Braking Distance Research Articles

Shortening the Braking Distance of a Passenger Car through Coordinated Control of Brakes and Active Suspension

Aktif süspansiyon – fren entegre kontrolü, akademik ve otomotiv sanayi literatüründe popüler bir araştırma konusudur. Bu araştırma alanına odaklanan bu çalışma, iki entegre kontrol alternatifi önermektedir. İlk metot, aracın arka süspansiyonuna yerleştirilecek doğrusal elektrik motorları gözetilerek tasarlanmıştır. Bu metotta, aracın frenleme performansını ve sürüş konforunu geliştirecek olan kontrol sinyalleri, teker kayması, ve arka doğrusal elektrik motor kuvvetlerine bölüştürülmektedir. İkinci metot ise, hem ön, hem de arka süspansiyonlara yerleştirilecek doğrusal elektrik motorları gözetilerek tasarlanmıştır. Bu kez kontrol hedefi, teker kuvveti – teker kayması karakteristik grafiğinin pik noktasında kalmaktır. Aynı zamanda aracın yunuslama hareketi de kısıtlanmaktadır. Her iki kontrol yaklaşımı, kontrol bölüştürme yöntemini uygulamaktadır. Çalışmada özetlenen simülasyon çalışmaları ile, önerilen kontrolcülerin, pasif süspansiyonlu konvansiyonel araç ile kıyaslandığında aracın frenleme mesafesini kısaltacağı gösterilmiştir.

ОЦЕНКА ЭФФЕКТИВНОСТИ РАБОТЫ ТОРМОЗНОГО ОБОРУДОВАНИЯ ИННОВАЦИОННЫХ ГРУЗОВЫХ ВАГОНОВ

The object of researches is brake systems of innovation freight cars. The work purpose consists in the assessment of braking system effectiveness in innovation freight cars and in standard ones at different operation modes. 
 The scientific novelty consists in the definition of the dependence of a slide block depth on the length of wheel pair skidding motion and braking distance dependence upon car speed. During the work there was carried out a retrospective analysis of cases with traffic safety violation connected with the formation of excessive sliders in freight cars in organized trains because of the violation of braking equipment normal operation. By means of the least-squares method there was obtained a linear equation defining the dependence of slider depth upon the skidding length of a wheel pair. As a result of the work there were defined parameters of defect formation on freight car wheels at their skidding, the calculations of braking system efficiency in different freight cars were carried out. 
 In the course of the analysis of freight car braking efficiency there are obtained equations of braking length in the accepted range of speeds at the beginning of braking for empty and loaded states. Minimum values of the design factor of braking block pressing in translation to a train length of 200 shafts in the empty state were 0.2256 for a speed of 40km/h, in the loaded one – 0.1781 for a speed of 120 km/h at the standard values 0.22 and 0.14 respectively. By means of calculations and experiments it is proved that composite braking block pressing force on a shaft exceeds 4tf/shaft, and that of cast-iron – 10tf. Accordingly, a car with the shaft load of 25 tf/shaft and accepted parameters of a braking system may be operated up to the speeds of 120 km/h inclusive without limitations.

Research on measuring device and quantifiable risk assessment method based on FMEA of escalator brake

To improve the accuracy of braking distance measurement and reduce the impact of human factors on brake risk assessment of escalators, a non-contact braking distance measuring device based on infrared ranging principle is designed. Futher, a quantifiable risk assessment method of brake based on failure mode and effects analysis (FMEA) is propose in this paper. Characteristics and trends of distance changes during emergency braking process of the escalator are theoretically analyzed. To extract, process, and recognize the distance change signals, and finally to realize accurate measurement of the braking distance, a high-speed infrared distance measurement technology is used. Influencing factors of the escalator brake performance are studied. The risk analysis method based on FMEA is used to analyze its failure mode, failure mechanism, and consequences of the failure. A risk index assessment system is constructed and quantified. The test results show that the measurement error of the device designed is 1.6%, which is 1/6 of the traditional measurement method. The repeated measurement error of the device is 1.4%, which is 1/7 of the traditional measurement method. Application results show that the quantifiable risk assessment method quantifies and assigns the risk level according to the weight, which effectively avoids the inconsistent results caused by human bias. The evaluation results are more scientific and reliable.

