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Trudy NAMI

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No 3 (2021)
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AUTOMOBILE DEVELOPMENT

6-21 248
Abstract

Introduction (problem statement and relevance). The graphs, logic and game-tree structures methods have been used in mechanics. The purpose of modeling an automatic gearbox with graphs can be versatile, namely: determining the transmission ratio of individual gears, analyzing the speed and acceleration of individual rotating elements.

The purpose of the study. The article presents the application of decision trees in the analysis of automatic gearboxes modeled with the Hsu graph.

Methodology and research methods. The paper presents a method of generating game tree structures that allow to change the values of decision parameters in the issues of decision making and knowledge generation. Specifying the rank of importance, in which order you should change individual items to active, allows you to detect the so-called redundant or temporarily redundant components for a given gear currently under consideration.

Scientific novelty and results. At each stage of optimization, a tree is generated, selecting the optimal decisions. Then, vertices can be added to the tree that represent the optimal responses of the system to changes in arithmetic construction parameters.

Practical significance. The most important in this regard will be the selection of the optimal programming environment with the possibility of installing the program in laboratory

22-29 265
Abstract

Introduction (problem statement and relevance). In connection with the development of the vehicle technical inspection system in the Russian Federation, it is relevant to compare the requirements for vehicles, which Russia supports, in the international agreements and at the national level.

Methodology and research methods. The analytical method is applied.

The purpose of the study was to analyze the current state of safety requirements for vehicles during regular technical inspections in the Russian Federation, that is UN Regulations annexed to the Vienna Agreement of 1997, and the technical regulations of the Eurasian Economic Union “On the safety of wheeled vehicles”.

Scientific novelty and results. The scientific novelty results in the analysis which shows that the 1997 Vienna Agreement documents introduce a level classification of defects discovered during the technical inspection, but the existing uncertainty of the defect interpretation can cause a conflict between the inspector and the owner of the inspected vehicle. In contrast to these documents, the diagnostic card of the technical inspection in Russia sets the requirements out clearly and unambiguously, which excludes their ambiguous interpretation.

Practical significance. The research results can be used to improve the technical regulations of the Eurasian Economic Union in the field of automobiles and to develop national legislative acts of the Russian Federation in this area, as well.

30-36 272
Abstract

Introduction (problem statement and relevance). The need to increase the operating speeds and input torque of automobile transmissions because of their vibration is becoming a more and more urgent problem.

The purpose of the study was to substantiate the applicability of harmonic analysis, which makes it possible to determine the actual values of vibration values during a steady oscillatory process, for the initial assessment of the gearbox vibration activity.

Methodology and research methods. The calculation of the gearbox vibration activity was carried out by modal and harmonic analyses, implemented by the finite element method, and followed by the experimental study of gearbox vibration on a test bench.

Scientific novelty and results. The presented experimental and calculated results of the research show that the difference between the experimental and calculated values is no more than 4.2%. This proves the possibility of applying modal and harmonic analysis to predict the gearbox vibration state at an early stage of product design at the stand.

Practical significance. The given calculation algorithm makes it possible to predict, with a sufficient degree of accuracy, the vibration of the gearbox before the manufacture of a prototype in experimental production.

37-47 241
Abstract

Introduction (problem statement and relevance). This article deals with the problem of training artificial neural networks intended to analyze images of the surrounding space in automotive computer vision systems. The conventional training approach implies using loss functions that only improve the overall identification quality making no distinction between types of possible false predictions. However, traffic safety risks associated with different types of prediction errors are unequal being higher for false positive estimations.

The purpose of this work is to propose improved loss functions, which include penalties for false positive predictions, and to study how using these functions affects the behavior of a convolutional neural network when estimating the drivable space.

Methodology and research methods. The proposed loss functions are based on the Sørensen-Dice coefficient differing from each other in the approaches to penalizing false positive errors. The performance of the trained neural networks is evaluated using three metrics, namely, the Jaccard coefficient, False Positive Rate and False Negative Rate. The proposed solutions are compared with the conventional one by calculating the ratios of their respective metrics.

Scientific novelty and results. The improved loss functions have been proposed to train computer vision algorithms featuring penalties for false positive estimations. The experimental study of the trained neural networks using a test dataset has shown that the improved loss functions allow reducing the False Positive Rate by 21%.

The practical significance of this work is constituted by the proposed method of training neural networks that allows to increase the safety of automated driving through an improved accuracy of analyzing the surrounding space using computer vision systems.

48-57 285
Abstract

Introduction (problem statement and relevance). One of the most promising and intensively developing directions in the automation field of road transport management is the creation of highly automated vehicles.

