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Electronic Stability Control (ESC) is an important measure to proactively guarantee vehicle safety. In this paper, the method of four-wheel hub-motor torque control is compared with the traditional single-wheel hydraulic brake control in ESC system. The control strategy adopts the hierarchical structure. In upper controller, the stability of the vehicle is identified by threshold method, the additional yaw moment control uses a way to get the moment including feedforward and feedback parts based on the linear quadratic regulator (LQR). The medium controller is tire slip rate control, in order to get the optimal target slip rate from the upper additional yaw moment, a method of quadratic programming to optimize the longitudinal force is proposed for each wheel. The inputs of tire state for the magic tire model is introduced so as to calculate the target slip rate from the target longitudinal force.

In automatic driving application, the velocity planner can be considered as a key factor to ensure the safety and comfort. One of the most important tasks of the velocity planner is to simulate the velocity characteristics of human drivers. In this paper, two Driver In-the-Loop (DIL) experiments are designed to explain velocity characteristics of human drivers. In the first experiment, static obstacles are placed on both sides of the straight road to shorten the cross range that vehicles can driver across. Moreover, different cross ranges are set to study the influence of the steering wheel error. In the second experiment, velocity characteristics are investigated under the condition of different road widths and curvatures in a U-turn road contour. In both tests, different drivers’ preview behavior is analyzed through the operation of throttle, braking, and steering.

The retarder is an important auxiliary braking device of heavy vehicles. However, the stirring air in the working wheels of the idle retarder would cause the transmission loss when the vehicle is traveling in non-braking state [1]. For certain driving conditions, the air-friction characteristics in the working wheels of the idle retarder are analyzed first. Then the relationship between the air density and the torque produced by stirring air is studied. The thermal characteristics of the retarder in the idle condition are also concerned according to the energy flow and heat transfer. Meanwhile, the increased transmission loss caused by the rising temperature of the stirring air and its inference on the transmission stability are also studied. Finally, the optimal range of air vacuum degrees in the working wheel of the idle retarder is determined and the evaluations for the air-friction and the heat transfer characteristics are given for the vacuum degrees.

The basic principle of wavelet transform is presented and the method of wavelet theory is used in vibration signal analysis of vehicle in this paper. The vibration signals which generated in the locations such as cab floor, engine, transmission, band spring and frame under the usual work condition are measured by the vibration test system. The vibration signals are decomposed with the principle of wavelet decomposition at level six, and eigenvectors of signal energy are gained. According to the correlation coefficient of eigenvectors of signal energy distribution, two signals correlativity is determined. It could be an effective method that identificate the main vibration source.

Hydraulic retarder has been widely applied on military vehicles and heavy commercial vehicles because of it could provide great brake torque and has lasting working time [1]. In order to reduce driver's frequent actions in braking process and prevent hydraulic retarder system from overheating, it is need to apply constant braking torque control, this control target has a strict requirement to hydraulic control system design. Many parameters often require repeated test to determine, which increases the R&D cost and extends the research cycle. This paper tries to find a time-efficient research method of hydraulic retarder control system through studying on a heavy military vehicle hydraulic retarder system. Hydraulic retarder model is set up through test data. The hydraulic control system is built based on AMESim. Controller model is set up based on PID control. The whole vehicle brake model is built based on MATLAB/Simulink.

The hydraulic servo brake system for passenger car plays a central role in occupant protection, which directly affects the automotive active safety and road handling. In this paper, an integrated parameterized software platform of hydraulic servo brake systems is proposed to realize fast and efficient braking system development. At first, according to the structure and working principle of the hydraulic servo brake system, the relationship among amount of fluid required for brake caliper, pedal feel and performance of the brake system is analyzed. Then, based on kinematics and dynamics of the hydraulic servo brake system, a simulation model for analyze pedal feel and amount of fluid required for brake caliper is built in AMESim, which is composed of brake pedal, vacuum booster, brake master cylinder, brake hoses and brake calipers, etc.

In order to perform differential control instead of the mechanical differential and improve the steering performance of distributed electric vehicles, a two-level differential speed steering control strategy is proposed. Firstly, an upper-layer controller to track the yaw rate is designed based on PID feedback and 3-D lookup table model, which could shorten the response time and reduce the impact of model parameters mismatch. Then, in order to improve the robustness to external disturbances and parameter uncertainties, a lower-layer controller to track the wheel speed is proposed based on integral sliding mode control. Moreover, three simulations are conducted to validate the proposed strategy. The first simulation results indicate that the driving torques of the inner and outer wheels are distributed properly to avoid wheel slip. In the second simulation, when the conventional steering system fails, the proposed control strategy could avoid vehicle losing steering function.

