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This paper sets up a simplified dynamic model for simulating the yaw/roll stability of heavy tractor-semitrailer using Matlab/Simulink. A linear quadratic regulator (LQR) based on partial-state feedback controller is used to optimize the roll stability of the vehicle. The control objective for optimizing roll stability is to be reducing the lateral load transfer rate while keeping the suspension angle less than the maximum allowable angle. The simulation result shows that the LQR controller is effective in the active roll stability control of the heavy tractor-semitrailer.

Aiming at estimating the vehicle mass and the position of center of gravity, an on-line two-stage estimator, based on the recursive least square method, is proposed for buses in this paper. Accurate information of the center of gravity position is crucial to vehicle control, especially for buses whose center of gravity position can be varied substantially because of the payload onboard. Considering that the buses start and stop frequently, the first stage of the estimator determines the bus total mass during acceleration, and the second stage utilizes the recursive least-square methods to estimate the position of the center of gravity during braking. The proposed estimator can be validated by the co-simulation with MATLAB/Simulink and TruckSim software, simulation results exhibit good convergence and stability, so the center of gravity position can be estimated through the proposed method in a certain accuracy range.

Steering-By-Wire (SBW) system has advantages of advanced vehicle control system, which has no mechanical linkage to control the steering wheel and front wheels. It is possible to control the steering wheel actuator and front wheels actuator steering independently. The goal of this paper is to use a joystick to substitute the conventional steering wheel with typical vehicle SBW system and to study a variable steering ratio design method. A 2-DOF vehicle dynamic reference model is built and focused on the vehicle steering performance of drivers control joystick. By verifying the results with a hardware-in-the-loop simulation test bench, it shows this proposed strategy can improve vehicle maneuverability and comfort.

Steering-by-wire(SBW) system makes the vehicle not constrained by the steering wheel control. Joystick, button and touch screen can all be used for automobile steering control. Using joystick to achieve steering operations has its unique advantages and many problems which are needed to be resolved at the same time. This paper firstly introduced the components of traditional steering wheel steer-by-wire system, then came up with the difference between joystick steer-by-wire system and traditional steer-by-wire system about transmission ratio, transmission ratio control strategy of joystick steer-by-wire system is proposed at the same time. At last, this paper studied driver’s busy degree when the vehicle running with a big turning radius at low speed and the effect of different angle transmission ratio on vehicle handing stability when the vehicle running at intermediate speed.

Nowadays, electric control steering system has been a main tendency. It consists of Electric Power Steering (EPS) system, Steer by Wire (SBW) system and Active Front Steering (AFS) system. EPS is more widely applied and its technology is more developed. By 2010, the cars equipped with EPS have reached almost 30%. This paper describes one integrated test bench which can test and verify electric control steering system. The main target of the paper is to design and set up a resistance loading system for the test bench referred. The paper takes EPS as a prototype to verify the designed resistance loading system. If the resistance loading system provides a precise simulated torque for the bench, the results of tests will be more approximate with vehicle tests and the acquired data will be reliable for electric control steering system's design and improvement. The linear electric cylinder applied in the loading system is used to provide simulated torque for the bench.

As electric technique develops fast, steering system changes from conventional mechanic steering system to Hydraulic Power Steering (HPS). Flowing HPS, Electrically Controlled Steering (ECS) system, including Electric Power Steering (EPS) system, Active Front Steering (AFS) system and Steer-by-Wire (SBW) system. ECS makes it easy for a driver to control a steering wheel using a less torque at a low speed, which is usually called steering portability Besides, ECS could also help a driver steer a vehicle stably at a high speed, which is usually called steering stability ECS provides an optional method to solve the contradiction between steering portability and steering stability. [1] [2] The study of ECS involves mechanic design, detection of electric components, software design and so on. Researches of ECS need a lot of trials and errors. By now, the development of ECS mostly depends on experiments on Hardware-in-the- Loop (HIL) and real vehicles.

Nowadays, conventional steering system cannot meet consumers' requirements as their environmental awareness increasing. Electrically controlled steering system can solve this problem well [1] [2]. Electrically controlled steering system has been not only applied widely in automobile steering technique but also becomes an important section of automobile integrated chassis control technology. It is necessary for vehicles to test their every component repeatedly before every component assembled. So a test bench becomes an essential part for vehicle products' design and improvement. The electrically controlled steering system consists of Electric Power Steering system (EPS), Active Front Steering (AFS) and Steer by Wire (SBW). The similarity among them is containing pinion-and-rack mechanical structure, so it is viable to design a test bench suitable for these three systems. This paper takes EPS as a prototype to verify the design's availability.

