Method for parameterizing a software damper for damping chatter vibrations

Abstract

A method for parameterizing a software damper is disclosed. A target clutch torque affected in specified operating states by chatter vibrations is corrected by a software damper, wherein a transfer behavior of a clutch torque transferred via a friction clutch based on the target clutch torque is ascertained during a modulation of the target clutch torque. The software damper is parameterized with the help of the ascertained transfer behavior. To parameterize the software damper quickly and comprehensively, the target clutch torque is modulated by a broadband excitation in a frequency range of the chatter vibrations, and the transfer behavior is ascertained depending on operating parameters of the drivetrain.

Claims

1. A method for parameterizing a software damper connected to a clutch control system for damping chatter vibrations of a clutch torque being transferred by an automated friction clutch which is controlled by the clutch control system by a target clutch torque and which is positioned between a combustion engine and a drivetrain of a motor vehicle, comprising correcting the target clutch torque affected in specified operating states by chatter vibrations by the software damper, including ascertaining a transfer behavior of the clutch torque transferred via the friction clutch on the basis of the target clutch torque during a modulation of the target clutch torque, parameterizing the software damper with the ascertained transfer behavior, modulating the target clutch torque by a broadband excitation in a frequency range of the chatter vibrations, and ascertaining the transfer behavior depending on operating parameters of the drivetrain.

2. The method according to claim 1, further comprising generating the broadband excitation by a PRBS signal.

3. The method according to claim 1, further comprising generating the broadband excitation by a sinusoidal signal with time-variable frequency.

4. The method according to claim 1, further comprising ascertaining the transfer behavior depending on a mean clutch torque.

5. The method according to claim 1, further comprising ascertaining the transfer behavior depending on a selected gear of the transmission.

6. The method according to claim 1, further comprising ascertaining the transfer behavior depending on masses of the drivetrain which are coupled with each other.

7. The method according to claim 1, further comprising ascertaining the transfer behavior depending on masses of the drivetrain which are coupled vibrationally with the drivetrain.

8. The method according to claim 1, further comprising ascertaining the transfer behavior depending on at least one temperature of a component of the drivetrain.

9. The method according to claim 1, further comprising ascertaining the transfer behavior depending on a driving resistance of the motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in further detail on the basis of the exemplary embodiment depicted in FIGS. 1 through 4. The figures show the following:

(2) FIG. 1 a time sequence of a sine sweep,

(3) FIG. 2 a diagram to depict a broadband excitation of the target clutch torque by means of a linear feedback shift register to generate a PRBS signal,

(4) FIG. 3 a diagram with the time sequence of a PRBS signal that modulates the clutch torque,

(5) and

(6) FIG. 4 a diagram with the spectrum of a PRBS signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) The sine sweep shown in FIG. 1 is created by means of a signal generator. A sinusoidal signal with a specified frequency and torque amplitude is produced. In the exemplary embodiment shown, the frequency is increased in a fixed interval, which results in a stepped frequency pattern. The frequency range used typically lies between 1.5 Hz and 30 Hz, which yields the modulated signal shown. This procedure yields a very broadband spectrum, which makes it possible to obtain the most detailed possible frequency response of the system over the control link.

(8) FIGS. 2 through 4 show an alternative method to the method in FIG. 1, in order to achieve a broadband excitation of the target clutch torque. This method is based on the excitation using a pseudorandom binary sequence (PRBS) signal. To this end, a so-called linear feedback shift register (LFSR) is implemented, which outputs zero or one quasi at random after every call. This generates a randomly varying signal level with a given amplitude. The linear feedback shift register shown in FIG. 2 is realized by a binary-interpreted number of desired magnitude. The following values are generated by first capturing certain places in the number dependent on the length of the register, and joining them into a new bit by means of appropriate logical links. This new bit is then inserted at the beginning of the register, and the rest of the bits are each displaced by one position. A random level is realized by the capture of the last bit. In FIG. 3, the random level S is added to the target clutch torque from a driving strategy to set a static clutch torque at the friction clutch. By means of this modulation, an excitation of the drivetrain is achieved with a broadband modulation of the clutch torque. The level S depicted in FIG. 3 represents a rectangular modulation, which is distinguished in the spectrum by an amplitude dependency of the form

(9) $\frac{\sin \left(\frac{}{50\mathrm{Hz}}.Math.v\right)}{v}.$

(10) The switchover time of 20 ms causes the amplitude dependency to become noticeable only at frequencies starting around 50 Hz, since the first frequency components disappear here.

(11) FIG. 4 shows the spectrum of the PRBS signal for this. This is present at any time. As a result, the required duration of an experiment to ascertain the transfer behavior of the modulated target clutch torque is determined essentially by the frequency resolution desired in the transfer function and the desired signal-to-noise ratio. This applies, according to the interconnections of the discrete Fourier transformation, for the minimum entire duration T.sub.Ex=1/v of the experiment, where v is the desired frequency resolution. For a typical measurement of adequate quality for designing and parameterizing the software damper, a measurement period of typically at least 30 s is used.