Braking Deceleration Research Articles

The dynamic parameters correlation assessment of the textile machine high-speed bearings in changed technological conditions

The paper describes the correlation of the changed manufacturing and technological conditions of the spinning device applicable in the textile industry with the change of the dynamic parameters of the spinning rotor bearings. Special ball bearings for textile machines are designed for high rotational speeds and relatively low loads. They are characterized by high dimensional accuracy and reliable running, which guarantees their great utility value. In the diagnostics of the spinning machine spindle high-speed bearings, absolute vibrations were measured according to the recommendation of STN ISO 10816-3 norm. The conducted experiments focused primarily on the assessment of the impact of the unstable technological process on the change of the monitored dynamic parameters. The measurements showed a statistical increase of the measured dynamic parameters by 50% when the spinning machine spindle rotor speed was increased by 15%. The measured vibration values showed that technological instability (rotor clogging by fiber during combing and subsequent braking and speed deceleration, a signal from a damaged drive belt, variable dynamic imbalance of the rotor, and at the same time an uneven bowl wear caused by the fiber friction) had a noticeable impact.

FRICTION BUFFER STOP DESIGN

Friction buffer stops are the favoured construction of buffer stop, mainly due to its high resistance and variety of layout. Last but not least is its manner of deceleration induced upon impact and during the braking what makes it smart solution in railway transport safety. The general approach of designing buffer stops is via usage of the kinetic energy and its conversion into work. Paper describes input parameters such as train velocity or buffer stop vicinity which is expressed by the safety coefficient implanted within the calculation. Furthermore, the paper shows the principle of calculation the friction buffer stop work, or to be more precise, the work of its braking jaws and optionally the work of additional braking jaws located behind the buffer stop. Last section of the paper is focused on the examples of designing friction buffer stops, points out the main complications and shows the charts of relation amongst braking distance, kinetic energy and braking force and the charts of relation between deceleration rate and braking distance.

Accuracy Analysis of the Analytical Solution for the Lunar Lander Terminal Guidance Problem

An analysis of the accuracy and reliability of the proposed analytical solution for the lunar lander terminal guidance problem was carried out. The analytical solution for 3D terminal guidance problem was obtained for a constant acceleration trajectory and thrust vector orientation programs, which are essentially linear with time. In order to achieve 6 terminal conditions (position and velocity terminal vector components) 6 guidance law parameters were used: time-to-go, braking deceleration, initial pitch angle and pitch rate, initial yaw angle and yaw rate. The simulation results of the lunar lander terminal guidance using the proposed analytical solution were presented. The analysis of the proposed terminal guidance scheme and some similar schemes were carried out by mathematical modeling of the landing maneuver from a certain initial state to the desired spot near the lunar surface. By varying the initial position and the velocity parameters, when the terminal point was fixed, the statistic characteristics of the terminal guidance solution errors in the terminal position and velocity were estimated. An analysis of the simulation results validates the basic performance of the proposed terminal guidance scheme for the lunar pinpoint landing. Estimates of the terminal guidance accuracy for the proposed scheme exceed the corresponding estimates for the alternative considered schemes. The next phase of this research will be intended for studying the influence of variations in the initial prelanding orbit parameters (obliquity, ascending node longitude, argument of periapsis, periapsis height, apoapsis height) on the terminal guidance accuracy.

Hydraulic regenerative braking system studies based on a nonlinear dynamic model of a full vehicle

To obtain a reasonable match of the main parameters of a hydraulic regenerative braking system and to improve the energy recovery efficiency, this paper establishes the corresponding mathematical models and testbed for a hydraulic regenerative braking system. The proposed system is analysed and verified through simulation and experiments. Then, the linear and nonlinear mathematical models of a full vehicle are built, with joint simulation of the hydraulic regenerative braking system, and the influence of the hydraulic regenerative braking system on braking performance under different running conditions is discussed. The results indicate that the deviations in the simulation results between the linear and nonlinear dynamic models are very small. When the brake deceleration and road adhesion coefficient are 0.2, deviations are within 1.38 %. With an increase in the braking deceleration and road adhesion coefficient, the deviations in braking time and distance between the systems become larger and larger. When the braking deceleration and road adhesion coefficient are 0.7, the deviation reaches 30 %. Finally, with braking energy recovery efficiency and braking distance as the optimization objectives, the nonlinear braking energy recovery system parameters are optimized. After optimization, the energy recovery efficiency of the nonlinear system reaches 76.3 %, and the braking distance is 22.8 m.