The steer-by-wire (SBW) system, an integral component of the drive-by-wire chassis responsible for controlling the lateral motion of a vehicle, plays a pivotal role in enhancing vehicle safety. However, it poses a unique challenge concerning steering wheel return control, primarily due to its fundamental characteristic of severing the mechanical connection between the steering wheel and the turning wheel. This disconnect results in the inability to directly transmit the self-aligning torque to the steering wheel, giving rise to complications in ensuring a seamless return process. In order to realize precise control of steering wheel return, solving the problem of insufficient low-speed return and high-speed return overshoot of the steering wheel of the SBW system, this paper proposes a steering wheel active return control strategy for SBW system based on the backstepping control method.

With rapid development of the automobile industry and the growing maturity of the automotive electronic technologies, the distributed-traction electric vehicle with four-wheel-distributed steering/braking/traction systems is regarded as an important development direction. With its unique chassis structure, it is the ideal benchmark platform used to evaluate active safety systems. The distributed-traction electric vehicle with four-wheel-distributed steering system is essentially full drive-by-wire vehicle. With its flexible chassis layout and high control degrees-of-freedom, the full drive-by-wire electric vehicle acted as a kind of redundant system is an ideal platform for the research of integrated control. In this treatise, the longitudinal dynamics of the electric vehicle as well as its lateral and yaw motions are controlled simultaneously.

With the popularity of electrification and driver assistance systems on vehicle dynamics and controls, the steering performance of the vehicle put forward higher requirements. Thus, the steer-by-wire technology is becoming particularly important. Through specific control algorithm, the steer-by-wire system electronic control unit can receive signals from other sensors on the vehicle, realize the personalized vehicle dynamics control on the basis of understanding the driver’s intention, and grasp the vehicle movement state. At the same time, to make these driver assistance systems better cooperate with human drivers, reduce system frequent false warning, full consideration of mutual adaptation for the systems and the driver’s characteristics is critical. This paper focuses on the steering performance of steer-by-wire vehicle. Feature parameters are obtained from the virtual turning experiment designed on the driving simulator experimental platform.

The rapid development of city traffic makes the driving conditions faced by vehicles increasingly complex. The drive-by-wire chassis vehicle has the characteristics of four-wheel independent steering, four-wheel independent drive and four-wheel independent braking, which has become a current research hotspot because that can meet various complex working conditions. However, it is precisely because of the high degree of controllability of the drive-by-wire chassis that the research on the control strategy has become difficult. In this paper, an integrated control strategy based on the hierarchical algorithm framework is designed for the drive-by-wire chassis vehicle, which includes a centralized control layer, a tire force distribution layer and an actuator control layer.

Active steering technology can improve the operability of the driver by the involvement to the steering system. Driver is the major controller of the vehicle Therefore, the involvement of advanced technologies including the active steering technology shouldn’t interfere with the intention of the driver, and the driver should still have great control of the vehicle. The aim of this paper is to solve the problem of the driver’s control when the active steering system works to improve the flexibility of the low speed and the stability of the high speed, and the active steering model based on the driver’s steering intention is established. Through the CarSim simulation software, this paper adopts 9 parameters related to the vehicle steering of the DLC (Double Line Change). And PCA (Principal Component Analysis) algorithm, a tool of statistical analysis, is applied to select 4 parameters which can stand for the DLC from the 9 parameters, which makes the data processing easier.

Heavy vehicles have the characteristics of with high center of gravity position, large weight and volume, wheelbase is too narrow relative to the body height and so on, so that they always prone to rollover. In response to the above heavy security problems of heavy vehicle in running process, this paper mainly analyzes roll stability and yaw stability mechanism of heavy vehicles and studies the influence of vehicle parameters on stability by establishing the vehicle dynamics model. At the same time, this paper focuses on heavy vehicles stability control methods based on simulation and differential braking technology. At last, verify the effect of heavy vehicle stability control by computer simulation. The results shows that self-developed stability control algorithm can control vehicle stability effectively, so that the heavy vehicles instability can be avoided, the vehicle driving safety and braking stability are improved.

The quality of the brake system is a significant safety factor in commercial vehicles on the roads. With the development of automobile technology, the single function ABS system didn't meet active safety requirements of the user. The Electronically Controlled Brake System (EBS) system will replace the ABS system to become the standard safety equipment of commercial vehicles in the near future. EBS can be said an enhanced ABS system, it contains load sensor, brake valve sensor and pressure sensor of chamber, etc, and it is more advantages than ABS. This paper describes a flexible integrated test bench for ABS/EBS Electronic Control Unit (ECU) based on Hardware-In-the-Loop (HIL) simulation technique. It consists of most commercial vehicle pneumatic braking system components (from brake pedal valve, brake caliper to brake chambers), and uses the dSPACE real-time simulation system to communicate to the hardware I/O interface.

