The direct yaw moment control can effectively enhance the yaw stability of the vehicle under extreme conditions, which has become one of the essential technologies for the distributed driving electric bus. Due to the features of a large mass and high center of gravity of the bus, lateral instability is more likely to occur under extreme driving conditions. To reduce the uncertainty and interference in the yaw movement process of the bus, this paper targets the instability caused by the coupling problem between the sideslip angle and yaw rate. An adaptive fuzzy sliding mode control is proposed to execute direct yaw moment control. The weight coefficient of the sideslip angle and the yaw rate is adjusted via fuzzy control in real time. The optimal direct yaw moment is finally obtained. A distribution method based on the vertical load proportion is adopted for the allocation of four motors’ torque. Under three typical working conditions, a joint simulation test was carried out. The simulation results demonstrate that the raised method decreases the amplitude of the sideslip angle by 20.90%, 12.75%, and 23.67% and the yaw rate is 8.62%, 6.89%, and 9.28%, respectively. The chattering and sudden changes in the additional yaw moment are also lessened. The control strategy can realize the control target, which effectively strengthens the yaw stability of the bus.

/pdf/yaw-stability-research-of-the-distributed-drive-electric-bus-1xy2tnx2.pdf

Yaw Stability Research of the Distributed Drive Electric Bus by Adaptive Fuzzy Sliding Mode Control

Research on the dynamic characteristics of pneumatic proportional regulator in pneumatic-loading system and design of fuzzy adaptive controller

The invention relates to a safe distance adjusting platform applying big data processing. The platform comprises a distance adjusting device, real-time distance measuring equipment and a real-time alarm device, wherein the distance adjusting device is used for reducing a safe distance of a front vehicle to be lower than a default value of the current safe distance when receiving a first driving command, otherwise, the current safe distance is recovered to be the default value; the real-time distance measuring equipment is arranged near a headlamp of the vehicle and is used for detecting a real-time distance of the front vehicle based on an infrared distance measuring mode or an ultrasonic distance measuring mode; and the real-time alarm device is connected with the distance adjusting device and the real-time distance measuring device and used for sending out a command that the vehicle distance is too short when the received real-time distance is smaller than the current safety distance, and otherwise, the command that the vehicle distance is normal is sent out. The safe distance adjusting platform applying big data processing is safe, reliable and wide in application. The safety distance of the front vehicle can be adjusted on site according to whether a current driving environment is in a snowfield environment or not so that the platform can adapt to various vehicle driving environments.

Safe distance adjustment platform applying big data processing

Under extreme working conditions such as high-speed driving on roads with a large road surface unevenness coefficient, turning on a road with a low road surface adhesion coefficient, and emergency acceleration and braking, a vehicle’s stability deteriorates sharply and reduces ride comfort. There is extensive existing research on vehicle active suspension control, trajectory tracking, and control methods. However, most of these studies focus on conventional operating conditions, while vehicle stability analysis under extreme operating conditions is much less studied. In order to improve the stability of the whole vehicle under extreme operating conditions, this paper investigates the stability of a vehicle under extreme operating conditions based on linear quadratic regulator (LQR) control. First, a seven degrees of freedom (7-DOF) dynamics model of the whole vehicle is established based on the use of electromagnetic active suspension, and then an LQR controller of the electromagnetic active suspension is designed. A joint simulation platform incorporating MATLAB and CarSim was built, and the CarSim model is verified by real vehicle tests. Finally, the stability of the vehicle under four different ultimate operating conditions was analyzed. The simulation results show that the root mean square (RMS) values of body droop acceleration and pitch angle acceleration are improved by 57.48% and 28.81%, respectively, under high-speed driving conditions on Class C roads. Under the double-shift condition with a low adhesion coefficient, the RMS values of body droop acceleration, pitch acceleration, and roll angle acceleration are improved by 58.25%, 55.41%, and 31.39%, respectively. These results indicate that electromagnetic active suspension can significantly improve vehicle stability and reduce driving risk under extreme working conditions when combined with an LQR controller.

/pdf/vehicle-stability-analysis-under-extreme-operating-1e3ni845.pdf

Vehicle Stability Analysis under Extreme Operating Conditions Based on LQR Control

The invention discloses an electric vehicle battery life evaluation system and method. The system comprises a battery state monitoring module, an automobile mileage monitoring module, a battery temperature acquisition module, a data evaluation module and a remote information processing module, wherein the battery state monitoring module, the remote information processing module and the data evaluation module are electrically connected, the automobile mileage monitoring module, the battery temperature acquisition module and the battery state monitoring module are electrically connected, the battery state monitoring module comprises a battery service life monitoring sub-module, a battery loss monitoring sub-module, a battery voltage monitoring sub-module and a battery capacity monitoring sub-module, the battery loss monitoring sub-module is used for receiving monitoring results of the battery service life monitoring sub-module, the battery voltage monitoring sub-module and the battery capacity monitoring sub-module, judging the battery loss degree, therefore transmitting data to the data evaluation module, and evaluating the battery life.

Electric vehicle battery life evaluation system and method

Due to the bus characteristics of large quality, high center of gravity and narrow wheelbase, the research of its yaw stability control (YSC) system has become the focus in the field of vehicle system dynamics. However, the tire nonlinear mechanical properties and the effectiveness of the YSC control system are not considered carefully in the current research. In this paper, a novel adaptive nonsingular fast terminal sliding mode (ANFTSM) control scheme for YSC is proposed to improve the bus curve driving stability and safety on slippery roads. Firstly, the STI (Systems Technologies Inc.) tire model, which can effectively reflect the nonlinear coupling relationship between the tire longitudinal force and lateral force, is established based on experimental data and firstly adopted in the bus YSC system design. On this basis, a more accurate bus lateral dynamics model is built and a novel YSC strategy based on ANFTSM, which has the merits of fast transient response, finite time convergence and high robustness against uncertainties and external disturbances, is designed. Thirdly, to solve the optimal allocation problem of the tire forces, whose objective is to achieve the desired direct yaw moment through the effective distribution of the brake force of each tire, the robust least-squares allocation method is adopted. To verify the feasibility, effectiveness and practicality of the proposed bus YSC approach, the TruckSim-Simulink co-simulation results are finally provided. The co-simulation results show that the lateral stability of bus under special driving conditions has been significantly improved. This research proposes a more effective design method for bus YSC system based on a more accurate tire model.

