The Research Of Control System For Electronically Controlled Air Suspension

Suspension is one of important components for the vehicle,which links vehicle-briage and frame(the vehicle body),and which alleviates the impact when the vehicle travels. Electronically controlled air suspension(ECAS) is a very advanced suspension so far.Because of its better performance,more and more applications are presented in the field of the vehicle vibration control.Compared with development to ECAS of foreign contries,development of our contry is only beginning.So it is very significant to research ECAS.In the beginning,the principle of ECAS,control model,system components and air spring are analysed.On the basis of actual state and parameters of Yaxing YBL6891H coach, electronic control unit(ECU) is designed.Hardware and software of ECU are introduced and measure of the vehicle body's height is important in this paper.So the signal detecting circuit and related program for the vehicle body's height sensor are introduced in detail.In addition,for testing effect of environment temperature on the circuit,experiments in different temperatures were carried out.The results of the experiment show that effect by temperature for the circuit is little and the detecting circuit satisfies the detecting precision's demand.For the sake of testing the peribrmance of ECU,ECU was installed on modified Yaxing YBL6891H coach and this coach's perfbrmance was tested when the speed was from 40km/h to 60km/h.Perpendicular vibration acceleration of the rear suspension was measured during experiment.In order to acquire information about degree of improvement for the ride comfort, another coach with leaf spring was used to experiment,when the condition of experiment was same as condition of last experiment.Through experiment,following is concluded:ECAS is better than leaf spring suspension system in the aspect of ride comfort.The good control policy is an important approach of improving suspension performance, so fuzzy control method was appied to suspension system and the stiffness of the air spring suspension was controlled to achieve improvement of the ride comfort.According to detailed parameters of Yaxing YBL6891H coach,the quarter-vehicle suspension model was set up and simulation was carried out.The simulation result indicates that the fuzzy controller in the paper can increase the ride comfort and handling stability of the vehicle markedly.