 1 and to a corresponding device according to the preamble of patent claim 8.

wobei dψ_soll/dt die Soll-Giergeschwindigkeit, v die Fahrgeschwindigkeit, δ_H der Lenkradwinkel, I der Radstand, i_L die Lenkübersetzung und v_ch die so genannte charakteristische Geschwindigkeit ist. Die Sollwertbildung der Giergeschwindigkeit dψ/dt ist eine der wichtigsten, aber auch eine der schwierigsten Aufgaben bei der Fahrdynamikregelung, da der berechnete Sollwert einen direkten Einfluss auf die Eingriffsschwelle des Fahrdynamikregelungssystems hat. Bei einer Abweichung des berechneten Sollwerts vom tatsächlich gewünschten Fahrverhalten kann es daher zu verfrühten oder auch zu verspäteten Stelleingriffen des Fahrdynamikreglers kommen.Driving dynamics controllers known from the prior art, such as ESP, comprise a control unit with a control algorithm stored therein, which usually controls the yaw rate of the vehicle. In a critical driving situation in which the vehicle, for example, greatly over- or understeer, the vehicle dynamics controller intervenes by means of the vehicle brakes and possibly also by means of the steering in the driving operation to stabilize the vehicle again. The current actual value of the yaw rate is usually measured with the aid of a yaw rate sensor. The target value of the control, which is determined by the driver's default (steering wheel angle, accelerator pedal position), is generally calculated using the so-called single-track model. From the linear single-track model follows for the yaw rate: $${\dot{\psi }}_{\text{Should}}=\frac{\text{v}}{\text{I}\cdot \left(1+\frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

where dψ _soll / dt the desired yaw rate, v the driving speed, δ _H the steering wheel angle, I the wheelbase, i _L the steering ratio and v _ch is the so-called characteristic speed. The setpoint formation of the yaw rate dψ / dt is one of the most important, but also one of the most difficult tasks in vehicle dynamics control, since the calculated setpoint has a direct influence on the intervention threshold of the vehicle dynamics control system. In the event of a deviation of the calculated target value from the actual desired driving behavior, it may therefore be premature or even too late control actions of the vehicle dynamics controller.

The calculation of the setpoint value according to equation (1) is sufficiently accurate, especially at low driving speeds, but deviates significantly at average speeds of between about 10 m / s and 20 m / s from the real behavior of the vehicle. It is therefore often necessary in practice, between different target yaw rates, with different values for the characteristic speed v _ch were calculated to interpolate. In principle, an average value is formed from two values calculated on the basis of equation (1). This is relatively expensive and beyond that often relatively inaccurate.

From the generic DE 199 19 180 A1 a control circuit for controlling the driving stability of a vehicle is known, in which the determining the trajectory determining inputs are input to a vehicle model circuit, which at least one setpoint for due to one in the vehicle model circuit, the properties of the vehicle modeled vehicle reference model a controlled variable determined in dependence on the vehicle reference model stored parameters. To adapt the parameters to the vehicle, a vehicle identifier is provided, the output signals of which are supplied to the vehicle reference model, the output signals, taking into account individual state variables of the vehicle, adapting the parameters stored in the vehicle reference model or replacing them with newly formed parameters.

The DE 195 15 046 A1 discloses a device for controlling the yaw moment of a vehicle, in which based on the information of a sensor, the current Schwimmwinkelgeschwindigkeit is determined.

Disclosure of the invention

It is therefore the object of the present invention to provide a method by which the target yaw rate of the vehicle can be calculated more accurately, as well as to provide a vehicle dynamics controller which performs a more accurate calculation of the target yaw rate.

This object is achieved according to the invention by the features specified in claim 1, and in claim 8. Further embodiments of the invention are the subject of dependent claims.

An essential aspect of the invention is to calculate the desired yaw rate by means of an extended one-track model, which comprises at least one additional parameter, which can be adapted to the current state of the vehicle, compared with the aforementioned model. This has the significant advantage that the desired yaw rate can be calculated much more accurately. The at least one additional parameter is preferably adjusted regularly to the current state of the vehicle.