Steer-By-Wire (SBW) system directly transmits the driver's steering input to the wheels through electrical signals. However, the reliability of electronic equipment is significantly lower than that of mechanical structures, and the risk of failure increases, so it is important to conduct functional safety studies on SBW systems. This paper develops the functional safety of the SBW system according to the requirements of the international standard ISO26262, and first defines the relevant items and application scope of SBW system. Secondly, the Hazard and Operability (HAZOP) method was used to combine scenarios and possible dangerous events to carry out Hazard Analysis and Risk Assessment (HARA), and the Automotive Safety Integrity Level (ASIL) was obtained according to the three evaluation indicators of Exposure, Severity and Controlabillity, and then the corresponding safety objectives were established and Fault Tolerant Time Interval (FTTI) was set.

Electric power steering (EPS), active front wheel steering (AFS) and steer by wire systems (SBW) can enhance the handling stability and safety of the vehicle, even in dangerous working conditions. Now, the development of the electric control steering system (ECS) is mainly based on the way that combines the test of the electric steering hardware-in-loop (HIL) test bench with real vehicle tests. However, the real vehicle tests with higher cost, long cycle and vulnerable to space weather have the potential safety problems at early development. On contrast, electronic control steering HIL test bench can replace real vehicle tests under various working conditions and make previous preparations for real vehicle road tests, so as to reduce the number of real vehicle test, shorten the development cycle, lower development costs, which has gradually become the important link of research and development of electronic steering system.

This essay aims to develop an electrically controlled steering test bench and lay a solid foundation for the development of steering system. The first part mainly introduces the function, structure and working principle of the test bench. For the hardware system, it includes the steering system, fixture, sensors as well as a frameless disk motor for carrying out automatic motor input, and a dual linear motor system selected as the road resistance simulation actuator. As for the software, MATLAB/Simulink, CarSim, RTI and ControlDesk are used. Therefore, with the help of real-time simulation platform, researchers can not only build control strategy and dynamic model but also control the experiment and tune parameters in real-time. The second part of the essay aims to identify both electric and mechanical parameters of R-EPS system by carrying out tests on the proposed test bench. As parameters are successfully identified, the feasibility of the test bench is also verified.

In order to improve the trajectory tracking accuracy and yaw stability of vehicles under extreme conditions such as high speed and low adhesion, a coordinated control method of trajectory tracking and yaw stability is proposed based on four-wheel-independent-driving vehicles with four-wheel-steering. The hierarchical structure includes the trajectory tracking control layer, the lateral stability control decision layer, and the four-wheel angle and torque distribution layer. Firstly, the upper layer establishes a three-degree-of-freedom vehicle dynamics model as the controller prediction model, the front wheel steering controller is designed to realize the lateral path tracking based on adaptive model predictive control algorithm and the longitudinal speed controller is designed to realize the longitudinal speed tracking based on PID control algorithm.

Both active front wheel steering (AFS) and differential braking control (DBC) can improve the vehicle handling and stability. In this article, an AFS strategy and a DBC strategy are proposed and compared. The strategies are as follows: A yaw instability judging module and a rollover instability judging module are put forward to determine whether the coach is in a linear state and whether the additional torque/angle module should be actuated. The additional torque module based on linear quadratic regulator (LQR) and the additional steering wheel angle module based on adaptive proportion integral differential (PID) fuzzy controller are designed to make the actual yaw rate and sideslip angle track the reference yaw rate and sideslip angle. Under some typical driving conditions such as sinusoidal, J-turning, crosswind, and straight-line brake maneuver on the μ-split road, simulation tests are carried out for the coach with no control, DBC strategy, and AFS control, respectively.

Electro-hydraulic power steering system (EHPS) maintains the advantages of Hydraulic power steering system (HPS) and Electric power steering system (EPS).It is even more superior than this two. In the foreseeable future, this system will have a certain development space. Assistant characters analysis was carried out in this paper. Control strategy based on steering states and feedback control strategy were designed too. Besides, aiming at the emergency steering conditions, steering angular velocity additional controlling strategy was brought out. Under emergency steering conditions, steering angular velocity additional controlling strategy will be applied. Additional steering moment will be calculated to ensure the assistant follow steering rapidly.