scholarly journals Supporting locomotive functions of a six-legged walking robot

2011 ◽  
Vol 21 (2) ◽  
pp. 363-377 ◽  
Author(s):  
Krzysztof Walas ◽  
Dominik Belter
Keyword(s):  
Expert Knowledge ◽  
Static Stability ◽  
Population Based ◽  
Walking Robot ◽  
Support Unit ◽  
Fitting Method ◽  
Kolmogorov Theorem ◽  
On Line ◽  
Check Procedure ◽  
The Stability

Supporting locomotive functions of a six-legged walking robotThis paper presents a method for building a foothold selection module as well as methods for the stability check for a multi-legged walking robot. The foothold selection decision maker is shaped automatically, without expert knowledge. The robot learns how to select appropriate footholds by walking on rough terrain or by testing ground primitives. The gathered knowledge is then used to find a relation between slippages and the obtained local shape of the terrain, which is further employed to assess potential footholds. A new approach to function approximation is proposed. It uses the least-squares fitting method, the Kolmogorov theorem and population-based optimization algorithms. A strategy for re-learning is proposed. The role of the decision support unit in the control system of the robot is presented. The importance of the stability check procedure is shown. A method of finding the stability region is described. Further improvements in the stability check procedure due to taking into account kinematic correction are reported. A description of the system for calculating static stability on-line is given. Methods for measuring stance forces are described. The measurement of stance forces facilitates the extended stability check procedure. The correctness of the method is proved by results obtained in a real environment on a real robot.

A Piezoelectrically Actuated Biomimetic Walking Robot

2006 ◽  
Vol 326-328 ◽  
pp. 1435-1438 ◽  
Author(s):  
Abdul A. Yumaryanto ◽  
Jae Bum An ◽  
Li Li Xin
Keyword(s):  
Mobile Robots ◽  
Piezoelectric Ceramic ◽  
Static Stability ◽  
The Other ◽  
Walking Robot ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Composite Type ◽  
Reinforced Plastic ◽  
Tripod Gait

In this paper we present the design and prototype of a six-legged walking robot which uses Lightweight Piezoceramic Composite curved Actuator (LIPCA) as its actuator. LIPCA consists of multiple layers of glass/epoxy and carbon/epoxy that encapsulate a unimorph piezoelectric ceramic actuator. It uses lightweight fiber-reinforced plastic layers, and it is a lighter structure and generates a higher force and a larger displacement than other conventional piezo-composite type actuators. Like most six-legged walking insects including cockroaches, our robot uses the alternating tripod gait where the front and rear legs on the same side move together with the middle leg on the other side for its locomotion. Two LIPCA strips in different phases are used for actuating each tripod so that only one tripod may touch the ground ensuring static stability while walking. All the experiments with the prototype show that LIPCA can be used as an alternative actuator for small and light mobile robots.

Some Stability and Control Aspects of Airframe/Propulsion System Interactions on the YF-12 Airplane

1974 ◽  
Vol 96 (3) ◽  
pp. 820-826 ◽  
Author(s):  
D. T. Berry ◽  
G. B. Gilyard
Keyword(s):  
Static Stability ◽  
Propulsion System ◽  
Jet Propulsion ◽  
Stability And Control ◽  
The Stability ◽  
And Control ◽  
Large Aircraft

Airframe/propulsion system interactions can strongly affect the stability and control of supersonic cruise aircraft. These interactions generate forces and moments similar in magnitude to those produced by the aerodynamic controls, and can cause significant changes in vehicle damping and static stability. This in turn can lead to large aircraft excursions or high pilot workload, or both. For optimum integration of an airframe and its jet propulsion system, these phenomena may have to be taken into account.

