Dynamic modeling and characteristics analysis of lateral-pendulum unicycle robot

Robotica ◽  
2015 ◽  
Vol 35 (3) ◽  
pp. 537-568 ◽  
Author(s):  
Yohanes Daud ◽  
Abdullah Al Mamun ◽  
Jian-Xin Xu
Keyword(s):  
Inverted Pendulum ◽  
Point Of View ◽  
Circular Motion ◽  
Robot Dynamics ◽  
Theoretical Point ◽  
Integral Action ◽  
Characteristics Analysis ◽  
Turning Motion ◽  
Path Curvature ◽  
And Control

SUMMARYLateral-pendulum unicycle robot is a type of single-wheeled mobile robot which utilizes an inverted pendulum mounted laterally for its stabilization and control. Even though this concept was first mentioned in the 1980s, it has not been sufficiently explored especially from the theoretical point of view. Therefore, this robot represents a niche which is still open for more thorough research. This paper presents four contributions to the research of this particular robot. First, the complete model of the robot dynamics is derived and this model can facilitate more accurate study of the robot's static and dynamic behaviors. Secondly, two important constants namely (1)lateral-statics boundaryand (2)lateral-statics constant, which are useful for the lateral stabilization, are derived and analyzed. Thirdly,turning constant, required for the control of the turning motion, is derived and used to study the achievable path curvature in maneuvering control. Lastly, dynamics couplings during steady linear motion and steady circular motion are studied and the necessity of integral action in the lateral controller for circular motion is shown and explained. Throughout this paper, numerical simulation is used intensively and two case studies are presented to illustrate the concepts.

scholarly journals Tractable models of ecological assembly

2020 ◽  
Author(s):  
Carlos A. Serván ◽  
Stefano Allesina
Keyword(s):  
Complex Dynamics ◽  
Point Of View ◽  
Priority Effects ◽  
Stable Configuration ◽  
Theoretical Point ◽  
Ecological Communities ◽  
Top Down ◽  
Bottom Up ◽  
Coexisting Species ◽  
And Control

AbstractEcological assembly, the way natural communities form under ecological time-scales, is a fundamental and yet poorly understood process. Recent theoretical and empirical approaches to assembly consider systems in which a group of species is introduced in a new environment, and dynamics prune the system down to a sub-community of coexisting species. This “top-down” assembly approach contrasts with the well-studied “bottom-up”, or sequential, assembly, in which species from a pool enter the system one at a time, giving rise to priority effects and complex dynamics. Here we determine under which conditions the two approaches are equivalent, i.e., lead asymptotically to the same exact set of coexisting species. To achieve this result, we represent the assembly process as a network in which nodes are sub-communities and edges stand for invasions shifting the composition of the ecological community from a stable configuration to another. This abstraction makes it easy to determine which states the community can occupy, as well as highlight the potential for priority effects or cyclic species composition. We discuss how the equivalence between bottom-up and top-down assembly can advance our understanding of this challenging process from an empirical and theoretical point of view, informing the study of ecological restoration and the design and control of ecological communities.

scholarly journals Properties of nematic LC planar and smoothly-irregular waveguide structures: research in the experiment and using computer modeling

2019 ◽  
Vol 43 (6) ◽  
pp. 976-982
Author(s):  
A.A. Egorov ◽  
L.A. Sevastyanov ◽  
V.D. Shigorin ◽  
A.S. Ayriyan ◽  
E.A. Ayriyan
Keyword(s):  
Liquid Crystal ◽  
Computer Modeling ◽  
Control Systems ◽  
Point Of View ◽  
Theoretical Point ◽  
Irregular Waveguide ◽  
Integrated Optical ◽  
Lc Sensors ◽  
And Control ◽  
Experimental Researches

Nematic liquid crystal planar and smoothly-irregular waveguide structures were studied experimentally and by the computer modeling. Two types of optical smoothly-irregular waveguide structures promising for application in telecommunications and control systems are studied by numerical simulation: liquid crystal waveguides and thin film solid generalized waveguide Luneburg lens. Study of the behavior of these waveguide structures where liquid crystal layer can be used to control the properties of the entire device, of course, promising, especially since such devices are also able to perform various sensory functions when changing some external parameters, accompanied by a change in a number of their properties. It can be of interest to researchers not only in the field of the integrated optics but also in some others areas: nano-photonics, optofluidics, telecommunications, and control systems. The dependences of the attenuation coefficient (optical losses) of waveguide modes and the effective sizes (correlation radii) of quasi-stationary irregularities of the liquid-crystal layers on the linear laser radiation polarization and on the presence of pulse-periodic electric field were experimentally observed. An estimate was made of the correlation radii of liquid-crystal waveguide quasi-stationary irregularities. The obtained results are undoubtedly important for further research of waveguide liquid crystal layers, both from the theoretical point of view, and practical – in the organization and carrying out new experimental researches, for example, when developing promising integrated-optical LC sensors.