Simulation on elevator emergency brake

Modern calculation methods used for hoisting units are reduced to obtaining the value of the required braking force when the values of mass and speed have been captured. Copies of the oscillograms with kinematic parameters on braking of passenger elevator cabins show that the acceleration tendencies when landing on soft braking devices are not linear. Consequently, the cabin braking forces also do not change linearly and are not constant since the moment after braking has started to the moment when it stops. The calculation methods give only the maximum value of the required braking force and the length of the cabin braking distance. The elevator cabin braking (counterweight) with safety devices takes some time. During this time, the braking force changes from zero to the maximum value, which, at high speeds of the cabin (counterweight) affects the acceleration of slow-down process, and the brake-path length. When simulating the braking force of elevator catchers, it is necessary to take into account the change of the braking force value.

Calculation of the dependence of friction coefficient of locomotive composite ridge brake shoes on pressing force and braking speed

JSC “FRITEX” has developed non-asbestos ridge composite brake shoes UR 01-01 with a reduced coefficient of friction, which, in contrast to the cast iron ridge brake shoes currently used on locomotives, have high wear resistance and more stable frictional properties at high speeds. They are much lighter than traditional cast iron shoes, resulting in lower logistics costs and easier replacement by service departments. However, the new materials used for the production of the shoe, as well as its innovative design, which combines the two types of materials, require a detailed study of its frictional properties. For this, the braking modes of a locomotive equipped with UR 01-01 shoes were simulated in a full-scale unit of a brake mechanism on an inertial stand at fixed pressures and speeds. Based on the results of the experiments, the values of the friction coefficients of the brake shoes were determined and the dependence of the friction coefficient of the shoes on the pressing force and braking speed was established. The data obtained were used in braking calculations for an electric locomotive of the VL80 series, including the determination of the braking distance, holding a single locomotive by the parking brake on a slope, and ensuring the antiskid braking due to higher values of the friction coefficient of the UR 01-01 shoe at high speeds. The composite ridge brake shoe ensures compliance with the standard values of the braking distance, antiskid braking and slope parking for the VL80 series electric locomotive. In this case, the use of these composite shoes is possible without changes in the device of the lever transmission of the electric locomotive. It is necessary to conduct running brake tests to make approbation of obtained empirical dependence of the friction coefficient of new shoes on the pressing force and the braking speed of the locomotive and its widespread use in the calculation of brake systems.

Расчет тормозного пути судна при воздействии ветра и морского волнения

The article considers the methods of estimating the wind effect on the braking characteristics and the vessel behavior under the wind and waves. A model with regular sea waves is illustrated, in which the wave ordinate changes according to the sine law. It is stated that in reality the wave ordinate varies approximately by the sum of an infinite number of harmonics, the so-called irregular excitation. There are given differential equations of wind effect on the inertial-braking characteristics, of braking, of calculating the braking distance, etc. There has been estimated the braking distance of the motor vessel “Yuri Maksarev” with four rows of containers in headwinds up to 15 m/s. The wind has been proved to influence greatly the length of the braking distances, with the length of braking distance becoming two cables less after three minutes. The diagram of the apparent wind influencing the ship is presented. The apparent wind impacts the vessel’s hull above the waterline. Drift angle estimating is performed using a programmable calculator, a table or a nomogram. There is proposed a nomogram that greatly simplifies preliminary calculating and reduces the time costs. There have been compiled the programs for calculating the wind drift angle and constructing the corresponding nomogram in the application Microsoft Excel 97 using the programming language Visual Basic. The developed programs allow automating the most frequently performed calculations for determining the angle of wind drift, for which little time is needed during the maneuvering process. The arrangement of the diagram on the paper is illustrated, the process of building a nomogram is presented in stages. A case of the calculated nomogram for the motor ship “Yuri Maksarev” has been presented.

