In order to improve the braking performance of electric vehicles, a novel brake-by-wire actuator based on an electro-magnetic linear motor was designed and manufactured. For the purpose of braking force regulation accuracy and high robust performance, the state observer and the anti-disturbance controller were designed in this paper after describing the actuator structure, braking principle, and mathematical model. The simulation and experimental results showed that the brake actuator responded rapidly, since its response time was only 15 ms. Compared to traditional PID (Proportion Integration Differentiation) methods, the controller proposed in this paper is able to regulate the braking force more precisely and has better anti-disturbance performance, thus the braking process can be accurately controlled according to the driver’s demand. The vehicle simulation results showed that the braking distance and braking time were shortened by 12.19% and 15.54%, respectively compared with those of the conventional anti-lock brake system (ABS) in the same braking conditions.

In order to improve the response characteristics of magnetorheological fluid brake (MRB) and reduce the braking fluctuation rate, an improved grey wolf optimization algorithm was proposed to adjust the parameters of the proportion integration differentiation (PID) controller. Firstly, an MRB system was designed and constructed, and its transfer function was determined. Moreover, by adopting the iterative method of logistic curve, an enhanced grey wolf optimization algorithm (EGWOA) was presented. Using the EGWOA, the parameters of the PID controller were optimized to improve the control performance of the system. Finally, the simulation and experiment were carried out. The results showed that EGWOA has a faster response output and overall better performance without overshoot compared with the conventional PID and grey wolf optimization algorithm (GWOA) PID controller.

In order to solve the problem of quantitative detection of corroded reinforced concrete of different sizes, the quantitative detection experiment based on spontaneous magnetic flux leakage (SMFL) was carried out in batches. Electrochemical corrosion of 27 reinforced concrete specimens was carried out, and the SMFL signals of reinforcement were obtained by magnetic detection equipment. Four-dimensional magnetic indicators M₁–M₄ that can characterize the corrosion degree of the specimens were defined. The influence of different sizes on the magnetic indicators were analyzed. It is concluded that the thicknesses of the concrete covers affect the magnetic indicators by affecting the lift-off heights z. The influence of diameter of the rebars on the quantitative detection can be eliminated by describing the corrosion degree with the average cross-section loss rate α. The influence of length of the rebars on quantitative detection is not clear yet. Finally, Support Vector Machine (SVM) was introduced to establish a classification model of corrosion classes and magnetic indicators. Using the model to predict the corrosion classes of the specimens can achieve a high classification accuracy. The research provides a new method for the quantitative detection of steel corrosion.

Aiming to prepare high-property magnetorheological fluids (MRFs), experiment materials, optimized preparation processes, experimental methods, experimental procedures and test methods were elaborated for high-performance MRFs. Two carrier fluids, novel additives and three antiwear agents were selected to prepare MRFs. The characteristics of the MRFs samples including the settlement stability, zero-field viscosity, shear yield stress and wear resistance were tested and analyzed. The measurement of shear yield stress was obtained using a self-designed MRFs characteristics testing test-bed. The microstructure of unworn and worn magnetic-particles were observed using scanning electron microscope. Experimental results showed that HFGEL-310 and SD-104 mixed in a certain proportion can enhance settlement stability of MRFs, three antiwear agents can slow down the wear of MRFs to a certain extent and MRFs-31 with AlN had the best anti-wear performance. MRFs based on PAO10 with HFGEL-310 2.7%, SD-104 2.9% and AlN 5% was high-performance MRFs with good overall properties.

This paper focuses on the cooperative driving challenges of connected and automated vehicles (CAVs) at single-lane roundabouts. First, a geometric path planning method is proposed for CAVs navigating a single-lane roundabout. Based on this method, a vehicle roundabout model is established. Four potential traffic scenarios for CAVs are established, and the optimal arrival times at conflict points are analyzed. By correlating the optimal arrival times at conflict points with the optimal entry times into the roundabout, the multi-vehicle coordination problem in complex intersections is simplified to a speed control issue during entry. Utilizing the principles of optimal control and Pontryagin minimization, two speed optimization strategies are proposed. Finally, MATLAB is employed for simulation analysis. The results indicate that the control strategy proposed in this paper enables the system to clearly identify potential conflicts between vehicles and implement an optimal control strategy, ensuring that vehicles can navigate the roundabout efficiently in terms of time and fuel without collisions. Additionally, the minimum time interval is established at 0.2 seconds to completely prevent vehicle collisions. In this study, the fusion problem involving two vehicles at a single conflict point is further expanded to encompass multiple vehicles at multiple conflict points. Thus, the efficient scheduling of multiple vehicles in single-lane roundabouts is realized.