Abstract

Excellent braking performance is the premise of safe driving, and improve the braking performance by upgrading structures and optimizing parameters of braking systems has become the pursuit of engineers. With the development of autonomous driving and intelligent connected vehicle, new structural schemes such as electro-mechanical brakes (EMBs) have become the future of vehicle braking systems. Meanwhile, many scholars have dedicated to the research on the parameters optimization of braking systems. While, most of the studies focus on reducing the brake size and weight, improving the brake responses by optimizing the parameters, almost not involving the braking performance, and the optimization variables are relatively single. On these foundations, a multi-objective optimal design of EMB parameters is proposed to enhance the vehicle's braking performance. Its objectives and constraints were defined based on relevant standards and regulations. Subsequently, the decision variables were set, and optimal math model was established. Furthermore, the co-simulation platform was constructed, and the optimal design and simulation analyses factoring in the crucial structural and control parameters were performed. The results confirmed that the maximum braking pressure response time of the EMB is decreased by approximately 0.3 s, the stopping distance (SD) of 90 km/h-0 is shortened by about 3.44 m. Moreover, the mean fully developed deceleration (MFDD) is increased by 0.002 g, and the lateral displacement of the body (LD) is reduced by about 0.037 m. Hence, the vehicle braking performance is improved.

Highlights

  • With the economic and social development, there are some trends such as flexible mechanical layouts, compatible control architectures and integrated functions in vehicle subsystems

  • With reference to ECE R13 [26], GB 12676–2014 [27] and GB 7258–2017 [28], the braking efficiency and stability requirements of the M3 vehicles are shown in Table 4: Combining with Table 4 and [29], the stopping distance (SD), the mean fully developed deceleration (MFDD) and the maximum lateral displacement of the body (Max LD) are set as optimal objectives in this study

  • There are two kinds of necessary parameters in the model operation: the first is the decision variables, which is generated after the non–dominated sorting genetic algorithm with elitism mechanism (NSGA–II) running and transferred to Simulink by Matlab, and the value of these parameters are changed with the iterations

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Summary

Introduction

With the economic and social development, there are some trends such as flexible mechanical layouts, compatible control architectures and integrated functions in vehicle subsystems. To improve the vehicle’s braking performance, the objectives and constraints were defined based on relevant standards and regulations, and the decision variables were set from the structural and the control parameters. The first is to consider both the structural and the control parameters when selecting the decision variables; the second is to set the optimal objectives from the perspective of vehicle braking performance, which is no longer limited to the brake responses. In these ways, the influences of the load transfers, the braking distribution and the parameters coupling can be decreased. This section firstly introduces the structure and working principle of the improved EMB, establishes the EMB system model and control prototype, and gives the parameters of the model and the prototype

EMB structure and working principle
EMB system model
Overall control architecture
Model parameters
Multi–objectives optimization of the EMB parameters
Optimal objectives
Decision variables
Equality constraints
Inequality constraints
Optimization algorithm
Co–simulation platform
Discussions
Simulation analyses
Findings
Conclusions

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