Fixed-Time Slip Control With Extended-State Observer Using Only Wheel Speed for Anti-Lock Braking Systems of Electric Vehicles

In this paper, we propose a fixed-time slip control with an extended-state observer (ESO) using only wheel speed for anti-lock brake systems (ABS) in electric vehicles. In the proposed control strategy, the longitudinal tire-road friction is defined as the disturbance. The ESO is designed to estimate the wheel speed, longitudinal tire-road friction, and longitudinal vehicle speed. Based on the estimated longitudinal tire-road friction, an optimal desired slip generator is designed, which provides optimal desired slip in real-time to maintain a nearly maximum tire-road friction coefficient (TFC), according to road surface conditions. A fixed-time controller is developed to guarantee an upper bound of convergence time determined regardless of the initial slip tracking errors. The proposed method guarantees a uniform ultimate boundedness of the wheel-slip tracking error based on an analysis of closed-loop stability. The performance of the proposed method is validated via simulations by using CarSim and MATLAB/Simulink for three scenarios on a jump TFC road surface, on a split TFC road surface, and on a suddenly cornering jump TFC road surface. The proposed method, which only employs a wheel speed sensor, achieves a shorter braking distance and stopping time in comparison with classical ABS.

Influence Relationship between Mathematical Model-Based Elevator braking Distance and Equilibrium Coefficient

A mathematical model was developed to compare the association between the braking distances between the unloaded upward and downward braking inspection of the elevator at 125% load, and to derive the corresponding mathematical relationship and the interrelationship between the two braking distances as a function of the equilibrium coefficient. Then, by substituting typical values for specific parameters, the corresponding conclusions were drawn.At a equilibrium coefficient between 0.4 and 0.5, the two braking distances have some similarity with some reference value.

Research on vehicle performance test based on DirectInput data acquisition

Aiming at the high cost of high-performance driving simulator at present, a low-cost vehicle simulation system with universal applicability was developed based on Microsoft Visual C++6.0 software platform. A data acquisition interface program based on DirectInput components and the real-time data acquisition program of driving operation was designed. Based on the dynamic model of vehicle simulation, a data output conversion model was established for the driver operation input collected in real time. For real-time vehicle dynamics simulation model, the real-time simulation control process was realized, the simulation description and decoding quality of the ground, hanging, no suspension quality coordinate system and the real-time simulation for buses with nine degrees of freedom dynamic model were established. Finally, the real-time and reliability of the simulation system were verified through the simulation test. The experiment results show that the average response time of the simulation system is 11.465ms. Emergency braking time is 4.40s with an error of 4.762%. The braking distance is 70.145m and the error is 5.959%.

ОБОСНОВАНИЕ ПРИМЕНЕНИЯ ПРОТИВОГОЛОЛЕДНЫХ ХИМИЧЕСКИХ РЕАГЕНТОВ НА АВТОМОБИЛЬНЫХ ДОРОГАХ С ЦЕМЕНТОБЕТОННЫМ ПОКРЫТИЕМ

In this paper, we consider the problem associated with the fight against slipperiness on roads with a hard type of road surface. It is known that on cement-concrete surfaces, the length of the braking distance is up to 10 times longer than on a snow roll formed on asphalt-concrete surfaces. This phenomenon is especially dangerous in winter, as a sharp increase in humidity (as a result of warming) significantly reduces the strength properties of cement concrete. Chloride de-icers are highly hygroscopic. Being in the pores of cement concrete, chemical solutions begin to absorb moisture from the atmosphere. In asphalt concrete, such phenomena are practically absent. Moisture, which is located in the pores of cement concrete, on its surface occurs "staining" and peeling. In the article, the authors pay special attention to the climatic conditions of Kazakhstan. The average air temperature of the coldest month on average in the Akmola region is 25-27oC, in the Eastern region-31-36oc, in the North– -26-29 OS, and in the South-3-10 OS. Annual precipitation amounts to 260-300, 340-370, 300-340 and about 150 mm, respectively. the duration of the cold period in the year varies between 6-7, 6-7, 5-6 and 3-4 months. It is climate factors that make it difficult to use chemical reagents as anti-icing materials on roads with a cement-concrete surface. This article discusses the theoretical basis for the destruction of the crystal structure of snow and ice formations from the influence of chemical reagents. They established a natural dependence of the freezing force of snow and ice formations on the impact of various types of salt solutions. Also, laboratory studies have established the effect of the concentration of salt solutions on the loss of strength of cement concrete over time.

