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Abstract With the development of automated vehicles, researches related to automated vehicle platoon (AVP) have received more and more attention. AVP is considered one of the effective means to alleviate traffic congestion and reduce vehicle energy consumption. This paper studies a three‐layer method of avoiding obstacle vehicles in traffic by switching the formation for the automated heavy vehicle platoon. In the decision‐making layer, a decision‐making system based on the finite‐state machine is established for formation switching. In the second layer, the lane‐changing trajectory is optimized based on the quantic polynomial curve fitting for vehicles that need to change lanes. In terms of vehicle control layer, each vehicle has a longitudinal controller based on sliding mode control and a lateral controller based on model predictive control to track the planned trajectory to complete the target formation. Finally, the proposed method is simulated in MATLAB/TruckSim. The simulation results show that the proposed method could effectively avoid the obstacle vehicles by switching the formation and has a small average value of errors in speed tracking and trajectory tracking.

Connected and automated vehicle platoons (CAVPs) are considered an effective way to alleviate traffic congestion, reduce the incidence of traffic accidents, and improve vehicle economy in the intelligent transportation system (ITS). Vehicles in the CAVPs can communicate with each other through V2X technology, which could optimize the economy of the platoon. Cooperative adaptive cruise control (CACC) can make effective use of the characteristics of CAVPs and contribute to resource conservation, ecological driving, and traffic system development. In this paper, a two-stage CACC method is proposed for CAVPs to reduce fuel consumption in the multislope road section. In the first stage, the optimal velocity profiles for the leader based on dynamic programming (DP) are planned according to the road information and the fuel consumption model. In the second stage, a vehicle longitudinal third-order differential dynamics model is utilized to build the platoon time-delay system considering communication delay and actuator delay. A feedback controller is developed for each vehicle considering the internal stability and the string stability of the CAVPs. Results show that the proposed method can save 5.33% of fuel consumption compared to the constant speed cooperative adaptive cruise control (CS-CACC) method and has a better tracking performance compared to the model predictive control (MPC) method. The CACC method proposed in this paper can provide a theoretical basis and data support for building an ecological CACC strategy for CAVPs.

Many crystals in nature have simple interatomic microstructures, such as simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC) lattice symmetries, making these structures extremely stable. Inspired by these arrangements, a series of architected micro-channel heat exchangers with rationally designed 3D microstructures were established. A multi-physics mathematical model using thermal-fluid-structure interaction (TFSI) was employed to investigate the coupled heat transfer performance and mechanical properties of these architected heat exchangers. When compared with the corrugated straight plate (CSP) microchannel heat exchanger, the thermal-hydraulic performance factors (TPC) of FCC and BCC microchannel heat transfer were 2.20 and 1.70 times that of SC microchannel heat exchanger, respectively. The micro-channel heat exchanger with FCC architectures could enhance the convective heat transfer performance by 201.0%, while the micro-channel heat exchanger with SC architectures reduced the Von-Mises equivalent (VME) stress by 20.0% when compared with the conventional 2D CSP heat exchanger. The proposed architected micro-channel heat exchangers could find a wide range of potential applications ranging from power electronics in electric vehicles to concentrated solar power systems, where both good convective heat transfer performance and high mechanical strength are simultaneously pursued.

This paper investigates the effects of tire characteristics on vehicular rollover and lateral stability. Two tire types with different adhesion coefficients were selected to evaluate the relation between vehicular rollover propensity and lateral stability. Simulations were used to calculate the critical rollover factor and to analyze the effects of vehicular parameters on handling, including the center of gravity, payload condition, and vehicle speed, with the two proposed types of tires. To replicate an actual vehicular response, particularly during extreme driving operations, a two-degrees of freedom (DOF) planar two-track model with nonlinear Pacejka’s Magic Tire Formula was applied. Subsequently, a 7-DOF vehicle vibration and roll model was developed to consider the effects of suspension and road excitation. The tire, steering, and vehicle vibration models were implemented in MATLAB/Simulink by subjecting them to the Fishhook maneuver steering input defined by the National Highway Traffic Safety Administration. The results confirm that the adhesion capacities of tires have an opposite effect on lateral vehicle stability and rollover propensity, while both suspension parameters and road excitation inputs significantly influence vehicle rollover and lateral stability. Additionally, we identified a positive correlation between vehicle properties and lateral handling, especially when tire characteristics are considered.

