NUTRONS

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NUTRONS

• Drivetrains and Arms
• Kyle Henry
• 8/16/2008

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Agenda

• Drive Trains
• Arms and Accessories

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Drive Trains - Type

• Tank Drive
• Left and Right Independent motion
• Drive it like a tank
• 2, 4 6 Wheel as well as tank tread (usually
  timing belt)
• Swerve Drive
• Rotate the wheels to the direction of travel
• Crab Drive
• 2 sets of DTs set 90º from each other.
• Holonomic
• Special Omni-wheels that while varying

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Drive Train - Criteria

• Choosing the right Drive Train for you
• Speed
• How fast do you need to go?
• Agility
• Are there obstacles on the field or do you want
  to be able to out maneuver around other teams?
• Pushing Power
• Do you have to pull or push something?
• Do you want to be able to push people around?
• Traction
• What will you be driving on?

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Drive Trains

• The game and what you want to do in the game is
  what will determine what type of drive train
  required.
• Some drive trains take years of development to
  work right
• Need to start somewhere and sometime.
• Can be a fall/summer project.
• Ultimately you can get any specific one to work
  and do what you want, its just the resources and
  development time that you want to invest in it.

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Accessory Devices

• Accessories are game dependant.
• Examples include
• Arms
• Elevator
• Ball Intake devices
• Hoppers
• Ball Shooters
• Grippers
• Wings
• Ramps

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Arms, Elevators and Wings

• Arms
• General goal is to lift and object
• Generally use rotating joints to move.
• Elevator
• Uses linear motion to raise or lower an object
• Wings
• Increase your size generally used to push or
  herd objects.

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Arms

• Arms us rotation about a point to lift or move
  objects.
• Torque is critical criteria.
• Need to count for several weights and differences
• End Effecter
• Game Piece
• Weight of the arm itself
• Place this weight at the geometric center of the
  arm
• Should look at how fast you want to accelerate
  the piece
• Design for X Safety factor
• 50 added torque is adequate
• 2 X Structural, if you can.
• Always use worse case loading scenario
• When arm is fully extended and parallel to the
  ground.

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Elevators

• Good for lifting objects.
• Generally require less power
• Lower forces
• Friction is the biggest obstacle.
• Need low sliding friction between pieces
• Pulley systems need to be wound correctly
• Size can be an issue
• Not always a large area for you to put things
  into.

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Appendix A - DTs
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Drive Trains Number of Wheels

• 2 Wheel
• Easy Turning
• One end is little resistance to being pushed
• Need something to create a wheel base
• Casters
• Low Friction Skids
• Omni-wheels

• 4 Wheel
• Hard to push from the side
• Difficult Turning
• Have to overpower friction of the wheels
• Greater traction with 4 wheels on the ground

• 6 Wheel (2 ways)
• Dropped Center Wheel
• Agility (small wheel base)
• Only 4 wheels on the ground at one time
• Level Wheels
• Need to overpower friction to turn
• More traction

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Drive Trains Typical Alternative

• Crab
• 2 drivetrains
• 1 is lowered/ raised
• Set 90 apart from each other
• Allow transverse or strafing type motion

• Swerve
• Rotate the wheels to the direction you want to
  travel in
• Typical 4 wheel arrangement
• Can be independent power source or central source.

• Holonomic (2 ways)
• Mechanum Wheels
• 4 wheels controlled independently
• 360 travel instantaneously
• Omni
• 4 omni wheels
• 2 sets 90 from each other