Obstacle Capability of an Air-Ground Amphibious Reconnaissance Robot with a Planetary Wheel-Leg Type Structure

According to the requirements of the reconnaissance robot for the ability to adapt to a complex environment and the in-depth study of the obstacle climbing mechanisms, a planetary wheel-leg-combined mechanism capable of adapting to complex terrains is proposed. According to the proposed planetary wheel-leg-combined mechanism, the land part of the air-ground amphibious reconnaissance robot is designed. Considering the obstacle and fast marching performance, four groups of combined wheel-leg mechanisms are adopted in the land bank. Under the action of three kinds of obstacles, the stability and the movement ability of the robot are analyzed by using the static method. The parameter model of the reconnaissance robot is built by a virtual prototype dynamics software MSC.ADMAS. The kinematic characteristic curves of each component and the whole prototype are obtained, which provides a theoretical basis for the design and numerical calculation of the robot structure. Finally, the climbing ability tests of the reconnaissance robot prototype verify the reliability and practicability of the body structure of the reconnaissance robot.

Instant Center Identification of Single-Loop Multi-DOF Planar Linkage Using Virtual Link

Instant center is an important kinematic characteristic which can be used for velocity and singularity analysis, configuration synthesis and dynamics modeling of multi-degree of freedom (multi-DOF) planar linkage. The Aronhold–Kennedy theorem is famous for locating instant centers of four-bar planar linkage, but for single-loop multi-DOF linkages, it fails. Increasing with the number of the links of single-loop multi-DOF planar linkages, the lack of link relationship makes the identification of instant center become a recognized difficulty. This paper proposes a virtual link method to identify instant centers of single-loop multi-DOF planar linkage. First, three types of instant centers are redefined and the instant center identification process graph is introduced. Then, based on coupled loop chain characteristic and definition of instant center, two criteria are presented to convert single-loop multi-DOF planar linkage into a two-loop virtual linkage by adding the virtual links. Subsequently, the unchanged instant centers are identified in the virtual linkage and used to acquire all the instant centers of original single-loop multi-DOF planar linkage. As a result, the instant centers of single-loop five-bar, six-bar planar linkage with several prismatic joints are systematically researched for the first time. Finally, the validity of the proposed method is demonstrated using loop equations. It is a graphical and straightforward method and the application is wide up to single-loop multi-DOF N-bar (N ≥ 5) planar linkage.

Macroseismic and instrumental studies of the Verkhniy Fiagdon earthquake on January 26, 2020

