Braking Strength Research Articles

Simulation Research on the Braking Characteristics between Tires of the 3-Module Virtual Track Train

The virtual rail train is a new type of urban rail transportation, which integrates some of the characteristics of buses, trams and light rail trains. In order to study its braking stability, the paper appeared from the perspective of vehicle dynamics, studying the braking force allocation strategy of the train under different working conditions. It is proposed to calculate the articulation force of the train from the motion parameters of the train, and analyze the dynamic change of the tire vertical load. The lateral force is prioritized to ensure that the train turns stably and avoiding tire slip. After that, the remaining braking force is used to maximize the utilization of braking force. The results show that this method of braking force allocation between tires can ensure that the tires are not locked, while ensuring the braking strength.

Structure design and coordinated control of electromagnetic and frictional braking system based on a hub motor.

A new type of built-in composite electromagnetic and frictional braking structural scheme and its corresponding coordinated control strategy were proposed to enhance the braking effects for the electric vehicle. Fuzzy control theory was applied to design the coordinated control strategy for the electromagnetic and frictional braking system. In comparison to lower braking strength and moderate braking strength, the slip ratio of high braking strength was maintained at near 0.15. It effectively avoided the wheel getting locked and provided relatively large braking torque in the process of braking. The integrated system using a fuzzy control strategy can effectively shorten the braking time, enhance the braking safety in the braking process.

Design and analysis of brake disc assembly for an FSAE vehicle

When it comes to driver’s safety, the quality of car’s braking system plays a crucial part. The objective of this paper is to design and fabricate a reliable brake disc assembly which is both structurally and thermally stable along with selecting suitable brake calipers for an FSAE vehicle. To enhance the vehicle performance, it is necessary to optimize and design a light weight brake disc assembly yet having high braking power, strength and rigidity. In order to achieve desirable results, parameters of assembly like effective diameter of brake disc, thickness of brake disc, heat flux, maximum temperature, fluid parameters, caliper specifications, design and arrangement of floaters, etc. are determined and calculated to have an optimized geometry. These values are determined on the basis of vehicle parameters such as overall weight, velocity of vehicle, braking time, kinetic energy of vehicle, static and dynamic weight distribution, height of center of gravity of vehicle, wheelbase, wheel diameter and coefficient of friction of tyres. Multiple simulations and topology optimizations are performed to finalize the material and corresponding manufacturing technique, so as to make assembly efficient and cost effective without compromising on strength.

Variable transmission ratio strategy for improving brake feeling based on driver’s target braking strength

Due to the absence of vacuum sources for electric vehicle, the vacuum booster is replaced by electronic brake boosting (EBB) system. In order to improve the driver’s brake feeling based on EBB, this work fully exploits the flexible and variable power-assisted characteristics, and designs different transmission ratios according to the driver’s target braking strength. To identify the driver’s braking strength, an improved radial basis function (IRBF) neural network, combining self-organization method and supervised learning method, is proposed to establish the relationship between the driver’s braking strength and the characteristic parameters. Based on this, the variable transmission ratio strategy is designed, and its main optimized parameters are optimized by means of multi-objective optimization algorithm to provide the driver with a satisfactory brake feeling. The strategies under fixed and variable transmission ratios are simulated and analyzed in low-speed with gentle-brake and high-speed with emergency-brake. The simulation results show that, compared with the fixed transmission ratio, the proposed variable transmission ratio shows excellent performances in both brake feeling and brake safety.

Power-Following Control Strategy of a Wheel-Drive Hydraulic Hybrid Vehicle

Energy management strategy is a critical technology for improving the fuel economy of wheel-drive hydraulic hybrid vehicles. For driving, a power-following control strategy is proposed in this study by adding several working points of the engine in the optimal fuel economy power curve. For braking, the “I” curve distribution strategy based on critical braking strength zmin was adopted. A test bench was constructed according to the quarter of the prototype vehicle. Taking the typical working conditions of Federal Urban Driving Schedule (FUDS) and the selfset extra-urban driving schedule (EUDC-1) cycle condition into consideration, the energy management strategy was studied. The torque and speed of the simulated engine and pressure of the accumulator were obtained. The test fuel consumption in this research was compared with the original fuel consumption of the prototype vehicle. It was found that the proposed energy management strategy could effectively improve the fuel economy by more than 24 % under the requirement of satisfying the dynamic performance of the whole vehicle.

