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Electromagnetic suspension systems have increasingly gained widespread attention due to their superiority in improving ride comfort while providing fast response, excellent controllability and high mechanical efficiency, but their applications are limited due to the accuracy of the underlying control actuation tracking. For addressing this problem, this study presents a novel hierarchical control strategy for an electromagnetic active suspension (EMAS) system equipped with an electromagnetic actuator (EMA) structure. The structure of the EMA device and the working principle of the motion conversion model are introduced in detail first, and the motion conversion equation is derived based on the force-torque relationship. Based on this, a linear quadratic regulator (LQR) control method is proposed to be applied to a half-vehicle suspension system to improve the vibration isolation performance of the vehicle and ensure the ride comfort.

This paper intends to present a novel optimal trajectory planning method for obstacle avoidance on highways. Firstly, a mapping from the road Cartesian coordinate system to the road Frenet-based coordinate system is built, and the path lateral offset in the road Frenet-based coordinate system is represented by a function of quintic polynomial respecting the traveled distance along the road centerline. With different terminal conditions regarding its position, heading and curvature of the endpoint, and together with initial conditions of the starting point, the path planner generates a bunch of candidate paths via solving nonlinear equation sets numerically. A path selecting mechanism is further built which considers a normalized weighted sum of the path length, curvature, consistency with the previous path, as well as the road hazard risk.

Optimization design for vehicle front-end structures has proven rather essential and been extensively used to improve the vehicle performance. Nevertheless, the front-end structure needs to meet the requirement of both pedestrian safety and structural stiffness which are somewhat contradicting to each other. Furthermore, an optimal design could become less meaningful or even unacceptable when some uncertainties present. In the paper, a multi-objective discrete robust optimization (MODRO) algorithm is used to minimize the injury of head and maximize the structural stiffness involving uncertainties. MODRO algorithm is achieved by coupling grey relational analysis (GRA) and principal component analysis (PCA) with Taguchi method. The optimized result shows that the MODRO algorithm improved performance of pedestrian head injury and robustness of the vehicle front-end structure.

This paper presents an optimal cooperative path planning method considering driver’s driving intention for shared control to address target path conflicts during the driver-automation interaction by using the convex optimization technique based on the natural cubic spline. The optimal path criteria (e.g. the optimal curvature, the optimal heading angle) are formulated as quadratic forms using the natural cubic spline, and the initial cooperative path profiles of the cooperative path in the Frenet-based coordinate system are induced by considering the driver’s lane-changing intention recognized by the Support Vector Machine (SVM) method. Then, the optimal cooperative path could be obtained by the convex optimization techniques. The noncooperative game theory is adopted to model the driver-automation interaction in this shared control framework, where the Nash equilibrium solution is derived by the model predictive control (MPC) approach.

The around view monitor (AVM) system for the long-body road vehicle with multiple articulated carriages usually suffers from the incomplete distortion rectification of fisheye cameras and the irregular image stitching area caused by the change of relative position of the cameras on different carriages while the vehicle is in motion. In response to these problems, a set of calibration and stitching methods of AVM are proposed. First, a radial-distortion-based rectification method is adopted and improved. This method establishes two lost functions and solves the model parameters with the two-step optimization method. Then, AVM system calibration is conducted, and the perspective transformation matrix is calculated. After that, a static basic look-up table is generated based on the distortion rectification model and perspective transformation matrix.

A 3D grid model of engine brake is established for an automobile engine. The dynamic compression release braking process is simulated by using this model. In the process of engine braking, the movement of valve and piston causes changes of the internal flow field of the engine. In this paper, the movement of valve and piston were defined by using the dynamic grid technology, so that the numerical simulation is closer to the actual situation via the updating of grid. Based on the relevant parameters of compression release engine brake (including the opening of the exhaust valve, the engine speed and the exhaust back pressure), the pressure and power of the compression release braking system were simulated under the conditions of multiple operating conditions and experimental verification was carried out. The results showed that the braking works of the compression release engine brake are mainly from the compression stroke and the exhaust stroke.

This paper introduces a vehicle model in CarSim, and replaces a portion of its standard suspension system with an HIS model built in an external software to implement co-simulations. The maneuver we employ to characterize the HIS vehicle is a constant radius method, i.e. observing the vehicle’s steering wheel angle by fixing its cornering radius and gradually increasing its longitudinal speed. The principles of the influence of HIS systems on cornering mainly focus on two factors: lateral load transfer and roll steer effect. The concept of the front lateral load transfer occupancy ratio (FLTOR) is proposed to evaluate the proportions of lateral load transfer at front and rear axles. The relationship between toe and suspension compression is dismissed firstly to demonstrate the effects of lateral load transfer and then introduced to illustrate the effects of roll motion on cornering.

