Teilinstitut Dynamik/Mechatronik - Mitarbeiter
Institut für Technische Mechanik

M.Sc. Simon Schröders

  • Postanschrift:
    Karlsruher Institut für Technologie
    Institut für Technische Mechanik
    Teilinstitut Dynamik/Mechatronik
    Postfach 6980
    76049 Karlsruhe

    Haus- und Lieferanschrift:
    KIT-Campus Süd
    Institut für Technische Mechanik
    Teilinstitut Dynamik/Mechatronik
    Geb. 10.23, 2.OG
    Kaiserstraße 10
    76131 Karlsruhe

Dynamics and Control of Hydraulic Systems

Pressure-controled variable displacement vane pump
Identified volume flow of a pressure relief valve

Hydraulic valves are known to show interesting dynamic behavior. Nevertheless they have not yet been investigated extensively from the viewpoint of nonlinear dynamics and are not suffciently understood. An elementary hydraulic pressure control valve can be described as a system of third order with a non-smooth nonlinearity.

The transition from an ideally impermeable valve to a valve allowing for leakage flow uncovers an instability mechanism for for certain valve geometries. Leakage changes the character of the equilibrium position from a set-valued equilibrium position to a unique one. A loss of stability of the equilibrium position and the birth of a limit cycle due to leakage can be shown when increasing leakage flow or the working point pressure of the system. A bifurcation analysis reveals the different solution types for the system under external forcing, yielding evidence of period-doubling phenomena up to quasi-periodic solutions.

Building on the findings for the dynamics of the foundational element in hydraulics - the valve - a variable displacement vane pump is currently investigated. This type of pump is frequently used in automotive engineering in order to provide the required pressure for the actuation of a clutch mechanism. A subfunction of the pump is to provide the volume flow required by a cooling unit. The system under investigation shows many aspects which are characteristic for hydraulic systems. In steady state, the valve regulating the system pressure is lapped critically, therefore giving rise to non-smooth dynamics. Apart from analyzing the stability behavior of the pump system in a first step, in a second step control strategies shall be devised that result in a change of the working point of the system. Drawing on the control strategies identified, the task then is to synthesize hydraulic elements and their topology such that the control strategies can be implemented by means of hydraulic action.

The hydraulic consumer provided with volume flow from the variable displacement vane pump is the third field of interest in this research project. As pointed out, it is a clutch actuation mechanism. In order to simulate the dynamics of clutch systems adequately, reasonable estimates of the system parameters have to be known. By means of Kalman filtering, important parameters of the clutch actuation mechanism can be identified. To do so, the clutch actuation system is subjected to transient volume flow excitation. Measurements of the system responses to the transient excitation are then synchronized with a slave model of the consumer, resulting in good estimates of the true parameters to be identified.

Contact: Prof. A. Fidlin, S. Schröders


Analyse des dynamischen Verhaltens zweier gekoppelter Druckregelventile.
Schröders, S.; Fidlin, A.
2020. Forschung im Ingenieurwesen, 84 (2), 205–213. doi:10.1007/s10010-020-00401-6
Two-degree-of-freedom MIMO control for hydraulic servo-systems with switching properties.
Schröders, S.; Maier, C. C.; Ebner, W.; Fidlin, A.; Hametner, C.
2020. Control engineering practice, 95, Article no: 104246. doi:10.1016/j.conengprac.2019.104246
Oscillations in a system of two coupled self‐regulating spool valves with switching properties [in press].
Schröders, S.; Fidlin, A.
2019. Proceedings in applied mathematics and mechanics, 19 (1). doi:10.1002/pamm.201900340
Modeling and nonlinear parameter identification for hydraulic servo-systems with switching properties.
Maier, C. C.; Schröders, S.; Ebner, W.; Köster, M.; Fidlin, A.; Hametner, C.
2019. Mechatronics, 61, 83–95. doi:10.1016/j.mechatronics.2019.05.005
Nonlinear Pressure Control of a Switched Hydraulic System.
Schröders, S.; Fidlin, A.
2017. Proceedings in applied mathematics and mechanics, 17 (1), 817–818. doi:10.1002/pamm.201710376

Analytische und numerische Untersuchung der nichtlinearen Schwingungen in hydraulischen Druckregelventilen