| Multi-axle vehicle stability is a very important performance because of its influence on transportation safety. Vehicle braking performance is the important guarantee to safety driving. Ever since a long time ago, people did a lot of research on ABS. Although it has improved the braking stability to some extent, and shorten the braking distance, it still cannot solve the problem of vehicle braking stability fundamentally. And many of research results aimed for two-axle vehicles.Through discussing the problems of calculation for the braking of multi-axle vehicle, which was based on the classical model and described the general dynamic models for the straight line braking of multi-axle vehicle. The models reserved the constrain of the suspension and introduced the suspension distortion harmonizing equations. Based on the models, it deduced the general formulas for calculating the vertical counterforce from road. Then it put forward a method for getting the lock sequence of multi-axle vehicle, which is easy to be implemented with computer language, and deduced the general calculation formulas for the brake power, braking acceleration and braking distance of the line braking. The vehicle straight line braking experiment was done to verify the feasibility of the model that was built in this paper and the vehicle stability, and comparison was made to the calculated results.Enough longitudinal force and lateral force must be provided by the tire, when the vehicle steers and brakes for multi-axle vehicle. Straight line braking conditions will not satisfy. Some researches have been done by scholars home or abroad, but limited to ABS. On the basis of these researches,4+2n degree-of-freedom model of multi-axle vehicle and BP neural networks model were built in order to avoid losing control. This paper presents a novel controller for ABS of heavy vehicles. This controller uses PID Logic to keep the maximum braking force between the wheels and the road. The braking systems of heavy vehicles are driven by pneumatic actuators. The controller uses the wheels speeds and accelerations to actuate the air flow valves that control the pneumatic cylinders of the brake canvas. To evaluate the vehicle model and the novel ABS controller, a simulator for heavy vehicles is developed.In this study, a simulation tool is developed to investigate non steady-state steering performance of 6WS multi-axle vehicles.6WS vehicles are believed to have good performance in off-the-road maneuvering and to have fail-safe capabilities. But the steering performance of 6WS vehicles are not yet well understood in the relevant literature.In this paper,6WS vehicles are modeled as an 18 DOF system that considers non-linear vehicle dynamics, tire models, and kinematic effects. The vehicle model is constructed as a simulation tool using MATLAB/Simulink so that input/output and vehicle parameters can be changed easily with the modulated approach. Steering performance of 6WS vehicles is analyzed for steering braking. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the side-slip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.Vehicle stability control strategy was proposed. Using direct yaw moment control algorithm, joint control of side slip angle and yaw rate based on the dynamic model were proposed with fuzzy control strategy. Limited side slip angle and yaw rate within a certain range.The turning braking stability of vehicle was simulated according to the designed control algorithm.While the multi-axle vehicle is driving on an irregular adhesion coefficient lane road at great speed, the imbalance braking force on both sides of the wheel interfere with the vehicle, large yaw moment will be generated that leads to lane-change, thus, emergency braking will be applied to the vehicle. So far, some studies have been done on vehicle steering and braking stability, but they are limited to how to deal with and control the instability phenomena during braking maneuver. There are few researches about how to take proactive measures i.e. all-wheel active steering technology that will make the vehicle fast recovery to the correct trajectory, and the majority of them are concerned with two-axle vehicles.Therefore,it is essential to study on multi-axle vehicle braking performance using AWAS technology to improve the vehicle braking stability. This study proposes a control system to improve vehicle braking stability under severe driving conditions by actively controlling the steering angle and the distribution of braking forces on tires. With the application of a model-matching control technique, this proposed control system makes the performance of the actual vehicle model follow that of an ideal vehicle model with consideration of nonlinearity of tire characteristics.In this paper, the two degree-of-freedom three-axle vehicle model based on all-wheel active steering (AWAS) and yaw moment combination control technology was built. Relative control strategy and control method were proposed using fuzzy control theory. Finally, this paper investigates the effectiveness of control system during the following conditions:steering braking and lane change braking. The performances of ABS control method,yaw moment control method and AWAS and yaw moment combination control method were evaluated through simulating and analyzing by means of MATLAB.
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