Design and locomotion analysis of a novel deformable mobile robot with worm-like, self-crossing and rolling motion

Robotica ◽  
2014 ◽  
Vol 34 (9) ◽  
pp. 1961-1978 ◽  
Author(s):  
Yaobin Tian ◽  
Yan-An Yao ◽  
Wan Ding ◽  
Zhiyuan Xun
Keyword(s):  
Mobile Robot ◽  
Degrees Of Freedom ◽  
Mode Analysis ◽  
Spherical Joint ◽  
Initial State ◽  
Motion Modes ◽  
Regular Triangle ◽  
Series Of Experiments ◽  
A Chain ◽  
Rolling Mode

SUMMARYThis paper presents a novel deformable mobile robot with five degrees of freedom (DOFs). The robot contains two equivalent expandable triangular platforms connected by three equivalent chains. Each platform is a regular triangle with a single DOF. Each chain consists of two links and three joints (one spherical joint at the middle of a chain, and one revolute joint at each end of the chain). Through kinematic and locomotion mode analysis, the robot exhibits three motion modes: worm-like, self-crossing, and rolling modes. The worm-like and self-crossing modes can be used for narrow passages (e.g., pipelines, holes, and caves). The rolling mode has three different directions at the initial state. By switching between these, the robot can operate on rough ground. To verify the locomotion modes and functionality of the robot, the results of a series of experiments performed on a manufactured prototype are reported.

A Novel Underactuated Tetrahedral Mobile Robot

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Zhirui Wang ◽  
Yaobin Tian ◽  
Yan-an Yao
Keyword(s):  
Mobile Robot ◽  
Degrees Of Freedom ◽  
Mobility Analysis ◽  
Universal Joint ◽  
Tetrahedral Structure ◽  
Planar Mechanism ◽  
Series Of Experiments ◽  
Low Costs ◽  
Locomotion Analysis ◽  
Rolling Locomotion

This paper presents a novel underactuated tetrahedral mobile robot with 12 degrees-of-freedom (DOFs). The robot contains four vertices and six URU chains (where U represents a universal joint and R represents an actuated revolute joint). The tetrahedral structure makes the robot have continuous mobile ability at any posture. The mobility analysis has been made and demonstrates the feasibility of underactuated which demands fewer devices and low costs. A kind of rolling locomotion of the robot is proposed, and the feasibility of the locomotion is proved by the kinematic and locomotion analysis based on an equivalent planar mechanism. Finally, a prototype is manufactured and a series of experiments are performed to verify the mobile capability of the robot.

Do Event-Related Brain Potentials Reflect Mental (Cognitive) Operations?

2002 ◽  
Vol 16 (3) ◽  
pp. 129-149 ◽  
Author(s):  
Boris Kotchoubey
Keyword(s):  
Cognitive Processes ◽  
Point Of View ◽  
Internal Variables ◽  
Brain Potentials ◽  
Cognitive Operations ◽  
External Variables ◽  
Series Of Experiments ◽  
Mental Operations ◽  
A Chain ◽  
Processing Mechanisms

Abstract Most cognitive psychophysiological studies assume (1) that there is a chain of (partially overlapping) cognitive processes (processing stages, mechanisms, operators) leading from stimulus to response, and (2) that components of event-related brain potentials (ERPs) may be regarded as manifestations of these processing stages. What is usually discussed is which particular processing mechanisms are related to some particular component, but not whether such a relationship exists at all. Alternatively, from the point of view of noncognitive (e. g., “naturalistic”) theories of perception ERP components might be conceived of as correlates of extraction of the information from the experimental environment. In a series of experiments, the author attempted to separate these two accounts, i. e., internal variables like mental operations or cognitive parameters versus external variables like information content of stimulation. Whenever this separation could be performed, the latter factor proved to significantly affect ERP amplitudes, whereas the former did not. These data indicate that ERPs cannot be unequivocally linked to processing mechanisms postulated by cognitive models of perception. Therefore, they cannot be regarded as support for these models.

Development of a chain-based mobile robot

2020 ◽  
Author(s):  
Sven Erchen ◽  
Max Triller ◽  
Lukas Sohlbach ◽  
Karsten Schmidt
Keyword(s):  
Mobile Robot ◽  
A Chain

Estimation of the Thermodynamic Properties of Branched Hydrocarbons

2000 ◽  
Vol 122 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Hui He ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Thermodynamic Properties ◽  
Degrees Of Freedom ◽  
Statistical Thermodynamic ◽  
Motion Modes ◽  
Branched Alkanes ◽  
Branched Hydrocarbons ◽  
Wide Range ◽  
On Line ◽  
Kinetic Calculations ◽  
Good Agreement

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures with special attention to the branched molecules. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A method to determine the number of degrees of freedom for different motion modes (bending and torsion) has been established. Branched rotational groups, such as CH3 and OH, have been considered. A modification of the characteristic temperatures for different motion mode has been made which improves the agreement with the exact values for simple cases. The properties of branched alkanes up to 2,3,4,-trimthylpentane have been calculated and the results are in good agreement with the experimental data. A relatively small number of parameters are needed in this model to estimate the sensible thermodynamic properties of a wide range of species. The model may also be used to estimate the properties of molecules and their isomers, which have not been measured, and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations. [S0195-0738(00)00902-X]

All-atomistic molecular dynamics study of the glass transition of amorphous polymers

2021 ◽  
Author(s):  
Zhiye Tang ◽  
Susumu Okazaki
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Spatial Scale ◽  
Degrees Of Freedom ◽  
Main Chain ◽  
Polymer Materials ◽  
Coarse Grained ◽  
Mode Analysis ◽  
Radius Of Gyration ◽  
Chemical Structures