Numerical analysis of local heat flux and thin-slab solidification in a CSP funnel-type mold with electromagnetic braking

In this article, based on the actual monitored temperature data from mold copper plate with a dense thermocouple layout and the measured magnetic flux density values in a CSP thin-slab mold, the local heat flux and thin-slab solidification features in the funnel-type mold with electromagnetic braking are analyzed. The differences of local heat flux, fluid flow and solidified shell growth features between two steel grades of Q235B with carbon content of 0.19%C and DC01 of 0.03%C under varying operation conditions are discussed. The results show the maximum transverse local heat flux is near the meniscus region of over 0.3 m away from the center of the wide face, which corresponds to the upper flow circulation and the large turbulent kinetic energy in a CSP funnel-type mold. The increased slab width and low casting speed can reduce the fluctuation of the transverse local heat flux near the meniscus. There is a decreased transverse local heat flux in the center of the wide face after the solidified shell is pulled through the transition zone from the funnel-curve to the parallel-cure zone. In order to achieve similar metallurgical effects, the braking strength should increase with the increase of casting speed and slab width. Using the strong EMBr field in a lower casting speed might reverse the desired effects. There exist some differences of solidified shell thinning features for different steel grades in the range of the funnel opening region under the measured operating conditions, which may affect the optimization of the casting process in a CSP caster.

Energy Recovery Strategy Based on Ideal Braking Force Distribution for Regenerative Braking System of a Four-Wheel Drive Electric Vehicle

Under raising pressure of global energy and environmental issues in recent years, electric vehicles (EVs) have been an alternative solution of the automobile industry owing to its high energy efficiency, low noise, and zero emission. However, the short driving range is an urgent problem to be solved for EVs. Energy recovery is an important technology to improve energy efficiency and extend driving range of EVs. In this paper, an improved braking energy recovery strategy based on ideal braking force distribution (curve I) was proposed for the regenerative braking system (RBS) of a small four-wheel drive (FWD) EV. Compared with previous study, the improved braking energy recovery strategy gives more consideration to braking stability and covers broader braking situations of the vehicle. The braking energy recovery strategy is extensively validated through numerical simulations of a previously built vehicle system model under different fixed braking strength and continuously varying braking strength. The simulation results show that the proposed braking energy recovery strategy is able to effectively achieve the regenerative braking function under different braking conditions while ensuring braking efficiency and braking stability.

A genetic-fuzzy control method for regenerative braking in electric vehicle

In order to improve the recovery ratio of the regenerative braking energy in electric vehicles, the influence factors on braking energy feedback in electric vehicles were analysed. Then, a parallel braking force distribution model was established, and a fuzzy controller on braking force distribution was designed, in which the inputs were vehicle speed, braking strength, battery SOC, and output was regenerative braking ratio. On the other hand, the implementation of genetic algorithm in optimisation process was studied. Furthermore, the genetic algorithm was used to optimise the fuzzy control rules, and new fuzzy distribution rules of electro-hydraulic braking force were obtained. The experimental results showed that the recoverable energy ratio was increased by 2.7% with the comparison of the optimised distribution rules and the original rules. So, the genetic-fuzzy control method is effective for regenerative braking in electric vehicles.

A genetic-fuzzy control method for regenerative braking in electric vehicle

In order to improve the recovery ratio of the regenerative braking energy in electric vehicles, the influence factors on braking energy feedback in electric vehicles were analysed. Then, a parallel braking force distribution model was established, and a fuzzy controller on braking force distribution was designed, in which the inputs were vehicle speed, braking strength, battery SOC, and output was regenerative braking ratio. On the other hand, the implementation of genetic algorithm in optimisation process was studied. Furthermore, the genetic algorithm was used to optimise the fuzzy control rules, and new fuzzy distribution rules of electro-hydraulic braking force were obtained. The experimental results showed that the recoverable energy ratio was increased by 2.7% with the comparison of the optimised distribution rules and the original rules. So, the genetic-fuzzy control method is effective for regenerative braking in electric vehicles.

