Integer 160 Project

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(No Transcript)
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THE CLIENT Mark Novak Outreach Specialist Biol
ogical Systems Engineering
The Needs Hand Controls for Safe
and Reliable Lawn Tractors Desig
n Practical and Efficient Adaptable/Mob
ile Design Des
ign
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PROBLEM STATEMENT

• Create a practical hand-controlled device to
  operate the for/aft movement for a lawn tractor
  which can be used by individuals with lower body
  disabilities without impeding normal operation.
  It must be safe, reliable, durable, and removable
  whilst remaining both cost effective and
  mechanically efficient.

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Brainstorming

• Joystick
• Box controls
• Alt kill switch
• Pressure sensitive
• Separate brake control
• Jet ski controls
• Pneumatic hand controls
• Cruise control
• Motor with gear
• Segway controls

• Cane/stick
• Throttle
• Water proofs
• Motorcycle control
• Wireless
• Pulley wire
• Mechanical brake
• 2nd battery source

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Evaluation

• Box controls
• Cane/stick
• Water proofs
• Pressure sensitive
• Jet ski controls
• Pneumatic hand controls
• Cruise control
• Segway controls
• Wireless
• Pulley wire
• 2nd battery source

• Throttle (10)
• Mechanical brake (8)
• Joystick (4)
• Motor with gear (3)
• Separate brake control (2)
• Motorcycle control(1)
• Alt kill switch (0)

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Decision of Throttle Design

• Basis of our Decision
• Most votes
• Easiest to assemble mechanically
• Easy to control
• Most cost effective

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Attachment of Throttle to Transmission

• Initial design modeling
• Test-bench/prototype
• Mounting of throttle
• Cross pieces/attachments to throttle
• Mounting plate
• Final product

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Initial Modeling Designs

• Throttle is attached to a series of levers
• Levers are connected to for/aft transmissions
• Open circles are loose joints that rotate
• Cylindrical bar is attached to the mounting
  plate
  

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Test-bench / Prototype

• Took measurements of dimensions from tractor and
  location of levers
  
• Constructed replica of tractor segments and
  operation of the throttle/levers
  

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MOUNTING of THROTTLE

• Aluminum box shape
• Notch attaches to back of throttle
• Throttle slides down into the mounting piece

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Cross Pieces / Attachments to Throttle

• 3 Types of
• Attachments
• Flat rectangular
• steel bar
• 2. Solid cylindrical steel bar used for
  rotation of levers
  
• 3. Screws / bolts for attachment

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Mounting Plate

• 2 aluminum plates that are mirror images of each
  other
  
• Placed on each side of the tractor frame and
  attached with screws
  
• Cylindrical bar is inserted through the bearings

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Final Product

• Adjusted length of the pieces and size of the
  screws in order to accommodate within actual
  confinements
  
• Culmination of previous designs

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Considerations

• We took the following into consideration
• Range of motion
• Reduced physical exposure of product
• Position of product on the tractor
• Types of materials used
• Strengths / durability of product

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Considerations(continued)
Shearing Stress calculations (Strength of
Material)

• t(ave) P/A F(force)/A (area)
• Shear, MPa of structural steel 145x106 Mpa
• Area p (.25in)(2.54cm/in)(1m/100cm)2
• Force At 4129 lbs (max stress)
• Calculations of Throttle yield
• 4129x F1y x 5 inches, y 9 inches
• F1 2293.89 lbs

(conservative number used, never put more than
2000 lbs force on throttle!!!)

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Considerations(continued)
Critical Design Analysis

• Excess motion that did not apply to for/aft
  movements
  
• Tight fit of levers and throttle
• Lack of proper testing
• Weather resistant

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Considerations(continued)
Steps for Improvement

• More time for testing and constructing
• Greater budget for better materials
• Customizable lawn tractor
• Experience

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• Through our ideas and intuitive thinking, we
  were able to complete the design of functioning
  hand-controls for the lawn tractor. We believe,
  you, the client, will accept our ideas and make
  improvements upon them and hopefully someday be
  able to apply it to the real world.