Glass transition is an important phenomenon of polymer materials and it has been intensively studied over the past a few decades. However, the influencing factors arising from the chemical structures of the polymers are often ignored due to a continuous or coarse-grained description of the polymer. Here, we approached this phenomenon using all-atomistic molecular dynamics (MD) simulations and two conventionally used polymer materials, polycarbonate (PC) and poly-(methyl methacrylate) (PMMA). We reproduced the glass transition temperatures (Tg) of the two materials reasonably well. Then we characterized and investigated the glass transition process by looking at the changes of potential energy, dihedral transition, and thermal fluctuation of the individual degrees of freedom in the systems, over the entire temperature range of glass transition. As previously reported, the dihedral angles stop their conformational changes gradually at the Tg, especially for the main chain dihedrals, and sidechain rotations immediately rooting from the main chain. The volumetric change during the temperature decrease is confirmed to be because of conformational adjustment, probably due to the tendency of chain stretching for the maintenance of the radius of gyration, and the loss of thermal energy. The strength of motions of single degrees of freedom and polymer chains, and overall slow motions obtained by normal mode analysis (NMA) shows that different motions at different spatial scale may gradually stop at distinct temperature in the MD simulation temporal and spatial scales. Presumably, the small spatial scale do not contribute to the glass transition at the experimental scale since the timescale is much longer than their relaxation time.

A Hybrid Highly Parallelizable Algorithm for the Dynamics of Rigid Body Chain Systems

1999 ◽  
Author(s):  
Shanzhong Duan ◽  
Kurt S. Anderson
Keyword(s):  
Rigid Body ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Equations Of Motion ◽  
Constraint Forces ◽  
Dynamics Of Rigid Body ◽  
A Chain ◽  
Explicit Determination ◽  
Order Algorithm

Abstract The paper presents a new hybrid parallelizable low order algorithm for modeling the dynamic behavior of multi-rigid-body chain systems. The method is based on cutting certain system interbody joints so that largely independent multibody subchain systems are formed. These subchains interact with one another through associated unknown constraint forces f¯c at the cut joints. The increased parallelism is obtainable through cutting the joints and the explicit determination of associated constraint loads combined with a sequential O(n) procedure. In other words, sequential O(n) procedures are performed to form and solve equations of motion within subchains and parallel strategies are used to form and solve constraint equations between subchains in parallel. The algorithm can easily accommodate the available number of processors while maintaining high efficiency. An O[(n+m)Np+m(1+γ)Np+mγlog2Np](0<γ<1) performance will be achieved with Np processors for a chain system with n degrees of freedom and m constraints due to cutting of interbody joints.

Kinematics Analysis and Motion Control of a Mobile Robot Driven by Three Tracked Vehicles

2018 ◽  
Author(s):  
Xin-Jun Liu ◽  
Zhao Gong ◽  
Fugui Xie ◽  
Shuzhan Shentu
Keyword(s):  
Mobile Robot ◽  
Motion Planning ◽  
Degrees Of Freedom ◽  
Inverse Kinematic ◽  
Planning Method ◽  
Tracked Vehicles ◽  
Loop Control ◽  
Point Motion ◽  
Point To Point ◽  
Motion Mode

In this paper, a mobile robot named VicRoB with 6 degrees of freedom (DOFs) driven by three tracked vehicles is designed and analyzed. The robot employs a 3-PPSR parallel configuration. The scheme of the mechanism and the inverse kinematic solution are given. A path planning method of a single tracked vehicle and a coordinated motion planning of three tracked vehicles are proposed. The mechanical structure and the electrical architecture of VicRoB prototype are illustrated. VicRoB can achieve the point-to-point motion mode and the continuous motion mode with employing the motion planning method. The orientation precision of VicRoB is measured in a series of motion experiments, which verifies the feasibility of the motion planning method. This work provides a kinematic basis for the orientation closed loop control of VicRoB whether it works on flat or rough road.

The statistical distribution of the length of a rubber molecule

1948 ◽  
Vol 44 (3) ◽  
pp. 342-344 ◽  
Author(s):  
P. A. P. Moran
Keyword(s):  
Normal Distribution ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Statistical Distribution ◽  
Equal Length ◽  
Fixed Angle ◽  
A Chain ◽  
Image Position ◽  
Three Degrees Of Freedom

A rubber molecule containing n + 1 carbon atoms may be represented by a chain of n links of equal length such that successive links are at a fixed angle to each other but are otherwise at random. The statistical distribution of the length of the molecule, that is, the distance between the first and last carbon atoms, has been considered by various authors (Treloar (1) gives references). In particular, if the first atom is kept fixed at the origin of a system of coordinates and the chain is otherwise at random, it has been conjectured that the distribution of the (n + 1)th atom will tend, as n increases, towards a three-dimensional normal distribution of the formwhere σ depends on n. Thus r2 (= x2 + y2 + z2) will be approximately distributed as σ2χ2 with three degrees of freedom.

HOLONOMIC AND OMNIDIRECTIONAL LOCOMOTION SYSTEMS FOR WHEELED MOBILE ROBOTS: A REVIEW

2015 ◽  
Vol 77 (28) ◽  
Author(s):  
M. Juhairi Aziz Safar
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Degrees Of Freedom ◽  
Wheeled Mobile Robot ◽  
Arbitrary Direction ◽  
Current Position ◽  
Wheeled Mobile Robots ◽  
Future Improvement ◽  
Position And Orientation ◽  
Three Degrees Of Freedom

Holonomic and omnidirectional locomotion systems are best known for their capability to maneuver at any arbitrary direction regardless of their current position and orientation with a three degrees of freedom mobility. This paper summarizes the advancement of holonomic and omnidirectional locomotion systems for wheeled mobile robot applications and discuss the issues and challenges for future improvement.

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