Simulation Study on Regenerative Braking System of Pure Electric Vehicle with Compound Power Supply

In order to enhance the recovery rate of regenerative braking energy on the premise of ensuring braking safety and stability, an improved braking force distribution scheme for front and rear wheels is proposed in combination with ECE regulations, ideal braking force distribution curve (I) and f lines. Meanwhile, a kind of fuzzy controller is designed, which takes the braking strength, vehicle speed and super-capacitor SOC as input and the ratio of regenerative braking force to total braking force of front wheels as output. The forward and backward simulation module is established in MATLAB and embedded into ADVISOR. In addition, combined with the secondary development of the top layer model of the compound power supply for pure electric vehicle to complete simulation and analysis under the CYC_UDDS driving cycle condition. The results show that the regenerative braking control strategy can improve the recovery rate of braking energy and increase the driving mileage of pure electric vehicle.

Riding Comfort of an Electric Vehicle Based on the Coupling Affection of Mechanical Friction and Electric Regenerative Brake

In order to satisfy the braking comfort of electric vehicles, the braking performance and braking force distribution schemes are studied for the coupling braking system of mechanical friction and electric regenerative braking of electric vehicles. First, the performance of the coupling brake system was analyzed. Then the problem of braking force distribution is studied, and the logical distribution of braking force based on comfortness is proposed. The influence of braking strength and braking speed on the braking comfort of electric vehicles is fully considered. So the braking force is distributed between the two braking systems and between the front and rear axles to meet the comfort. The consistency of the two braking systems is achieved through multidisciplinary modeling, comprehensive simulation and system optimization design. And the electric vehicle model was established on the MATLAB, AMESim and ADAMS co-simulation platform, then the braking comfort and safety of the electric vehicles were simulated. The simulation results were in compliance with the ECE regulations. Finally, the braking efficiency of the series and parallel braking distribution strategies under gravel pavement is compared. The results show that the braking efficiency of the series braking distribution strategy is better. Through theoretical simulation and experimental tests, it is found that the braking force distribution strategy is feasible and effective. Electro-hydraulic brake system has good performance, paving the way for the industrialization of electric vehicles.

Performance analysis and test of a novel eddy-current braking & heating system for electric bus

This paper proposes the eddy-current braking & heating system, which is a novel efficient braking energy recovery system for electric bus. The system is designed to solve two problems: one is the low recovery efficiency of regenerative braking energy, another is the driving range dramatic decline of electric bus when heating the bus cabin in winter. The system converts braking energy into heating energy directly by the principle of eddy-current braking and heating. It greatly improves the recovery efficiency of braking energy. The layout scheme of system is designed by considering the vehicle drive structure. The mathematical models of friction braking, regenerative braking, eddy-current braking & heating are established respectively. A blend braking control strategy considering braking strength, State of Charge, and supply air temperature is proposed. The energy-saving evaluation parameters of the system are presented. A simulation platform is built in the MATLAB/Simulink environment. The simulation and vehicle tests show that the calculated temperature and driving range agree well with the measured results and the models are validated. Compared with Positive Temperature Coefficient heating, the recovery efficiency of braking energy of the system increases from 23.8% to 65.3%, and the improvement rate of driving range reaches 81.4%. The system can satisfy the braking requirement of electric vehicle by blend braking control strategy. The system can effectively increase energy recovery of the regenerative braking. It can solve the reduced driving range problem of electric buses while heating in winter.

