Christian Benatzky

Comfort Enhancement By an Active Vibration Reduction System for a Flexible Railway Car Body

In order to improve the ride comfort of lightweight railway vehicles, an active vibration reduction system using piezo-stack actuators is proposed and studied in simulations. The system consists of actuators and sensors mounted on the vehicle car body. Via a feedback control loop, the output signals of the sensors which are measuring the flexible deformation of the car body generate a bending moment, which is directly applied to the car body by the actuators. This bending moment reduces the structural vibration of the vehicle car body. Simulations have shown that a significant reduction in the vibration level is achieved.

Vibration Damping of a Flexible Car Body Structure Using Piezo-Stack Actuators

In this work piezo-stack actuators mounted in consoles are utilized to actively dampen vibrations of a flexible car body structure by introducing bending moments. Using an example of a heavy metro vehicle the complete design for the active vibration damping system is presented. Both analytical modeling and a system identification of the vehicle are described, issues of modal representation and model reduction are covered, and a robust controller design is motivated and explained. The excellent performance of the proposed method is documented by both experimental results from a scaled model and an extensive co-simulation of the overall system.

Comparison of controller design methods for a scaled metro vehicle - flexible structure experiment

This paper addresses the design and implementation of different controllers on a 1/10 scaled flexible structure experiment of a metro vehicle car body. The particular controller design methods investigated are state vector feedback control combined with a Kalman-filter and the mu-synthesis procedure. Using experimental data it is shown, that with both design methods the structural response to disturbances can be reduced. Nevertheless, because of the fact that the mu-synthesis takes into account the uncertainty associated with the model of the structure as well as the fact that the performance variables to be controlled are not identical to the measurements a better performance is achieved in comparison to the state feedback controller. At the same time the control costs are considerably lower when the mu-synthesis controller is utilized.

Effects of local actuator action on the control of large flexible structures

Abstract Active vibration damping of flexible structures requires the positioning of actuators and sensors along the structure. When the actuators become particularly small in comparison to the structure a large number of modes is necessary to accurately represent the response of the structure. Neglecting these higher modes may result in a spillover phenomenon which is capable of destabilizing the closed loop system. Therefore proper correction methods to account for the dynamics of higher modes in the structural model have to be found. One such possibility is the utilization of Frequency Response Modes (FRM), a special form of the particular solution of the equations of motion of a flexible structure. In this paper the FRM is defined and used for model correction of a simply supported beam. Finally correction terms are used to quantize local actuator action.

NOx virtual sensor design via in-cylinder pressure feature extraction*

Abstract In this paper, a novel approach for NO x generation modeling in heavy-duty (HD) Diesel engines is proposed. Only the indicated pressure and the speed measurements are used, standing on the assumption that all combustion phenomenona are reflected by the crank angle resolved pressure trajectory. A principal component analysis is performed to describe the information included in the pressure by means of a limited set of variables; this enables the use of simple identification techniques to derive a simple and reliable predictor, also suited for on-line estimation. The proposed strategy is implemented on a off-road HD Diesel engine and validated on a standard test cycle.

Influence of actuator size and location on robust stability of actively controlled flexible beams

Abstract This paper addresses the influence of the actuator size on the closed loop stability of collocated and non-collocated transfer functions utilized in the structural control of flexible beams. Besides the well known robustness advantages of collocated transfer functions it is shown, that if the actuator is small compared to the flexible structure, a non-collocated actuator/sensor configuration provides larger stability margins. It is shown, that this effect arises from the uncertainty associated with the steady state gain of collocated transfer functions. The applicability to other types of boundary conditions and limitations due to length and spatial frequencies of the beam are also addressed.

Ein maßstäbliches Experiment zur aktiven Schwingungsdämpfung eines Eisenbahn-Wagenkastens A Scaled Experiment for Active Vibration Control of a Railway Car Body

Zusammenfassung Der Beitrag beschreibt Identifikation, Reglerentwurf sowie gemessene Resultate eines maßstäblichen Experiments für die aktive Schwingungsdämpfung eines Eisenbahn-Wagenkastens. Piezo Stack-Aktoren zusammen mit Piezo Patch-Sensoren werden zur aktiven Dämpfung der Struktur verwendet. Die optimale Platzierung der Aktoren und Sensoren, die Identifikation der Übertragungsfunktionen sowie der Entwurf eines robusten Reglers werden vorgestellt.