Braking Simulation Research Articles

Dynamic Analysis of Impact Model of Slipping Tramcar Prevention Equipment Based on an Energy Absorber

The protection equipment of slipping tramcar in inclined shaft is the important safety equipment to ensure safety production in mine transportation and equipment. The Slipping Tramcar Prevention Equipment is mainly composed of an intercepting door and a buffering system, in which an energy absorber is the key component. The braking dynamic model of the energy absorber is studied by establishing a Lagrange equation and simulating the braking progress by the software of Simulink. The braking simulation distances curves of the energy absorber are obtained under the different initial conditions of tramcar mass and velocity, which shows that the tramcar velocity and mass both have a significant influence on the braking distance. The analysis on variance and range is developed for further comparison on the two key factors implying that tramcar mass is of the most great importance. Moreover, a braking distance formula is built based on the analysis results. On the other hand, field experiments are conducted in Qishan Mine, and experiment results show that the maximum error between the braking distance formula value and the experiment value is 11.98%, and the minimum error is 2.72%. The experimental results are consistent with the theoretical results.

Self-Excited Torsional Oscillations under Locked-Wheel Braking: Analysis and Experiments

ABSTRACT This paper analyzes the effect of tire/vehicle parameters, specifically of tire/suspension torsional stiffnesses, on the stability of self-excited tire torsional oscillations during locked-wheel braking events. Using a torsionally flexible tire-wheel model and a dynamic tire-ground friction model, two system models for tire oscillations are considered: with suspension torsional compliance included in one but excluded in the other. Bifurcation analysis is conducted on both systems to derive the effect of tire/vehicle parameters on the stability. For the system without suspension torsional compliance, it is highlighted that the primary cause of unstable self-excited oscillations is the “Stribeck” effect in tire-ground friction. Based on the parameters obtained experimentally, the bifurcation surface of vehicle velocity with respect to tire/suspension torsional stiffness is also given. The effect of tire/suspension torsional stiffness to the stability of tire torsional oscillation is qualitatively validated via comparisons between locked-wheel braking simulations and experiments with tires with different torsional stiffnesses.

Road surface condition identification approach based on road characteristic value

The real-time knowledge of road friction information has a significant role in vehicle dynamics control. In this paper, with the application of Burckhardt model, roads are classified into six types and a road identification approach based on “road characteristic value” is developed. Six kinds of road surface characteristic intervals which represent typical road characterization are proposed according to the closed area under the segment of road friction coefficient-slip ratio curve before a pre-defined slip ratio. In addition, a varying road monitoring and identification algorithm is proposed to identify varying road surface conditions, composing of an integral road surface identification approach with road characteristic value method. A vehicle dynamics model of 14 DOF including the excitation of road roughness is built, and the effectiveness of the approach is verified by the braking simulation tests on both a uniform friction coefficient uneven road and a variable friction coefficient uneven road. The simulation results show that the proposed approach can identify current road surface conditions effectively including road type, maximum road friction coefficient as well as optimal slip ratio, and it is robust to external disturbances. The application of road identification results in the optimal slip ratio control of vehicle electronic control braking system achieves good performance.

Simulation of Temperature Distribution in Disk Brake Considering a Real Brake Pad Wear

This paper presents a methodology for the modeling of the transient thermal behavior of the disk brake of the vehicles using finite element methods. The influence of the wear properties of friction materials on thermoelastic behaviors is investigated to facilitate the conceptual design of the model. The coupled characteristics of the friction heat flow between the disk and pad as well as the effects of the brake disk thermal stress because of the variable applied pressure was considered. At the same time, the model was optimized by the experiment. Repeated brake processes with varying load, sliding speeds and temperature are applied in the simulation of the disk brakes. Experimental dependencies of the coefficient of friction and wear rate on the temperature of brake pad were approximated and applied to the model. The temperature and pressure on the contact surface of the pad/disk brake system obtained for constant and speed/pressure sensitivity applications were confronted and compared. The thermo-distribution is operated to visualize the disk temperature.