With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. To seek for an optimized volumetric ratio for ABE-diesel blends, the previous work in our team has experimentally investigated and analyzed the combustion features of ABE-diesel blends with different volumetric ratio (A: B: E: 6:3:1; 3:6:1; 0:10:0, vol. %) in a constant volume chamber. It was found that an increased amount of acetone would lead to a significant advancement of combustion phasing whereas butanol would compensate the advancing effect. Both spray dynamic and chemistry reaction dynamic are of great importance in explaining the unique combustion characteristic of ABE-diesel blend. In this study, a semi-detailed chemical mechanism is constructed and used to model ABE-diesel spray combustion in a constant volume chamber.

The traditional deterministic optimal design is mostly based on meeting regulatory requirements specified in impact standards, without taking the randomness of the impact velocity and angle at the real world situation into consideration. This often leads to the optimization results that converge to the boundary constraints, thus cannot meet the reliability requirements of the product design. Structure members of B-pillar (e.g. inner panel, outer panel, and the reinforcing plate) play a major role in the side impact safety performance. This paper dealt with optimization of B-pillar by considering its dimensions and materials as the design variables, and the impact velocity and angle from real-world traffic accident conditions as the random variable inputs. Using a combination of design of experiment, response surface models, reliability theory and the reliability of design optimization method, a B-pillar was constructed based on the product quality engineering.

Effectively obtaining physical parameters for vehicle dynamic model is the key to successfully performing any computer-based dynamic analysis, control strategy development or optimization. For a spring and lump mass vehicle model, which is a type of vehicle model widely used, its physical parameters include sprung mass, unsprung mass, inertial properties of the sprung mass, stiffness and damping coefficient of suspension and tire, etc. To minimize error, the paper proposes a method to estimate these parameters from vehicle modal parameters which are in turn obtained through full-car dynamic testing. To verify its effectiveness, a visual vehicle with a set of given parameters, build in the Adams(Automatic Dynamic Analysis of Mechanical Systems)/Car environment, is used to perform the dynamic testing and provide the testing data for the parameter estimation.

The combination of passive and active vehicle safety technologies can effectively improve vehicle safety. Most of them predict vehicle crashes using radar or video, but they can't be applied extensively currently due to the high cost. Another collision forecasting method is more economic which is based on the driver behavior and vehicle status, such as the acceleration, angular velocity of the brake pedal and so on. However, the acceleration and angular velocity of the brake pedal will change with the driver and the vehicle type. In order to study the effect of different drivers and vehicle types on the braking acceleration and angular velocity of the brake pedal, six volunteers were asked to drive five vehicles for simulating the working conditions of emergency braking, normal braking, inching braking and passing barricades under different velocities. All the tests were conducted on asphalt road, and comprehensive experimental design was used to arrange tests.

Hydraulic suspension systems with different interconnected configurations can decouple suspension mode and improve performance of a particular mode. In this paper, two types of interconnected suspensions are compared for off-road vehicle trafficability. Traditionally, anti-roll bar, a mechanically interconnected suspension system, connecting left and right suspension, decouples roll mode from the bounce mode and results in a stiff roll mode and a soft bounce mode, which is desired. However, anti-roll bars fail to connect the front wheel motions with the rear wheels', thus the wheels' motions in the warp mode are affected by anti-roll bars and it results an undesired stiffened warp mode. A stiffened warp mode limits the wheel-ground contact and may cause one wheel lift up especially during off-road drive. In contrast with anti-roll bars, two types of hydraulic suspensions which interconnect four wheels (for two-axis vehicles) can further decouple articulation mode from other modes.

Lightweight automotive body can be obtained by developing new body constructions, using lightweight materials and structural optimizations, etc. Usually, lighter materials and structural optimizations are main aspects considered in lightweight automotive body engineering. In fact, material costs and manufacturability play more important roles than others in lightweight design. Three lightweight design approaches are considered. The first approach of lightweight design is to replace steels with lighter materials using equal rigidity design method. The second approach is a single objective optimization of mass reduction with materials selection and cost penalty. The third approach is a multi-objective optimization of mass reduction and cost reduction using multi-material concept. These three approaches are applied to an automotive body design problem considering the side impact. Different optimization methods are used to obtain different results.