Dynamic modeling and state estimation are significant in the trajectory tracking and stability control of the intelligent vehicle. In order to meet the requirement of the stability control of the eight-in-wheel-motor-driven intelligent vehicle, a full vehicle dynamics model with 12 degrees of freedom, including the longitudinal, lateral, yaw and roll motion of the body, and rotational motion of 8 wheels, is established for the research of the intelligent vehicle in this paper. By simulation with MATLAB/SIMULINK and by comparison with the TruckSim software, the reliability and practicality of the dynamics model are verified. Based on the established dynamics model, an extended Kalman filter (EKF) state observer is proposed to estimate the vehicle sideslip angle, roll angle and yaw rate, which are the key parameters to the stability control of the intelligent vehicle.

The hydraulic retarder used in commercial vehicles can provide hydraulic damping to generate braking torque, reducing the pressure of the braking system on the slope section and increasing the safety. In this paper, the magnetorheological fluid with fast magnetic field reflection characteristics is used to increase the response speed of the hydraulic retarder, which can effectively reduce the response time of the hydraulic retarder. In this paper, the influence of the change of circumferential magnetic field on the braking torque of the magnetorheological fluid retarder is studied.

The paper studies on the basis of VOITH R133-2 hydraulic retarder, the inlet and outlet structures of the oil passage on the stator are rearranged, which are made a more uniform structure distribution. In order to find out the characteristics of this kind of structure arrangement. The flow passage models for two different structures are established, and the internal flow field characteristics are studied by using the CFD (Computational Fluid Dynamics) method. The flow rules of the internal oil, the distribution of pressure field and velocity field as well as output braking torque are obtained. The results show that rearranged structure retarder has a more uniform pressure distribution and a lower output braking torque than original structure retarder. And the simulation verifies the effectiveness of simulating true flow by CFD in hydraulic retarder flow field and conduct retarder design and structure optimization.

This paper presented a brief derivation of the energy dissipation by vehicle shock absorbers. Analysis between energy dissipation and damping coefficient, the road displacement power spectral density, the vehicle speed and the tire stiffness was carried out. Then an energy recovery scheme was put forward, and the bench test proved that the energy harvest scheme is feasible. In the end, this paper provided detailed derivation of the characteristics of the hydraulic electromagnetic energy-regenerative shock absorber, which increases its feasibility and practicability.

In order to improve the driving experience of drivers and the efficiency of vehicle development, a method of objective drivability for passenger car powertrain is proposed, which is based on prior knowledge, principal component analysis (PCA) and SMART principle. First, drivability parameters of powertrain for passenger cars are determined according to working principle of powertrain, including engine torque, engine speed, gearbox position, accelerate pedal, brake pedal, steering wheel angle, longitudinal acceleration and lateral acceleration, etc. The drivability quantitative index system is designed based on field test data, prior knowledge and SMART principles. Then, D-S evidence theory and sliding window method are applied to identify objective drivability evaluation conditions of powertrain for passenger cars, including static gearshift conditions, starting conditions, creep conditions, tip-in, tip out, upshift conditions, acceleration, downshift conditions and de-acceleration.

Semi-active suspension has been widely applied in commercial vehicle suspension in order to get good riding comfortableness. Fuzzy logic control (FLC) has been widely applied in the field of kinetic control because control rule of FLC is easy to understand. But the gain of fuzzy rules and adjustment of membership functions usually depend on experts' experiences and repeated experiments, thus the fuzzy rules and membership functions has strong subjectivity, also are easily affected by environment of experiments, so the main problem of fuzzy logic controller design is selection and optimization of fuzzy rules and membership functions. Genetic Algorithms (GA) is the algorithm that searches the optimal solution through simulating natural evolutionary process and is one of the evolution algorithms which have most extensive impact.

In this paper a new pressure control method of a modified accumulator-type Electro-hydraulic Braking System (EHB) is proposed. The system is composed of a hydraulic motor pump, an accumulator, an integrated master cylinder, a pedal feel simulator, valves and pipelines. Two pressurizing modes are switched between by-motor and by-accumulator to adapt different pressure boost demands. A differentiator filtering raw sensor signal and calculating pedal speed is designed. By using the pedal feel simulator, the relationship between wheel pressures and brake force is decoupled. The relationships among pedal displacement, pedal force and wheel pressure are calibrated by experiments. A model-based PI controller with predictor is designed to lower the influences caused by delay. Moreover, a self-tuning regulator is introduced to deal with the parameter’s time-varying caused by temperature, brake pads wearing and delay variation.