/pdf/an-adaptive-nonsingular-fast-terminal-sliding-mode-control-4a73hhu6uy.pdf

An adaptive nonsingular fast terminal sliding mode control for yaw stability control of bus based on STI tire model

The invention discloses an intelligent automobile braking system based on road surface visual inspection and a control method thereof, and belongs to the field of intelligent vehicle driving and braking safety control. The control method comprises the steps that an in-vehicle camera is used for obtaining a high-definition image of a road surface on which an automobile is running, a deep self-learning algorithm is used for determining the specific type of the road surface on which the automobile is running, and the maximum braking deceleration of the automobile on the road surface is determined; the maximum braking deceleration is divided into a plurality of braking intervals, and the multiple braking intervals are combined with the expected braking deceleration realized by the automobile and required by an upper control system to control the braking strength of the braking system; and the braking system is a grading braking system based on a floating caliper disc type brake, can achieve the braking strength of the automobile in a grading mode, and can achieve an anti-lock function. According to the intelligent automobile braking system based on road surface visual inspection and the control method thereof, grading control over the braking system is performed according to the maximum braking deceleration and the expected braking deceleration of the automobile based on the determination of the driving road surface type, so that the braking safety and reliability are ensured, and the system cost is greatly reduced.

Intelligent automobile braking system based on road surface visual inspection and control method thereof

The hybrid dynamic modeling and optimization control method for the intelligent automobile longitudinal dynamics system comprises the steps of establishing a whole automobile longitudinal dynamics model, and conducting segmented affine approximation on a nonlinear part existing in the model; based on hybrid dynamic model of the longitudinal dynamic system of the whole vehicle and a prediction control method, converting an intelligent vehicle longitudinal motion control problem into a mixed integer quadratic programming problem for solving to achieve the integration of a system optimization control law, and determining the optimal values of the driving torque and the braking torque and the optimal switching sequence between the driving mode and the braking mode in the intelligent vehicle longitudinal motion control process. The method solves the problems that an existing automobile longitudinal motion control method cannot accurately describe hybrid dynamic characteristics existing in asystem and a driving mode and a braking mode are smoothly switched in the automobile speed adjusting process.

Hybrid dynamic modeling and optimization control method for longitudinal dynamic system of intelligent automobile

The invention discloses a hydraulic-type automatic steering system of a pilotless automobile, and a control method of the hydraulic-type automatic steering system, and belongs to the field of automobile intelligent driving and steering safety control. The hydraulic-type automatic steering system is mainly constituted by a steering working cylinder, a working cylinder piston, a flow controllable throttle valve, a steering hydraulic pump, a steering oil tank, an oil return pipeline, an oil inlet pipeline, high-speed switch electromagnetic valves and the like; the opening-closing states of the four high-speed switch electromagnetic valves are controlled to form oil fluid pressure differences, in the different directions, of the left side and the right side of the working cylinder piston so asto achieve left turn or right turn of the automobile; during steering reversal, the opening-closing states of the high-speed switch electromagnetic valves are opposite to previous opening-closing states correspondingly; and the flow controllable throttle valve determines the oil fluid pressure differences of the left side and the right side of the working cylinder piston according to the expectedfront wheel rotating angle, and the flow of oil fluid flowing through the controllable throttle valve is obtained through an adaptive controller. Automatic steering of the pilotless automobile can beachieved, and the system is simple in structure, good in reliability and high in practicability.

Hydraulic-type automatic steering system of pilotless automobile, and control method of hydraulic-type automatic steering system

The invention discloses a piecewise affine identification modeling method for longitudinal sliding mechanical properties of tires. The piecewise affine identification modeling method includes the steps that a test of the longitudinal sliding mechanical properties of the tires is carried out, and test data reflecting the longitudinal sliding mechanical properties of the tires is accurately obtained; a three-dimensional curved surface map reflecting the nonlinear relationship between the tire longitudinal force, the tire vertical load and the tire longitudinal slip ratio is drawn based on the test data; a three-dimensional curved surface is divided into a finite number of sub-planes based on a heuristic approximation method, then the three-dimensional coordinates of points for dividing the sub-planes are determined, and a boundary line equation for dividing action areas of affine sub-models is further obtained; the trial and error method is used for determining the order of each affine sub-model, and then specific parameters of the sub-models are identified based on the least square method; and the output result of the piecewise affine models of the longitudinal sliding mechanical properties of the tires which is obtained by identification is compared with experimental data to verify the accuracy of the identification models. The piecewise affine identification modeling method meets the accuracy requirements of the tire models and performs the vehicle system dynamic control design base on the same.

Wang Yujun

Papers

An adaptive nonsingular fast terminal sliding mode control for yaw stability control of bus based on STI tire model

Intelligent automobile braking system based on road surface visual inspection and control method thereof

Hybrid dynamic modeling and optimization control method for longitudinal dynamic system of intelligent automobile

Hydraulic-type automatic steering system of pilotless automobile, and control method of hydraulic-type automatic steering system

Piecewise affine identification modeling method for longitudinal sliding mechanical properties of tires