The purpose of the study was to find a way to solve a wheeled vehicle safe automatic braking problem in terms of minimizing quality control of the quadratic functional and work out optimal software and hardware implementation of this system.

Methodology and research methods. To solve the problem, the method of the control algorithm analytical design was used, basing on the use of the necessary conditions for minimizing the elements of the functional for the control law synthesis. The maximum deceleration value was due to the identified tire grip, and the deceleration threshold from which braking begins was selected as the minimum of the working deceleration and two decelerations depending on the rear obstacle distance.

Scientific novelty and results. The tests of the developed function were carried out for the LADA Vesta vehicle equipped with an ABS valve body with the possibility of programmed control. The analysis of the research results showed that when solving the problem of safe automatic braking in front of an obstacle, the software limitation of braking deceleration did not allow wheel blocking and performed the functions of an anti-lock braking system at the permissible wheel slipping level; software backup of the distance calculation to the front obstacle from the moment of braking start allowed to prevent most of the situations with false data from the radar when the vehicle pecked during braking.

Practical significance. Software tuning of mathematical models parameters of the engine, transmission and braking system allows you to adapt the automatic braking system to a wide class of vehicle models.

ENGINE DEVELOPMENT

58-66 232
Abstract

Introduction (problem statement and relevance). Limited oil reserves and tightening environmental standards are forcing engine manufacturers to switch to alternative fuels in the near future, among which hydrogen is the most promising. The advantages of hydrogen are high specific heat of combustion and high combustion rate. Wide concentration limits of hydrogen combustion make it possible to use high-quality power control, thereby providing an increase in the efficiency of a hydrogen engine when compared to the basic internal combustion engine.

The purpose of the study was to ensure the operation of a serial gasoline engine running on hydrogen with a new experimental fuel supply system, as well as the modification of the intake manifold design without abnormal phenomena during combustion when operating on a lean mixture, and to obtain efficient and ecological characteristics of a hydrogen engine under bench test conditions, as a result.

Methodology and research methods. The work is experimental, the reliability of the results obtained is confirmed by the use of modern means for measuring and processing experimental data. The obtained results of measuring nitrogen oxides are adequate to the known Zel'dovich thermal mechanism. The value of the results lies in the fact that they show the feasibility of transferring serial internal combustion engines to hydrogen; in addition, these results are used to develop and verify mathematical 3D models of the hydrogen engine working process.

Scientific novelty and results. A new system providing the necessary characteristics (pressure, duration and cycle dose) for supplying hydrogen to the intake system with two injectors for each cylinder was designed, installed and tested on the prototype engine.

Practical significance. The expediency of the working cycle creation and efficiency of a hydrogen engine with an experimental lean-burn fuel supply system was confirmed, which made it possible to provide high-quality power control with external mixture formation and forced ignition.

REVIEWS, ANALYTICS

67-80 283
Abstract

Introduction (problem statement and relevance). Testing the vehicle automatic transmission and shifting gears without interrupting the power flow undesirable dynamic phenomena were revealed. The occurrence of “parasitic” centrifugal pressure in the clutch boosters was observed which resulted in self-activation of the control element, clamping the discs friction linings, which made the hydraulic cylinder emptying and piston removing from the package disks complicated. As a consequence of it there occurred a comfort decrease in the vehicle, and in some cases, the destruction of friction clutches. It was found that the reason for this occurrence was the filling degree instability of the compensation and piston chambers of the hydraulic cylinder clutch, which was not taken into account by the existing calculation and design methods under various initial conditions.

The purpose of the study was to improve the implementation accuracy of the required control law of the transmission clutches by purposeful regulating the working fluid volume in the compensation chamber of the hydraulic cylinder clutch.

Methodology and research methods. A road test technique was proposed for identifying and reproducing the conditions of the dynamic phenomenon manifestation. The developed mathematical model of the piston stroke made it possible to assess the dependence of the implementation quality of the required clutch control law when individual gears were engaged on the following parameters: the filling degree of the compensation chamber; features of solenoid valves operation; the stiffness of the return spring; the number of clutch friction pairs.

Scientific novelty and results. On the experimental research basis of the worked out design and the use of scientifically grounded technical solutions the dynamic effect manifestation of the unbalanced “parasitic” centrifugal pressure rise was excluded.

Practical significance. The developed and implemented technical solutions for stabilizing the pressure in the compensation chamber made it possible to ensure the required quality of gear shifting when limiting the dynamic and thermal loading of the friction discs, which made it possible to ensure the required level of dynamic characteristics and comfort ability of the product when shifting gears.



ISSN 0135-3152 (Print)