Pascal Serrier

Synthesis of a Limited-Bandwidth Fractional Differentiator Made in Hydropneumatic Technology

In a vibration isolation context, fractional derivative can be used to design suspensions which allow to obtain similar performances in spite of parameters uncertainties. This paper presents the synthesis and the achievement of a CRONE suspension. A CRONE suspension is synthesised using the CRONE control methodology. Its transfer function is a limited bandwidth fractional differentiator. After the formulation of vibration isolation problems as control law synthesis problems, a method to determine the technological parameters of a CRONE suspension is proposed and is applied to a CRONE hydraulic test bench. A parallel arrangement of dissipative and capacitive components and a gamma arrangement are compared. They lead to the same unusual performances: the stability degree robustness and the rapidity robustness.Copyright

Limited-Bandwidth Fractional Differentiator: Synthesis and Application in Vibration Isolation

The use of fractional differentiation in vehicle suspension design has many interests. This paper presents a hydropneumatic suspensions design method based on fractional differentiation. Once an hydraulic structure has been chosen for the suspension, it is possible to calculate the values of all technological parameters, so that the suspension force - deflection transfer function is a band-limited fractional differentiator. The combination of the CRONE control methodology and of hydropneumatic technology leads to remarkable performances of robustness.

Taking into Account of Non-Linearities in the CRONE approach: Application to Vibration Isolation

The interest of fractional differentiation in vibration isolation has been shown in many previous papers, in particular in the case of suspension achievements in hydropneumatic technology. This paper aims to show that the hydropneumatic components non-linearities do not deteriorate the remarkable performances of a particular CRONE suspension (suspension whose force-deflection transfer function is a band-limited fractional differentiator) realized in hydropneumatic technology and to propose a method to analyse these non-linearities influence. The suggested method to take into account the non-linearities is based on the Volterra series representation

Approximation of a Fractance by a Network of Four Identical RC Cells Arranged in Gamma and a Purely Capacitive Cell

In this paper a storage I-element and a fractance are associated, thus defining a fractional system. In order to achieve the fractance, an approximation by a network of 4 identical RC cells arranged in gamma and a purely capacitive cell is proposed, thus defining a rational system. When compared to each other, the dynamic behaviors of the fractional and the rational systems show an excellent superposition of frequency and time-domain responses. Moreover, the robustness of stability margins obtained with both systems is illustrated versus variations of the I-element.

VOLTERRA SERIES BASED ANALYSIS OF COMPONENTS NONLINEARITIES IN A LIMITED-BANDWIDTH FRACTIONAL DIFFERENTIATOR ACHIEVED IN HYDROPNEUMATIC TECHNOLOGY

Abstract The fractional differentiator is a linear operator but it can be very convenient to achieve it with nonlinear components. This paper presents an analysis method for components nonlinearities of a suspension whose force-deflection linearized transfer function is a limited-bandwidth fractional differentiator (CRONE suspension). The analysis method is based on Volterra series decomposition and on nonlinear systems association with George algebra.

Active roll control device for vehicles equipped with hydropneumatic suspensions

Abstract This paper presents a new active roll control device. This device uses an original hydraulic actuator, based on two tandem pumps, designed to be used in addition of a reduced anti-roll bar. The actuator control strategy is also original. It is based on hierarchical and hybrid control with a supervisor, a feedforward and a feedback loop whose robust controller is synthesized thanks to the CRONE control methodology. Because of the severe specifications sheets in term of power consumption, the simulated performances are thus limited but interesting.