Mathematical model for studying the braking distance of a car equipped with ABS in winter conditions

The article aims to develop a mathematical model for analytical studies of the braking process of a car equipped with an anti-lock braking system in order to identify the relationship between the stopping and braking distances of a car and pedestrian visibility in dark winter conditions, when headlights are contaminated with anti-icing materials. The mathematical model of the braking process of a car equipped with ABS was analyzed. Experimental studies of the braking process of a car with running and disabled ABSs were carried out on winter roads. The experimental studies of headlight contamination with chemical anti-icing materials (CAIM) and changes in luminous intensity were carried out in real road conditions in winter. The results are presented in the article. The results of the experimental studies of pedestrian visibility in dark conditions with contaminated headlights are presented. The adequacy of the mathematical model of the braking distance of a car with running and disabled ABSs in winter conditions was assessed. The trends characterizing the effect of headlight contamination on the pedestrian visibility in dark winter conditions are described. The results of the study are presented in tables, diagrams and equations. The values of the stopping distance were determined at different initial braking speed rates. The visibility distance for a car with contaminated headlights was determined in dark winter conditions.

Influence of Contact Area Deformation Distribution of Tire on Tire Noise, Rolling Resistance and Dry Grip Performance

Most tire properties are closely related to the pattern deformation. In order to explore the relationship between tire performance and defined deformation parameters in the contact area between the pneumatic tire and road surface, ten types of 205/55R16 passenger car radial (PCR) tires were selected as the research objects. Using VIC-3D non-contact strain measurement system and by subdividing the contact area, the pattern deformation in contact area under vertical load was tested, and the relevant deformation parameters of the contact area were extracted. Correlation analysis was used to establish the relationship between the identified deformation parameters and tire performance indicators. Then an evaluation method of tire performance based on the deformation parameters was proposed, as well as clarification of the contradictory mechanism between tire noise, rolling resistance and dry grip performance. While the results indicate tire noise having a significant negative correlation with radial deformation in the contact area, rolling resistance coefficient gave a significant positive correlation with its equivalent strain in the XY plane of the contact area, and dry braking distance positively correlates with tensile strain in the Y direction of contact area and negatively correlates with tensile strain in the X direction of the contact area.

Manipulation of Massive Objects in Space Using Flexible Joint Manipulators

Robotic manipulators used in space applications are often lightweight, exhibit significant joint flexibility, and have limited joint torques. Many applications of space manipulation involve the transport of massive objects, e.g., a captured satellite, well beyond the 1 g capability of these robots. This may cause challenges during manipulation, such as imprecise trajectory following during transport, oscillatory behavior, and difficulty berthing the object. Motivated by the space application, a fixed-base scenario is considered, and a methodology is proposed for massive object manipulation via flexible-joint manipulators in this Paper. The manipulation task includes the following phases: tracking and capture, path and trajectory planning, trajectory execution, and berthing. Visual servoing and compliance control are used to track and capture the object. Motion planning accounts for kinematic and dynamic constraints on joint stops, path smoothness, actuator limits, end effector slippage, and braking distance. Berthing is achieved through the use of compliance control. The efficacy of this methodology is experimentally investigated with a flexible-joint Rethink Baxter robot arm, and each manipulation phase is completed with a heavy load beyond the 1 g limit of the arm on an air bearing table.

Effectiveness of Active Luminous Lane Markings on Highway at Night: A Driving Simulation Study

Road lane markings play an essential role in maintaining traffic order and improving traffic safety and efficiency. Active luminous lane markings have emerged with advances in technology recently. However, it is still not completely clear what impact their application will have on drivers. This paper aimed to study the effectiveness of active luminous lane markings on highways at night. A driving simulation experiment was carried out based on advanced driving simulators at Tongji University. The driving simulation experiment involved 31 participants and 9 simulation scenes with 6 different types of lane markings models and the same 2-way highway segment, which was 5300-m long with four 3.75-m wide driving lanes. The study participants drove through the simulated highway while the vehicle operation data and the driver’s eyes changing data were continuously captured. Overall, the pupil area change rate, steering wheel speed, brake pedal force, gas pedal, lane departure, and operating speed indicators were selected to evaluate the effectiveness of the active luminous lane markings. The results are shown as follows: (1) the active luminous lane markings have excellent visual recognition performance at night. Compared with the passive luminous lane markings, the active luminous markings can reduce the mental and physical loads of drivers, increase the early braking distance significantly, improve the lane-keeping ability and smooth the operating speed; (2) for the specific parameter settings of the active luminous lane markings at night, the yellow lane markings are better than the white ones, the point-line-type lane markings are superior to the conventional-type ones, and the blinking frequency is reasonable to set, at a moderate level, as 40 times per min. The results suggest that there are positive effects of active luminous lane markings on the promotion of highway traffic safety and efficiency at night, providing theoretical support for the popularization and application of active luminous road lane markings.

