DE102012217132B4 - Method for reducing chatter vibrations - Google Patents

Abstract

Method for reducing chatter vibrations in a motor vehicle drive train with a drive unit, a vehicle transmission and an automated friction clutch, the following steps being carried out: current signal value of the signal of the transmission input speed (10) to a current value Sinus_Produkt (50) and multiplying a current signal value of a signal that describes a cosine function (20) with a start frequency over time with the current signal value of the signal of the transmission input speed (10 ) to a current value Cosine_Product (40), • Moving averaging over the current value Sinus_Product (50) as well as all values Sinus_Product (50) that were determined based on the current value Sinus_Product (50) over a period of the start frequency to a value Sinus_Anteil ( 70) and sliding averaging over the current value Cosinus_Produkt (40) as well as all values Cosinus_Produkt (40) which, starting from the current value Cosinus_Produkt (40) over a period of the start frequency, were determined to a value Cosinus_Produkt (60), • Determination of the amplitude (80) from the values Sin_Anteil (70) and Cosinus_Anteil (60), • Determination of the phase shift (90) between the signal of the transmission input speed (10) and the cosine function (20), • Determination of a signal (100) that represents the chatter oscillation, from the amplitude (80) and the phase shift (90), • Determination of a value of a phase shift of the signal (100), which represents the chatter oscillation, the value being selected such that a phase shift of the signal (100), which the chatter oscillation represents, around this value a control signal (110) to the clutch actuator results, which reduces the chatter vibration, characterized in that the determination of the phase curve Shift (90) between the signal of the transmission input speed (10) and the cosine function (20) takes place by means of the sign and the arctangent function from the two values Sinus_Anteil (70) and Cosinus_Anteil (60).

Description

The invention relates to a method with the features according to the preamble of claim 1. It is a method that is implemented as a software strategy in order to reduce chatter vibrations on a mechatronically controlled friction clutch.

DE 10 2008 030 481 A1 discloses a method for controlling slip of a vehicle clutch.

According to the state of the art for anti-judder control, such as the one for example DE 103 23 567 A1 represents, the difference between an unfiltered, vibrating transmission input speed signal and an associated filtered signal is used as the input signal of a control system. This input signal is added as a weighted sum with its derivative to the actuator voltage as an additional voltage. The purpose of the derivation is to get a signal that is 90 ° out of phase with an oscillating signal (note: the derivation of a sine function is the cosine function and this in turn is a sine function shifted by 90 °).

In the case of resonance, the main part of the weighted sum mentioned above is the time derivative of the difference signal. This is initially very noisy, so that a correspondingly noisy voltage must be given to the clutch actuator. In addition, higher frequency components are also amplified in the transmission input speed. Furthermore, only a single frequency is directly taken into account for the chatter oscillation, so that the phase shift is not correctly taken into account outside the resonance of the fundamental drive train natural frequency. If the observed oscillation is caused, for example, by a higher or lower frequency excitation, the system tends to oscillate in antiphase or in phase. This means that the weighting, which is designed for a 90 ° phase shift, is no longer correct, and in the worst case scenario, an oscillation is excited instead of attenuated.

The object of the present invention is to find a solution so that the clutch actuator is controlled in a phase-variable manner, depending on the oscillation frequency that occurs, with a signal that is as smooth as possible without excitation of higher frequency components.

The object is achieved by a method with the features according to claim 1.

