Zhiqun Yuan

Driveability is a key criterion for vehicular longitudinal motion control. Traditional adaptive cruise control (ACC) systems employ separate speed and range control, which injects unnecessary disturbances when switching between the strategies thus degrades the driveability significantly. This paper proposes a unified manifold-based architecture that integrates two key concepts: d-field control, which generates a control action based on the state’s distance to kernel function, and a-field control, a nonlinear kinematic accelerating/braking strategy. By unifying these approaches into a single continuous control law, the proposed manifold-based ACC (mACC) eliminates the switching. This not only enhances the single-vehicle driveability but also provides an intrinsic mechanism for alleviating platoon-level disturbances. System stability is formally proven using the Lyapunov principle, and a novel phase-portrait analysis offers a holistic assessment of global performance. Hardware-in-the-Loop (HIL) testing further validates the controller’s superior performance as well as the real-time feasibility. This work therefore establishes a foundation of developing an unified control strategy for the robust and stable multi-vehicle systems.

Large-span bridges often exhibit complex and variable flow fields around their bridge decks because of the coupling of natural and structural winds, which induce vortex-induced bridge vibrations, threatening the driving safety and comfort of vehicles. To capture the response characteristics of vehicles crossing bridges in this type of environment, a novel framework is proposed in this paper from aerodynamic and system dynamics perspectives for analyzing the dynamic responses and ride comfort of vehicles under the coupled effects of crosswinds and vortex-induced vibrations. The real driving behavior of a vehicle is simulated by establishing a 14-degree-of-freedom dynamic model, incorporating a driver preview controller, for the entire vehicle. Subsequently, a wind tunnel test and a numerical simulation are combined to measure the vortex-induced bridge vibrations and the aerodynamic loads imposed on the vehicle body, producing dynamic response parameters that are used to evaluate the driving stability and ride comfort of the vehicle under these disturbances. The results show that the proposed analytical framework effectively reproduces the driving characteristics of the vehicle under different levels of crosswinds and vortex-induced vibration excitations, accurately simulating the dynamic responses of the vehicle.

In this study, a comparative analysis of the impact of the attack angle and windscreen height on the vortex-induced vibration (VIV) in a streamlined closed-box girder was conducted using a 1:50 scaled model of a coastal cable-stayed bridge through wind tunnel tests and numerical simulations covering a range of attack angles and windscreen heights. The simulations were validated through experimental data, grid sensitivity analysis, and time-step independence. The results revealed that the VIV amplitude increased with increasing attack angle because of the interaction between vortices from the traffic lane and those in the wake region. Specifically, under a [ ] attack angle, pronounced VIV was observed in the section, with the maximum torsional VIV amplitude reaching up to 4.1[ ]times the code-specified limit. Spectral analysis revealed that within different wind speed lock-in ranges, the vibrations consistently corresponded to the torsional fundamental frequency mode. Further insight from proper orthogonal decomposition (POD) based on singular value decomposition (SVD) revealed that the large-amplitude torsional VIV of the section was caused by separated vortices over the traffic lane persistently transferring energy to the wake Kármán vortices, forming large-scale vortices that could lock in with the torsional mode of the main girder. Windscreens on both sides of the section effectively reduce the VIV amplitude through distinct mechanisms: the windward screen delays flow separation. Moreover, the leeward screen altered the path of the vortices toward the wake region. When the windscreen height reached 4.5[ ]m, the vortex movement path to the leeward side was completely blocked, fully suppressing the VIV. The effect of windscreen height on VIV was closely linked to lift, surface pressure, and their correlation. These findings provide valuable insights into wind-induced vehicular safety measures and VIV suppression strategies for sea-crossing bridges.