Study on Braking Characteristics of Regenerative Brake-By-Wire System Based on Mechanical-Electron-Magnetism Integration for Electric Vehicles

For the disadvantages of current electric vehicles regenerative braking, a new design of regenerative brake-by-wire system based on mechanical-electron-magnetism integration is proposed. The new system has electromagnetic braking mode and hybrid braking mode, the former uses electromagnetic braking and the latter combines electromagnetic braking with friction braking. In the hybrid braking mode, the new system can realize friction braking without extra actuator energy. To research the braking characteristics and braking principle of the regenerative brake-by-wire system, the vehicle dynamic model is established. The braking performance and energy recovery efficiency of the system are studied under emergency braking condition. The results show the regenerative brake-by-wire system based on mechanical-electron-magnetism integration not only meets brake comfort under low braking strength and stability under high braking strength, and brake efficiency, but also has better braking response and robustness. With the feature of variable pedal ratio, it conforms to driver’s pedal feeling. The control parameters are reduced and the performance of control system is improved. The new braking system can maintain a high recovery efficiency in a wide range of brake strength and increase the driving range of electric vehicles effectively.

Research on regenerative braking control strategy of plug-in hybrid electric vehicle considering CVT ratio rate of change

At present, the regenerative braking control strategies for hybrid electric vehicles equipped with continuously variable transmission (CVT) mainly focus on improving the regenerative braking efficiency. But the influence of dynamic change of the CVT ratio is not considered with regard to the intended braking effect. For a CVT ratio control strategy based on steady-state optimal efficiency, the performance of motor-only braking and engine/motor combined braking modes are analyzed. The analysis of these modes shows that actual braking strength deviates from that required during the dynamic braking process. After analyzing the dynamic characteristics of a transmission system, a CVT ratio control strategy based on the limitations of the ratio rate of change is proposed, with the use of a discrete exhaustive optimization method. The simulation results show that, under a variety of braking conditions, the proposed regenerative braking control strategy can make the actual braking strength follow the requirements and recover more braking energy.

Optimization of Regenerative Braking Control Strategy for Pure Electric Vehicle

The regenerative braking strategy for precursor pure electric vehicle was studied in this paper. Firstly, a constraint optimization model was established for the braking force distribution, in which both braking stability and recovery efficiency of braking energy were taken into account. Secondly, Particle Swarm Optimization (PSO) algorithm was applied to optimize the multi key parameters in the model. Finally, the optimized braking torque of the motor was obtained at different speed, different braking strength and different battery charge state. A vehicle model was built to validate the optimized results through simulation. The results showed that, compared with the original control strategy, the optimized control strategy not only could increase the braking stability effectively, but also improve the energy recovery efficiency in a certain extent.

Chemical profiling of Pterolobium hexapetalum leaves by HPLC analysis and its productive wound healing activities in rats

Research on wound healing agents is one of the developing areas in modern biomedical sciences. Several drugs have been used in the management of wounds and a large variety of treatment modalities are available for wound repair. Among these medicines, herbal origin has been the basis of treatment and cure for healing of wounds. Pterolobium hexapetalum is well known medicinal plant of Caesalpiniaceae family was used by many tribal groups for wound treatment in India. Different extracts of P. hexapetalum leaves are evaluated for its antiradical activity and in vivo wound healing activity by excision, incision, and dead space wound models in Wistar rats, further respective phyto constituents are profiled using High Performance Liquid Chromatography. In this present study methanol extract of leaves depicted the maximum amount of phenolics and flavonoids content and also registered highest DPPH (IC50: 3.40μg/mL), ABTS+(8869.36μM TE/g extract) and Superoxide (87.72%) radical scavenging activity. Methanolic leaf extract are further studied for wound healing property, highest wound contraction percentage and lowest epithelialization period (16.33days) of 5% methanolic extract treated group exhibits highest wound healing activity compare to control group and it was confirmed by histopathology results and scoring analysis. Maximum tensile strain (110.69%) of incision and highest hydroxyproline (16.28mg/g) content of dead space wound model are comparable with standard 5% Neomycin. HPLC employed quantification of phyto constituents explores the presence of catechin (367.54μg/mg), caffeic acid (87μg/mg), rutin (289.20μg/mg), quercetin (239.39μg/mg) and naringenin (24.42μg/mg). From the results leaves of P. hexapetalum significantly stimulate wound contraction, braking strength and hydroxyproline content of treated group. It showed remarkable wound healing activity and may be recommended for treating various type of wound.

