Bio-Inspired Locomotion of Circular Robots With Diametrically Translating Legs

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Eric Steffan ◽  
Sudeshna Pal ◽  
Tuhin Das
Keyword(s):  
Mobile Robots ◽  
Degrees Of Freedom ◽  
Analytical Framework ◽  
Degree Of Freedom ◽  
Translational Degree ◽  
Simulation Results ◽  
Cellular Locomotion ◽  
Kinetics Of ◽  
Kinematics And Kinetics

Abstract In this paper, we develop an analytical framework for designing the locomotion of mobile robots with a circular core and equispaced diametral legs, each having a radial translational degree of freedom. The mechanism has resemblance with certain cellular locomotion. The robot travels by radial actuation of the legs in a sequential and synchronized manner. Two elementary regimes of motion are first designed using the geometry and degrees of freedom of the mechanism. Overall motion of the robot is generated by repeated switching between the two regimes. The paper addresses both kinematics and kinetics of the mechanism, enabling the prediction of trajectories and computation of constraint as well as actuation forces. Simulation results are provided in support of the theory developed.

The thermodynamics of intracrystalline sorption I. Models of the sorbed state

1956 ◽  
Vol 234 (1196) ◽  
pp. 24-34 ◽  
Keyword(s):  
Mobile Phase ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Translational Degree ◽  
Sorbate Concentration ◽  
The Ideal

Three basic models of the intracrystalline sorbed state are discussed: a localized phase, a mobile phase possessing two translational degrees of freedom, and a mobile phase with one translational degree of freedom. The isotherm and entropy of each of these models have been investigated for the ideal phase, and where possible the influence of sorbate-sorbate interactions has been considered. Expressions for the molal and differential entropies of each model are given as a function of sorbate concentration. The method of comparing theoretical isotherms and entropies with experimental observations is outlined.

A Novel 3-DOF Parallel Robot and its Kinematic Analysis

2014 ◽  
Vol 607 ◽  
pp. 759-763
Author(s):  
Xiao Bo Liu ◽  
Xiao Dong Yuan ◽  
Xiao Feng Wei ◽  
Wei Ni
Keyword(s):  
Motion Control ◽  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
The Novel ◽  
Forward Displacement ◽  
Simulation Based ◽  
Simulation Results

This paper deals with the design and analysis of a novel and simple two-translation and one-rotation (3 degrees of freedom, 3-dof) mechanism for alignment. Firstly, degree of freedom of the parallel robot is solved based on the theory of screw. Secondly considering the demand of motion control, we have conducted the analysis on the 3-dof parallel robot, which includes inverse displacement, forward displacement, and simulation based on SolidWorks Motion. The simulation results indicate that the novel 3-dof robot is suitable for performing the required operations.

The thermodynamics of intracrystalline sorption II. Argon in chabazite

1956 ◽  
Vol 234 (1196) ◽  
pp. 35-45 ◽  
Keyword(s):  
Experimental Data ◽  
Mobile Phase ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Translational Degree ◽  
Sorbed Phase

The experimentally observed isotherms and entropies of the intracrystalline sorbed phase of argon in natural and calcium chabazites are compared with those predicted by models. For sorbate concentrations between approximately θ = 0.1 and 0.7, the experimental data are incompatible with the properties of a localized phase but are in agreement with those of a mobile phase. It is demonstrated that it is impossible for the argon to possess two degrees of translational freedom and that it is best described as having one translational degree of freedom and two vibrational degrees of freedom each with a frequency of 1 x 10 12 to 2 x 10 12 s -1 . The examination of the entropy of the system also shows that at concentrations greater than θ = 0.7 the mobile concept breaks down and it is probable that the translational degree of freedom passes to a vibration due to the mutual caging action of sorbate molecules, so that the phase becomes a system of oscillators.

Develop a Vision Based Auto-Recharging System for Mobile Robots

2010 ◽  
Vol 44-47 ◽  
pp. 1340-1344 ◽  
Author(s):  
Kuo Lan Su ◽  
Yung Chin Lin ◽  
Yi Lin Liao ◽  
J. Hung Guo
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Degrees Of Freedom ◽  
Control Device ◽  
Degree Of Freedom ◽  
Usb Interface ◽  
Compression Spring ◽  
Real Time Image ◽  
Wireless Rf Interface ◽  
Time Image

The article develops a vision based auto-recharging system for mobile robots, and programs a new docking processing to enhance successful rate. The system contains a docking station and a mobile robot. The docking station contains a docking structure, a control device, a charger and a detection device and a wireless RF interface. The mobile robot contains a power detection module (voltage and current), an auto-switch, a wireless RF interface, a control system and a camera. The docking structure is designed with one active degree of freedom and two passive degrees of freedom. The active degree of freedom can move forward to contact the recharging connect points that are arranged in the mobile robot. The two passive degrees of freedom can rotation in the Z-axis and use compression spring moving on various docking condition. In image processing, the mobile robot uses a webcam to capture the real-time image; and transmits the image signal to the computer via USB interface, and uses Otsu algorithm to recognize the position of the docking station. In the experiment results, the system had been successfully guided the mobile robot moving to the docking station using the proposed method.