• • Multiplizieren eines aktuellen Signalwerts eines Signals, das im zeitlichen Verlauf eine Sinus-Funktion mit einer Startfrequenz beschreibt mit dem aktuellen Signalwert des Signals der Getriebeeingangsdrehzahl (IPS_Signal) zu einem aktuellen Wert Sinus_Produkt und Multiplizieren eines aktuellen Signalwerts eines Signals, das im zeitlichen Verlauf eine Cosinus-Funktion mit einer Startfrequenz beschreibt mit dem aktuellen Signalwert des Signals der Getriebeeingangsdrehzahl (IPS_Signal) zu einem aktuellen Wert Cosinus_Produkt,
• • Gleitende Mittelwertbildung über den aktuellen Wert Sinus_Produkt sowie alle Werte Sinus_Produkt die, ausgehend vom aktuellen Wert Sinus_Produkt über eine Periode der Startfrequenz ermittelt wurden zu einem Wert Sinus_Anteil und gleitende Mittelwertbildung über den aktuellen Wert Cosinus_Produkt sowie alle Werte Cosinus_Produkt die, ausgehend vom aktuellen Wert Cosinus_Produkt über eine Periode der Startfrequenz ermittelt wurden zu einem Wert Cosinus_Anteil,
• • Ermitteln der Amplitude (Amplitude) aus den Werten Sinus_Anteil und Cosinus_Anteil,
• • Ermitteln der Phasenverschiebung (Phase) zwischen dem Signal der Getriebeeingangsdrehzahl (IPS_Signal) und der Cosinus-Funktion,
• • Ermitteln eines Signals, das die Rupfschwingung repräsentiert, aus der Amplitude (Amplitude) und der Phasenverschiebung (Phase),
• • Ermittlung eines Werts einer Phasenverschiebung des Signals, welches die Rupfschwingung repräsentiert, wobei der Wert derart gewählt ist, dass sich bei Phasenverschiebung des Signals, welches die Rupfschwingung repräsentiert, um diesen Wert ein Steuersignal an die Kupplungsaktorik ergibt, welches die Rupfschwingung vermindert.

According to the invention, a method for reducing chatter vibrations in a motor vehicle drive train with a drive unit, a vehicle transmission and an automated friction clutch is proposed, the following steps being carried out:

• • Multiplication of a current signal value of a signal that describes a sine function with a start frequency over time with the current signal value of the signal of the transmission input speed (IPS_Signal) to a current value Sin_Product and multiplication of a current signal value of a signal that has a cosine over time -Function with a start frequency describes with the current signal value of the signal of the transmission input speed (IPS_Signal) for a current value Cosine_Product,
• • Moving averaging over the current value Sin_Product as well as all values Sin_Product that were determined based on the current value Sin_Product over a period of the start frequency to a value Sin_Anteil and moving averaging over the current value Cosine_Product as well as all values Cosine_Product, starting from the current value Cosine_Product a period of the start frequency was determined to a value Cosinus_Anteil,
• • Determination of the amplitude (amplitude) from the values Sin_Anteil and Cosinus_Anteil,
• • Determination of the phase shift (phase) between the signal of the transmission input speed (IPS_Signal) and the cosine function,
• • Determination of a signal that represents the chatter vibration from the amplitude (amplitude) and the phase shift (phase),
• • Determination of a value of a phase shift of the signal which represents the chatter oscillation, the value being selected such that a phase shift of the signal which represents the chatter oscillation by this value results in a control signal to the clutch actuator which reduces the chatter oscillation.

In a preferred embodiment of the invention it is provided that the value of the phase shift of the signal which represents the chatter oscillation is 90 °.

In a further preferred embodiment of the invention it is provided that the determination of the amplitude (amplitude) from the values Sin_Anteil and Cosinus_Anteil takes place by forming the root of the square sum of the two values Sin_Anteil and Cosinus_Anteil.

According to the invention, it is provided that the phase shift (phase) between the transmission input speed signal (IPS_Signal) and the cosine function is determined by means of the sign and the arctangent function from the two values Sinus_Anteil and Cosinus_Anteil.

In a further preferred embodiment of the invention it is provided that a frequency correction is determined from the time derivative of the determined phase shift between the signal of the transmission input speed (IPS_Signal) and the cosine function, whereby by means of forming the difference from the start frequency or an already available, most current corrected frequency ( Frequency_Corrected) and frequency correction a corrected frequency (Frequency_Corrected) is determined.