Изучение землетрясений территории Северного Кавказа не просто актуальная задача. Ее решение является насущной необходимостью, требует ежедневного, кропотливого труда для повышения уровня комфортности жизни населения. Целью работы является представить достаточно подробный анализ ощутимого тектонического землетрясения, случившегося 26января 2020 года в 21h01m по Гринвичу с интенсивностью сотрясений в эпицентре 4-5 баллов, произошедшего на территории Республики Северная Осетия-Алания. Методы исследования включали: определение параметров гипоцентра сейсмического события с помощью программно-вычислительных комплексах WSG и HYPO71; описание геолого-тектонической позиции очага; расчет и графическое представление механизма очага землетрясения по знакам первых вступлений P-волн; сбор макросейсмических данных путем выездов на места проявления землетрясения для определения интенсивности сотрясений земной поверхности в баллах; рассмотрение историческойи современнойсейсмичности в области исследуемого землетрясения. В результате получено следующее решение параметров гипоцентра землетрясения: φ=42,69°N, φ=44,15°E, h=6 км, Кр=11,2. Очаг землетрясения находился вблизи зоны возникновения очагов землетрясений (ВОЗ) Главного хребтав сейсмотектоническом блоке, расположенном между Главным Кавказским и АдайкомКазбекским разломами. По знакам первых вступлений продольных P-волн на 20 станциях рассчитан механизм очага землетрясения. Согласно полученному решению очаг землетрясения возник в верхней части земной коры под действием сжимающих напряжений, тип движения – взбросо-сдвиг, что согласуется с кинематической характеристикой зоны Главного хребта. Землетрясение, получившее название Верхне-Фиагдонское, характеризуется отсутствием заметного афтершокового процесса, однако анализ имеющихся волновых форм ближайшей сейсмической станции показал наличие последовательности слабых сейсмических событий. Макросейсмический эффект землетрясения был исследован сотрудниками Северо-Осетинского филиала ФИЦ ЕГС РАН в 25 населенных пунктах. Согласно результатам опроса, максимальная интенсивность сотрясений составила 4-5 балла. По результатам оценки интенсивности построена соответствующая карта пунктов-баллов землетрясения. Приведены сведения по истории сейсмичности очаговой зоны исследуемого землетрясения за более чем 150 лет The earthquakes study in the North Caucasus is not just an urgent task. Its solution is an urgent need. It requires daily, painstaking work to increase the comfort level of the population’s life. The aim of the work is to present a sufficiently detailed analysis of the tangible tectonic earthquake on January 26 at 21h01m GMT, which occurred on the territory of the Republic of North Ossetia-Alania. Intensity of the shok equaled 4-5 in the epicenter. Research methods included: determination of the parameters of the seismic event hypocenter using the WSG and HYPO71 software complexes; description of the geological and tectonic position of the source; calculation and graphical presentation of the earthquake source mechanism by the signs of the first arrivals of P-waves; collection of macroseismic data by visits to the places of earthquake manifestation to determine the intensity of shaking the earth’s surface in points; consideration of historical and modern seismicity in the area of the investigated earthquake. As a result, the following solution of parameters of an earthquake is received: φ=42,69°N, φ=44,15°E, h=6 km, KР=11,2. The epicenter of the earthquake occurs near the Main ridge zone. In more detail, the earthquake happened in the seismotectonic block located between the Main Caucasian and Adaykom-Kazbek faults. For the earthquake, the mechanism of the focus was calculated according to the signs of the first arrivals of longitudinal P-waves at 20 stations. According to the solution, the earthquake occurred in the upper part of the earth’s crust under the action of compressive stresses, the type of motion is upthrust-strike-slip, which is consistent with the kinematic characteristic of the Main Ridge Zone. The earthquake, called Verkhniy Fiagdon earthquake, is characterized by the absence of a noticeable aftershock process, but the analysis of the available wave forms of the nearest seismic station showed the presence of a sequence of weak seismic events. The macroseismic effect of the earthquake was investigated in 25 settlements by the staff of the North Ossetian branch of the Geophysical Survey of the Russian Academy of Sciences. According to the survey results, the maximum intensity of concussions was 4-5 points. A map of earthquake manifestations in localities constructed based on the results of the intensity assessment. The history of seismicity of the focal zone of the investigated earthquake for the last 150 years is studied

A genetic ant colony algorithm-based driving cycle generation approach for testing driving range of battery electric vehicle

In this article, an approach of driving cycle generation for battery electric vehicle is proposed based on genetic ant colony algorithm. The real-world traffic information is utilized to build up a local driving cycle database, in which definitions of the short trip and kinematic characteristic parameters are discussed to describe the driving cycle. A method of principal component analysis is taken as a preprocessor for reducing the dimension of driving cycle data. And then, genetic ant colony algorithm is used to classify the type of short trips and generate the driving cycle. The experimental results on board indicate that, compared with the Economic Commission for Europe driving cycle, the error of driving range and characteristic parameters tested by genetic ant colony driving cycle are reduced by 18.1% and 18.3%, respectively. Therefore, genetic ant colony driving cycle is a good candidate to test driving range of battery electric vehicle.

Development of the Flexible Ring on an Elastic Continuous Foundation Tire Model for Planar Vibration of the Heavy Load Radial Tire

This paper investigates the planar vibration characteristic of heavy load radial tires with a large flat ratio. A proposed tire model with a flexible ring on an elastic continuous foundation is investigated utilizing kinematic modeling and experimental modal analysis. Planar coupling deformation of the radial and tangential direction is considered to enrich the kinematic characteristic of the flexible belt and the continuous sidewall; a flexible ring on an elastic continuous foundation tire model is proposed to investigate the coupling vibration characteristic between the flexible belt and the continuous sidewall. In-extensibility assumption is utilized to simplify the proposed tire model and the planar vibration modal features of the heavy load radial tire are discussed. The variation of the inflation pressure on the radial and tangential stiffness of the sidewall spring model is enriched into the flexible ring on an elastic continuous foundation tire model to extend the modal prediction of the tires with a different inflation pressure. Taking the relative error between the experimental and analytical modal resonance frequency of the tested tire with a different inflation pressure as the object value, structural parameters of the proposed tire model are identified by a backward genetic algorithm. Experimental and theoretical results show that: the planar coupling vibration characteristic of the heavy load radial tire can be predicted precisely with the flexible ring on an elastic continuous foundation tire model; meanwhile, considering the linear variations of the radial and tangential sidewall stiffness due to the inflation pressure, the proposed tire model can be extended to analyze the vibration characteristic of the heavy load radial tire with a different inflation pressure.