Design and Test Development of a Comprehensive Performance Test Bench for Electric Wheel

In order to research the driving performance of electric vehicle driven by the electric wheels and provide the test basis to the design of electric vehicle, the author of the paper designed and developed a multifunctional comprehensive performance test bench for electric wheel. Such test bench has the basic functions of road simulation, resistance simulation, vehicle weight simulation and inertia simulation, and the other functions of steering simulation, coupling simulation of electric braking and mechanical coupling, wheel hub motor performance test lamp. The author of the paper made certain design for the relevant test items, which has far-reaching significance for the test and research of the battery electric vehicle (BEV) driven by the wheel hub motor.

A method to model anticipatory postural control in driver braking events

Human body models (HBMs) for vehicle occupant simulations have recently been extended with active muscles and postural control strategies. Feedback control has been used to model occupant responses to autonomous braking interventions. However, driver postural responses during driver initiated braking differ greatly from autonomous braking. In the present study, an anticipatory postural response was hypothesized, modelled in a whole-body HBM with feedback controlled muscles, and validated using existing volunteer data. The anticipatory response was modelled as a time dependent change in the reference value for the feedback controllers, which generates correcting moments to counteract the braking deceleration. The results showed that, in 11m/s2 driver braking simulations, including the anticipatory postural response reduced the peak forward displacement of the head by 100mm, of the shoulder by 30mm, while the peak head flexion rotation was reduced by 18°. The HBM kinematic response was within a one standard deviation corridor of corresponding test data from volunteers performing maximum braking. It was concluded that the hypothesized anticipatory responses can be modelled by changing the reference positions of the individual joint feedback controllers that regulate muscle activation levels. The addition of anticipatory postural control muscle activations appears to explain the difference in occupant kinematics between driver and autonomous braking. This method of modelling postural reactions can be applied to the simulation of other driver voluntary actions, such as emergency avoidance by steering.

Fuzzy PID Control of ABS Based on Real-Time Road Surface Identification

Road surface identification is of great significance in vehicle active safety electronic control systems. This paper proposes a real-time road surface identification algorithm on the basis of the estimated instantaneous road adhesive coefficient. Based on Fuzzy-PID controller and automatic road surface identification, the actual slip ratio can be controlled at the optimal slip ratio precisely, which can promote the ABS and braking performance largely. The braking simulation tests are conducted on pre-set varying road surface conditions. And the results show that the identified results are in good agreement with the pre-set road surface, the proposed algorithm can be conveniently used for various active safety electronic control systems of vehicles.

Thermovision in the Validation Process of Numerical Simulation of Braking

Abstract This article presents the validation process of a brake FE model by means of temperature measured on a special stand using infrared technology. Unlike many other publications, the authors try to show the interaction between measurement technology and numerical modeling rather than only nice, perfectly correlated graphs. Some difficulties in choosing and using validation parameters are also pointed out and discussed. Finally, results of FE analyses are compared with measured data, followed by explanation of applied numerical technology and estimation of validation process effectiveness.

Моделирование движения астероида в атмосфере Земли

Моделирование движения астероида в атмосфере Земли

Performance and robustness analysis of a Hardware In the Loop full-scale roller-rig for railway braking and traction testing

Traditionally, braking and traction on-board subsystems, such as traction systems, braking plants and safety subsystems (e.g. WSP devices) can be tested and verified through fullscale roller-rigs, to avoid expensive on-track tests. In this work the authors investigate the test-rig built in the research center “Centro di Dinamica Sperimentale Osmannoro-Firenze (CDSO)” by Rete Ferroviaria Italiana (RFI), in which the braking and traction systems are tested using an innovative Hardware In the Loop (HIL) architecture able to perform the simulation of a known wheel-rail adhesion pattern (in particular degraded adhesion condition). The objective of this work is to study, starting from the knowledge of the system characteristics, the performances and the robustness of the HIL architecture during a simulation of braking and traction phases under degraded adhesion conditions. This work has been developed in collaboration with Italcertifer S.p.a. and Trenitalia S.p.a. that provided the technical data of the test rig and the considered railway vehicle (the E464 locomotive).