Brake pedal feel plays an important role in the driver's comprehensive subjective feeling when braking, which directly affects the active safety and riding comfort of passenger car. A systematical mathematical model of the vehicle brake system is built in according with the structure and system characteristics of hydraulic servo brake system. A complete hydraulic servo brake system simulation model composed of brake pedal, vacuum booster, brake master cylinder, brake pipe, brake wheel cylinders, brake calipers is established in AMESim. The effects of rubber reaction plate stiffness, rubber valve opening, brake master cylinder piston, brake caliper, brake pipe deformation and friction liner deformation on brake pedal feel are considered in this model. The accuracy of this model is verified by real road vehicle tests under static and dynamic two different conditions.

Focusing the vehicle riding safety and global environmental problems, plenty of solutions on vehicle braking systems appeals during the recent period. Criteria and standards set up for commercial vehicles which should have equipped assisted braking systems were established by amounts of governments. Since eddy current retarders plays an important role in the area of assisted braking system, this article presents an energy-recuperation retarder, which is parallel connected with the driveline through a planet gear system. This paper offers a particular Energy-Recuperation Eddy Current Retarder (ERECR) system with a pedal control system and its characteristics is presented, either. Initially, the constitution of the energy-recuperation eddy current retarder system is established whereas the working principle of the energy-recuperation eddy current retarder is presented by modeling the system and simulation.

Analogous to a vacuum boosted system, Electro-Hydraulic Braking System (EHB) is free from engine vacuum and supplies a braking force proportional to driver input. The independence of engine vacuum makes it especially suitable to be used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). As a key component of EHB, master cylinder is driven by the pump rather than the vacuum booster. Even if the pump fails, the cylinder can also build proper pressure. Meanwhile, in order to maintain the pedal feeling, a pedal stroke simulator is applied in the system. In this paper, aiming at decreasing the size and cost of master cylinder and providing an ideal pedal feeling without compromise of performance, a new integrated master cylinder of EHB system is designed including two parts: master cylinder and pedal stroke simulator. The key components of the integrated master cylinder are motor pump, solenoid valves and composite springs.

Focusing on distributed electric vehicles with in-wheel motors, a novel regenerative braking control strategy based on braking intention is proposed. Firstly, a design scheme for the regenerative braking system is described. Four in-wheel motors and an Electro-Hydraulic Braking (EHB) system are respectively designed for regenerative braking and hydraulic braking. Then, Braking intention recognition self-learning libraries are trained based on Hidden Markov Model method, which is validated by driver-in-loop tests. According to three speed states and four braking intentions, the regenerative braking control strategy for multiple brake modes is developed. The coefficient of regenerative braking is defined to describe the intervening time and proportion of motor maximum regenerative braking.

The current paper proposes a hydraulic interconnected suspension system (HIS) based on a hydraulic energy-regenerative shock absorber (HESA) comparatively with the passive suspensions. The structure and working principles of the HIS system are introduced in order to investigate the damping performance and energy regeneration characteristics of the proposed system. Then, the dynamic characteristics of the HIS-HESA system have been investigated based on a 4-DOF longitudinal half vehicle model. In the simulation, two different road inputs were used in the dynamic characterization of the HIS-HESA; the warp sinusoidal excitation, and the random road signal. In addition, a comparative analysis was provided for the dynamic responses of the half vehicle model for both the HIS-HESA and the conventional suspension. Furthermore, a parametric analysis of the HIS-HESA has been carried out highlining the key parameters that have a remarkable effect on the HIS-HESA performance.

This paper presents a novel application of hydraulic electromagnetic energy-regenerative shock absorber (HESA) into commercial vehicle suspension system and vehicle road performance are simulated by the evaluating indexes (e.g. root-mean-square values of vertical acceleration of sprung mass, dynamic tire-ground contact force, suspension deflection and harvested power; maximum values of pitch angle and roll angle). Firstly, the configuration and working principle of HESA are introduced. Then, the damping characteristics of HESA and the seven-degrees-of-freedom vehicle dynamics were modeled respectively before deriving the dynamic characteristics of a vehicle equipped with HESA. The control current is fixed at 7A to match the similar damping effect of traditional damper on the basis of energy conversion method of nonlinear shock absorber.