SCIENCE & EDUCATION

Currently, developers of multi-wheeled vehicles (MWV) show growing interest in an electro-mechanical drive in the «motor-axis»implementation. However, in designing such types of traction electric drive (TED) the problems arise, mainly, from a lack of creating experience and of ready algorithmic solutions to control the traction motors. Methods for implementing the individual TED cannot be used because of the cross-axle differential available in the leading axle drive, which does not enable the input torque control of each wheel singly. The paper offers a law to control a traction electric drive of MWV leading axles that includes the law to control the traction and braking torques on the leading axles as well as algorithms of anti-lock brake and traction control systems.Simulation methods of mathematical modeling have proven efficiency and effectiveness of the proposed control law, when performing MWV maneuvers. Research results can be useful for companies in automotive industry, which, first of all, deal with design and manufacturing of special multi-wheeled vehicles of various classes and purposes, as well as for institutions, which develop control systems for wheeled transport equipment.

Exploring the development trends of the modern automobile, you can see that manufacturers are constantly improving a control level of parameters of wheeled vehicles motion, achieving the maximum level of car stability and controllability. The slow development of similar systems in the Russian automotive industry is the cause of the lack of research in the field of power-distribution under specific driving conditions, typical for the automobile all-wheel drive vehicles. The purpose of work is a development of methods to control the curvilinear motion hire 4x4 with a link to the rear axle, providing the increase of stabilization and tracking stability of the car. The paper presents developed algorithms of torque redistribution between driving axles and wheels of a car 4x4 with the torque redistribution between the driving axles  in the range of 100:0 - 0:100 and 100:0 - 50:50 and with the torque redistribution between the wheels of the rear axle in the range of 0:100, ensuring the stabilization and tracking stability of the car. The paper offers a criterion for system operation to have dynamic stability of the wheel vehicle motion. It also presents analysis to compare the efficiency of different algorithm combinations for motion stabilization of cars with a link to rear axle.

The article describes the design of control systems for automobile transmission. It gives a classification and distinct characteristics of transmissions. Kinematic schemes of rotary shafts and planetary gearboxes of leading companies in the field of world automotive engineering are presented. The advantages of automated transmissions have been studied. The prospects of creating the control systems of transmissions based on artificial intelligence techniques are offered. The article is intended for specialists in the field of automation control of car transmissions.

The paper presents theoretical dependences which allow to calculate the main parameters of a pneumatic actuator of a multi-step mechanical synchronized gearbox, depending on the parameters of an engine, a gearbox and conditions of traveling resistance during the synchronization process with alternating pressure and various air escapes into a pneumatic cylinder: critical and subcritical escapes at constant pressure. Results of theoretical investigations and bench tests were compared. Calculated values of synchronization time at separate stages and at the whole cycle of gear actuation differed from experimental data no more than by 10-25%.

The article deals with a problem of optimal control of caterpillar machine movement with regard to the driver as a feedback loop of the dynamic system. In order to build a control algorithm a mathematical model of caterpillar machine motion which takes into account non-holonomic links between caterpillars and soil was used. External control action was formalised in the form of an objective function. State parameters of an object were determined by the measuring system which was also subject to random perturbations. The maximum principle of P.S. Pontryagin was used for synthesising optimal control of a caterpillar machine. During optimization of an object one wants to find a vector of control action considering constraints from the minimum of composed functions expressing specified criteria. A problem of synthesizing time optimal control was considered. It was noticed that a system is time optimal if minimal transition time is provided, considering restrictions imposed on control and output coordinates. The principle of forcing dynamic processes at certain time intervals by increasing control signal within the specified range was used to reduce duration of the transition process.

It was proposed to carry out performance evaluation of active vibration damping in multi-mass dynamic systems of metal structures of excavators and jib cranes when damper’s power body is located between oscillating masses, in comparison with external resistance damping. Results of synthesis of damping effect which provides a specified degree of oscillation decline in metal structures under force excitations and self-oscillations were presented. It was shown that allocation of the active damper’s power body between the working body’s installation unit and metal structures of machines allowed one to improve dynamic properties of the specified machines significantly.