Longitudinal Collision Avoidance Control of Electric Vehicles Based on a New Safety Distance Model and Constrained-Regenerative-Braking-Strength-Continuity Braking Force Distribution Strategy

This paper presents a new control scheme for longitudinal collision avoidance (CA) systems to improve the safety of four-in-wheel-motor-driven electric vehicles (FIWMD-EVs). There are two major contributions in the design of longitudinal CA systems. The first contribution is a new safety distance model to make vehicle adapt to different driving roads with an adhesive coefficient between tire and road and to conform to drivers' characteristics with a driving intention parameter. The second contribution is a new braking force distribution strategy based on constrained regenerative braking strength continuity (CRBSC). By optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, the safety-brake range could be linearized to simplify the calculation of braking force distribution on the premise of ensuring braking safety. Furthermore, it is the constraint conditions that could solve the coexistence problem of positive and negative braking forces based on regenerative braking strength continuity (RBSC) to conform to actual requirements. The feasibility, effectiveness, and practicality of the proposed safety distance model and braking force distribution strategy are, respectively, verified by computer simulation experiments. Rapid control prototyping (RCP) and hardware-in-the-loop (HIL) simulation experiments using dSPACE are carried out to demonstrate the effectiveness in the control scheme, simplicity in structure, and flexibility in implementation for the proposed longitudinal CA system.

Fragrance Finishing of Cellulosic Fabrics

This work deals with terry towels treatment by using Reactive β-cyclodextrin to produce fragrance fabrics. Factors affecting on the performance properties (nitrogen content, towel wettability, braking strength and elongation) of towels such as β-cyclodextrin concentration, curring temperature, durability (washing) and storage time are studied. The obtained results by One-Way ANOVA (Analysis of Variance) and correlation coefficients show that the treatment of the fabric occurred by Reactive β-cyclodextrin concentration 30% , curring temperature 140 °C for 2 minutes, the percent loss of the fragrance was 18% and 55% after 20 washing cycles and 90 days respectively.

A new braking force distribution strategy for electric vehicle based on regenerative braking strength continuity

Regenerative braking was the process of converting the kinetic energy and potential energy, which were stored in the vehicle body when vehicle braked or went downhill, into electrical energy and storing it into battery. The problem on how to distribute braking forces of front wheel and rear wheel for electric vehicles with four-wheel drive was more complex than that for electric vehicles with front-wheel drive or rear-wheel drive. In this work, the frictional braking forces distribution curve of front wheel and rear wheel is determined by optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, and then the safety brake range is obtained correspondingly. A new braking force distribution strategy based on regenerative braking strength continuity is proposed to solve the braking force distribution problem for electric vehicles with four-wheel drive. Highway fuel economy test (HWFET) driving condition is used to provide the speed signals, the braking force equations of front wheel and rear wheel are expressed with linear equations. The feasibility, effectiveness, and practicality of the new braking force distribution strategy based on regenerative braking strength continuity are verified by regenerative braking strength simulation curve and braking force distribution simulation curves of front wheel and rear wheel. The proposed strategy is simple in structure, easy to be implemented and worthy being spread.

Co-Simulation of Composite ABS Control for In-Wheel Motor Drive Electric Vehicle Based on Threshold Control Algorithm

According to the brake characteristics of in-wheel motor drive electric vehicles, and basing on threshold control method, we describe one kind of composite ABS control theory about electric motor ABS combined with hydraulic friction ABS, and establish a co-simulation vehicle model. The composite ABS control method is a control method that the electric motor ABS control works together with the hydraulic ABS control. Both of the two modes of ABS control logic were using logic threshold control method. The model of the in-wheel motor drive electric vehicle was established with AMESim, and the model of the composite ABS controller was built with Simulink. The control performance of composite ABS in different braking strength and different road friction coefficients is simulated. Co-simulation was carried out. Through analysis, a number of parameters curves were obtained. It proves that the composite ABS control method for in-wheel motor drive electric vehicles can effectively control the slip rate, and ensure braking stability.