scholarly journals On the origin and development of some notions of entropy

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Francisco Balibrea
Keyword(s):  
Applied Sciences ◽  
Dynamical Systems ◽  
Topological Entropy ◽  
Discrete Dynamical Systems ◽  
Point Of View ◽  
Topological Dynamics ◽  
Theoretical Point ◽  
Compact Metric Space ◽  
Continuous Maps ◽  
And Control

AbstractDiscrete dynamical systems are given by the pair (X, f ) where X is a compact metric space and f : X → X a continuous maps. During years, a long list of results have appeared to precise and understand what is the complexity of the systems. Among them, one of the most popular is that of topological entropy. In modern applications other conditions on X and f have been considered. For example X can be non-compact or f can be discontinuous (only in a finite number of points and with bounded jumps on the values of f or even non-bounded jumps). Such systems are interesting from theoretical point of view in Topological Dynamics and appear frequently in applied sciences such as Electronics and Control Theory. In this paper we are dealing mainly with the original ideas of entropy in Thermodinamics and their evolution until the appearing in the twenty century of the notions of Shannon and Kolmogorov-Sinai entropies and the subsequent topological entropy. In turn such notions have to evolve to other recent situations where it is necessary to give some extended versions of them adapted to the new problems.

Balance Recoverability and Control of Bipedal Walkers with Foot Slip

2021 ◽  
Author(s):  
Marko Mihalec ◽  
Mitja Trkov ◽  
Jingang Yi
Keyword(s):  
Inverted Pendulum ◽  
Robot Dynamics ◽  
Low Friction ◽  
Inverted Pendulum Model ◽  
Pendulum Model ◽  
Controller Performance ◽  
Measurement Noises ◽  
Simulation Results ◽  
And Control ◽  
Stability Results

Abstract Low-friction foot/ground contacts present a particular challenge for stable bipedal walkers. The slippage of the stance foot introduces complexity in robot dynamics and the general locomotion stability results cannot be applied directly. We relax the commonly used assumption of non-slip contact between the walker foot and the ground and examine bipedal dynamics under foot slip. Using a two-mass linear inverted pendulum model, we introduce the concept of balance recoverability and use it to quantify the balanced or fall-prone walking gaits. Balance recoverability also serves as the basis for the design of the balance recovery controller. We design the within- or multi-step recovery controller to assist the walker to avoid fall. The controller performance is validated through simulation results and robustness is demonstrated in the presence of measurement noises as well as variations of foot/ground friction conditions. In addition, the proposed methods and models are used to analyze the data from human walking experiments. The multiple subject experiments validate and illustrate the balance recoverability concept and analyses.

scholarly journals PRELIMINARY EVALUATION OF A COMMERCIAL 360 MULTI-CAMERA RIG FOR PHOTOGRAMMETRIC PURPOSES

2018 ◽  
Vol XLII-2 ◽  
pp. 1113-1120 ◽  
Author(s):  
L. Teppati Losè ◽  
F. Chiabrando ◽  
A. Spanò
Keyword(s):  
Point Of View ◽  
Preliminary Evaluation ◽  
Theoretical Point ◽  
Control Points ◽  
Spherical Image ◽  
Spherical Images ◽  
And Control ◽  
Orientation Parameters ◽  
Spherical Panorama

The research presented in this paper is focused on a preliminary evaluation of a 360 multi-camera rig: the possibilities to use the images acquired by the system in a photogrammetric workflow and for the creation of spherical images are investigated and different tests and analyses are reported. Particular attention is dedicated to different operative approaches for the estimation of the interior orientation parameters of the cameras, both from an operative and theoretical point of view. The consistency of the six cameras that compose the 360 system was in depth analysed adopting a self-calibration approach in a commercial photogrammetric software solution. A 3D calibration field was projected and created, and several topographic measurements were performed in order to have a set of control points to enhance and control the photogrammetric process. The influence of the interior parameters of the six cameras were analyse both in the different phases of the photogrammetric workflow (reprojection errors on the single tie point, dense cloud generation, geometrical description of the surveyed object, etc.), both in the stitching of the different images into a single spherical panorama (some consideration on the influence of the camera parameters on the overall quality of the spherical image are reported also in these section).

Theoretical and Experimental Study of Metallic Dot Agglomeration Induced by Thermal Dewetting

2015 ◽  
Vol 3 (2) ◽  
Author(s):  
Masahiko Yoshino ◽  
Zhenxing Li ◽  
Motoki Terano
Keyword(s):  
Experimental Study ◽  
Contact Angle ◽  
Free Energy ◽  
Point Of View ◽  
Theoretical Point ◽  
Fabrication Method ◽  
Comprehensive Understanding ◽  
Nanodot Array ◽  
And Control ◽  
Theoretical Minimum

The authors previously developed a new fabrication method for a metal nanodot array, by combination of nanogroove grid patterning and thermal dewetting of metal deposited on a substrate. However, a comprehensive understanding of the thermal dewetting mechanism is necessary to improve the quality and control the variation of the metallic nanodot array. In this study, thermal dewetting-induced nanodot agglomeration mechanism is studied from a theoretical point of view. An analytical model is proposed, based on the total free energy of a dot and substrate system. The theoretical minimum and natural dot sizes show the same trend with an increase of contact angle. The theoretical model is validated by the experimental results.