Inertia Simulation for Aircraft Braking Hardware-in-the-Loop Simulation

In this paper, the aircraft braking simulation platform is implemented to simulate the aircraft translational energy. Considering the disadvantages of conventional facilities with fixed-mass inertia disc, such as discontinuous regulation, one novel aircraft braking simulation platform structure and inertia simulation strategy is proposed. The simulated inertia can be regulated smoothly within a specific range with the proposed method and airplanes with different inertia can be simulated on one simulation platform. Another advantage of the proposed method is that the aerodynamic drag, engine thrust and nose-wheel rolling resistance can be compensated as well. The experiment results verify the proposed method.

Design of the Deployment Mechanism of Solar Array on a Small Satellite

This paper presents analytical simulation of drag braking during deployment of a solar array system of a small satellite within the space environment, and helps the designer to detect problems during ground testing. The deployment mechanism (DM) is modeled by using Mechanical Desktop (MDT) software and analyzed by using Finite Element Analysis Package (ANSYS 11). Design and Stress analysis of DM is performed at the most critical points during its functioning. Several finite element analysis models were considered to verify the DM integrity. These analyses were correlated with static, modal and random vibration testing. The present work can help in checking the survival of the mechanism under realistic operating conditions and makes sure that it will perform well after an orbit insertion of the satellite.

상용차의 제동시 쏠림 개선을 위한 조향 연결점 설계

차량의 제동시 쏠림 현상은 크게 타이어에 의한 원인과 현가시스템, 조향시스템 등의 차량구조의 이유로 발생한다. 그 중 차량구조의 원인은 드래그링크 방식의 조향시스템과 판스프링 형태의 현가 스프링 때문으로 볼 수 있다. 본 연구에서는 차량동역학 해석 프로그램인 ADAMS/CAR 를 사용하여 제동시 쏠림의 발생 원인에 대해 분석하였다. 제동시 드래그링크와 판스프링의 거동을 확인하고 그로 인해 발생하는 쏠림을 최소화 시키기 위해 최적화 프로그램인 Visual DOC 를 사용하여 쏠림을 감소시키기 위한 조향 연결점의 위치를 결정하였다. 설계 변경된 차량의 K&C (Kinematic & Compliance) Test 시뮬레이션을 통해서 다른 특성에 미치는 영향이 없음을 보였고, 전차량 제동시뮬레이션을 통해 제동시 쏠림이 감소함을 확인하였다.

Electric Vehicle Regenerative Braking System Based on Constant Current Control of Composite Power Sources

Due to the characteristics of high power density existing in super capacitor,the defects of low power density in power battery can be remedied,by using super capacitor as the auxiliary power source of electric vehicle. electric vehicle regenerative braking system is acted as the research object,the mathematical models of electric vehicle regenerative braking system of composite power sources are established,consisting of the brushless dc motor,Buck-Boost DC-DC converter,super capacitor as well as controller. In order to validate the electric vehicle regenerative braking system model,the regenerative braking simulation test system is designed and developed,the small power brushless dc wheel motor drive system is used to simulate electric vehicle drive system,the flywheel moment of inertia is used to simulate electric vehicle inertia load. The mathematical models of regenerative braking system are calculated and experimental verified,the results show that the mathematical model established is accurate and effective. In order to maintain small braking torque fluctuation range during the braking process,constant current control strategy is employed to control the armature current. As simulation results and experiment data shows,electric vehicle composite power source,consisting of power battery and super capacitor,can effectively absorb the regenerative braking energy. By adopting the constant current control strategies,stable braking torque can be implemented in the process of braking,and higher energy recovery efficiency is realized.