A 3D virtual prototype-finite element co-simulation of aircraft hydroplaning on a wet rough runway

ABSTRACT Skid-resistance performance of a runway greatly influences aircraft landing safety. A wet runway significantly increases the incidence rates of aircraft overrun. To study the influence of the skid-resistance performance of a runway on aircraft landing, a co-simulation method is proposed. First, a finite element (FE) model of the local tire-water film-runway simulation is established to obtain the combination coefficient-slip ratio curve of a tire on a wet runway. Second, a global model of an Airbus A320 virtual prototype (VP) is created. Then, on the basis of fuzzy control theory, a two-dimensional (2D) fuzzy controller of the aircraft AB is established. The friction coefficient-slip ratio curve of the tire on the wet runway obtained in the local simulation is introduced into the full-scale hydroplaning simulation model of the aircraft. Finally, the global-local multiscale simulation method is used to analyze the skid-resistance behaviour of the aircraft on three types of runways. It is found that the increase of water film thickness of the pavement and the increase of the grounding speed cause the attenuation of the friction coefficient of a runway, finally causing the reduction of the deceleration rate of the aircraft and the increase of the braking distance.

A novel aircraft anti-skid brake control method based on runway maximum friction tracking algorithm

As a dominant type of disturbance during aircraft braking, variation in maximum friction between the runway and the tires largely affects the efficiency of aircraft anti-skid braking systems (ABS). Conventional aircraft anti-skid braking control method, such as pressure-bias-modulated (PBM), are unable to identify and track the changing maximum friction between the runway and the tires, which results in reduced braking efficiency and long braking distances. This paper presents a novel anti-skid braking control method which can identify and track the maximum friction using only wheel angular velocity and brake pressure signals. An extended braking stiffness (XBS)-based runway maximum friction identification method is proposed to determine the runway maximum friction, where XBS is the differential of the friction to the differential of the slip ratio. Tracking differentiator (TD) is employed to derive the corresponding differential signals, which enables XBS to be calculated efficiently, without compromising calculation accuracy. By analyzing the dynamic characteristic of the wheel, a runway friction characteristic observation function is designed to observe changing friction characteristic during the entire braking. To be able to track the varying maximum friction in real time, a runway maximum friction tracking algorithm is designed, which can realize accurate brake pressure control according to the change in runway friction characteristic. The Lyapunov function is employed to prove the stability of the designed controller. Simulation tests are carried out under multiple sets of changes in runway friction characteristic. The comparison simulation test with PBM algorithm shows that the designed control method greatly improves the braking efficiency. Ground inertia test bench experiments are also conducted to further verify the correctness and effectiveness of the proposed aircraft anti-skid brake control method. Simulation and experiment results prove that the proposed control method is able to identify and track the varying maximum friction provided by different runways. The results of experiment also demonstrate that the control method still has good robustness and performance, even with the objective noise of the system.