Comparison and Analysis of Braking Load Capacity in Different Chinese City

In this paper we used the braking load index to illustrate the different braking load of cities under different braking conditions. The initial speed of braking, braking process speed difference, braking deceleration, temperature change of friction plate in braking process, the brake pedal force are different. Through the analysis of the measurement data, we comprehensively understood the differences of the braking conditions in different cities and the driving habits of consumers in different regions. The research could give a good theoretical support for the design process and after sales service.

Brake reactions of distracted drivers to pedestrian Forward Collision Warning systems

Introduction: Forward Collision Warning (FCW) can be effective in directing driver attention towards a conflict and thereby aid in preventing or mitigating collisions. FCW systems aiming at pedestrian protection have been introduced onto the market, yet an assessment of their safety benefits depends on the accurate modeling of driver reactions when the system is activated. This study contributes by quantifying brake reaction time and brake behavior (deceleration levels and jerk) to compare the effectiveness of an audio-visual warning only, an added haptic brake pulse warning, and an added Head-Up Display in reducing the frequency of collisions with pedestrians. Further, this study provides a detailed data set suited for the design of assessment methods for car-to-pedestrian FCW systems. Method: Brake response characteristics were measured for heavily distracted drivers who were subjected to a single FCW event in a high-fidelity driving simulator. The drivers maintained a self-regulated speed of 30km/h in an urban area, with gaze direction diverted from the forward roadway by a secondary task. Results: Collision rates and brake reaction times differed significantly across FCW settings. Brake pulse warnings resulted in the lowest number of collisions and the shortest brake reaction times (mean 0.8s, SD 0.29s). Brake jerk and deceleration were independent of warning type. Ninety percent of drivers exceeded a maximum deceleration of 3.6m/s2 and a jerk of 5.3m/s3. Conclusions: Brake pulse warning was the most effective FCW interface for preventing collisions. In addition, this study presents the data required for driver modeling for car-to-pedestrian FCW similar to Euro NCAP's 2015 car-to-car FCW assessment. Practical applications: Vehicle manufacturers should consider the introduction of brake pulse warnings to their FCW systems. Euro NCAP could introduce an assessment that quantifies the safety benefits of pedestrian FCW systems and thereby aid the proliferation of effective systems.

Impact of Cargo Distribution on the Vehicle Flatback on Braking Distance in Road Freight Transport

Vehicle centre of gravity influences directly the breaking characteristics. It dues through the actual each axle load and the actual gross weight of the vehicle. This fact is significant by full braking maneuver. Full braking measurements with different operational vehicle conditions - cargo weight and its location on the vehicle – were done to evaluate this influence. The medium sized good vehicle (category N2) was breaking on a wet asphalt surface. The value of the braking deceleration MFDD and the braking distance was measured by vehicle decelerometer. The results compare different axle- and vehicle load and show the area for future related measurements.

Practical Use of the Braking Attributes Measurements Results

This contribution deals with issues of braking the passenger car. The measurement of braking deceleration of the vehicle Kia Cee´d 1,6 16 V was carried out by an optical device Correvit system. The measurement was carried out on the airport of the village of Rosina located close to Zilina. 10 drivers of different age, praxis, and kilometers driven participated in the measurement. The measured process was the vehicle full braking with the service brake of the initial speed of approximately 50 km.h-1. Each of the drivers had 10 attempts. In the closure of this contribution the results of the performed measurements, their evaluation and comparison are presented. Practical result from the contribution is mainly the measurement set of braking deceleration of the respective vehicle during intensive braking.

Fault Diagnosis for Constant Deceleration Braking System of Mine Hoist based on Principal Component Analysis and SVM

Based on AMESim simulation platform, the pressure-time curve of constant deceleration braking system is obtained in this paper firstly, by simulating three typical faults of brake, the spring stiffness decrease, the brake shoe friction coefficient decrease and brake leaking. Then pressure data on the curve for each time are seen as a variable and the curve is chosen as the fault sample, analysed by the method of Principal Component Analysis (PCA). Last, principal components or sum of variance contribution rates more than 95% are selected as sample eigenvalues and Support Vector Machine (SVM) is used for fault diagnosis. Diagnosis results show that all testing faults can be identified accurately, which indicates SVM model has an extremely excellent ability to identify faults. To further verify the performance of SVM for fault identification, BP neural network is established to compare. The result shows that SVM model is more accurate than BP neural network in fault recognition.

