Hongfei Liu

Estimating Vehicle Stability Region Based on Energy Function

In order to improve the deficiency of vehicle stability region, according to vehicle nonlinear dynamic model, method of estimating vehicle spatial stability region was proposed. With Pacejka magic formula tire model, nonlinear 3DOF vehicle model was deduced and verified though vehicle test. Detailed detecting system and data processing were introduced. In addition, stability of the vehicle system was discussed using Hurwitz criterion. By establishing energy function for vehicle system, the vehicle’s stability region in 20 m/s was estimated based on Lyapunov theorem and vehicle system characteristics. Vehicle test in the same condition shows that the calculated stability region defined by Lyapunov and system stability theorem has good effect on characterized vehicle stability and it could be a valuable reference for vehicle stability evaluation.

Study on Transverse Baffle Design Parameters on Influence of Baffle Anti-Sloshing Effect by FLUENT Simulation

Longitudinal liquid sloshing in partially-filled tankers has great influence on vehicle braking performance, which results in serious tanker crash accidents. To investigate the influence of shape and location of holes that pierced on the baffle on reducing liquid sloshing and on the force analysis of baffles. Three different shapes of holes are designed and each hole has two assemble position on the baffle. FLUENT is used to simulate liquid sloshing in partially - filled tanks that equipped with different kinds of baffles which subjected to constant braking deceleration. Time-series analysis of forces on tank walls and baffles are carried out considering structural damage both the tank head and the baffles. It is drawn that the shape of manhole has great influence on baffle anti-sloshing effect and the position of manhole has giant impact on baffle force analysis.

Analysis of Bus Maneuverability and Stability Impact Elements Based on Matlab

Bus dynamics is analyzed and dynamics model is established according to basic dynamic characteristics of bus. The corresponding computer simulation program is developed by using Matlab software. From practical view, structural parameters which are impacted by bus maneuverability and stability such as tire cornering stiffness, center of mass motion, around the Z axis moment of inertia and roll resistance coefficient are discussed. The result can guide the design of bus maneuverability and stability and also can give a reference of maneuverability and stability in a way.

Research on Vehicle Control Strategy Evaluation Method

Method of vehicle control strategy evaluation was proposed to evaluate vehicle control strategy. 3DOF nonlinear vehicle model was deduced and verified though vehicle test. Based on Lyapunov theorem and vehicle system characteristics, vehicle’s spatial stability region was given. Though the spatial stability region, control effect of vehicle with four wheel steering (FWS) and direct yaw moment control (DYC) strategies were respectively evaluated. Results show that the stability region defined by Lyapunov and system stability theorem has good effect on characterized vehicle stability and could be a valuable method for vehicle control strategy evaluation.

Research on the Influence Factors for Bus Based on Nonlinear Model

Improved 5-DOF vehicle which contains nonlinear steering and tire models was established to solve the deficiency of conventional dynamic linear models to analyze coupling characteristics. Based on GPS technology, a developed vehicle handing and steering stability detecting system comprised by Steering Force and Angle Tester, GPS, Gyroscope and high precision Data Collector was introduced. According to Matlab/Simulink platform and vehicle test, the dynamic model was verified. Then some influence factors on bus handing and steering stability such as structure parameters, suspension parameters and tire parameters were analyzed. The results show that the longitudinal position of gravity and the vertical distance of gravity and roll axis have a good effect on vehicle yaw and roll responses. Spring roll stiffness is important parameter for vehicle roll. The pneumatic trail is closely related on steering reversibility and comfort. These researches have direct reference value for bus design.

Testing Analysis on Load Transfer of Tractor-Semitrailer Steering and Braking

An algorithm about tractor-semitrailer longitudinal load and lateral load transfer amount was proposed in order to research the driving stability of tractor-semitrailer steering and braking. A dynamic simulation model of tractor-semitrailer including load transfer was established by using S-Function. The results show that the model including load transfer is more actual than conventional model to describe the driving stability of vehicle Further analyzed the effect of factors on load transfer when tractor-semitrailer steering and braking.

Research on Lateral Stability of Tractor-Semitrailer Steering and Braking Based on Nonlinear Factors

A 18-DOF tractor-semitrailer nonlinear dynamics model was developed to describe the travelling characteristics of tractor-semitrailer braking in the cornering, considering the related nonlinear factors on the vehicle such as load transfer, saddle and tire. On this basis, it was calibrated that vehicle simulation model is reliable through real vehicle test. It was further analyzed the effects on lateral stability such as saddle position, load, braking force distribution and inside/outside wheel braking force difference through simulation when tractor-semitrailer braking in a turn.

Research on Decision Risk of Driving Behavior Based on Traffic Information Asymmetry Degree

Analyzing driving behavior decision risk is the key to evaluate the road traffic safety. In order to understand the production mechanism of behavior decision risk preferably, the application of information asymmetry theory will set up the decision risk of driving behavior model centering on the traffic accident probability, the accident severity and the traffic information asymmetry degree in this paper, finally, the practicality and accuracy of model were verified through examples. The case has showed that the road traffic information searching and judging is different for drivers of different vehicle type in the same road section, which also leads to the different running risk degree in some extent. The investigation result is that the integrated risk of heavy truck and large bus is highest, while the mini bus is lowest, and the light truck is middle, which has fully verified the effectiveness of the model.

Notice of Retraction Simulation analysis of influence factors on bus maneuverability and stability

Bus dynamics is analyzed and 4 degrees of freedom dynamics model is established according to basic dynamic characteristics of bus. The corresponding computer simulation program is developed by using Matlab software. From practical view, structural parameters which are impacted by bus maneuverability and stability such as tire cornering stiffness, steering wheel rotational inertia, steering transmission ratio, aligning torque, around the Z axis moment of inertia and steering resistance coefficient are discussed. The result can guide the design of bus maneuverability and stability and also can give a reference of maneuverability and stability in a way.