Nonintegrability of an Infinite-Degree-of-Freedom Model for Unforced and Undamped, Straight Beams

2003 ◽  
Vol 70 (5) ◽  
pp. 732-738
Author(s):  
K. Yagasaki
Keyword(s):  
Differential Equation ◽  
Hamiltonian Systems ◽  
Degrees Of Freedom ◽  
Galois Theory ◽  
Degree Of Freedom ◽  
Differential Galois Theory ◽  
Finite Degree ◽  
Chaotic Motions ◽  
Infinite Degree ◽  
Simulation Results

We study a mathematical model for unforced and undamped, initially straight beams. This system is governed by an integro-partial differential equation, and its energy is conserved: It is an infinite-degree-of-freedom Hamiltonian system. We can derive “exact” finite-degree-of-freedom mode truncations for it. Using the differential Galois theory for Hamiltonian systems, we prove that any two or more modal truncations for the model are nonintegrable in the following sense: The Hamiltonian systems do not have the same number of “meromorphic” first complex integrals which are independent and in involution, as the number of their degrees of freedom, when they are regarded as Hamiltonian systems with complex time and coordinates. This also means the nonintegrability of the infinite-degree-of-freedom model for the beams. We present numerical simulation results and observe that chaotic motions occur as in typical nonintegrable Hamiltonian systems.

Design and Evaluation of a Passive Ankle Prosthesis With Rotational Power Generation by a Compliant Coupling Between Leg Deflection and Ankle Rotation

2014 ◽  
Author(s):  
Jacob J. Rice ◽  
Joseph M. Schimmels
Keyword(s):  
Degrees Of Freedom ◽  
Gait Cycle ◽  
The Body ◽  
Degree Of Freedom ◽  
Rotational Degree ◽  
Kinematic Data ◽  
Active Behavior ◽  
Ankle Prosthesis ◽  
Compression Spring ◽  
Translational Degree

This paper presents the design and simulation results of a passive prosthetic ankle prosthesis that has mechanical behavior similar to a natural ankle. The presented design achieves active behavior with powered push-off to propel the body forward. The design contains a conventional compression spring network that allows coupling between two degrees of freedom. There is a translational degree of freedom along the leg and a rotational degree of freedom about the ankle joint. During a standard gait cycle, potential energy from the person’s weight is stored in the spring network from deflection along the leg. The energy is released by the spring network as rotation of the foot. With this design, capping the allowable leg deflection at 15 millimeters produces 45% of the rotational work that a natural ankle will produce. This is based on simulation using published average kinetic and kinematic data from gait analyses.

Controlled Maneuverability of an Articulated Tracked Mobile Robot

2010 ◽  
Author(s):  
Patrick Labenda ◽  
Tim Sadek ◽  
Thomas Predki
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Control Strategy ◽  
Degrees Of Freedom ◽  
Articulated Vehicles ◽  
Unstructured Environment ◽  
Translational Degree ◽  
Feedback Control Strategy ◽  
The Individual ◽  
Tracked Mobile Robot

Considerable potentials with regard to mobility in unstructured environment offer actively articulated mobile robots equipped with powered wheels or tracks. These potentials are obvious when dealing with a system’s trafficability and terrainability. However, maneuverability and steerability of articulated mobile robots are challenging. This is due to the fact that these robots represent a form of truck-trailer systems leading to interactions and influences between the individual vehicles resulting in significant problems like e.g. off-tracking with regard to a given path. Further on, when dealing with a mobile robot’s maneuverability there are only few scientific contributions covering articulated vehicles with actively powered trailers using tracks as propulsive elements. The described systems differ significantly with regard to their configuration with respect to the multi-redundant mobile robot in this work. To investigate the maneuverability of articulated tracked mobile robots a demonstrator has been developed. It is built up out of three identical modules which are connected with each other in a rowby means of a rotational and a translational degree-of-freedom. Each module has two tracks which can be powered independently. Overall, the system has got ten degrees-of-freedom whereas six of them are active and four passive. The developed demonstrator has been used for investigations dealing with maneuverability and steerability as well as modularization of the system’s control architecture. The paper summarizes the development of the mobile robot, its feedback control strategy as well as the tests carried out. The achieved results show a satisfying performance with regard to the implemented control strategy and the system’s maneuverability.