Another preferred embodiment of the invention provides that the sine function ( 30th ) and cosine function ( 20th ) are two mutually orthogonal, periodic, mathematical functions.

The advantage of the method according to the invention is that the clutch actuator is controlled in a phase-variable manner, depending on the oscillation frequency that occurs, with a signal that is as smooth as possible without the excitation of higher frequency components

Further advantages and advantageous embodiments of the invention are the subject of the following description and the following figure and its description.

To extract the relevant oscillating component of the chatter oscillation from the unfiltered transmission input speed signal, a start frequency is initially assumed. Obvious here is the fundamental natural drive train frequency, which is known for a system in a narrow band. Over a period of this start frequency, the unfiltered transmission input signal is multiplied once with a sine function and once with a cosine function with an arbitrarily chosen time zero point and a known phase for this, and the mean value - for example a sliding average over a period duration - is formed (Note: This is similar a Fourier transform for a frequency with a very limited integration range). Sine and cosine components can also be interpreted as amplitude (root of the sum of squares) and phase (arctan from the ratio) relative to the underlying, known phase, and amplitude and phase can be determined from the sine and cosine components. The calculation is carried out continuously over time. Fits the underlying start frequency ω ₀ ω the relevant vibrating part of the observed juddering vibration _Sig, so tune the frequencies ω ω match ₀ and _Sig, the resulting phase will remain stable.

ändern gemäß: $$\Delta \omega ={\omega }_{Sig}-{\omega }_0=\frac{d\varphi \left(t\right)}{dt}$$

If there is a (not too great) frequency deviation between ω ₀ and ω _Sig , the phase will be proportional to the frequency deviation $\frac{d\varphi \left(t\right)}{dt}$

change according to: $$\Delta \omega ={\omega }_{\mathrm{S.}iG}-{\mathrm{<figure-callout\; id="0"\; label="\omega "\; filenames="DE102012217132B4\_0003.png"\; state="\{\{state\}\}">\omega </figure-callout>}}_0=\frac{d\varphi \left(t\right)}{dt}$$

This frequency deviation can now be used to adjust the frequency relative to the start frequency and the method can be carried out again with the adjusted frequency. Alternatively, only the phase that changes over time - which corresponds to an effective frequency correction - is used as the frequency correction without explicitly determining an adaptation of the starting frequency value. Since with chatter vibrations usually only frequencies close to the fundamental drive train natural frequency - which was selected as the starting frequency - play a role, it is usually sufficient to take into account the frequency deviation that results from the phase that changes over time.

• Im eingeschwungenen Zustand entspricht die Schwingungsfrequenz der anregenden Frequenz.

In the following, the drive train is viewed in simplified form as a driven damped harmonic oscillator, as it is well known from the literature on physics and electrical engineering: This is characterized by the following properties:

• In the steady state, the oscillation frequency corresponds to the stimulating frequency.

If the stimulating frequency is significantly higher than the natural frequency, the stimulation and oscillation are out of phase.

If the stimulating frequency is significantly lower than the natural frequency, stimulation and oscillation are in phase.

If the exciting and natural frequencies are the same, there is a phase difference of 90 ° between them and the amplitude is maximal (resonance)

• Je nach zu dämpfender Frequenz muss zur Dämpfung ein Gegensignal mit entsprechender Phase erzeugt werden

This has the following consequences:

• Depending on the frequency to be attenuated, a counter signal with a corresponding phase must be generated for attenuation

The amplitude of the counter signal must also be adjusted accordingly

The counter signal can accordingly be generated in that a sinusoidal oscillation with a corresponding amplitude is generated relative to the detected phase and is used accordingly as a manipulated variable for torque modulation on the clutch. Time delays due to signal propagation times or hardware dynamics in the phase can also be taken into account accordingly, just as the detected frequency can be used for phase adjustment.

• IPS_Signal 10 sei die ungefilterte Getriebeeingangsdrehzahl.