Study of Regenerative Braking Model and Simulation of a Car

A regenerative braking control strategy and the braking force distribution are putted forward based on the basic theory of automotive brake. The model of vehicle regenerative braking system and simulation under urban driving cycles are carried out taking a certain type of hybrid car as the research object. The simulation results show that, in circulation conditions of ECE + EUDC drive, the regenerative braking control strategy that this paper puts forward can ensure the reasonable distribution of vehicle braking force and realize the energy recovery of 15.7%.

Automobile Braking Simulation Applied Research Based on ADAMS

The application of the ADAMS in automobile braking simulation system is described in this paper. Several aspects concerning the extension of the application using ADAMS in this field are discussed with special attention focused on braking simulation regarding to regulating device of breaking force.

Antiskid control of railway train braking based on adhesion creep behavior

In modern trains wheelset skidding leads to the deterioration of braking behavior, the degradation of comfort, as well as a boost in system hazards. Because of the nonlinearity and unknown characteristics of wheelset adhesion, simplifications are widely adopted in the modeling process of conventional antiskid controllers. Therefore, conventional antiskid controllers usually cannot perform satisfactorily. In this paper, systematic computer simulation and field tests for railway antiskid control system are introduced. The operating principal of antiskid control system is explained, which is fundamental to the simulation of antiskid brakes, and the simulation model is introduced, which incorporates both the adhesion creep curve and a pneumatic submodel of antiskid control system. In addition, the characteristics of adhesion curves and the simulation target are also provided. Using DHSplus, the pneumatic submodel is created to analyze the performance of the different control strategies of antiskid valves. Then the system simulation is realized by combining the kinematical characteristics of railway trains and the pneumatic submodel. The simulation is performed iteratively to obtain the optimized design of the antiskid control system. The design result is incorporated in the hardware design of the antiskid control system and is evaluated in the field tests in Shanghai Subway Line 1. Judging by the antiskid efficiency, the antiskid braking performance observed in the field tests shows the superiority of the optimized design. Therefore, the proposed simulation method, especially in view of its ease of application, appears to be a useful one for designing railway antiskid control systems.

Non-singular slip (NSS) method for longitudinal tire force calculations in a sudden braking simulation

In a dynamic vehicle simulation, longitudinal tire force is primarily based on the longitudinal slip (ratio). In the longitudinal slip formula, state variables are used in the denominator. This causes a divergence problem for numerical simulations of vehicle dynamics. To avoid this numerical singularity, a differential slip calculation method was developed for use in dynamic vehicle simulations. However, this method also causes a singularity when the wheel velocity approaches zero in a pure slip state, such as during sudden braking. In this paper, a new longitudinal slip calculation method, which can overcome singularities in all velocity conditions, is proposed. For this purpose, the Taylor series is adapted to the slip formula and the idea of virtual wheel rotation stiffness is introduced for the development of the slip equation. The physical phenomenon at the zero slip state is analyzed. Finally, the proposed slip formula is used to solve the numerical singularity problem, and the non-singular slip (NSS) calculation method is proposed. The proposed NSS method is applied to tire model performance test (TMPT) simulations to validate its performance.

Braking Distance Estimation by Simulation

The present-day computer power enables (parallel to tests) the simulation of processes of cars safety assurance by specialized software. This article describes a simulation of car braking and braking distance estimation in different conditions. The simulating model has been made in MATLAB/Simulink. The results of simulation give the braking distances, which are necessary for safety cars distance estimation for different road surfaces, cars speeds and other conditions.

Vibration Characteristics of Elastic Disc Brake Pad Device

A new elastic disc brake pad device is designed. A mathematical model on railway vehicle elastic disc brake is established compared with the non-elastic brake pad by uni-wheel set braking simulation. The simulation results show that the elastic brake pad could guarantee the vehicle braking performance as same as the non-elastic brake pad. When the friction surface of the brake disc or pad has defects, the elastic brake pad can effectively reduce the vibration of the friction force between the brake pad and the brake disc. It has been proved that the correctness and rationality of the design. A new idea for the design and analysis of the disc brake system is provides.