Mingli Shang

Estimation of Articulation Angle for Tractor Semi-trailer Based on State Observer

Jackknife is an unstable state of tractor semi-trailer combination, and there is no sensor available to detect the jackknife or measure the hitch articulation angle. A state observer is designed to estimate the articulation angle, where a 3 DOF tractor semi-trailer linear model is used. The steering wheel angle sensors, lateral acceleration sensor, yaw rate sensor and axle load sensor of electronic stability control system for commercial vehicle are available here, and the signals are used in the state observer. Utilized road adhesion coefficient is estimated with lateral acceleration to correct the linear tire model. The observer is validated on a 21 DOF tractor semi-trailer nonlinear model, the simulation results shown that the estimated articulation angle is accurate in either linear area or nonlinear area of tire lateral force model.

Integrated control of Active Front Steering and Electronic Stability Program

In this paper, an integrated vehicle dynamics control system is designed to improve vehicle handling and stability by coordinating control of Active Front Steering (AFS) and Electronic Stability Program (ESP). The integrated control system includes a coordinated controller in upper layer and two subsystem controllers in lower layer. The control algorithm based on β - β̇ phase plane is used to identify the driving situations. And a coordinated control rule based on integrated scheme is employed to determine and allocate the control tasks between the two subsystems. The simulation results show that the proposed control strategy is able to enhance the tracking performance of the reference yaw rate and improve the driving steer-ability of the vehicle.

Braking Force Distribution Strategy for HEV Based on Braking Strength

The possibility of recovering vehicle kinetic energy is one inherent advantage of hybrid electric vehicle (HEV). Due to the introduction of electric regenerative braking, the structure, design and control of a hybrid electric vehicle is quite different from the pure mechanical braking of conventional vehicles. In this paper, the decelerations of the vehicle in typical urban driving cycles and the influences of regenerative braking have been investigated. The results provide strong supports to the design of the braking force distribution strategy for the hybrid electric vehicle. This paper designs a deceleration sensitive braking force distribution strategy to distribute the desired total braking force to the front and rear axles. This strategy can recovery more braking energy and can keep the vehicle more stable while the vehicle is braked. The proposed distribution strategy is tested through the simulation, and the simulation results show the distribution strategy is effective.

Investigation of determining of regenerative braking torque based on associated efficiency optimization of electric motor and power battery using GA

Regenerative braking is an important means for realizing energy saving and emission reduction of hybrid electric vehicles, the given value of motors regenerative braking torque influences the energy recovery effect. Based on the Besturn HEV (Hybrid Electric Vehicle), a mathematic model of associated efficiency electric motor and battery according to the performance test of the permanent magnet synchronous motor and nickel-hydrogen power battery was set up in this paper, and the value of regenerative torque was determined through the optimization of the mathematic model using GA (Genetic Algorithm). The simulation results show that the method of determination of regenerative torque put forward in this paper is feasible, the motor and battery can achieve efficient operation in the process of regenerative braking and the recovery of braking energy can be improved obviously.

Braking force dynamic coordinated control for hybrid electric vehicles

The possibility of regenerative braking is one inherent advantage of hybrid electric vehicle. The motor and the hydraulic braking system are braking together while the hybrid electric vehicle is braking. But, the difference of the braking force dynamic response between the motor and the hydraulic braking system will lead the inadequate or excessive braking and will effect the braking felling of the driver. In this paper, we analyze the braking dynamic characteristics of the motor and the hydraulic braking system. Then, we analyze the hybrid electric vehicle working patterns of the braking process and design the hierarchical structure of the braking force control system. After that, we propose the braking force coordinated control strategy based on using the hydraulic braking force to compensate the motor braking force during the braking process of the hybrid electric vehicle. This paper used the integrated feed-forward and feedback control to design the braking force coordinated control strategy. This integrated control can maintain the stability of the control system while reduce the system error and increase the dynamic performance of the system. The simulation results show that braking force dynamic coordinated control is effective and the total braking force can meet the desired braking force during the braking of the hybrid electric vehicle.

Identification and control of split-μ road for antilock braking system

When braking on split-μ road, yaw moment and steering force of vehicle will be produced because the braking force is different for two side wheels. In order to deal with this problem, the modified independent control mode is widely applied, however, there also exits some defects. Because the gap of the adhensive coefficient of both sides is uncertain while braking, if the fixed modified coefficient is applied, it is difficult to keep vehicle direction stability and shorten the braking distance simultaneously under different gap former mentioned. This paper proposes a method named split-μ road identification. Compare the difference of slip integral of front wheels to threshold values during a certain pressure state in order to identify whether the vehicle brakes on split-μ road. According to the integral of slip from both side wheels and vehicle deceleration, the control mode dynamically changes the modified coefficients of pressure. Simulation results show that the algorithm can identify whether the vehicle is braking on split-μ road timely and also can identify the friction difference between the two sides accurately. The pressure regulation mode can regulate brake pressure appropriately and keep vehicle directional stability and shorten braking distance simultaneously.

Hydraulic braking force compensation control for hybrid electric vehicles

The possibility of regenerative braking is one inherent advantage of hybrid electric vehicle. The motor and the hydraulic braking system are braking together while the hybrid electric vehicle is braking. But, the difference of the braking force dynamic response between the motor and the hydraulic braking system will lead the inadequate or excessive braking and will affect the braking feeling of the driver. In this paper, we analyze the braking dynamic characteristics of the motor and the hydraulic braking system. Then, we propose the braking force coordinated control strategy based on using the hydraulic braking force to compensate the motor braking force during the braking process of the hybrid electric vehicle. And in order to improve the accuracy of the motor torque control, we use the adaptive fuzzy sliding model control method to control the motor torque. After that this paper used the integrated feed-forward and feedback control to design the hydraulic braking force compensation control strategy. This compensation control strategy can maintain the stability of the control system while reduce the system error and increase the dynamic performance of the system. The simulation results show that hydraulic braking force compensation control is effective and the total braking force can meet the desired braking force during the braking of the hybrid electric vehicle.

Development of a test bench for integrative evaluation of the pneumatic ABS/TCS performance

A test bench for integrative evaluation of the pneumatic activated ABS/TCS performance of a vehicle has been developed. The test bench is built based on the platform of Matlab/xPC. It can be used to test the performance of ABS/TCS ECU and the characteristic of pneumatic solenoid valve. It can also be used in guiding the design of a ABS/TCS product for original equipment manufactures (OEMs), or find the most suitable product among various market available ABS/TCSs for specific vehicle application for a vehicle manufacturer. The scheme of hardware and software of the bench is described in detail. The tests of braking and starting performance of a vehicle with ABS/TCS driving on the road with low adhesive coefficient and the road which experiences sharp changes in adhesive coefficient and the operating characteristic of the solenoid valve are taken as major test contents. The test results show that the bench can completely emulate the real operating characteristic of a ABS/TCS system as its operating on real roads