A method of setting a clutch control reference value may make it possible to more accurately learn the VKP of a hydraulic multi-plate clutch controlled by a solenoid valve, improving the accuracy of clutch control, and furthermore, to improve the quality of shifting a vehicle by the precise control of a transmission provided with such a clutch.

A method of setting a clutch control reference value may make it possible to more accurately learn the VKP of a hydraulic multi-plate clutch controlled by a solenoid valve, improving the accuracy of clutch control, and furthermore, to improve the quality of shifting a vehicle by the precise control of a transmission provided with such a clutch.

Techniques for using factor risk models to more accurately estimate the risk or active risk of an investment portfolio are disclosed. Inherent modeling error in factor risk models is identified and compensated for. One or more factors are added to compensate for factors that are unspecified or unattributed in the original factor risk model and which lead to modeling error. The approach can be used with a variety of different factor risk models, and for a variety of securities. Knowledge of the risk associated with modeling error can be utilized when estimating risk or active risk using factor risk models or when constructing optimal portfolios by mean-variance optimization or other portfolio construction strategies using factor risk models.

A method controls a clutch actuator, comprising a clutch cylinder piston of a clutch cylinder, which clutch cylinder piston moves an actuation element of a friction clutch along an actuation path, and comprising a hydraulic pump, which actuates the clutch cylinder piston by means of a pressure medium pumped along a hydrostatic path and which is operated by means of an electric motor. In order to determine an actuation state of the friction clutch, the operating state along the actuation path is estimated by means of a pressure medium volumetric flow rate produced by the pump and by means of a leakage volumetric flow rate of the pump.

A method is disclosed for reducing chatter vibrations of a friction clutch controlled automatically by a clutch actuator on the basis of a target clutch torque (M(s)) assigned to a clutch torque which is to be transmitted. The friction clutch is positioned in a drivetrain between an internal combustion engine and a transmission, having a present actual clutch torque which is marked by vibrations as a result of vibrations (M(i)). From a transmission behavior of the present actual clutch torque (M(i)), an absolute amplitude and a phase of an input signal detected at the output of the friction clutch and conveyed to a regulator are ascertained, and a phase-selective disturbance torque is ascertained. From the phase-selective disturbance torque, a phase-correct correction torque (M(k)) is determined, and the target clutch torque (M(s)) is corrected by the regulator. The correction torque (M(k)) is weighted with a specifiable intensification factor.

The invention relates to a method for reducing occasionally occurring vibrations, in particular chatter vibrations of a unit controlled automatically by an actuator, in particular a clutch actuator, on the basis of a target torque assigned to a clutch torque that is to be transmitted, in particular a target clutch torque, in particular a unit located in a drivetrain of a motor vehicle between a combustion engine and a transmission, in particular a friction clutch having an actual present clutch torque which is marked by vibrations as a result of occasionally occurring vibrations, wherein from an input signal which is representative of the vibration-marked torque on the basis of a known transfer behavior of the actual present torque vibration components of known form with unknown prefactors are continuously ascertained, a phase-correct correction torque is determined from these, and the target torque is corrected using the latter. In order to be able to separate a plurality of vibration components from one another and resolve them, an estimation model is made the basis of the input signal, and by means of the estimation model the prefactors are determined on the basis of a recursive method of the smallest square errors.

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.

Techniques for using factor risk models to more accurately estimate the risk or active risk of an investment portfolio are disclosed. Inherent modeling error in factor risk models is identified and compensated for. One or more factors are added to compensate for factors that are unspecified or unattributed in the original factor risk model and which lead to modeling error. The approach can be used with a variety of different factor risk models, and for a variety of securities. Knowledge of the risk associated with modeling error can be utilized when estimating risk or active risk using factor risk models or when constructing optimal portfolios by mean-variance optimization or other portfolio construction strategies using factor risk models.

The invention relates to a software damper and to a method for configuring a software damper connected to a clutch control system for damping chatter vibrations of a clutch torque being transferred by means of an automated friction clutch positioned between a combustion engine and a transmission and controlled by the clutch control system, wherein a transmission input speed (r(g)) is captured at the output of the friction clutch by means of the software damper, and the target clutch torque (m(k)) encumbered by chatter vibrations is corrected by means of negative feedback. To design the software damper, a transfer behavior is ascertained over a control link of the clutch control system while the target clutch torque is excited in a frequency range which is relevant for chatter vibrations, under this transfer behavior an undamped first frequency response of the transmission input speed (r(g)) and a second frequency response at the output of the software damper are ascertained, and the negative feedback of the software damper is determined by comparing the two frequency responses.

The invention relates to a method for reducing chatter vibrations of a friction clutch controlled automatically by a clutch actuator on the basis of a target clutch torque (M(s)) assigned to a clutch torque which is to be transmitted, which friction clutch is positioned in a drivetrain of a motor vehicle between an internal combustion engine and a transmission, having a present actual clutch torque which is marked by vibrations as a result of vibrations which occur occasionally (M(i)), wherein from a transmission behavior of the present actual clutch torque (M(i)) an absolute amplitude and a phase of an input signal detected at the output of the friction clutch and conveyed to a regulator are ascertained, from these a phase-selective disturbance torque is ascertained, from the latter a phase-correct correction torque (M(k)) is determined, and with this the target clutch torque (M(s)) is corrected by means of the regulator. In order to be able to design the method robustly, the correction torque (M(k)) is weighted with a specifiable intensification factor.