Calculation of Static Safety Coefficient about Loess Cave

2011 ◽  
Vol 189-193 ◽  
pp. 2366-2370
Author(s):  
Jun Hong Li
Keyword(s):  
Finite Element ◽  
Yield Criterion ◽  
Soil Layer ◽  
Engineering Application ◽  
Static Stability ◽  
Strength Reduction ◽  
Engineering Practice ◽  
Stability Calculation ◽  
Safety Coefficient ◽  
The Stability

For the loess cave characteristics, such as the thin coverage soil layer at the hole top, the poor self-stabilizing capacity, the large disturbance deformation after excavation and the easy collapse, thus in this paper, the loess cave safety factor is obtained by the method of strength reduction. And the stability calculation analysis is much more perfect. The Northwest Area Lishi loess cave is used in this paper, and the idea of strength reduction finite element method is applied, based on the Drucker-Prager yield criterion, the loess cave static stability analysis is made by the software of ANSYS.The results show that the actual situation can be reflected by the method of finite element strength subtraction. And the obtained loess cave stability coefficient is much closer to the actual steady state, thus showing the certain advantages of stability analysis.The method is also adopted in this paper. And its feasibility can be applied to the engineering practice, also a theoretical basis of reference is provided for engineering application.

Instability of Heated Panels in Supersonic Air Flow

2008 ◽  
Vol 33-37 ◽  
pp. 1101-1108
Author(s):  
Zhi Chun Yang ◽  
Wei Xia
Keyword(s):  
Stability Analysis ◽  
Stability Boundary ◽  
Boundary Curve ◽  
Static Stability ◽  
Static Deformation ◽  
Limit Cycle Oscillation ◽  
Aerodynamic Load ◽  
Aeroelastic System ◽  
Aerodynamic Pressure ◽  
The Stability

An investigation on the stability of heated panels in supersonic airflow is performed. The nonlinear aeroelastic model for a two-dimensional panel is established using Galerkin method and the thermal effect on the panel stiffness is also considered. The quasi-steady piston theory is employed to calculate the aerodynamic load on the panel. The static and dynamic stabilities for flat panels are studied using Lyapunov indirect method and the stability boundary curve is obtained. The static deformation of a post-buckled panel is then calculated and the local stability of the post-buckling equilibrium is analyzed. The limit cycle oscillation of the post-buckled panel is simulated in time domain. The results show that a two-mode model is suitable for panel static stability analysis and static deformation calculation; but more than four modes are required for dynamic stability analysis. The effects of temperature elevation and dimensionless parameters related to panel length/thickness ratio, material density and Mach number on the stability of heated panel are studied. It is found that panel flutter may occur at relatively low aerodynamic pressure when several stable equilibria exist for the aeroelastic system of heated panel.

scholarly journals Сombined ships stability analysis at the stage of design study

2021 ◽  
pp. 29-35
Author(s):  
Ilya A. Gulyaev Gulyaev ◽  
Evgeniy P. Ronnov
Keyword(s):  
Stability Analysis ◽  
Optimization Problems ◽  
Mutual Influence ◽  
Static Stability ◽  
Wind Effect ◽  
Stability Assessment ◽  
Design Study ◽  
Hull Design ◽  
The Stability ◽  
Russian River

. A method of stability analysis for combined ship (oil carrier/platform ship type) at the stage of design study is presented. It should be noted that not all of ship’s main seaworthiness and operational characteristics are the result of a simple addition of the characteristics of an oil carrier and a platform ship. Their mutual influence takes place, which should be taken into account when analysing the stability in the multivariant optimization problems of internal and external design of such ships. This leads to the requirement to adjust the known methods of stability analysis at the initial stages of ship design, which was the purpose of the present work and its originality. Taking into account the multivariance of the task and the hull design type, the stability assessment will be carried out through the analysis of the metacentric height extreme value on the assumption that the requirements of Russian River Register for admissible heeling angle at static wind effect are met. In order to account for nonlinearity of static stability curve when inclining up to the angles of deck immersion into water and emergence of bilge, it is suggested to apply an approximate method of metacentric radius determination. The proposed method of combined ship stability assessment is recommended to apply at the stage of justification and analysis of ship’s key elements as a limitation in the problems of mathematical modeling of optimization of such type of ships. The method allows to exclude from further consideration at the design study stage the possible options that do not meet the requirements of seaworthiness.

scholarly journals Influence of the Average per Capita Income on Credit and Savings Behavior of the Population in Russia