RESEARCH OF MOTORCYCLE BRAKING PARAMETERS / MOTOCIKLO STABDYMO EFEKTYVUMO TYRIMAS

From a technical point of view, in dangerous or emergency situation is very important motorcycle driver reaction and vehicle braking time. Motor-cycle deceleration parameters depend not only on the motorcycle brake system, but also on the driving experience. A significant influence on decel-eration the motorcycle has aerodynamic parameters, pavement type and condition, as well as the technical condition of the motocycle, shock absorb-ers, tire type and their technical condition. This article provides an analysis of the motorcycle longitudinal deceleration, braking modes of the mo-torcycle on a dry asphalt road surface. Motorcycle stopping – deceleration – acceleration efficiency issue, stopping in different modes. First ana-lyzed the dynamics of a motorcycle deceleration braking only the front wheel, then braked front and rear wheels and complex – then braked the front and rear wheels at the same time. The goal of experimental study is to determine the influence of braking modes intense fir motorcycle brak-ing deceleration when braking on dry road pavement, at three different braking modes, and set the braking path of change. Motorcycle decelera-tion in the longitudinal direction is an important parameter for analysis traffic accidents, for accident reconstruction process and the examination of motorcyclists technical possibility to avoid an accident. Pavojingoje ar avarinėje situacijoje techniniu požiūriu labai svarbus yra optimalus transporto priemonės stabdymas laiku. Motociklo lėtėjimo parametrai priklauso ne tik nuo motociklo stabdžių sistemos, bet ir nuo vairuotojo patirties. Didelę įtaką motociklo lėtėjimui turi aerodinaminiai parametrai, kelio dangos tipas ir būklė, taip pat motociklo techninė būklė, amortizatorių, padangų tipas ir jų techninė būklė. Šiame straipsnyje pateikiama motociklo išilginio lėtėjimo analizė, stabdant motociklą ant sausos asfalto kelio dangos. Motociklo stabdymo – lėtėjimo – pagreičio efektyvumas nagrinėjamas, stabdant skirtingais režimais. Pirmiausia analizuojama motociklo lėtėjimo dinamika stabdant tik priekinį ratą, paskui priekinį ir galinį ratus bei stabdant kompleksiškai – priekinį ir galinį ratus. Eksperimentinio tyrimo tikslas – nustatyti, kokią įtaką turi stabdymo režimai intensyviai stabdomo motociklo lėtėjimui stabdant ant sausos kelio dangos, trimis skirtingais stabdymo režimais ir nustatyti stabdymo kelio pokytį. Motociklo lėtėjimo pagreitis išilgine kryptimi yra svarbus eismo įvykių analizei parametras atkuriant eismo įvykio eigą ir nagrinėjant motociklo vairuotojo techninę galimybę išvengti eismo įvykio.

Upon an issue of correlation between the running speed of vehicles and traffic capacity of a road section

The paper focuses on current algorithms for calculating the traffic capacity of the road sections, provided in various national standards. These algorithms were jointly considering some common groups of factors, such as factors related to the dynamic performance of vehicles and factors related to geometrical - dimensional configuration of the road. The algorithms have particular forms for continuous traffic flow and for discontinuous traffic. As a first stage, there were considered the algorithms for the continuous flows, for which were studied the points of extreme variance for traffic capacity, depending on the running speed. Maximum traffic capacity analytical form for a road section, in continuous traffic flow variant does not depend explicitly of average speed, but allows the evaluation of certain important factors (length section, acceleration at start-up, braking deceleration of vehicles, driver's perception-reaction time, brake friction coefficient, etc.). Consequently, various ways are identified to improve road traffic capacity. The paper justifies reconsideration of the notion of traffic fluence as defined by various national standards; as it stands, the definition of fluency is artificial in relation to the maximum legal speed on that road section, even though the value of that speed is physically impossible.

Analysis of the influence of braking control laws on gear walk

The problem of gear walk on landing gear becomes increasingly serious. A rigid-flexible coupling dynamic half-axle main landing gear model, verified to be in accordance with the test data and the original deceleration control system, are built to study the gear walk problems. The co-simulation method is adopted. According to the severe gear walk phenomenon under the deceleration braking system, two modified braking control laws-only the reference speed-speed difference (with PBM) control and the one combining the PBM with the fuzzy control are designed for this type of airplane to weaken the gear walk. The simulating results show that the modified braking control law weakens the gear walk considerably. The braking frequency increases by about 17 %. The average wheel axle gear walk average amplitude decreases by 73 % and the longitudinal acceleration drops by about 91 %. The braking frequency decreases by 50 % so that the vibration frequency of the gear walk decreases by about 59 %. The combined braking control law is verified that is of great stability, adaptability and robustness under variable external conditions.

