Study On Effects Of Steering System Characteristics On Commercial Vehicle Steering And Handling Behavior

Based on the objectives of commercial vehicle steering and handling behavior, this paperevaluates the performance of commercial vehicle steering system on four aspects includingclearance, stiffness, friction and assist characteristic. Evaluation methodology of characteristictest is discussed in this paper and test has been conducted on steering system and powersteering gear of a test truck to analyze the components of clearance and stiffnesscharacteristics for modeling. The test results are also used for modeling input and verification.This paper also studies the motion principles of commercial vehicle steering system andworking principles of power steering gear, then deduces the mathematical model of steeringsystem considering clearance, friction, stiffness and assist characteristic, and buildscalculation model of steering system using MATLAB/Simulink. Then we analyze angle andtorque transfer characteristics of the steering system, and verify the steering model by resultsof characteristic test.Steady static circular test, on center steering test and steering effort test has beenconducted on the test truck and assessments of the steering performance are used to verify thefull vehicle model. As the main verification point aligning torque characteristics of tire arerecorded during these tests to verify the tire model and improve the accuracy of modeling.The main subsystems that influence the steering and handling behavior of commercial vehicleare studied in this paper. Based on basic parameters of full vehicle, steering system,suspension system and tire characteristics, a commercial vehicle dynamic model is establishedusing TruckSim, and co-simulation is performed with Simulink model of steering system. Themodel is verified by the results of steering and handling test.Based on the current characteristics of the test truck steering system, this paperconstructs three levels of steering system characteristics: below current, current, and abovecurrent. Then we calculate the stable steering behavior, high speed steering behavior andsteering effort behavior using TruckSim&Simulink co-simulation model, and make asensitivity analysis about the vehicle steering and handling performance on steering systemcharacteristics, and then propose the critical point of steering system characteristics control toimprove commercial vehicle steering and handling performance, and specify the technicalmeasures to achieve the performance improving objectives for the test truck.