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

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1.1 The Pioneer 3-AT Robot 8four horizontal side wheels are also installed at the platform level such that when the robotobliquely encounters a wall they rotated against wall’s surface allowing the robot to continueits motion smoothly. For high obstacles a pressure sensitive switch is installed for the entirealuminum frame. Thus, if the robot encounters a door handle, for example, the robot willstop. During testing, this system has been found to be largely effective but not perfect. Therewere a few objects in the environment that could defeat these features and cause the robotto overturn itself, potentially incurring damage. In addition, some difficulties have been encounteredwith the safety features being activated during normal operation due to the jerkymotion of the skid-steering. Furthermore, jerky motion shakes the camera off the Velcro andit disrupts the image and adds delay while the operator waits for the camera view to settledown. This jerky motion is often due to the fact that telepresence operators tend to swivel therobot in place because that corresponds to ¨looking around¨, which is a very natural actionfor humans but it is not an easy one for the robot. Thus, the main aim of our future workwill be reducing the robot jerky motion and large-scale vibrations during sharp turns andespecially while swiveling in place.(a)(b)Figure 1.1: (a) The Pioneer 3-AT robot; (b) the extended Pioneer 3-AT robot.
1.2 The sensors 91.2 The sensorsFor this project, we employed three SCA620-CF8H1A 1-AXIS ANALOG ACCELEROMETERS[13]. The main characteristics are: power supply V dd = +5 V, voltage output V out ∈ [−0.3, V dd +0.3] V, acceleration range a ∈ [−1.7g, 1.7g], sensitivity error e a = [−3, +3]% and low-passbandwidth, in laboratory conditions, at 80 Hz [13].In order to characterize the robot vibrations as well as identify some dynamic parameters,each accelerometer was welded to one face of a small cube of wood, so that the accelerometer’sacceleration coincides with the cube’s acceleration. They were also fixed in such away that their axes intersect in one point, the origin of the cube frame, and their positivedirections satisfy the right-hand rule (Figure 1.2).The data are acquired from the accelerometers as Voltage signals by using the NI-DAQmxdevice, as data acquisition device (DAQ), and LabVIEW software, both produced by NationalInstruments Co.Figure 1.2: Picture of the wood-cube with the three 1-axis analog accelerometers and their axes.Also, the eXpert 2653 ADMET universal testing machine [14] in the mechanics laboratoryat Roger Williams University was utilized to perform tests for the identification ofthe tire reaction forces. The testing machine is capable of performing compression, tension,and flexure tests, thanks to its axial alignment, stiffness and cross-head guidance. The mainsystem specifications are: load capacity 50 kN, speed range [0.0025, 508] mmminand position
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Page 3 and 4: IINothing great in the World has be
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
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Page 14 and 15: Introduction 4The robot employed, i
Page 16 and 17: Chapter 1Hardware and SoftwareIn th
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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
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Page 36 and 37: 2.2 Generalized Modeling 26V = [v T
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Page 42 and 43: 2.2 Generalized Modeling 32where we
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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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