The additional parameter is preferably a variable which is dependent on the steering wheel angle. In this case, for example, a characteristic of the parameter depending on the steering wheel angle can be stored in the controller system.

dabei sind die Faktoren k₁ ,k₂ zusätzliche Parameter, v die Fahrgeschwindigkeit, δ_H der Lenkradwinkel, I der Radstand, iL die Lenkübersetzung und v_ch die so genannte charakteristische Geschwindigkeit.According to the invention, the target yaw rate is calculated according to the following formula: $${\dot{\psi }}_{\text{should}}={\text{k}}_1\frac{\text{v}}{\text{I}\cdot \left(1+{\text{<figure-callout id="2" label="k" filenames="DE102006044424B4\_0009.png" state="{{state}}">k</figure-callout>}}_2\cdot \frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

Here are the factors k ₁ . k ₂ additional parameters, v the driving speed, δ _H the steering wheel angle, I the wheelbase , iL the steering ratio and v _ch the so-called characteristic speed.

The parameter k ₁ can be specified either analytically or eg in the form of a characteristic as a function of the steering wheel angle.

The parameter k ₂ is preferably calculated directly from equation (2). In this case, preferably initially a raw value for the parameter k ₂ calculated and the raw value then filtered by time.

Typical values for the parameter k ₁ For example, values are between 1.0 and 1.3. The value range of the parameter k ₂ is preferably between about -3 and +40.

The absolute value of the parameters k ₁ . k ₂ is preferably limited to a minimum or maximum value. As a result, in particular, unrealistically small or large values of the desired yaw rate can be prevented.

list of figures

• 1 eine schematische Darstellung eines Fahrdynamikregelungssystems gemäß einer speziellen Ausführungsform der Erfindung.

The invention will now be described by way of example with reference to the accompanying drawings. Show it:

• 1 a schematic representation of a vehicle dynamics control system according to a specific embodiment of the invention.

Embodiment of the invention

1 shows a schematic representation of a vehicle dynamics control system, such as ESP, which is essentially a controller 4 with a control algorithm stored in it 5 comprising yaw rate control. The control unit 4 is in the vehicle 1 integrated. In a critical driving situation in which the actual driving behavior of the vehicle deviates too much from the setpoint behavior, the control algorithm generates 5 an adjustment request for the wheel brakes 3a - 3d selected wheels. Due to the automatic braking intervention, the vehicle is decelerated and at the same time a yawing moment is generated which counteracts the yawing behavior of the vehicle and thus stabilizes the vehicle again.

wobei dψ_soll/dt die Soll-Giergeschwindigkeit, v die Fahrgeschwindigkeit, δ_H der Lenkradwinkel, I der Radstand, i_L die Lenkübersetzung und v_ch die so genannte charakteristische Geschwindigkeit ist.As part of the scheme, the target yaw rate dψ / dt is calculated according to the following formula: $${\dot{\psi }}_{\text{should}}={\text{k}}_1\frac{\text{v}}{\text{I}\cdot \left(1+{\text{<figure-callout id="2" label="k" filenames="DE102006044424B4\_0009.png" state="{{state}}">k</figure-callout>}}_2\cdot \frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

where dψ _soll / dt is the desired yaw rate, v is the vehicle speed, δ _{H is} the steering wheel angle, I is the wheelbase, i _L the steering ratio and v _ch is the so-called characteristic speed.

The parameter k ₁ can for example analytically or in the form of a characteristic, depending on the steering wheel angle δ _H be deposited in the system.

wobei die Giergeschwindigkeit dψ/dt gemessen wird und v_ch die charakteristische Geschwindigkeit des adaptiven Einspurmodells ist. Da der Parameter k₂ auch negative Werte annehmen kann, um das übersteuernde Fahrverhalten des Fahrzeugs nachbilden zu können, darf v_ch des adaptiven Einspurmodells nicht zu klein gewählt werden. Der Parameter k₂ hat daher vorzugsweise Werte von mehr als 70 m/s, insbesondere etwa 100 m/s. Der Rohwert k_2,roh wird dann gefiltert, um den Parameter k₂ zu erhalten. Beispielsweise kann folgende PT1-Filterfunktion angesetzt werden: $${\text{T}}_{\text{a}}\cdot {\dot{\text{k}}}_2+{\text{k}}_2={\text{k}}_{\mathrm{2,}\text{roh}}$$