ШВИДКІСНИЙ ВАНТАЖНИЙ ПОЇЗД ДЛЯ ПЕРЕВЕЗЕННЯ КОНТЕЙНЕРІВ ЗІ ШВИДКІСТЮ 200 КМ/ГОД

The article is devoted to building of freight trains for transportation of containers with railway transport at speed of 200 km/h. The article considers building experience of the high speed freight trains for transportation of containers at speed of 350 km/h. Main technical characteristics of the rolling stock, involved in freight high speed railway transportation in foreign countries are analyzed. The purpose of the article is to discover design features of the rolling stock for freight transportations at speed of 200 km/h and in modeling of the braking processes during electro pneumatic and pneumatic braking of the rolling stock from speed of 200 km/h to 160 km/h. The concept of the rolling stock for high speed freight transportation of containers is proposed. A specialized platform with bogies, disc brake and air-spring suspension Installed on it is used as a rolling stock. A brief description of the brake system is given; its main features are shown. A pneumatic scheme of the container block of the braking equipment and the general view of container block is given. Classified freight train, which consists of 30 platform cars and has two locomotives on each side is proposed for high speed transportation. Brake distance during electro pneumatic and pneumatic braking at freight train speed of 160 km/h is calculated. The results of calculated studies of the trains braking efficiency are given, which showed that at the speed of the freight train of 200 km/h, the brake distances at electro pneumatic and pneumatic braking are represented by 1472 m and 1571 m respectively, which corresponds to the technical requirements of the European Union TSI. Key words: high-speed freight trains, container, speed, brake distance, disc brakes.

Оценка функциональной пригодности тормозных систем легковых автомобилей по изменению пути торможения в процессе эксплуатации

The article discusses a methodology for assessing the functional suitability of brake systems to change the braking path of passenger cars, taking into account various operating conditions. The goal is achieved by using the method of mathematical modeling of the emergency braking process, taking into account the possible operating conditions of cars performing emergency braking at certain initial speeds, in particular, exceeding 100 km / h. Based on the analysis of scientific sources, it has been established that the determination of the braking efficiency of a vehicle classically occurs on the verge of blocking all wheels with known methods of distributing braking forces between the axles of the vehicle. In this case, the standards set the maximum value of the minimum deceleration and braking distance. In addition, the jump in the maximum possible value of the braking force between the wheels of each axle makes it possible to compare it with the requirements of DSTU 3649: 2010, and the assessment of the magnitude of this jump for each braking of the car is to establish its functional suitability. As a result, according to the magnitude of the jump in the maximum possible value of the braking distance, the change in the maximum allowable braking force of the car sets, and according to the magnitude of its jump, it is possible to assess the functional suitability of its braking system. As a result, the use of expert information on the value of jumps in the maximum possible value of the braking force of a car, affecting the braking torques and braking coefficient, can reduce the amount of experimental research and significantly reduce the time to reach an objective decision on the functional suitability of the brake systems of operated cars. The paper presents the results of theoretical studies of passenger cars Chevrolet Aveo, Lada Priora and Forza with different loads, performing emergency braking at an initial speed of 40-150 km / h on a road with dry asphalt concrete. The boundaries of the coefficient of the relative change in the braking distance of the tested passenger car, at which it is possible to make a conclusion about the functional suitability of its braking system, have been established.

Study of braking strategy considering comfort

A driving safety model considering comfort during the driver's actual driving experiences is established. The value of acceleration is used to measure the comfort. In order to balance the safety and comfort of drivers during the braking process, the model is setup by multi-objective optimisation method of combining with driving comfort, braking distance and pedal force. Then the output of the model is analysed by memetic algorithm to make the braking distance smaller than the safety distance, and the driving comfort is optimised as well. The results of experiment show that the best solution of the model can satisfy the constraints of the comfort and safety distance at the same time. The braking strategy proposed in this paper is feasible and practical.

Situation-aware Switching of the Communication Topology in Heterogeneous Platooning Applications

Communication based controllers for platooning are often designed for a homogeneous vehicle composition in a nominal driving situation. However, in real applications, platoons will comprise different vehicles and, thus, be heterogeneous, which increases the requirements for safe operation. Furthermore, controllers which are designed for the nominal cruising state can not necessarily cope with external disturbances such as the cut-in of a foreign vehicle or an emergency braking of the whole platoon. In this paper, we present a concept of switching the communication topology according to the current driving situation in a heterogeneous vehicle platoon. Examined driving situations are the cut-in of a foreign vehicle and an emergency braking. For these situations, we show that varying the communication topology of an otherwise unchanged controller can prevent collisions within the platoon. Furthermore, it is shown that improvements, e. g. regarding the braking distance of the leading vehicle, can be achieved by taking the different vehicle types and their order into account. For both situations, possible solutions by switching the communication topology are discussed and evaluated in the simulation framework Plexe.