In the following, the procedure will be based on 1 can be illustrated using a specific exemplary embodiment:

• IPS_Signal 10 be the unfiltered transmission input speed.

Cosine_function 20th and Sin_Function 30 are the two periodic (and mutually orthogonal) functions with the start frequency with which IPS_Signal is multiplied. The drive train's natural frequency is selected as the start frequency.

The result of the multiplication is cosine_product 40 and Sinus_Product 50 .

The two moving averages over a period of the start frequency are Cosinus_Anteil 60 and Sinus_Anteil 70 .

The root of the sum of squares of the two components (Cosinus_Anteil 60 and Sinus_Anteil 70 ) gives the amplitude 80 .

The phase shift between IPS signals 10 and cosine_function 20th can be made up of the two components (Cosinus_Anteil 60 and Sinus_Anteil 70 ) and is in 1 as a phase 90 designated.

From amplitude 80 and phase 90 a filtered signal can now be calculated that represents the chatter vibration and is shown in 1 as isolated_vibration 100 is designated. This changes the frequency of the signal 100 over time due to the changing phase 90 .

This signal 100 can be charged with a phase, in the example the 1 with 90 °. The result is in 1 as control signal 110 designated.

From the time derivative of the determined phase 90 the result is a frequency correction which, as the difference to the start frequency, is a corrected frequency 130 represents. This corrected frequency 130 can now be used to repeat the procedure with the corrected frequency instead of the start frequency 130 perform. Such a repetition can take place once or, for example, until the frequency correction falls below a predeterminable threshold value, that is to say is sufficiently small. As above for determining the isolated_vibration 100 from the amplitude 80 and phase 90 already described, only the phase that changes over time can be used as a frequency correction 90 - which corresponds to an effective frequency correction - can be used without explicitly determining an adaptation of the start frequency value. Since chatter vibrations usually only occur at frequencies close to the start frequency in practice, it is usually sufficient to take into account the frequency deviation, which only results from the phase that changes over time 90 results.

Depending on the determined frequency - be it, depending on the presence, the unchanged start frequency or that by means of the effective frequency correction from the phase which changes over time 90 obtained frequency in the signal of the isolated_swing 100 or if the corrected frequency 130 then the corrected frequency 130 - can now be a phase shift, as above when determining the control_signal 110 by applying the signal 100 with a phase already carried out in such a way that the above-mentioned properties of a forced oscillation and the reaction time of the system are taken into account, so that the chattering oscillation is damped when it is transferred to the clutch torque. In a simplified embodiment, the control_signal 110 by applying the signal of the isolated oscillation 100 obtained with a phase shift of 90 degrees.

Using this phase shift and the determined amplitude 80 and depending on the presence of the start frequency or the one from the isolated oscillation 100 obtained frequency or if the corrected frequency 130 then the corrected frequency 130 , so becomes the control signal 110 generated, which is used as a target torque modulation of a clutch actuator in order to actively dampen the disruptive chatter vibration.

An interfering vibration is extracted from a transmission input speed signal 10 or another signal that reflects an undesired torque modulation on the clutch.

This is done on the basis of the fundamental natural frequency of the drive train - the chatter frequency - when the clutch is slipping. Both a frequency deviation of the interfering vibration that occurs and the chatter frequency as well as an amplitude and phase are determined.

A particularly advantageous property of this method is the suppression of noise and higher and / or lower frequency components.

Depending on the amplitude, phase and frequency deviation, a control signal is generated that can be used, for example, as a target torque modulation of a clutch actuator in order to actively dampen the vibration.

The calculation of the moving average using the product of the input signal (IPS_Signal) and the generated oscillation with start frequency (start frequency) or the corrected frequency (Frequency_Corrected) takes place continuously.

The application is intended to improve driving comfort with jerky, dry double clutches. In particular, this is intended to increase the tolerance to torque irregularities in the hardware and thus to reduce scrap.

