Bench Tests of Slow and Full Active Suspensions in Terms of Energy Consumption

Abstract

This paper is focused on the problem of active suspensions of wheeled vehicles with electro-hydraulic actuators. Two dynamic structures first with actuator connected with spring in series and second in parallel -called slow active and full active respectively -were considered. The considerations described in the paper concern physical quarter-vehicle models of suspensions. These models were constructed and installed on a rig for dynamic tests of structures. A laboratory rig enables the simulation of real conditions by disturbing investigated suspension by kinematic excitation. Research was carried out for various algorithms controlling the actuator of the active unit. For evaluation of laboratory research results, comparisons were proposed of frequency response functions and of time curves of instantaneous power taken by the active system from supply, obtained at the same excitation signals. Quantitative aggregated indicators in the form of an averaged coefficient of vibration transmissibility and power required for the active unit to achieve vibration transmissibility function were also proposed. s, Φ(·,·)-nonlinear part of equation governing the actuator dynamic, Φ (t) -function Φ on trajectories of the system, Y(f) -Fourier transform of output signal y(t) , X(f) -Fourier transform of input signal x(t), f start -low frequency limit of considered bandwidth, f stop -high frequency limit of considered bandwidth. INTRODUCTION Mechanical structure of the active suspension -overviewSuspensions of vehicles historically have been divided into passive, semi-active and active. The essence of controlled suspensions classification [1,2] is the division into five kinds of suspensions ordered according to external energy demand: adaptive suspension, semi-active suspension, load levelling suspension, slow active suspension and full active suspension. The first two kinds are suspensions in which the efficiency of vibration reduction is obtained by controlling changes in parameters such as viscous damping or spring ratio [3]. In these systems energy supplied to the controlled suspension is used entirely for changes in parameters such as stiffness and/or damping [4,5]. The difference between these suspensions consists of the frequency range of operation. Adaptive systems are limited to slow changes (below 5 Hz [2]) to which they adapt, for example, changes in road irregularities -from gravel to asphalt surface. In turn semi-active suspensions reduce vibration of frequencies up to as much as 40 Hz [6]. Load levelling, slow active and full active suspensions are characterised by the direct use of energy for generating force and/or displacement, causing a decrease in vibration intensity. The efficiency of vibration reduction in the case of these three suspensions is better than for adaptive and semi-active systems. The first system in which energy is supplied to the suspension through generating forces or displacement, in the opposite direction as disturbances from road irregularities is the load levelling system. In thi...

Optimal control based on a modified quadratic performance index for systems disturbed by sinusoidal signals

“…where j; k ¼ 1; …; n w , ja k. The existence of the limit equal to zero (21) immediately follows from the definition of the components u j ð Þ and formula (23).…”

“…Since the function u t ð ÞAŨ , the existence of decomposition (16)- (19) is an immediate conclusion of condition (15). The uniqueness of the decomposition has been proved from equalities (21) and (22). These equalities follow immediately from the properties of the trigonometric functions (23) and (24).…”

“…A physical model of the suspension was built and its mathematical model was formulated [22]. The vehicle suspension system under consideration is of the slow-active type [21]. A view of the laboratory model is depicted in Fig.…”

“…Optimal control was selected in such a way that it should be solely dependent on the disturbance signal vector (optimal control does not depend on the state vector and the initial conditions). In order to verify the proposed method, a control system was developed for an active suspension system of the slow-active type [6,21]. The results of simulation studies on the designed suspension system are presented.…”

Technical Note. Optimization of Parameters for a Damped Oscillator Excited by a Sequence of Random Pulses

“…Research is carried out in the areas connected with the problems of propagation of the noise produced by road traffic, wind power plants (Kasprzak et al, 2014;Wszołek et al, 2014), and industry, especially ducted systems with flow (Jurkiewicz et al, 2012). These studies are aimed at reducing vibroacoustic noise to a minimum and application of vibroacoustic signals in assessment and control of technological processes Sibielak et al, 2013;Konieczny et al, 2013). Vibroacoustic diagnostics also includes studies regarding the theory of vibration processes occurring in vibrating systems as well as studies concerning semi-active and active methods of reduction of vibrations (Wiciak, 2007; Trojanowski, Wiciak, 2010).…”