A spatial model of interaction between a wheel vehicle and a road surface was considered in this article. Expressions for kinematic and power factors that determine motion and oscillations of a wheel vehicle, transmission elements and its running gear under spatial loads were obtained. It was shown that specifying wheels displacement in the coordinate system connected with the vehicle’s body allowed to make this mathematical model of motion significantly more precise. This approach provides a possibility to obtain a reliable estimate of exploitation operating modes of aggregates and systems of a wheel vehicle under conditions of passing engineering constructions.

The purpose of this paper is to develop methods of improving design of a truck cab at a dynamic impact on A-pillars; the aim of this design is to increase characteristics of passive safety. According to the results of the calculation the authors estimate maximum movements of primary elements of the design and residual living space; the authors analyse behaviour of the door frames, window frames, pillars, frame girders, other elements of the truck cab, etc. The design is experiencing contact, buckling, crumpling, bending, appearance of plastic hinges. To improve the design, the most sensitive areas and locations of plastic hinges were found. As an indirect assessment of stiffness in the cab as a whole, the authors suggest that, besides the recommended living space, acceleration of the mass center of a dummy should be used; the maximum value of acceleration at a certain time interval should be regulated, too. Basing on a comprehensive analysis of the impact of structural factors on passive safety of a truck cab at an impact on A-pillars, modifications to vehicle interior (increased thickness of the main parts of cab doors, introduction of local pads and foam aluminium racks inside the truck cab), which improved truck passive  safety. Key words: passive safety, truck cab, pillar, pads, foam aluminium, impact load, LS-DYNA.

In this article the author compares dynamic characteristics of a vehicle with both a usual and combined power installation which includes an internal combustion engine and flywheel energy storage; the comparison was carried out with the use of a developed mathematical model. Influence of power consumption of a flywheel on dynamic characteristics of a vehicle with hydrostatic transmission was estimated. Factors limiting power coefficients and possibilities of using combined power installation were established. The obtained results allow to optimize overall dimensions of the flywheel, control laws of its drive and the vehicle’s transmission.

Nowadays various methods of capacity regulation are or may be applied to screw compressors (SC). This paper presents research results of two methods: changing rotation frequency of the driving engine’s shaft and restriction of air in the suction passage. Comparative analysis of the research results allows to select the most suitable method for any particular case. Exergy efficiency coefficient was chosen as an economical operation criterion; this coefficient allows to estimate the degree of thermodynamic perfection of the screw compressor quantitively, when using various regulation methods.

In this paper processes of formation of dynamic loading were investigated; ways of improving durability of shrink disks of transport vehicle transmissions were justified. A hypothesis of destruction of these disks due to the impact of high-frequency perturbations produced by both an engine and a hydraulic torque converter was proposed; parametric resonance oscillation conditions were determined. Unstable zones for parametric oscillations were defined, using the Mathieu equation; need for filtration of high-frequency perturbations was determined in order to limit the parameter of modulation depth. Estimation of the influence of developed procedures on durability of shrink disks was conducted.

In this article the authors analyze various energy recovery systems of hybrid vehicles. Conclusions on inadequacy of existing technical solutions were drawn. The article also describes principles of selecting an energy recovery device that meets the performance level requirements of a hybrid vehicle. The authors describe the construction of an experimental vehicle with a hybrid powertrain. They also developed an algorithm of the operation of a vehicle with a hybrid powertrain during its movement in the urban cycle, which takes power balance in the drive into account. Results of the experimental research of a vehicle confirmed existence of limitations associated with a mounted energy storage device and electrical components. In addition, requirements for an "ideal" battery were specified.

The purpose of this article is to analyze the influence of structural factors of truck cabs on parameters affecting passive safety (doors, lining boards, use of aluminum foam, etc.). According to the calculation results, the maximum movement of the primary elements of the design was estimated along with the residual living space; the authors also analyzed behavior of door frames, window frames, pillars, side members, the remaining elements of the cabin. The design experiences contact, buckling, wrinkling, bending, appearance of plastic hinges. In order to improve the design, the most flexible areas and areas with plastic hinges were determined. For indirect assessment of the cabin stiffness it was proposed to use, beside the recommended volume of the living space in a cab, acceleration of the mannequin’s center of mass the maximum value of which in a certain moment of time is also specified. Design modifications for the truck cab were developed on the basis of a comprehensive analysis of the influence of structural factors on passive safety on the frontal impact; these modifications improved safety of the truck.

