Jancirani et al. 2015. Int. J. Vehicle Structures & Systems, 7(1), 36-39 International Journal of Vehicle Structures & Systems Available online at www.maftree.org/eja ISSN: 0975-3060 (Print), 0975-3540 (Online) doi: 10.4273/ijvss.7.1.07 © 2015. MechAero Foundation for Technical Research & Education Excellence 36 Comparison of Air Spring Actuator and Electro-Hydraulic Actuator in Automotive Suspension System J. Jancirani a,b , P. Sathishkumar a,c , Manar Eltantawie e and Dennie John a,d a Department of Mechanical Engg., Anna University, Chennai, India b Email: jancijeyaraj@yahoo.com c Corresponding Author, Email: sathishkumar8989@gmail.com d Email: dennie.john@gmail.com e Mechanical Engg. Dept., Higher Technological Institute, Sixth of October City, Giza, Egypt Email: manartantawie@gmail.com ABSTRACT: The present article introduces an approach that combines modelling and simulation of air spring actuator and electro- hydraulic actuator for comparison in automotive suspension system. Both hydraulic and air spring actuators are controlling the vehicle body by developing a desired force between sprung mass and unsprung mass using fuzzy logic controller. The vehicle body along with the wheel system is modelled as a two degree of freedom quarter car model. The actuator performance is investigated using the quarter car suspension model under single road bump with severe peak amplitude excitations and random road input. From the results of simulation, it can be concluded that air spring actuator gave better performance than electro-hydraulic actuator in all conditions under vertical body deflection. KEYWORDS: Air spring actuator; Electro-hydraulic actuator; Quarter car model; Automotive suspension; Fuzzy logic controller CITATION: J. Jancirani, P. Sathishkumar, M. Eltantawie and D. John. 2015. Comparison of Air Spring Actuator and Electro- Hydraulic Actuator in Automotive Suspension System, Int. J. Vehicle Structures & Systems, 7(1), 36-39. doi:10.4273/ijvss.7.1.07. 1. Introduction The major purpose of any vehicle suspension system is to isolate the body from road unevenness disturbances and to maintain the contact between road and the wheel. Therefore, the vehicle suspension system is responsible for the ride quality and driving stability [1]. The conventional suspension system has coil or leaf springs in combination with hydraulic or pneumatic shock absorbers [2-4]. The design of a classical passive suspension system is a compromise between these conflicting demands. However, the improvement in vehicle dynamics in vertical direction is possible by developing an air spring actuator [5, 6] and electro- hydraulic actuator controlled suspension system [7, 8]. Air spring actuators are well-known for their low transmissibility coefficients and their ability to vary load capacities easily by changing only the gas pressure within the springs. Another important characteristic of air springs, which can be used for a mechatronic approach in suspension design, is the ability to provide a controlled variable force in terms of spring rate [9-11]. Moreover, they offer simple and inexpensive automatic levelling [12]. Nonlinear electro-hydraulic actuator can develop a desired force between the vehicle body and wheel axle [13]. This desired force is to achieve certain performance objective under external disturbances, such as passenger’s comfort under road imperfections [14-16]. Developing a desired force between masses according to the incoming signal is difficult. Due to this both the actuators are tested for automotive suspension application and their performance is evaluated. The following sections detail the development of a quarter car model, control design using air spring actuator and electro-hydraulic actuator followed by simulations using MATLAB Simulink to compare their performances. 2. Quarter car model The quarter car suspension system model consists of one-fourth of the body mass, suspension components and one wheel [15] as shown in Fig. 1. The assumptions of a quarter car model are as follows:  The tire is modelled as a linear spring without damping.  There is no rotational motion in vehicle body and wheel.  The behaviour of spring and damper are linear.  The tire is always in contact with the road surface.  Effect of friction is neglected so that the residual structural damping is not considered in the vehicle modelling [15]. Both of the actuators will provide a desire force. The equations of motion for the sprung and unsprung masses of the quarter car model are given by,     0       a s u s s s u s s s s F Z Z K Z Z C Z M    (1)