wobei die Zeitkonstante T_a von der Abtastzeit zwischen den Messwerten der Giergeschwindigkeit dψ/dt abhängt. Die Zeitkonstante T_a kann relativ groß gewählt werden, da sich das Fahrverhalten während der Fahrt nur langsam ändert.The second parameter k ₂ is preferably calculated directly from equation (2). The following equation initially results in a raw value k _{2, raw} : $${\text{<figure-callout id="2" label="k" filenames="DE102006044424B4\_0009.png" state="{{state}}">k</figure-callout>}}_{\mathrm{2,}\text{raw}}=\frac{{\text{v}}_{\text{ch}}^2}{{\text{<figure-callout id="2" label="v" filenames="DE102006044424B4\_0009.png" state="{{state}}">v</figure-callout>}}^2}\cdot \left(\frac{{\text{k}}_1\cdot \text{v}\cdot {\mathrm{\delta }}_{\text{H}}}{\dot{\psi }}\cdot \frac{1}{\text{I}\cdot {\text{i}}_{\text{L}}}-1\right)$$

wherein the yaw rate dψ / dt is measured and v _ch is the characteristic speed of the adaptive one-track model. Because of the parameter k ₂ can also assume negative values in order to be able to simulate the oversteering driving behavior of the vehicle v _ch of the adaptive one-track model should not be too small. The parameter k ₂ therefore preferably has values of more than 70 m / s, in particular about 100 m / s. The raw value k _{2, raw} is then filtered to the parameter k ₂ to obtain. For example, the following PT1 filter function can be used: $${\text{T}}_{\text{a}}\cdot {\dot{\text{k}}}_2+{\text{<figure-callout id="2" label="k" filenames="DE102006044424B4\_0009.png" state="{{state}}">k</figure-callout>}}_2={\text{<figure-callout id="2" label="k" filenames="DE102006044424B4\_0009.png" state="{{state}}">k</figure-callout>}}_{\mathrm{2,}\text{raw}}$$

where the time constant T _a depends on the sampling time between the measured values of the yaw rate dψ / dt. The time constant T _a can be chosen relatively large, since the driving behavior during the journey changes only slowly.

The parameter k ₂ should also be limited in absolute value, especially to avoid large negative values. The parameter k ₂ can for example be limited between -5 and +30.

Claims (8)

Method for controlling the driving dynamics of a vehicle (1), in which a desired yaw rate is calculated, the setpoint Yaw rate (dψ / dt) is calculated by means of an extended one-track model, which in addition to the state variables and parameters of the linear one-track model at least one additional parameter (k ₁ , k ₂ ), characterized in that the target yaw rate (dψ / dt) to the following Formula is calculated: $${\dot{\psi }}_{\text{should}}={\text{k}}_1\cdot \frac{\text{v}}{\text{I}\cdot \left(1+{\text{k}}_2\cdot \frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

where k ₁ , k _{2 are} two additional parameters, v is the vehicle speed, δ _{H is} the steering wheel angle, I is the wheelbase, iL is the steering ratio and v _{ch is} the so-called characteristic speed. Method according to Claim 1 , characterized in that the additional parameter (k ₁ , k ₂ ) is dependent on the steering wheel angle (δ _H ) or an angle proportional thereto. Method according to Claim 1 , characterized in that the parameter k _{2 is} calculated from the formula, wherein the yaw rate (dψ / dt) is a measured value. Method according to Claim 3 , characterized in that the value thus calculated is filtered. Method according to Claim 1 , characterized in that the parameter k _{1 is} in a range of values between 1.0 and 1.3. Method according to Claim 1 , characterized in that the parameter k _{2 is} in a value range between -3 and +40. Method according to Claim 1 , characterized in that the parameters k ₁ , k ₂ are limited with respect to their absolute value. Device for driving dynamics control of a vehicle (1), comprising a control unit (4) with a control algorithm that calculates a target yaw rate (dψ / dt) and automatically intervenes in the driving mode by excessive control deviation by means of one or more actuators (3a-3d) , wherein the control algorithm (5) calculates the desired yaw rate (dψ / dt) by means of an extended one-track model, which comprises at least one additional parameter (k ₁ , k ₂ ) compared to the linear one-track model, characterized in that the desired yaw rate (dψ / dt) is calculated according to the following formula: $${\dot{\psi }}_{\text{should}}={\text{k}}_1\cdot \frac{\text{v}}{\text{I}\cdot \left(1+{\text{k}}_2\cdot \frac{{\text{v}}^2}{{\text{v}}_{\text{ch}}^2}\right)}\cdot \frac{{\mathrm{\delta }}_{\text{H}}}{{\text{i}}_{\text{L}}}$$

where k ₁ , k _{2 are} two additional parameters, v is the vehicle speed, δ _{H is} the steering wheel angle, I is the wheelbase, iL is the steering ratio and v _{ch is} the so-called characteristic speed.

Images