Research On Bus Handling Stability Analysis And Control Strategy

Vehicle security and handling stability demand need to improve with the rapiddevelopment of road construction and transportation. The stability of bus which isused as the main tools of convenient and fast transportation is directly related tohuman life and property safety. Because of bus especially coach is different from busin function, structure, loading forms and so on; the research on bus handling stabilityhas an important significance. Therefore, researching dynamics of bus system deeply,mastering motion characteristics, analyzing effect to the performance with majorparameters changing of vehicle system, effective controlling of bus to improve activesafety driving in turn driving and complex conditions, etc., have become a importanttopic in the handling and stability research fields of bus.Based on vehicle system dynamics, kinematic characteristics and turn drivingcharacteristics of bus has been analyzed by using computer simulation technology. Bybuilding bus handling stability detection system and designing vehicle road testprocedure of bus, handling stability characteristics are analyzed and effectiveness ofbus dynamics model is verified. Bus roll stability is analyzed by using method of rootlocus. In order to improve bus stability in turn driving control, research on vehiclecontrol strategies are analyzed, and adaptive control methods are proposed. Thedetailed contents are as follows:1. Coordinate system of bus and tire are used to identify the relationship of eachvariables and positive and negative. By establishing bus simplify coordinate systemmodel and equivalent mechanical model, inertial forces and external forces areanalyzed through vehicle lateral movement and vehicle's yaw motion and roll motion.Three degrees of freedom linear motion equation of bus is established and it can besolved by using method of state space equation. Measurement method of vehicle basicparameters, suspension parameters and tire characteristics and some empiricalformula are proposed, which is very useful for bus simulation and its parameter canbe obtained through this method. By using bus simulation parameter, bus kinematiccharacteristics are analyzed. Bus in steering wheel angle step response is analyzedunder the conditions of different tire wheel cornering stiffness, moment of inertia,centroid height. Simulation results provide a theoretical basis and reference for theselection and design of bus. Finally, turn driving characteristics of bus with differentspeeds in different steering wheel angle input are analyzed. The result laid foundationfor introduction of bus handling stability control for the following.2. Bus handling stability detection system was built by VBOX series equipment,and then it was integrated. Bus handling stability detection system was constituted by VBOX3, gyroscope, vehicle handling and power angle measurement, data acquisitionmodule and notebook computers. Through calibration gyro coordinate system, a clearrelationship between gyro coordinate system and right-hand coordinate system and itsdata processing were obtained. By calibration vehicle handling and power anglemeasurement, the relationship between VBOX3collection voltage signal and steeringwheel angle is identified. The error of GPS antenna installation distance and locationis eliminated through VBOX3dynamic calibration. In order to test the stability andreliability of detection system, a fixed angle of the static detection and dynamicdetection of bus uniform linear motion and steady-state circular motion is designed.Detection system measurement precision and accuracy is verified through theoreticalanalysis and experimental results compared, which provides an experimental basis forbus handling stability detection.3. Based on existing domestic and foreign vehicle handling stability testprocedure, road test program was formulated through the combination of buscharacteristics and the use of testing equipment. Bus handling stability detectionsystem was used to detect bus road test characteristics through steady static circulartest procedure, double lane change test procedure and pylon course slalom testprocedure. Influence between testing equipment installation location andmeasurement point position about measured variables are analyzed and analysismethod of experimental data is given. Test results are used to analyze handlingstability characteristics and state parameter variation through steady static circular testprocedure, double lane change test procedure and pylon course slalom test procedure.Bus dynamic model is verified by comparing between MATLAB simulation andsteady static circular test. Vehicle motion characteristics compared betweensimulation and experimental are basically the same, which verify the effectiveness ofbus dynamics model.4. Basic concepts of roll stability was introduced, vehicle roll stability impactfactor of driver was analyzed from three stages of perception, judgment and operationphase, which is from the view of driver-vehicle-road environment. Vehicle rollstability impact factor of driver was analyzed from road surface adhesion coefficientand the formation degree of the angle of the road geometry. Vehicle roll stabilityimpact factor of vehicle-related parameters was analyzed from driving system,steering system and vehicle overall parameters. Based on analysis of vehicle handlingstability evaluation method, root locus analysis is used to analysis bus handlingstability. Turn driving characteristics of bus is analyzed under fixed speed withdifferent steering wheel angle input. Bus yaw rate and roll angle of the root locus areanalyzed, which are used to analysis and evaluation bus handling stability. The resultsshow that root locus analysis method can analyze bus handling stability effectivelyand given a new method for bus analysis.5. Thought analysis of Vehicle Stability Control and Vehicle Stability Failure, bus direct yaw moment control objectives and control methods are proposed based onvehicle direct yaw moment control principle. Based on PID and fuzzy logic controltheory, PID control method was used in yaw rate control, fuzzy logic control methodwas used in slip angle and PID and fuzzy logic joint control was also used in bussystem. Simulation results show that PID control, fuzzy logic control and joint controlcan effectively reduce steady-state value of bus state parameters. PID and fuzzy logicjoint control can solve the troublesome problem of control parameters in theconventional PID control tuning methods, its control effect is better than separatecontrol. In order to enhance adaptive of controller, adaptive fuzzy logic controlmethod was proposed. Quantization factor and scale factor were optimized by usinggenetic algorithm, and then was simulated. The simulation results can effectivelyimprove the quality of vehicle systems response and security and given an effectivecontrol method for bus turn driving.