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1 Drivetrains Presented by: John & Paul Hines

1 Drivetrains Presented by: John & Paul Hines. Purpose of this Presentation. Drivetrain Selection Types of drivetrains Types of wheels Drivetrain mechanics Best drivetrain for your team Maintenance . Ideal Drivetrain.

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1 Drivetrains Presented by: John & Paul Hines

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  1. 1 Drivetrains Presented by: John & Paul Hines

  2. Purpose of this Presentation • Drivetrain Selection • Types of drivetrains • Types of wheels • Drivetrain mechanics • Best drivetrain for your team • Maintenance

  3. Ideal Drivetrain • Gets your robot where it needs to be, when it needs to be there • Is robust and reliable • Can push/pull objects and other robots • Meets your strategy goals • Fits with the game • Can be built with your resources  • Rarely needs maintenance • Can be fixed quickly

  4. Basics • Know your resources • Decide after kickoff: • Speed, power, shifting, mobility • Use the most powerful motors on drivetrain • Don’t drive ½ of your robot… WEIGH IT DOWN! • Break it early • Give software team TIME to work • Give drivers TIME to drive

  5. Wheel Types:  Traction Standard wheels with varying amounts of traction, stength and weight AndyMark  Plaction VEX Pro AndyMark  Pneumatic AndyMark KOP

  6. Wheel Type:  Holomonic Special Wheels that allow the robot to achieve Holomonic motion Omni Mecanum Crab Module

  7. Drivetrain Types: 2 Wheel Drive Driven Wheel Motor(s) Motor(s) + Easy to design + Easy to build + Light weight + Inexpensive + Agile - Not much power - Will not do well on ramps  - Easily turned Caster, Omni, Slide

  8. Drivetrain Types: 4 Wheel Drive 2 Gearboxes Driven Wheels Motor(s) Motor(s) + Easy to design + Easy to build + Inexpensive + Powerful + Sturdy and stable - Not agile - Turning is difficult Chain or belt Driven Wheels

  9. Drivetrain Types: 4 Wheel Drive 4 Gearboxes Drive Wheels Motor(s) Motor(s) + Easy to design + Easy to build + Powerful + Sturdy and stable + Many options: Mecanum, traction - Heavy - Costly Drive Wheels Motor(s) Motor(s)

  10. Drivetrain Types: 6 Wheel Drive 2 Gearboxes • Check out 1114’s Kitbot on Steroids • Simbotics.org • Resources • Kitbot en esteroides + Easy to design + Easy to build + Powerful + Stable + Agile* This is very common in FRC + simple + easy + fast and powerful + agile Gearbox Gearbox • *2 ways to be agile • Lower contact point on center wheel • Omni wheels on front or back or both  - Heavy **  - Expensive ** ** - depending on wheel type

  11. Drivetrain Types: Tank Treads 2 Gearboxes Gearbox Gearbox + Powerful + VERY Stable - NOT AGILE  - HEAVY  - Inefficient  - EXPENSIVE  - Hard to maintain Sole benefit: Ability to go over things For turning, lower the contact point on center of track wheel Will NOT push more than a well-controlled 6wd

  12. Tank vs. Holomonic • Tank Drive • 2 Degrees of Freedom • Rotation • Forward-back Motion • Holomonic Drive • 3 Degrees of Freedom • Rotation • Forward-back Motion • Side-side Motion

  13. Drivetrain Type: Killough 4 wheel drive or 3 wheel drive + Immediate Turning + Simple Control – 4 wheel independent - No brake - Minimal pushing power - Jittery ride, unless w/ dualies - Incline difficulty

  14. Drivetrain Type: Mecanum + Simple mechanisms+ Immediate turn+ Simple control – 4 wheel independent-  Minimal brake -  Minimal pushing power -  Should have a suspension -  Difficulty on inclines

  15. Team 1346 Mechanum Drive http://www.youtube.com/watch?v=xgTJcm9EVnE

  16. Drivetrain Type:  Crab/Swerve > Each wheel rotates to steer + High-traction wheels + No friction losses in wheel-floor interface + Ability to push or hold position + Simple wheels -  Complex system to control and program -  Mechanical and control issues -  Difficult to drive -  Wheel turning delay

  17. 368’s Crab Drive in 2010 http://www.youtube.com/watch?v=q9uck-wRa_8

  18. Drivetrain Top Speeds • Game dependent • Determined by wheel size and gear ratios • Controllable top speed: 15 ft/sec • Average 1-speed rate: 9 ft/sec • Good pushing speed: 4-5 ft/sec

  19. Center of Gravity (CG) • Robot mass is represented at one point • Mobility increases when Cg is low and centered • High parts = light weight • Low parts = heavy (within reason) Which is more Stable? ME!

  20. Gearboxes/Transmissions • Gear ratio determines top speed and motor load • Single Speed and Shifting options • CIMple Box shipped in 2011 KOP • 1 or 2 CIMs per gearbox • 2011 4 CIMs allowed • Must be greased to reduce friction

  21. Belts + Don’t Stretch + Can reach far - Need to buy in custom sizes

  22. #25   +  Lightweight   +  Easy to install   +  Smaller   -  Easy to derail   -  "Steches" over time #35   +  Allows for slop   +  Minimal "stretching"   +  Heavy duty applications   -  More weight Chain Selection

  23. Working with Chains • Tensioning • Critical to keep robot from throwing chains • Must be accessible and easily adjustable • Does not need to be used on ALL chains but should be on drive systems

  24. Look at other Designs! • Competitions • chiefdelphi.com • Team websites • YouTube • thebluealliance.com

  25. Presented by:     Paul Hines John Hines Drive Types + Wheel Pictures  www.AndyMark.com  (FRC Supplier) Swerve Drive Revolution Custom Frame www.team221.com  (FRC Supplier) Check out 1114’s Kitbot on Steroids • Simbotics.org • Resources • Kitbot en esteroides

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