Dynamic Analyze of Snake Robot

A Dynamic Single Actuator Vertical Climbing Robot
Abstract—A climbing robot mechanism is introduced, whichuses dynamic movements to climb between two parallel verticalwalls. This robot relies on its own internal dynamic motionsto gain height, unlike previous mechanisms which are quasistatic.One benefit of dynamics is that it allows climbingwith only a single actuated degree of freedom. We showwith analysis, simulations and experiments that this dynamicrobot is capable of climbing vertically between parallel walls.We introduce simplifications that enable us to obtain closedform approximations of the robot motion. Furthermore, thisprovides us with some design considerations and insights intothe mechanism’s ability to climb.

http://www.cs.cmu.edu/~biorobotics/papers/IROS07_Degani_0490.pdf

3-D Snake Robot Motion: Nonsmooth Modeling,Simulations, and Experiments
Abstract—A nonsmooth (hybrid) 3-D mathematical model ofa snake robot (without wheels) is developed and experimentallyvalidated in this paper. The model is based on the framework ofnonsmooth dynamics and convex analysis that allows us to easilyand systematically incorporate unilateral contact forces (i.e., betweenthe snake robot and the ground surface) and friction forcesbased on Coulomb’s law of dry friction. Conventional numericalsolvers cannot be employed directly due to set-valued force lawsand possible instantaneous velocity changes. Therefore, we showhow to implement the model for numerical treatment with a numericalintegrator called the time-stepping method. This methodhelps to avoid explicit changes between equations during simulationeven though the system is hybrid. Simulation results for theserpentine motion pattern lateral undulation and sidewinding arepresented. In addition, experiments are performed with the snakerobot “Aiko” for locomotion by lateral undulation and sidewinding,both with isotropic friction. For these cases, back-to-back comparisonsbetween numerical results and experimental results are given.

http://www.zfm.ethz.ch/~leine/papers/Transeth%20&%20Leine%20&%20Glocker%20&%20Pettersen%20-%203-D%20Snake%20Robot%20motion%20nonsmooth%20modeling%20simulations%20and%20experiments.pdf

Dynamic Analyze of Snake Robot

Abstract—Crawling movement as a motive mode seen in natureof some animals such as snakes possesses a specific syntactic anddynamic analysis. Serpentine robot designed by inspiration fromnature and snake’s crawling motion, is regarded as a crawling robot.In this paper, a serpentine robot with spiral motion model will beanalyzed. The purpose of this analysis is to calculate the vertical andtangential forces along snake’s body and to determine the parametersaffecting on these forces. Two types of serpentine robots have beendesigned in order to examine the achieved relations explained below.

http://www.waset.org/journals/waset/v29/v29-56.pdf

http://water.engr.psu.edu/reed/Education/CE%20563%20Projects/Mehta%20snakebot_nsga2%20%20Sp%2007.pdf

Optimal Gait Analysis of Snake Robot Dynamics

ABSTRACT

Though there have been a lot of research in the area ofsnake-robot kinematics and dynamics, a little attention hasbeen given to ¯nd out an optimal gait for the robot. Thisoptimal gait until now is being calculated using a graphicalmethod. An attempt, here, is made to get these optimumgait parameters using evolutionary algorithms.We intend to optimize the input power consumed by therobot for a given propulsive speed. A popular multi-objectiveevolutionary algorithm developed by Deb et al., NSGA-II isused in this work and the results are presented.Results from an approximation of objective function throughpolynomials and from the actual simulation are presented.Two di®erent frictional models are considered and their re-sults are given. The results are in good agreement with theliterature. A parametric study is also included to ¯nd min-imum population size and number of generations. The per-formance metrics are used to justify the parametrization.

AmphiBot I: an amphibious snake-like robot

Abstract

This article presents a project that aims at constructing a biologically inspired amphibious snake-like robot. The robot isdesigned to be capable of anguilliform swimming like sea-snakes and lampreys in water and lateral undulatory locomotionlike a snake on ground. Both the structure and the controller of the robot are inspired by elongate vertebrates. In particular, thelocomotion of the robot is controlled by a central pattern generator (a system of coupled oscillators) that produces travellingwavesof oscillations as limit cycle behavior. We present the design considerations behind the robot and its controller. Experimentsare carried out to identify the types of travelling waves that optimize speed during lateral undulatory locomotion on ground. Inparticular, the optimal frequency, amplitude and wavelength are thus identified when the robot is crawling on a particular surface.

http://birg2.epfl.ch/publications/fulltext/crespi05.pdf

Analysis and Design of A Multi-Link Mobile Robot (Serpentine)

Abstract

This paper is a study on dynamic behavior of a :snakerobot, called Serpentine robot, 2”* version (SR#2). TheSR#2 is the latest version of snake robots developed atFIBO as a research platform for studying serpmtinegaits. The gait is in form of sinusoidal curve, consi,deredone of the most effectiveness crawling pattem i:n thenatural world. The Active Cord Mechanism (ACM)assumption, initiated by Hirose, is implemented. Therobot motion results from different joint torquer, andfrictional reacting forces in each wheel. In this stud:y, weproposed a modified serpeniod function with steeringcommand to control the robot’s direction. We alsoperformed dynamic analysis using Kane’s method.Holonomic constraints under frictional forces andnonholonomic constraints unders velocities wereconsidered. We verified our algorithm .for directionalcontrol on this Serpentine robot both simulation andexperiment.