The invention is intended to contribute to the fact that the tendency of clutch systems to chatter - since it can be reduced by means of the invention - is no longer so important and thus other parameters can be optimized (torque capacity, wear, etc.).

For reasons of running time, the oscillation calculation should only be carried out with one basic frequency - the start frequency - as this allows the calculation of the moving average to be greatly optimized. However, frequency feedback is also conceivable in order to further increase the signal quality.

A sine function or cosine function does not necessarily have to be used for detection; in principle, another periodic function can also be used (e.g. box function). An adapted function can also be used to generate the manipulated variable, which e.g. also takes into account non-linearities in the response behavior of the system. A phase shift can also be generated in different ways.

Various input and output signals could be used that correspond in the broadest sense to a drive train torque, e.g. the vehicle's longitudinal acceleration as an input signal or an actuator pressure as an output signal.

The aim of the invention is to actively dampen chatter vibrations occurring on a friction clutch by modulating the clutch position in order to increase driving comfort. If possible, no higher or lower frequency vibrations should be excited. The approach of the invention pays particular attention to the in-phase negative feedback even at stimulating frequencies apart from the fundamental drive train natural frequency.

List of reference symbols

10

IPS_Signal (transmission input shaft signal)

20th

Cosine_function

30th

Sine_function

40

Cosine product

50

Sinus_Product

60

Cosine_part

70

Sinus_Anteil

80

amplitude

90

phase

100

Isolated_vibration

110

Control_Signal

120

Starting frequency

130

Frequency_Corrected

Claims (5)

Method for reducing chatter vibrations in a motor vehicle drive train with a drive unit, a vehicle transmission and an automated friction clutch, the following steps being carried out: Current signal value of the signal of the transmission input speed (10) to a current value Sinus_Produkt (50) and multiplying a current signal value of a signal that describes a cosine function (20) with a start frequency over time with the current signal value of the signal of the transmission input speed (10 ) to a current value Cosine_Product (40), • Moving averaging over the current value Sinus_Product (50) as well as all values Sinus_Product (50) that were determined based on the current value Sinus_Product (50) over a period of the start frequency to a value Sinus_Anteil ( 70 ) and sliding averaging over the current value Cosinus_Produkt (40) as well as all values Cosinus_Produkt (40) which were determined, starting from the current value Cosinus_Produkt (40) over a period of the start frequency to a value Cosinus_Produkt (60), • Determination of the amplitude (80 ) from the values Sin_Anteil (70) and Cosinus_Anteil (60), • Determination of the phase shift (90) between the signal of the transmission input speed (10) and the cosine function (20), • Determination of a signal (100), which represents the chatter vibration, from the amplitude (80) and the phase shift (90), • Determination of a value of a phase shift of the signal (100), which represents the chatter vibration, the value being selected in such a way that a phase shift of the signal (100), which represents the chatter vibration, by this value results in a control signal (110) to the clutch actuator, which reduces the chatter vibration, characterized in that the determination of the phase shift (90) between the signal of the transmission input speed ( 10) and the cosine function (20) by means of the sign and the arctangent function from the two values Sin_Anteil (70) and Cosinus_Anteil (60). Procedure according to Claim 1 , characterized in that the value of the phase shift of the signal (100) which represents the chatter vibration is 90 °. Method according to one of the Claims 1 or 2 , characterized in that the amplitude (80) is determined from the values Sin_Anteil (70) and Cosinus_Anteil (60) by forming the root of the square sum of the two values Sinus_Anteil (70) and Cosinus_Anteil (60). Method according to one of the preceding claims, characterized in that a frequency correction is determined from the time derivative of the determined phase shift between the signal of the transmission input speed (10) and the cosine function (20), with the difference formation from the start frequency or an already available, most recent corrected frequency and frequency correction a corrected frequency (130) is determined. Method according to one of the preceding claims, characterized in that the sine function (30) and the cosine function (20) are two mutually orthogonal, periodic, mathematical functions.

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