scholarly journals Kinematic performance evaluation of 2-degree-of-freedom parallel mechanism applied in multilayer garage

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879171
Author(s):  
Tianhua He ◽  
Junpeng Shao ◽  
Yongde Zhang ◽  
Jingang Jiang
Keyword(s):  
Parallel Mechanism ◽  
Evaluation Method ◽  
Degree Of Freedom ◽  
Evaluation Index ◽  
Global Symmetry ◽  
Symmetric Structure ◽  
Lower Mobility ◽  
Translational Degree ◽  
Kinematic Performance ◽  
Simulation Results

In this article, our recent work on a kind of 2-degree-of-freedom lower-mobility parallel mechanism, which has one rotation degree of freedom and one translational degree of freedom, used in multilayer garage is presented. It has the following characteristics: lower-mobility, non-symmetric structure but can realize symmetric movement and a good compatibility for different kinds of lifting work. Kinematic performance should be considered in the first of designing a new kind of mechanism, the optimal kinematic design and analysis of this lower-mobility parallel mechanism are primarily investigated. In process of study, the global conditioning index over workspace is adopted, we establish a new evaluation method for the lower-mobility parallel mechanism, called global symmetry index and simulation results are shown. In addition, the flexible workspace of this lower-mobility parallel mechanism is also proposed. The evaluation index can be also applied on other lower-mobility parallel mechanism, which needs steady and symmetric movement.

On the Repetitive Impact Dynamics of One and Two Degree of Freedom Systems

2005 ◽  
Author(s):  
Baris Yagci ◽  
Matt Iannacci ◽  
Burak Ozdoganlar ◽  
Jonathan Wickert
Keyword(s):  
Degrees Of Freedom ◽  
Period Doubling ◽  
Degree Of Freedom ◽  
Quantitative Character ◽  
Impact Dynamics ◽  
Milling Machines ◽  
Gear Trains ◽  
Simulation Results ◽  
Repetitive Impact ◽  
The Impact

Repetitive collision occurring between structural and machine components is a topic of practical and scientific importance. Some types of machinery are inherently susceptible to impacts because of the small clearances present between adjacent components, thermal expansion, and relative motion as in gear trains. One can observe repetitive impacts in milling machines, shakers and off-shore structures. Energy transfer between components that are subjected to repetitive impacts is a complex phenomenon that often exhibits deceptive and non-intuitive behavior. Even in seemingly simple structures, period-doubling bifurcations, sub-harmonic resonances, and chaotic responses occur. This paper presents detailed experimental data obtained from an impact vibration test stand that was instrumented for displacement, velocity, and impact force measurements. In addition, the apparatus was fabricated in such a way to allow for precise positioning of the impact point, and varying of the gap distance between impacting components. The paper includes companion simulation results obtained from a model for the repetitive impact dynamics of otherwise linear single or multiple degree of freedom discrete structures. Simulation results are presented for the effect of natural frequency placement, model dimension, and gap clearance on the qualitative and quantitative character of the response. Of particular interest is the transition of behavior as the system’s model is augmented from having one to several degrees of freedom.

Multi-Degree-of-Freedom Modeling of Mechanical Snubbing Systems

2011 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Experimental Data ◽  
Data Collection ◽  
Rigid Body ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Rigid Frame ◽  
Identification Technique ◽  
Simulation Results ◽  
Stiffness And Damping ◽  
Three Degrees Of Freedom

This paper presents a multi-degree-of-freedom model for the analysis of mechanical snubbing in elastomeric isolators. The model uses a system of elastomeric isolators and snubbers to assemble a rigid body with three degrees-of-freedom to a rigid frame. The isolators are supplemented by the snubbing system so as to limit the displacement of the rigid body in all three directions of motion when the system undergoes transient loading or overloading conditions. The model is piecewise non-linear and uses normalized Bouc-Wen elements in order to capture inherent hysteresis of the elastomeric isolators and the snubbing system as well as the transition in stiffness and damping properties resulting due to inherent coupling between the isolators and the snubbing system. Separate elements are used to model the enhanced stiffness resulting from the snubbing system in the translational directions of motion. A set of elastomeric isolators and snubbing systems is used for data collection, characterization and model validation. The data collection is carried out at multiple strain amplitudes and strain rates. A conventional least squares based parameter identification technique is used for characterization. The completely characterized model is then used for simulating the response of the rigid body and the simulation results are compared to experimental data. The simulation results are found to be in general agreement with the experimental data.

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