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FTC Mechanical design considerations 2012 edition

This edition discusses the rules, ideas, and manipulators for the 2012-2013 FTC competition. It covers the use of preformed robotics components, different motors and gears, materials, lifts, and general design practices. The aim is to guide teams in designing efficient and effective robots for the competition.

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FTC Mechanical design considerations 2012 edition

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  1. FTC Mechanical design considerations 2012 edition by: Andrew Rudolph

  2. What we’re going to talk about the rules ideas manipulators

  3. 2012-2013 rules You’ve already read them right?

  4. rules • Only can use preformed robotics components from: • Lego • Tetrix • Matrix

  5. matrix • Designed to bring costs down of FTC overseas • Designed off standard lego grid • Different motors • Different motor controllers • Different Gears and wheels • Possibly thinner metal • Belt system • CV Axles • Check some of the offerings at: • http://matrixrobotics.com Observed at World Cmp

  6. http://www.chiefdelphi.com/forums/showthread.php?t=106017 matrix

  7. rules • Only COTS (Custom Off The Shelf) items allowed: • Linear Slide • Non-motorized Turntables and Lazy Susan • Lead screws and threaded rod plus compatible nuts • Servo Blocks • #25 Chain and connector or half links

  8. rules • Unlimited in quantity or size of the following: • Raw material available to all teams from standard distributors • Standard bearings or bushings • Fasteners • Rope, Cord, Cable, monofilament, … • Rubber bands • Latex tubing • Zip ties • Nonslip pad without adhesive backing • Electrical solder, tape and any type of glue/cement • Any COTS lubricant as long as it doesn’t get on stuff

  9. materials • Readily available from many retailers • Cut and drill with simple tools • Strong and lightweight • Most commonly 6061 Aluminum • 7075 Aluminum for higher strength www.onlinemetals.com Extrusions www.8020.net

  10. materials • Readily available from many retailers • Cut and drill with simple tools • Or Water Jet, Laser Cut, CNC Break for complex parts Sheet metal

  11. materials • Lexan (NOT ACRYLIC) easy to find and work with • Bend with heat • Lots of shapes and different mechanical characteristics available Polycarbonate (lexan) Coroplast Sintra Teflon Nylon Delrin HDPE Plastics

  12. materials You can now Rapid Prototype Parts! You can now 3D print Parts! ABS Polycarbonate PLA Plastics

  13. materials Steel wire rope Paracord 150 lb test = 0.56mm diameter Solid steel wire Rope, cord, etc… Braided fishing line

  14. 88725K33@ McMaster for $2.68 for 3’ materials Drill rod (tool steel rod) Bushing 6338K311@ McMaster for $0.75 ea! Lubricants Lead screw or Acme screw Shoulder Bolts drive components Linear Bearing

  15. Lifts! You mastered these last year…right?

  16. lifts We saw them last year

  17. lifts What did we miss last year? Precision lifting Variable position lifting Lifts go up Lifts go down

  18. lifts • Short height, Wide base • Lift over base • Requires lots of power • Lots of moving parts • Difficult to synchronize two sides • Difficult to lift from ground • Difficult too have finite control • Poor lateral loading Scissor lift

  19. lifts FRC 343 circa 2000 Lead screw or Acme screw

  20. lifts • Simple to build • Can move fast • Can reach fore and aft • Light weight • Object orientation changes • Strong Lateral load • Lift outside base • Object orientation changes • Difficult to multi position • Do not lift high Single joint arm

  21. lifts • Lots of freedom • keep lift inside or outside of base • complex to build • heavy • Lots of motors • Difficult to control multi joint arm

  22. lifts • Simple to build • Light weight • Object orientation stays the same • Lift outside base • Lots of torque required at shoulder Four bar linkage

  23. lifts • twice the weight of four bar • Object stays the same • Higher lift than four bar • Lift outside base • Lots of torque required at shoulder • More joints to create friction and wobbles six bar linkage

  24. lifts • Straight lift • multiple positions • small footprint • COMPLEX • difficult to maintain • high CG Telescoping

  25. lifts Combine multiple mechanisms hybrid

  26. Ideas General design practices

  27. ideas What tasks within my strategy do I need to perform? Let strategy drive your robot design, not the opposite • Are you going to… • acquire it? • manipulate it? • store it? • lift it? • position it? • release it?

  28. ideas Think like a robot about the game piece • What does the game piece look like from the robots POV? • What are all the ways the game piece could lay? • What is the most usable or stable position? • How does the object react?

  29. ideas other design considerations Maximize your “Acquisition Zone”

  30. ideas other design considerations Alignment Devices

  31. ideas other design considerations Make it easy to drive

  32. ideas other design considerations Will stray objects interfere?

  33. ideas other design considerations Keep your Center of Gravity (CG) low

  34. ideas other design considerations Design is an iterative process

  35. ideas Some design mantras Really, simple IS better. You don’t have to prototype everything… Just the parts you want to work. Assume nothing. Sometimes wild ideas lead to champions.

  36. Celebrity Endorsed.

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