http://gicl.cs.drexel.edu/wiki-data/images/f/fc/AnalysisAndDesignOfAMulti-LinkMobileRobot(Serpentine).pdf

Robotic Manipulator Dynamic article

Reliability-Based Design Optimization of Robotic System Dynamic PerformanceAbstract
In this investigation a robotic system’s dynamic performance isoptimized for high reliability under uncertainty. The dynamic capabilityequations (DCE) allow designers to predict the dynamicperformance of a robotic system for a particular configurationand reference point on the end-effector (i.e.,point design). Herethe DCE are used in conjunction with a reliability-based designoptimization (RBDO) strategy in order to obtain designs withrobust dynamic performance with respect to the end-effector referencepoint. In this work a unilevel performance measure approach(PMA) is used to perform RBDO. This is important forthe reliable design of robotic systems in which a solution to theDCE is required for each constraint call. The method is illustratedon a robot design problem.

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Velocity Effects on Robotic Manipulator Dynamic Performance

Abstract

Background. This article explores the effect that velocities haveon a nonredundant robotic manipulator’s ability to accelerate itsend-effector, as well as to apply forces/moments to the environmentat the end-effector. This work considers velocity forces, includingCoriolis forces, and the reduction of actuator torque withrotor velocity described by the speed-torque curve, at a particularconfiguration of a manipulator. The focus here is on nonredundantmanipulators with as many actuators as degrees-of-freedom.Method of Approach. Analysis of the velocity forces is accomplishedusing optimization techniques, where the optimizationproblem consists of an objective function and constraints whichare all purely quadratic forms, yielding a nonconvex problem.Dialytic elimination is used to find the globally optimal solutionto this problem. The proposed method does not use iterative numericaloptimization methods.

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Dynamic Performance as a Criterion for Redundant Manipulator Control

Abstract

Kinematically redundant manipulators havebeen proven to offer certain advantages over more heavilyconstrained systems. One such advantage is the extra degreesof-freedom can be used for other tasks such as maintaininga posture which affords higher acceleration capability in thedirection of the desired motion. However certain issues arisewhen considering the control of these mechanisms due tothe lack of invertability of the rectangular Jacobian matrix.Here this issue is addressed by augmenting the rectangularJacobian with a characterization of the null space motions.This approach allows for a gradient-based control scheme,based upon the Dynamic Capability Equations, to increase ormaintain the local performance capability of a manipulator asit performs some task. Simulation results of the application ofthis control scheme to a six degree-of-freedom (DOF) planarmanipulator are given to illustrate the control’s advantageson a highly redundant system.

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The Actuation Effciency, a Measure of Acceleration Capability for Non-Redundant Robotic Manipulators

Abstract

This article presents a performance measure, the ActuationEffciency, which describes the imbalance betweenthe end-effector accelerations achievable in differentdirections of non-redundant robotic manipulators.A key feature of the proposed measure is thatin its development the differences in units betweentranslational and rotational accelerations are treatedin a physically meaningful manner. The measure alsoindicates oversized actuators, since this contributes tothe imbalance in achievable accelerations. The developmentof this measure is based on the formulation ofthe Dynamic Capability Equations. The shape of theDynamic Capability Hypersurface, which is desined bythe Dynamic Capability Equations, is a weak indicatorof the level of imbalance in achievable end-effectoraccelerations.

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The Dynamic Capability Equations: A New Tool for Analyzing Robotic Manipulator PerformanceAbstract

The Dynamic Capability Equations (DCE) provide anew description of robot acceleration and force capabilities. Theserefer to a manipulator’s ability to accelerate its end-effector,and to apply forces to the environment at the end-effector. Thekey features in the development of these equations are that theycombine the analysis of end-effector accelerations, velocities andforces while addressing the difference in units between translationaland rotational quantities. The equations describe themagnitudes of translational and rotational acceleration and forceguaranteed to be achievable in every direction, from a particularconfiguration, given the limitations on the manipulator’s motortorques. They also describe the effect of velocities on thesecapabilities contributed by the Coriolis and centrifugal forces, aswell as the reduction of actuator torque capacity due to motorspeed. This article focuses on non-redundant manipulators withas many actuators as degrees-of-freedom.

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Non-Redundant Robotic Manipulator Acceleration Capability andthe Actuation Efficiency Measure

Abstract

This article presents a performance measure, the actuationeficiency, which describes the imbalance betweenthe end-effector accelerations achievable in differentdirections of non-redundant robotic manipulators.A key feature of the proposed measure is that inits development the unitam differences between linearand angular accelerations are treated in a physicallymeaningful manner. The memure also indicatesoversized actuators, since this contributes to the imbalancein achievable accelerations. The developmentof this measure is based on the formulation of theDynamic Capability Hypersurface. The shape of thishypersurface is a weak indicator of the level of imbalancein achievable end-effector accelerations.

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SOME PROBLEMS OF MANIPULATOR MOTION CONTROL

The purpose of manipulator control is tomaintain the dynamic response of a computer-basedmanipulator in accordance with some prespecifiedsystem performance and desired goals. In general,the dynamic performance of a manipulator directlydepends on the efficiency of the control algorithmsand the dynamic model of the manipulator. Thecontrol problem consists of obtaining dynamicmodels of the physical robot arm system and thenspecifying corresponding control laws or strategiesto achieve the desired system response andperformance.

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