The operational temperature of the magnetorheological (MR) fluid retarder is usually over 80 °C, and it reaches 150 °C when heat dissipation doesn't function well. The high temperature will seriously affect the working efficiency of the MR fluid by decreasing the viscosity of the fluid, which affects the generated braking torque. For the analysis of the heat dissipation behavior of MR fluid retarder, an experimental study of a thermal management system using thermoelectric cooling (TEC) module with heat sink as the cooling unit was conducted. The variation tendencies of temperature for the TEC module were investigated during the working process of the MR fluid retarder using the TEC module and natural convection air-cooling. The performance of the MR fluid at the desired temperature was analyzed by applying one-dimensional thermodynamic model and a numerical calculation method. The influences of temperature on the performance of MR fluid retarder were analyzed by comparing the performance characteristics of the TEC modules with Peltier-Seebeck effect and natural convection air-cooling systems. The results indicate that TEC has a better effect on the MR fluid retarder performance compared to the natural convection air cooling systems. The TEC module coupled with heat sink achieved a higher heat transfer efficiency, maintained the working temperature of the MR fluid in the retarder, improved the retarder's efficiency, and maximized the braking torque generated. The proposed system will further enhance the longevity of the retarder and provide a platform for heat dissipation and cooling of automobile systems.

In a regenerative air sweeper, airflow and dust particles entering the system are filtered and recirculated within the system. The uncirculated portion of the exhaust air in the system spreads to the ambient air, and PM2.5 dust in the air can poison the environment and adversely affect human health. The development of an airflow control system to reduce road dust emissions and improve air quality was the main contribution of this study. A regenerative air sweeper airflow control system is designed to direct the air from the centrifugal fan back into the pickup head to fully absorb the dust particles and balance the positive and negative air pressures inside the pickup head. The modeling and analysis of the dust control system were performed using an experimental test rig system. A mathematical model of the fundamental parameters of the regenerative air sweeper and dust control system was established. Computational fluid dynamics (CFD) ANSYS was used for the analysis to determine the direction of airflow via the suction and inlet ducts. The discrete particle model (DPM) accurately predicted particle trajectories and measured the suction efficiency of particles of different shapes and types. By controlling the circulating harmful air flow in the system, the amount of PM2.5 released into the atmosphere was reduced by 90%. The suction efficiency of the 200 μm sized sand particles was higher than 95%. The results provide theoretical and methodological assistance for the development of improved road sweeper dust control systems.

Based on the requisition for an ideal precise power source for a hybrid electric emergency rescue vehicle (HE-ERV), we present an optimistic parameter matching and optimization schemes for the selection of a HE-ERV. Then, given a set of optimized power source components, they are classified into different types of HE-ERV. In this study, due to the different design objectives of different types of emergency rescue vehicles and the problems of hybrid electric vehicle parameter matching, a multi-island genetic algorithm (MIGA) and non-linear programming quadratic Lagrangian (NLPQL) is proposed for the matched parameters. The vehicle dynamic model is established based on the AVL Cruise simulation platform. The power source performance parameters are matched by theoretical analysis and coupled to the simulation platform. Finally, the optimized matched parameters are classified based on the support vector machines classification model to determine the category of the HE-ERV. The classification results showed that there is an unprecedented level for categorizing several factors of the power source parameters. This research showed that its more logical and reasonable to match HE-ERVs with medium motor/engine power output and battery capacity, as these can attain dynamic performance, extended driving range, and reduced energy consumption.

Vehicle parameters and operation conditions play a critical role in vehicular handling and stability. This study aimed to evaluate vehicle stability based on cornering tire stiffness integrated with vehicle parameters. A passenger vehicle is considered in which a two-state linear bicycle model is developed in the Matlab/Simulink. The effect of the vehicle parameters on lateral vehicle stability has been investigated and analyzed. The investigated parameters included CG longitudinal position, wheelbase, and tire cornering stiffness. Furthermore, the effects of load variation and vehicle speed were addressed. Based on a Fishhook steering maneuver, the lateral stability criteria represented in lateral acceleration, yaw rate, vehicle sideslip angle, tire sideslip angles, and the lateral tire force were analyzed. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the cornering stiffness coefficient and the CG longitudinal location. The findings also indicated a positive correlation between vehicle properties and lateral handling and stability.

