Vehicle Suspension Control Using Recurrent Neurofuzzy Wavelet Network

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www.seipub.org/ve Vehicle Engineering (VE), Volume 3, 2015 doi: 10.14355/ve.2015.03.002

Vehicle Suspension Control Using Recurrent Neurofuzzy Wavelet Network Shahid Qamar*1, Usman Khalid2, M. Bilal Qureshi3 Electronic Engineering Department, International Islamic University, Islamabad, Pakistan

1

Electrical Engineering Department, COMSATS Institute of Information Technology, Abbottabad, Pakistan

2

Electrical and Computer Engineering Department, North Dakota State Univrsity, Fargo, ND, USA

3

*1

shahidqamar@ciit.net.pk; 2usmankhalid@ciit.net.pk; 3Muhammad.qureshi@ndsu.edu

Abstract The main aim of this paper is to design the controller for a vehicle suspension system to reduce the uneasiness felt by passengers which arises from road disturbances and to increase the road holding related with the movements of pitch and roll of the vehicle. This demands an accurate and quick adaptive controller to obtain such control objectives, because, the passive suspension system and semi‐active suspension cannot perform better. Therefore, an adaptive Recurrent Fuzzy Wavelet Neural Network (RFWNN) based active suspension systems are designed to give better ride comfort and vehicle stability. The proposed adaptive RFWNN model combines the traditional TSK fuzzy model and the wavelet neural networks. The RFWNN controller is highly nonlinear and robust to meet the control objectives and can handle the nonlinearities faster than other conventional controllers. An online learning algorithm, which consists of parameter learning, is also presented. The learning parameters are based on the steepest‐descent method, to train the proposed RFWNN. The proposed approach is used to minimize the vibrations of seat, heave pitch and roll of the vehicle when traveling on rough road. The performance of the proposed RFWNN control strategy is being assessed by comparing with passive and semi‐active suspension systems. Keywords Fuzzy Logic; Neural Network; Wavelet; Full Car; Suspension System

Introduction For many years vehicle dynamics engineers have struggled to achieve a compromise between vehicle handling, ride comfort and stability. The results of this are clear in the vehicles we see today. In general, at one extreme are large sedan and luxury cars with excellent ride qualities but only adequate handling behavior. Passive suspension system is capable to a mass energy through the spring and dissipate it through damper. Parameters of passive suspension system are usually fixed and are chosen to attain the compromise between vehicle control and the comfort of passenger. In case of passive suspension, only damper and spring are used. So, the only choice is to design an active controller to deal with stiffness and damping rate. Feature of the passive suspension is its simplicity and cost. In semi‐active suspension, damper having variable damping constant is used. Though, having largetime constant its damping can be varied, i.e., can be of several distinct or continues values. Furthermore, energy is dissipated only. The feature is that energy demand is small. An active suspension system is capable to store, dissipate and introduce energy into the system. Its parameters are usually variable and depend upon the operating conditions. Whereas, in an active suspension system the energy source is added hence passengerʹs comfort and vehicle handling can be improved. As a consequence, complexity in design, larger cost and particularly big amount of energy demand. As vehicle suspension system is very important as far as vehicleʹs stability and ride comfort is concerned. So, many researchers worked on the control of suspension system of car to give better ride comfort and vehicleʹs stability. (S.I.Frank. et al. 2000) presented an active suspension control where an ʺinput decoupling transformationʺ and altered feedback control scheme was combined. In order to minimize roll, pitch and heave motions and to perk up the passengerʹs ride comfort, both inner and outer control loops were used. (D.Hana 2010) designed a semi‐active suspension system by mounting a variable shock absorber in parallel with that of passive suspension system. Intelligent system identication is used to capture the dynamics of car. The effect shows that semi‐active suspension system tracked the input signal well. This indicates that PID controller has

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