In this work rational finite element models of head restraints of car seats were developed. Assessment of those models regarding errors of simulation and correspondence to the requirements of UNECE Regulations № 25 was carried out. Those models were also evaluated regarding errors of results; labor cost of development and solving with the use of software packages which implement the FEM (ANSYS, Femap and LS-DYNA) was also carried. Calculations based on the finite element method provide a possibility to obtain the whole information on the process of emergency loading required for estimating safety of car seats in case of  rear-end collisions.

The authors describe a project technology of solving multi-criteria parametric optimization problems in the field of motor transport. This technology is based on a two-stage approach. Stage 1 is optimization of performances of units and devices of a car, presented as a generalized description. Stage 2 is optimization of design parameters of units and devices of real designs. Performances of units and devices should be moved close to “optimal” ones obtained at the previous stage. Test items (two- and tri-axial cars) used for verification of the mathematical description are presented in the article. Application software STABCON 2.0 was developed for solving design and finishing tasks in the field of automotive industry. The software system is flexible and can be adjusted for solving design problems in the field of automotive technology beyond limits of controllability and stability properties. A designer can use previously created models. The authors draw a conclusion on the need for setting up a competence center for training industry experts and assisting them in solving optimal design tasks.

In this work rational finite element models of head restraints of car seats were developed for studies of passive safety under impact loading, affected in accordance with the current standard of passive safety. Assessment of those models regarding errors, labor cost of development and solving with the use of software packages which implement the FEM (ANSYS, Femap and LS-DYNA) was carried out along with assessment of influence of head restraint’s materials on the solution. Calculations based on the finite element method make it possible to obtain the whole information on the process of emergency loading required for estimating the safety of car seats in case of  rear-end collisions.

The authors present a computational model of a pneumatic tubeless tire developed with the use of the finite element method in a physically and geometrically nonlinear formulation. This model takes into account: tire design features and mechanical properties of materials from which it is made; the nature of the tire contact interaction with the supporting rough surface. Adequacy of the tire model was confirmed experimentally. Interaction between road wheels (fitted with a tubeless pneumatic tire) with a supporting surface with irregularities of various shapes and sizes was investigated. The obtained results are intended to clarify the wheeled mover in dynamic models of vehicle for study of oscillation when driving on different types of roads and off-road.

Creation of means of effective protection from external dynamic effects has always been one of the most important problems of modern equipment. The aim of this work is to increase smooth running of multi-wheeled vehicles using an adaptive control of elastic-damping elements of the suspension system. On the basis of application of methods of fuzzy logic, adaptive laws of a continuous suspension control system of multi-wheeled vehicles, namely the “inertial damper” adaptive law and the adaptive law of the counteraction of a linear-angular fluctuations, were developed. Methods of simulation modeling were used to determine that efficiency (reduction of the variance of the vertical accelerations at the driver's place compared to the unmanageable adaptive suspension) of the “inertial damper” law is 7...20%; one of the laws of counteraction of linear-angular fluctuations - 0...13%.

The required level of damping a multiple-seated oscillatory system, as it is known, depends on the nature of the external impact. In this case, regulation of damping characteristics depending on the operation mode of depreciation systems is one of the main directions of further improvements. Increasing the quality of primary control systems for suspension of multi-wheeled vehicles with the number of axes more than three appears to be very promising. An adaptive relay control law for damped suspension of multi-wheeled vehicles was developed in order to prevent linear-angular fluctuations in the housing. Methods of simulation modeling were used to determine that efficiency (reduction of variance of vertical accelerations at the driver's place compared to the unmanageable suspension) of the adaptive law of counteraction to linear-angular fluctuations is 7...22%. Introduction of an adaptive component increases efficiency of the algorithm by 5...10% compared to the non-adaptive law.

The required level of damping a multisupporting oscillatory system, as it is known, depends on the nature of the external impact. In this case, regulation of damping characteristics depending on the operation mode of depreciation systems is one of the main directions of further improvements. Direction of increasing the quality of primary control systems for suspension of multi-wheeled vehicles (MWV) with the number of axes more than three appears to be very promising. A mathematical model and calculation methodology of design parameters of a pneumohydraulic cushion with backpressure and three-level damping for controlled suspensions of multi-axis chassis were developed. An example of calculation of a cushion for MWV suspension with a 8x8 wheel formula and total mass of 60 tons is given. The adaptive law of relay control of MWV suspension system, namely the “inertial damper” adaptive law, was developed with the use of fuzzy logic methods.