Lateral stability is quite essential for the vehicle. For the vehicle with an articulated steering system, the vehicle load and steering system performance is quite different from the passenger car with the Ackman steering system. To investigate the influence of the tire characteristics and vehicle parameters on lateral stability, a single-track dynamic model is established based on the vehicle dynamic theory. The accuracy of the built model is validated by the field test result. The investigated parameters include the tire cornering stiffness, vehicle load, wheelbase, and speed. Based on the snaking steering maneuver, the lateral stability criteria including the yaw rate, vehicle sideslip angle, tire sideslip angle, and lateral force are calculated and compared. The sensitivity analysis of the tire and vehicle parameters on the lateral stability indicators is initiated. The results demonstrated that the parameters that affect the lateral vehicle stability the most are the load on the rear part and the tire cornering stiffness. The findings also lay a foundation for the optimization of the vehicle’s lateral stability.

This paper investigates the bandwidth sensitivity of automobile handling, comfort, and stability based on Monte Carlo sensitivity simulations. Performed bandwidth sensitivity simulations include the effects of vehicle geometry and suspension parameters on lateral acceleration, roll angle, front/rear sideslip angles, and yaw rate angle, including both time- and frequency-domain sensitivity analyses. To replicate actual automobile responses, a full-vehicle roll-oriented suspension seven-degree-of-freedom (7-DOF) model was developed and implemented considering a 2-DOF planar two-track model with a nonlinear Pacejka tire model. During the Monte Carlo simulations, 10 mm and 20 mm amplitude sine-wave excitations were used for the left and right sides, respectively, and the frequency was uniformly sampled over the range of 0–30 Hz. Simultaneously, each investigated vehicle parameter varied by ±25% relative to the reference model parameters. These simulations illustrate the sensitivity of the lateral acceleration, roll angle, yaw angle, and sideslip angles to their parameter variations. The results confirm that the road excitation frequency, tire properties, vehicle geometry, and suspension parameters significantly influence the vehicular lateral and roll stabilities when considering the lower and higher peaks and the frequency bandwidths of the lateral and roll stabilities. Interestingly, the longitudinal location of the center of gravity and the tire properties can achieve more significant peak lateral stability responses, as represented by the front and rear sideslip angles and the frequency bandwidth, compared to the other vehicle parameters at high frequencies. Choosing the correct tire properties and vehicle geometry, as well as suspension characteristics, plays an essential role in increasing the vehicular lateral stability and the rollover threshold. Variations in the studied parameters allow for higher vehicular stability when a vehicle is driven on random road surfaces.

To reduce energy consumption or improve energy efficiency, the regenerative devices recently have drawn the public’s eyes. In this paper, a novel hydraulic energy-regenerative shock absorber (HERSA) is developed for vehicle suspension to regenerate the vibration energy which is dissipated by conventional viscous dampers into heat waste. At first, the schematic of HERSA is presented and a mathematic model is developed to describe the characteristic of HERSA. Then the parametric sensitivity analysis of the vibration energy is expounded, and the ranking of their influences is k1≫m2>m1>k2≈cs. Besides, a parametric study of HERSA is adopted to research the influences of the key parameters on the characteristic of HERSA. Moreover, an optimization of HERSA is carried out to regenerate more power as far as possible without devitalizing the damping characteristic. To make the optimization results more close to the actual condition, the displacement data of the shock absorber in the road test is selected as the excitation in the optimization. The results show that the RMS of regenerated energy is up to 107.94 W under the actual excitation. Moreover it indicates that the HERSA can improve its performance through the damping control.

The rotor and stator blade lean angle of a hydraulic retarder is one of its main geometrical design parameters. The objective of this study is to clarify the effects of blade lean angle on hydraulic retarder performance. In this article, we employ a computational fluid dynamic approach to numerically investigate the fluid flow of a hydraulic retarder for rotor blade lean angles of 35°, 40°, 43°, and 45° in the direction of rotation, where the stator employs an equivalent angle, and all other geometries are held constant. The numerical results of the braking torque were validated against available experimental results. Analyses of torque performance, flow field, and energy loss are conducted in this study. Additionally, the outer loop oil flow rate is used as another indicator of hydraulic retarder heat exchange performance. The results indicate that with increasing blade lean angle, both the braking torque and oil volume flow rate first increase and then decrease, reflecting an optimal value. The lean angle affects secondary vortex flows and separate flows. Relatively large lean angles may enhance the occurrence of separate flow, whereas relatively small lean angles may cause in the oil inlet region. An optimal blade lean angle achieves a smooth oriented inner flow and a maximum braking torque.