asme mars rocks

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unc Charlotteunc CharlotteAsme Design TeamAsme Design Team

2008-20092008-2009

Members:Rodger Adams

Philip BrownJohn Cillie

Dory LoBeanAndrew Misenheimer

Dylan Sylvester

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Mars Rocks! Design and build a vehicle that will:

Retrieve rocks and bring them to a designated spotReturn to its starting location and be ready for another runBe able to surmount small obstacles while travelling to the

rocks and carrying the rocks back

Figure 1. Mars Rover2

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Course Description I Flat, level section of any floor type

Marked off with masking tapeCourse size is 2290mm x 3660mmThree barriers–either two 2x4’s on the side or one

4x4

Figure 2. Course Layout 3

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Course Description II

Parking area will be 300x610mm Receiving area will be three concentric

circles ranging from 50mm to 200mm in 75mm increments

Figure 2. Course Layout 4

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Rock Locations Rocks will be approximately placed as

indicated by the circles below

Figure 2. Course Layout

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Rock Description Must range in size of up to

40mm across the widest dimension and at least 20mm in the other dimension

Must weigh between 10 to 80 grams

Must be irregular in shape Must not roll more than one-

half of a rotation when placed on a flat surface Figure 3. Rocky Surface

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Vehicle Requirements Dimensional and Electrical Constraints

Vehicle must have a master ON/OFF switchVehicle and controller must fit within a constraining box of

370mm x 165mm x 165mmVehicle must be powered with over the counter

rechargeable batteriesThe device must be controlled either through a

transmitter/receiver radio link or through an umbilical cordAn umbilical cord controller may not contain any batteries

while a transmitter may contain its own batteriesThe transmitter/receiver radio link may be any

commercially available model controller

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Design Concept I

Figure 5. UGV (Unmanned Ground Vehicle) MATILDA

Figure 4. British Mark V, WWI Tank

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Design Concept II

Figure 6. Proposed 2008-2009 UNC-Charlotte ASME Mars Rocks! Rover. Designed in Pro/Engineer Wildfire 4.0

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Drive train Tank style tread Climbing tread

extension 2 motors, planetary

gearbox with 60:1 final drive ratio

RP plastic and aluminum composite frame

Figure 7. Bottom View of Drive Train Assembly

Figure 8. Exploded View of Drive Train Assembly10

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Gripping Mechanism Gripping:

Servo driven dual arm gripping mechanism

Lifting:Second Servo driven

flipping mechanism Rubberized spherical

cups for friction lifting

Figure 9. Top View of Gripping Mechanism

Figure 10. Side View of Lifting Mechanism 11

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Storage System Inclined rock receptacle

Assists in depositing of rocks

Swinging entry-safety gatePrevents backflow of stored

rocks Servo driven exit gate Houses power supply and

micro servo 40.6 cubic inches

Figure 11. Inclined Rock Receptacle with Swinging Gate Opened

Figure 12. Inclined Rock Receptacle ShowingPower Supply and Servo Placement 1

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Electrical System I 6 channel digital Proportional

72MHz aircraft transmitter 4 Axis, 6 Button Controller Adjustable servo travel Adjustable servo speed Programmable mixing for

drive train control Battery: 11.1V Lithium

Polymer

Figure 13. Hitec Optic 6 Transmitter

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Electrical System II

2 channels used for independent throttle and steering control via 2 ESC’sElectronic mixing programmed within the

transmitter will allow both independent and non-independent control of treads off of 2 axis joystick

1 ch. for servo operated trap door 1 ch. for up/down movement of gripper 1 ch. for open/close of gripper

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Proposed BudgetTable 1. Proposed Budget

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Continuing Concerns

Capacity of batteryWill be determined by scoring formula and trial

and error analysis upon completion of robot Backup Components Material Properties within ProE for safety

factor calculationsIntuitively designed along with supporting

calculations

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Questions, Comments, Input

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Appendix I-Calculations

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Gripping and Lifting System Critical InformationServo Motor Torque 2 in-lbf

Servo Motor Speed4.55 rad/s

Estimated Cycle time 1.5 sRock Gripping Force 0.6 lbfCoefficient of Friction for gripping with safety factor of 2.5 0.7Safety factor for gripping stress on the arm 3.88Safety factor for lifting stress on the arm 6.65

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Appendix II

Servos:Eflite S75 Sub-Micro Servo-Trap

Door○ Torque: 17.2 oz-in. @ 4.8V○ Speed: 0.12sec/60˚ @ 4.8V

Futaba S3003 Std. Servo-Gripper and Flipping Mechanisms○ Torque: 44.0 oz-in. @ 4.8V○ Speed: 0.23sec/60˚ @ 4.8V

Figure 14. Eflite S75 Micro Servo

Figure 15. Futaba S3003 Standard Servo19

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Appendix III Motor and Gearbox:

Table 2. ML-30 Motor Information, 30:1 Reduction

Figure 16. ML-30 Motor with Planetary Gearbox

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Appendix IV

PC-ABS41 MPa Tensile StrengthSG 1.2High Impact Resistance

Al 6061 T6430 MPa Tensile Strength72 GPa Elastic Modulus

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