Air spring due to its superior ride comfort performance has been widely used in distance passenger transporting vehicles. Since the requirements for ride comfort and handling performance are contradict to each other, handling performance and even roll stability are sacrificed to some extent to obtain good ride comfort. Due to the complex terrain and limited manufacturing level, in the past several years, bus rollover accidents with serious casualties have been reported frequently and bus safety has attracted more and more attention from bus manufacturers in China. On one hand the bus standards have to be raised, and on the other hand, novel solutions which can effectively improve the roll stability of air spring bus are needed to replace the inadequacy of anti-roll bars.

This paper employs the motion-mode energy method (MEM) to investigate the effects of a roll-plane hydraulically interconnected suspension (HIS) system on vehicle body-wheel motion-mode energy distribution. A roll-plane HIS system can directly provide stiffness and damping to vehicle roll motion-mode, in addition to spring and shock absorbers in each wheel station. A four degree-of-freedom (DOF) roll-plane half-car model is employed for this study, which contains four body-wheel motion-modes, including body bounce mode, body roll mode, wheel bounce mode and wheel roll mode. For a half-car model, its dynamic energy contained in the relative motions between its body and wheels is a sum of the energy of these four motion-modes. Numerical examples and full-car experiments are used to illustrate the concept of the effects of HIS on motion-mode energy distribution.

In vehicles equipped with conventional Electric Power Steering (EPS) systems, the steering effort felt by the driver can be unreasonably low when driving on slippery roads. This may lead inexperienced drivers to steer more than what is required in a turn and risk losing control of the vehicle. Thus, it is sensible for tire-road friction to be accounted for in the design of future EPS systems. This paper describes the design of an auxiliary EPS controller that manipulates torque delivery of current EPS systems by supplying its motor with a compensation current controlled by a fuzzy logic algorithm that considers tire-road friction among other factors. Moreover, a steering system model, a nonlinear vehicle dynamics model and a Dugoff tire model are developed in MATLAB/Simulink. Physical testing is conducted to validate the virtual model and confirm that steering torque decreases considerably on low friction roads.

In this paper, a passive anti-pitch anti-roll hydraulically interconnected suspension is proposed for compromising the control between the pitch and roll mode of the sprung mass. It has the advantage in improving the directional stability and handling quality of vehicles during steering and braking manoeuvres. Frequency domain analysis of a 7-DOF full-car model with the proposed system is presented. The modeling of mechanical subsystem is established based on the Newton's second law. Then the mechanical-hydraulic system boundary conditions are developed by incorporating the hydraulic strut forces into the mechanical subsystem as externally applied forces. The hydraulic subsystem is modelled by using the impedance method, and each circuit are determined by the transfer matrix method. And then the modal analysis method is employed to perform the vibration analysis between the vehicle with the conventional suspension and the proposed HIS.

Good handling stability becomes very important for heavily-laden electric wheel dump trucks that are operated on rough roads. To improve handling stability of mining dump trucks, nonlinear stiffness and nonlinear damping of the hydro-pneumatic suspension were considered as optimization variables. In this paper, based on the Daubechies wavelet's compactness and regularization and least-square method, the nonlinear stiffness and damping are identified. In order to verify the results of the parameter identification, the multi-body system dynamic model of the truck was built in ADAMS/view. By comparing the simulated results and tested ones, we find acceleration-history and power spectral density of acceleration are very close. And then, based on the approximate model method, the optimization model was built in ISIGHT. The nitrogen column and the orifice diameter were defined as the design variables. Finally, the handling stability was optimized by applying the genetic algorithms method.

Realizable k-ε turbulence model has been used widely for engineering development. In this turbulence model, the default values of empirical coefficients such as C₂, σk and σε are obtained from some particular experiments. They are a good choice for most simulations-though may be not the best choice for simulating the aerodynamic characteristics of road vehicle. In order to improve the accuracy of simulation, a set of new empirical coefficients should be designed especially for simulating the aerodynamic characteristics of road vehicle. These empirical coefficients are found out by DoE (design of experiments) in this paper. Firstly the value range of empirical coefficients is decided by the laws that the aerodynamic force coefficients change with altering of empirical coefficients. Secondly 20 sets of empirical coefficients are obtained randomly by applying optimal Latin Hypercube method in Isight.

This study investigates the fundamental stiffness and damping properties of a self-damped pneumatic suspension system, based on both the experimental and analytical analyses. The pneumatic suspension system consists of a pneumatic cylinder and an accumulator that are connected by an orifice, where damping is realized by the gas flow resistance through the orifice. The nonlinear suspension system model is derived and also linearized for facilitating the properties characterization. An experimental setup is also developed for validating both the formulated nonlinear and linearized models. The comparisons between the measured data and simulation results demonstrate the validity of the models under the operating conditions considered. Two suspension property measures, namely equivalent stiffness coefficient and loss factor, are further formulated.