2021 ◽  
Vol 17 (1) ◽  
pp. 57-66
Author(s):  
Valerij Gamukin ◽  
Olga Miroshnichenko
Keyword(s):  
Banking System ◽  
Population Based ◽  
Graphical Analysis ◽  
Behavioral Approach ◽  
Savings Behavior ◽  
Savings Bank ◽  
Per Capita ◽  
Negative Balance ◽  
The Stability ◽  
The Relationship

The successful functioning of the national economy is largely determined by the stability of its banking system. The article is aimed at studying the features of credit and savings behavior of the population based on the reporting data of the Central Bank of Russia and Rosstat for the period 01.02.2011 – 01.08.2020. It is proposed to characterize the features of such behavior based on an analysis of the relationship between the volumes of deposit and credit transactions of the population. The theoretical part of the article considers various aspects of determining the behavioral approach to savings: bank contribution, as a form of realization of investments; conservation as a form of reaction to instability; appeal to the bank as part of the fight against the economic crisis, etc. In the practical part of the study, using comparison and graphical analysis methods, 3 periods of transformation of these types of population behavior were identified based on a change in the relationship between the volume of debt on loans and the volume of deposits. Absolute parameters of marginal sizes of fluctuations of indicators of deposit and credit transactions for use in prognostic purposes were evaluated. The value of the deposit volume shift was calculated, which ensured a reduction in the size of the negative balance of deposit and loan operations in the domestic banking system during the crisis of 2015–2016, which contributed to the stability of this system. The analysis of the compared indicators showed the comparability of the dynamics of the change in the ratio of deposits and debt on loans with the dynamics of the average per capita monetary income of the population. The study revealed a stable increase in the volume of deposits of the population in most monthly indicators, which allows us to expect the stability of the banking system of Russia in terms of a balanced subsystem of deposit and credit operations.

Walking Stability Analysis of Multi-Legged Crablike Robot over Slope

2013 ◽  
Vol 572 ◽  
pp. 636-639
Author(s):  
Xi Chen ◽  
Gang Wang
Keyword(s):  
Mathematical Model ◽  
Stability Analysis ◽  
Stability Criterion ◽  
Stability Margin ◽  
Static Stability ◽  
Matlab Simulation ◽  
And Performance ◽  
The Stability ◽  
The Mathematical Model ◽  
The Relationship

This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.

scholarly journals Establishment and functioning of the Vascular Registry in Hungary

2014 ◽  
Vol 155 (19) ◽  
pp. 755-760 ◽  
Author(s):  
Gábor Menyhei ◽  
Gábor Simó ◽  
Zoltán Szeberin ◽  
Gábor Bíró ◽  
Tamás Kováts
Keyword(s):  
Vascular Surgery ◽  
Organizational Development ◽  
Vascular Diseases ◽  
Artery Aneurysm ◽  
Population Based ◽  
The Past ◽  
Carotid Artery Aneurysm ◽  
Surgical Units ◽  
On Line ◽  
Scientific Results

Randomized controlled trials provide the best evidence in clinical trials; however, they do have limitations. In order to evaluate the effectiveness of treatments, population based registries may also yield useful information about the actual practice and they may enable users to carry out a dynamic follow-up. To evaluate the outcome of vascular procedures, the Vascular Registry in Hungary has been established in 2002. This article presents the establishment and functioning of the Vascular Registry and provides information about scientific results obtained during the past years. The Vascular Registry is an internet based database with on-line input. The backup server is provided by the National Institute for Quality and Organizational Development in Healthcare and Medicines. The database collects data in three different fields: interventions for carotid artery, aneurysm (any type) and lower extremity vascular diseases. Twenty five vascular surgical units record interventions in the registry, which corresponds to two thirds of the whole activity. Since joining the Vascunet Group of the European Society for Vascular Surgery, the registry has contributed to several publications based on evaluation of a large common dataset in different fields of vascular surgery. A validation process has been recently performed which confirmed the internal and external validity of the database. The authors conclude that despite unsolved problems related to financing issues, the Vascular Registry has proved to be a useful tool during the past years. In order to take advantage of the registry to its fullest, measures should be taken to achieve a more complete data recording, increase publication activity on the national dataset, improve the flow of information during operation and develop a system of regular feedback. Orv. Hetil., 2014, 155(19), 755–760.

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