The influence of twin-box girder attachments on the driving wind environment of a long-span coastal bridge under crosswind was experimentally studied in a boundary layer wind tunnel. First, the particle image velocimetry (PIV) technique and anemometers were used to determine the optimal PIV window size. Then, the effects of attachments and vehicles on average wind speed, turbulent kinetic energy, Reynolds stress, and equivalent wind speed reduction coefficient on the driving wind environment were analyzed. Results indicate that bridge attachments alter both the magnitude and distribution of average wind speed on the windward side of the vehicle. Turbulent kinetic energy peaks were observed near the windward side of attachments, particularly in the wake region above the vehicle. Reynolds stress peaks were primarily located on the windward side of the attachments; increasing the height of the attachments expanded the peak area above the vehicle while reducing the wake region’s area. The coefficient of equivalent wind speed reduction provides a reasonable quantification of changes in the driving wind environment. However, the difference between conditions with and without the vehicle was significant, suggesting that practical wind barrier solutions should prioritize aerodynamic measurements of vehicles behind wind barriers.

The cruising propulsion process of the bionic robotic fish under the swinging tail motion presents a strong periodic dynamic response, and accurate prediction of its performance is the key to the overall design. Taking the two‐jointed bionic robotic dolphin as the research object, five kinds of movement modes were designed, and the coupled analysis model of the propulsion motion of the bionic robotic dolphin was established based on the hydrodynamic and Lagrangian dynamics methods, and the hydrodynamic performance of different movement modes and its linear propulsion dynamic response process were investigated. The results show that the coupled analysis method proposed in the paper can accurately obtain the motion response parameters of the robotic dolphin as well as the forces and moments of each joint, and the speed error with the hydrodynamic simulation is controlled within 5%. The research method and results have good application value to guide the selection design and performance prediction of bionic robotic fish.

Understanding the crosswind stability of cars under strong wind loads and research on wind resistance methods is important for improving the safety performance of wind-induced driving on bridges. Taking van-body trucks as the research object, numerical calculation methods and wind tunnel test methods are used to conduct the wind-induced driving safety analyses of van trucks on a cross-sea bridge. The influence of the structural parameters of the barrier-type wind barrier on the aerodynamic characteristics and straight-line driving stability of the trucks on the bridge is studied and analyzed quantitatively. The results show that the decrease in the porosity of the wind barrier can effectively reduce the average wind speed of the bridge deck, and increasing the height of the wind barrier can effectively reduce the wind speed and increase the occlusion height of the bridge deck. The lateral acceleration, yaw rate, and lateral displacement of trucks decrease with the decrease in the porosity of the wind barrier and decrease with the increase in the height of the wind barrier. The research conclusions can not only provide data support for wind-induced driving safety analysis and the wind-resistant design of bridges but also provide a new method to balance the requirements of bridge wind-induced driving safety and bridge wind-induced structure safety.

To explore the influence of bridge wind barriers, with their specific opening shapes and arrangements, on bridge deck wind fields and vehicle driving stability under different crosswinds, five bridge wind barrier schemes were designed. For two incoming wind speeds, the wind speed at different heights over three traffic lanes and the aerodynamic six-component force of the vehicle model were measured, and the influence of the wind barrier parameters on the vehicle driving stability was analyzed. The equivalent wind speed reduction coefficient of the wind barrier was compared with the dimensionless coefficients of the aerodynamic side force, roll moment, and aerodynamic lift to verify the accuracy of the shielding effect evaluation indices. The final conclusions provide a useful reference for designing bridge wind barriers.

To investigate the aerodynamic behavior of underbody structure in crosswind conditions, two numerical simulation models have been developed by using computational fluid dynamics method. First, to validate the accuracy of these models, the wind tunnel experiment of model with simplified flat underbody has been designed. The computationally predicted results of realizable k-e model show consistency with experimental data, and the correlation deviation of aerodynamic force is less than 10%. By using such model, the aerodynamic force and flow field of car under steady crosswind are simulated using underbody structure, and the influence on the aerodynamic characteristic has been analyzed. It can be found that the aerodynamic force increased significantly under different yaw angle. The physical mechanism response has been clearly shown by investigating the flow field around car body by vortices visualization technique. The results of this study can be served as a suggestion for studying the vehicle stability of high-speed under crosswind.