New evaluation methodology of regenerative braking contribution to energy efficiency improvement of electric vehicles

Comprehensive research is conducted on the design and control of a regenerative braking system for electric vehicles. The mechanism and evaluation methods of contribution brought by regenerative braking to improve electric vehicle’s energy efficiency are discussed and analyzed by the energy flow. Methodologies for calculating the contribution made by regenerative brake are proposed. Additionally a new regenerative braking control strategy called “serial 2 control strategy” is introduced. Moreover, two control strategies called “parallel control strategy” and “serial 1 control strategy” are proposed as the comparative control strategy. Furthermore, two different contribution ratio evaluation parameters according to the deceleration braking process are proposed. Finally, road tests are carried out under China typical city regenerative driving cycle standard with three different control strategies. The serial 2 control strategy offers considerably higher regeneration efficiency than the parallel strategy and serial 1 strategy.

Investigation of in-train stability and safety assessment for railway vehicles during braking

In-train stability of railway vehicles has becoming a major concern for railway vehicles, which refers to the jackknifing behavior of couplers under large in-train forces. For the train to train rescue scenario, braking induced impacts from couplers can adversely affect the dynamic performance of the coupled train. It is indicated from field tests that in-train forces if combined with large rotational angles of couplers can produce vertical components, which will further lead to the interference of adjacent carbodies and structural damages. In this paper, the dynamic model of the train and coupler system is developed. The model verifications are conducted by comparing the calculated responses with the tested results. The safety indices are formulated on the basis of which the running safety of the coupled train is evaluated. The propelling test in the laboratory is conducted to reproduce the coupler jackknifing behavior. The quasi-static analysis and anti-jackknifing mechanism under compressing in-train forces are analysed. Parametric studies are then conducted to propose some limitations for the application of train to train rescue. It is indicated from numerical and testing results that the decrease of the braking deceleration or a limitation of the free rotational angle of couplers is beneficial to lower the amplitude of braking induced impacts.

Analysis of Driver Evasive Maneuvering Prior to Intersection Crashes Using Event Data Recorders

Objective: Intersection crashes account for over 4,500 fatalities in the United States each year. Intersection Advanced Driver Assistance Systems (I-ADAS) are emerging vehicle-based active safety systems that have the potential to help drivers safely navigate across intersections and prevent intersection crashes and injuries. The performance of an I-ADAS is expected to be highly dependent upon driver evasive maneuvering prior to an intersection crash. Little has been published, however, on the detailed evasive kinematics followed by drivers prior to real-world intersection crashes. The objective of this study was to characterize the frequency, timing, and kinematics of driver evasive maneuvers prior to intersection crashes.Methods: Event data recorders (EDRs) downloaded from vehicles involved in intersection crashes were investigated as part of NASS-CDS years 2001 to 2013. A total of 135 EDRs with precrash vehicle speed and braking application were downloaded to investigate evasive braking. A smaller subset of 59 EDRs that collected vehicle yaw rate was additionally analyzed to investigate evasive steering. Each vehicle was assigned to one of 3 precrash movement classifiers (traveling through the intersection, completely stopped, or rolling stop) based on the vehicle's calculated acceleration and observed velocity profile. To ensure that any significant steering input observed was an attempted evasive maneuver, the analysis excluded vehicles at intersections that were turning, driving on a curved road, or performing a lane change. Braking application at the last EDR-recorded time point was assumed to indicate evasive braking. A vehicle yaw rate greater than 4° per second was assumed to indicate an evasive steering maneuver.Results: Drivers executed crash avoidance maneuvers in four-fifths of intersection crashes. A more detailed analysis of evasive braking frequency by precrash maneuver revealed that drivers performing complete or rolling stops (61.3%) braked less often than drivers traveling through the intersection without yielding (79.0%). After accounting for uncertainty in the timing of braking and steering data, the median evasive braking time was found to be between 0.5 to 1.5 s prior to impact, and the median initial evasive steering time was found to occur between 0.5 and 0.9 s prior to impact. The median average evasive braking deceleration for all cases was found to be 0.58 g. The median of the maximum evasive vehicle yaw rates was found to be 8.2° per second. Evasive steering direction was found to be most frequently in the direction of travel of the approaching vehicle.Conclusions: The majority of drivers involved in intersection crashes were alert enough to perform an evasive action. Most drivers used a combination of steering and braking to avoid a crash. The average driver attempted to steer and brake at approximately the same time prior to the crash.

