Advance Modeling of a Skid-Steering Mobile Robot for Remote ...

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AbstractThe robot employed, in this project, for telepresence applications is a Pioneer 3-AT Robot,which is a four-wheeled skid-steering mobile robot (SSMR). For SSMRs, the non-holonomicconstraint of zero lateral velocity considered for standard differential-driven mobile robots,such as unicycles or car-like robots [1], [2], [3], does not hold and the wheel slip must betaken into account. In particular, the tire/ground dynamics occurring during skidding canproduce large amplitude vibrations, which can eventually lead to the robot instability. Althoughsuch large vibrations never arise when using only the Pioneer 3-AT Robot platform,they significantly characterize the extended Pioneer 3-AT Robot employed in this project,due to the inertia of its vertical structure. These vibrations lead to an erratic motion duringsharp turns, in particular when the robot is swiveling in place, which causes unacceptabledisruption of the video stream and destabilizes the structure. As the user needs full maneuverabilityin small environment, the robot motion must be fully controlled. In order toprovide a stabilization control strategy for the robot jerky motion, an advance modeling ofSSMRs reproducing the real robot vibrations must be first provided.In this thesis, a novel three-dimensional dynamic model of SSMRs, including a springdampertire model, is presented. Some experimental data acquired from three 1-axis accelerometersand a force sensor are presented and analyzed to characterize the nature ofthe robot vibrations and the tire reaction forces. On the basis of the experimental data, aspring-mass-damper model separately for tire lateral, longitudinal and vertical reaction forceis provided. A dynamic friction model, based on the work proposed in [4], [5], is also providedto include the contribution of the wheel longitudinal slip into the reaction force model.Finally, after identifying the robot geometric and dynamic parameters, the Simulink modelimplementing the propose three-dimensional skid-steering model is presented and validatedby qualitatively comparing the results of the simulation to the data acquired from the accelerometersand the force sensor.
IINothing great in the World has been accomplishedwithout passion and friends.G. W. F. HegelAcknowledgmentsI have been indebted in the preparation of this thesis to my supervisor at Roger WilliamsUniversity, Professor Matthew Stein, whose patience and kindness, as well as his academicexperience, have been invaluable to me. I am extremely grateful to my supervisor at Universityof Genoa, Professor Fulvio Mastrogiovanni, who helped me in the completion of thisthesis in Genoa, and whose proficiency and helpfulness have made this work more completeand fulfilling.I want also to heartily thank my great friend and colleague Mariella Buttaci, who has accompaniedme in this unique experience abroad and without whom this thesis would probablynot have existed.
Page 1: Università degli Studi di GenovaRo
Page 5: CONTENTSIV6 Simulation 786.1 Simuli
Page 8 and 9: LIST OF FIGURESVII6.4 (a) Block sch
Page 10 and 11: List of Tables5.1 Table of the geom
Page 12 and 13: Introduction 2boDynamics, VGo Commu
Page 14 and 15: Introduction 4The robot employed, i
Page 16 and 17: Chapter 1Hardware and SoftwareIn th
Page 18 and 19: 1.1 The Pioneer 3-AT Robot 8four ho
Page 20 and 21: 1.2 The sensors 10control resolutio
Page 22 and 23: 2.1 State of the Art 12not negligib
Page 24 and 25: 2.1 State of the Art 14velocity vec
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Page 28 and 29: 2.1 State of the Art 18Finally, by
Page 30 and 31: 2.1 State of the Art 20constraint (
Page 32 and 33: 2.1 State of the Art 22approximates
Page 34 and 35: 2.2 Generalized Modeling 24⎡1 0¯
Page 36 and 37: 2.2 Generalized Modeling 26V = [v T
Page 38 and 39: 2.2 Generalized Modeling 28where T(
Page 40 and 41: 2.2 Generalized Modeling 30⎡g R(J
Page 42 and 43: 2.2 Generalized Modeling 32where we
Page 44 and 45: Chapter 3Experimental DataIn this c
Page 46 and 47: 3.1 The accelerometer 36(a)(b)Figur
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3.2 Characterization of the Vibrati
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3.3 Characterization of the Tire Fo
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4.1 Tire Lateral Force 56Figure 4.1
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4.1 Tire Lateral Force 58velocity b
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4.1 Tire Lateral Force 600 ≤ µ i
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4.3 Tire Vertical Force 62f ix (t)
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Chapter 5Identification of the Robo
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5.1 Identification of the Geometric
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5.2 Identification of the Tire Dyna
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Chapter 6SimulationIn this chapter,
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6.1 Simulink Model 80On the right h
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6.1 Simulink Model 82Figure 6.3: Bl
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6.1 Simulink Model 84(a)(b)Figure 6
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6.1 Simulink Model 86that v icx can
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6.2 Simulation Results 88(a)(b)Figu
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6.2 Simulation Results 90enough to
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6.2 Simulation Results 92hand side
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6.2 Simulation Results 94(a)(b)Figu
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6.2 Simulation Results 96• For λ
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AppendixesAppendix A1 %% Main progr
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Appendixes 10080 title([conf,’; A
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Appendixes 10224 Hd = design(h,filt
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Appendixes 1043031 % Filter the dat
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Appendixes 106(a)(b)(c)Figure 6.10:
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Appendixes 120(a)(b)Figure 6.24: Pe
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Bibliography[1] G. Oriolo, A. De Lu
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