Design optimization of minivan MacPherson-strut suspension system based on weighting combination method and neighborhood cultivation genetic algorithm

In this paper, the kinematic characteristic analysis and optimization design of a minivan MacPherson-strut suspension system are performed. Design requirements of a minivan suspension system are described first, and then the design process is presented. A typical MacPherson suspension model of the minivan is conducted. Through the established model, the simulation of parallel wheel travel of the suspension system of the minivan is carried out and analyzed. After initial analysis, wheel alignment parameters especially the toe angle and camber angles need to be optimized to meet the requirements of the desired design value. The characteristic curves of wheel alignment parameters are drawn and the corresponding non-ideal characteristics are found. The optimization objective is to reduce the variation of the unreasonable alignment parameters, and the design variables are given through the sensitivity analysis. The design parameters are reasonably grouped according to different kinematic characteristics, thus, a unified objective function is established by direct weighing combination method. Finally, the established objective function is optimized and designed with neighborhood cultivation genetic algorithm. By comparing the original and optimized results, the better wheel alignment parameters are obtained and the system performances of suspension are further improved.

A novel accuracy model for the intrinsic kinematic property of a prismatic pair

A novel accuracy model is proposed to analyze the intrinsic kinematic property of the prismatic pair. The geometric error of guide rails, the elastic constrained structure of moving joints, and fixed joints are considered synthetically. The geometric error is measured by the 5D laser interferometer system with slide blocks. The elastic moving joints are equivalent to the springs, while the fixed joints to contact layers. The equilibrium equations are then set up and the analytical solution for five degrees-of-freedom errors of the moving table is revealed. The global invariant errors, including the straightness error space and the spherical image error surface, are proposed to describe the global kinematic characteristic of the moving table. Along with the comparison between the measured and theoretical indicators, the verification experiment to prove the availability of the model is carried out. As the movement of the table can be forecast precisely and evaluated objectively, the new methodology provides a theoretical basis for machine tool manufacture.

Roots Characteristics of a flexible and mature vegetation: Preliminary results of experimental investigation in a meandering laboratory flume

Vegetation controls sediment dynamics and affects the kinematic characteristics of flow in rivers. The uprooting mechanism is strongly affected by mechanical properties, morphology and branching of the roots system. This work presents preliminary results of experimental work conducted in a laboratory meandering flume. The work aims to investigate how the geometrical and mechanical characteristics of the roots of a real, flexible and mature vegetation could vary along the bend. Results show that both the geometrical and the mechanical characteristics of the roots assume higher/lower values in peculiar sections of the bend suggesting that they could be affected by the kinematic characteristic of flow.

Theoretical Approach of Wear for Slide-Friction Pairs

A number of different mechanisms and devices in mechatronic systems may involve sliding-friction surfaces. The issues of service life and its prediction for the details of such surfaces have always been of particular importance. Having studied the wear process prediction theories that have been developed in the course of time, which can be classified by dividing them in definite groups based on similar theoretical approach one can state that each of them has different shortcomings, which might affect the result precision, when essential basic parameters have been disregarded, as well as create a need for useless additional practical experiments, as a result of which theoretical calculation becomes unnecessary. [4] The article determines the most suitable wear calculation model that allows considering the set of parameters necessary for calculating slide-friction pair. Wearing usually proceeds in three stages: the running-in stage, the normal wear stage, and the intensive wear stage. The proposed model is provided for normal wear stage calculations. The proposed model for wear calculation is based on the application of theories from several branches of science to the description of 3D surface micro-topography in accordance with random field theory, assessing the material’s physical and mechanical characteristic quantities, substantiating the regularities in creation of material particles separated during the wear process and taking into consideration definite service conditions of fittings. Since the wear process is variable and many-sided, it is influenced by numerous different parameters, for example, surface geometry (roughness, waviness, form deviation, etc.), physical and mechanical conditions of the upper layer, material components, wear regime, wear temperature, etc. Based on the regularities stated in the article one can propose the following wear calculation sequence [4]:1) Initial data should be stated which will be further necessary in calculations: constructive-kinematic characteristic quantities (rated area Aa of wearing component, load P, gliding movement speed v, movement time t), fatigue characteristic of friction component material (friction coefficient f (f≤0,1) and material fatigue destruction parameters (m, σ-1, N0), mechanical characteristic quantities of material (E, μ);2) Parameters should be stated after attachment: surface roughness parameters (Sa, Sm1, Sm2, Sm2a), initial wear Up and corresponding time Tp, tolerated wear Umax.