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

A novel cryptosystem based on abstract automata and Latin cubes

2015 ◽  
Vol 52 (2) ◽  
pp. 221-232
Author(s):  
Pál Dömösi ◽  
Géza Horváth
Keyword(s):  
Block Cipher ◽  
Finite Automata ◽  
Theoretical Background ◽  
Point Of View ◽  
Theoretical Point ◽  
Transition Matrices ◽  
Encryption And Decryption ◽  
Secret Keys ◽  
Automata Network ◽  
Fully Functioning

In this paper we introduce a novel block cipher based on the composition of abstract finite automata and Latin cubes. For information encryption and decryption the apparatus uses the same secret keys, which consist of key-automata based on composition of abstract finite automata such that the transition matrices of the component automata form Latin cubes. The aim of the paper is to show the essence of our algorithms not only for specialists working in compositions of abstract automata but also for all researchers interested in cryptosystems. Therefore, automata theoretical background of our results is not emphasized. The introduced cryptosystem is important also from a theoretical point of view, because it is the first fully functioning block cipher based on automata network.

Graffiti als Version und Subversion–Praxen kultureller Re-Regulierung und die Möglichkeit von Gratiforschung

2010 ◽  
Vol 55 (2) ◽  
pp. 11-25 ◽  
Author(s):  
Bernd Dollinger
Keyword(s):  
Social Life ◽  
Point Of View ◽  
Theoretical Point ◽  
Research Practice ◽  
Wird Eine ◽  
Multiple Perspectives

Der Beitrag geht von Versuchen aus, integrative Perspektiven einer überaus heterogenen Graffitiforschung zu bestimmen. In Auseinandersetzung insbesondere mit Bruno Latours Ansatz des »Iconoclash« wird eine kulturtheoretische Referenz bestimmt, die Graffiti als Version identifiziert, d. h. als semiotisch orientierte Veränderung räumlich situierter Ordnungs- und Regulierungspraxen. Ihnen kann, wenn auch nicht zwingend, eine subversive Qualität zukommen. Durch die Ausrichtung am Konzept einer Version wird beansprucht, Forderungen einer normativ weitgehend abstinenten, nicht-essentialistischen und für komplexe Fragen der Identitäts- und Raumpolitik offenen Forschungspraxis einzulösen.<br><br>The contribution attempts to integrate multiple perspectives of current largely heterogeneous graffiti scholarship. Referring to Bruno Latour’s concept »iconoclash«, we discuss graffiti from a cultural-theoretical point of view as a »version«. It appears as a semiotically oriented modification of spatially situated practices that regulate social life. Often, but not necessarily, these practices involve subversive qualities. The concept of »version« facilitates a non-normative and non-essentialist strategy of research. This enables an explorative research practice in which the complex matters of identity and space politics that are associated with graffiti can be addressed.

DEVELOPMENT OF COMPUTERIZED MONITORING AND CONTROL SYSTEM OF THE MOBILE ROBOT’S POSITIONING ON LARGE FERROMAGNETIC SURFACES BASED ON INTELLIGENT TECHNIQUES. COMPLEX OF TASKS OF MONITORING AND AUTOMATIC CONTROL OF MOBILE

2019 ◽  
pp. 37-47
Author(s):  
Yao Yueqin ◽  
Oleksiy Kozlov ◽  
Oleksandr Gerasin ◽  
Galyna Kondratenko
Keyword(s):  
Automatic Control ◽  
Point Of View ◽  
Monitoring And Control ◽  
Large Area ◽  
Monitoring And Control System ◽  
Technical Parameters ◽  
Automatic Control Systems ◽  
Current State ◽  
Computerized Monitoring ◽  
And Control

Analysis and formalization of the monitoring and automatic control tasks of the MR for the movement and execution of various types of technological operations on inclined and vertical ferromagnetic surfaces are obtained. Generalized structure of mobile robotic complex is shown with main subsystems consideration. Critical analysis of the current state of the problem of development of universal structures of mobile robots (MRs) for the various types of technological operations execution and elaborations of computerized systems for monitoring and control of MR movement is done. In particular, wheeled, walked and crawler type MRs with pneumatic, vacuum-propeller, magnetic and magnetically operated clamping devices to grip with vertical and ceiling surfaces are reviewed. The constructive features of the crawler MR with magnetic clamping devices capable of moving along sloping ferromagnetic surfaces are considered. The basic technical parameters of the MR are shown for the further synthesis of computerized monitoring and automatic control systems. Formalization of the tasks of monitoring and control of the MR positioning at the processing of large area ferromagnetic surfaces is considered from the point of view of control theory.

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