Possibilities of Finding out the Braking Parameters with Using GPS Equipment and Cameras

This article deals with results of testing, what level of reliability and accuracy can be reached by GPS devices and cameras when using them for purposes of detection of extreme braking and determination of its parameters. Braking tests with a van and with semi-trailer truck were done for purposes of this research. The main aim is to find out, whether this equipment can be used for detection of extreme braking as a situation, which can cause hidden damages on transported cargo. The article contains evaluation of differences between data measured by GPS equipment and those measured by equipment with accelerometer. Here are also stated examples of runs of braking deceleration as there were recorded by particular types of equipment.

Braking Deceleration Measurement Using the Video Analysis of Motions by Sw Tracker

Abstract This contribution deals with the issue of car braking, particularly with the one of M1 category. Braking deceleration measurement of the vehicle Mazda 3 MPS was carried out by the declerograph XL MeterTM Pro. The main aim of the contribution is to perform comparison of the process of braking deceleration between the decelograph and the new alternative method of video analysis and to subsequently examine these processes. The test took place at the Rosina airfield, the airstrip in a small village nearby the town of Žilina. The last part of this paper presents the results, evlauation and comparison of the measurements carried out.

Shifting Control Strategy of Deceleration Braking for Automated Mechanical Transmission Vehicle

Shifting Control Strategy of Deceleration Braking for Automated Mechanical Transmission Vehicle

A Human Body Model With Active Muscles for Simulation of Pretensioned Restraints in Autonomous Braking Interventions

Objective: The aim of this work is to study driver and passenger kinematics in autonomous braking scenarios, with and without pretensioned seat belts, using a whole-body finite element (FE) human body model (HBM) with active muscles.Methods: Upper extremity musculature for elbow and shoulder flexion–extension feedback control was added to an HBM that was previously complemented with feedback controlled muscles for the trunk and neck. Controller gains were found using a radial basis function metamodel sampled by making 144 simulations of an 8 ms−2 volunteer sled test. The HBM kinematics, interaction forces, and muscle activations were validated using a second volunteer data set for the passenger and driver positions, with and without 170 N seat belt pretension, in 11 ms−2 autonomous braking deceleration. The HBM was then used for a parameter study in which seat belt pretension force and timing were varied from 170 to 570 N and from 0.25 s before to 0.15 s after deceleration onset, in an 11 ms−2 autonomous braking scenario.Results: The model validation showed that the forward displacements and interaction forces of the HBM correlated with those of corresponding volunteer tests. Muscle activations and head rotation angles were overestimated in the HBM when compared with volunteer data. With a standard seat belt in 11 ms−2 autonomous braking interventions, the HBM exhibited peak forward head displacements of 153 and 232 mm for the driver and passenger positions. When 570 N seat belt pretension was applied 0.15 s before deceleration onset, a reduction of peak head displacements to 60 and 75 mm was predicted.Conclusions: Driver and passenger responses to autonomous braking with standard and pretensioned restraints were successfully modeled in a whole-body FE HBM with feedback controlled active muscles. Variations of belt pretension force level and timing revealed that belt pretension 0.15 s before deceleration onset had the largest effect in reducing forward head and torso movement caused by the autonomous brake intervention. The displacement of the head relative to the torso for the HBM is quite constant for all variations in timing and belt force; it is the reduced torso displacements that lead to reduced forward head displacements.

Extended-Kalman-filter-based regenerative and friction blended braking control for electric vehicle equipped with axle motor considering damping and elastic properties of electric powertrain

Because of the damping and elastic properties of an electrified powertrain, the regenerative brake of an electric vehicle (EV) is very different from a conventional friction brake with respect to the system dynamics. The flexibility of an electric drivetrain would have a negative effect on the blended brake control performance. In this study, models of the powertrain system of an electric car equipped with an axle motor are developed. Based on these models, the transfer characteristics of the motor torque in the driveline and its effect on blended braking control performance are analysed. To further enhance a vehicle's brake performance and energy efficiency, blended braking control algorithms with compensation for the powertrain flexibility are proposed using an extended Kalman filter. These algorithms are simulated under normal deceleration braking. The results show that the brake performance and blended braking control accuracy of the vehicle are significantly enhanced by the newly proposed algorithms.