Cornell Battlebots Spring 2003 Review

1
Cornell BattlebotsSpring 2003 Review

• Team Leaders
• Justin Manzo, Edward Kelleher, Adam DuChene,
  Jason Harris
• Team Members
• Ryan Connell, Melody Hung

2
Semester Review

• Justin Manzo

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Accomplishments - Weapons

• Weapon Prototype functional
• First iteration proved feasability
• Second iteration attempted functionality
• Final design accommodates previous shortcomings

4
Accomplishments - Drivetrain

• Drivetrain developed gearing solutions
• Prototype gearbox developed
• Hub designed, implemented, redesigned to
  accommodate changing weapon designs
• Motor mounts created

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Accomplishments - Framing

• Initial Frame implemented
• Facilitates communication between drivetrain and
  weaponry groups major inconsistencies
• Allows for potential placement of components
• Second Frame designed, under construction
• Meets demands of all subteams, fully optimized

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Accomplishments - Electrical

• Motor controllers finished, fully functional
• Control board designed, printed, assembled
• Control logic generated
• Initial radio contact made in lab environment

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Accomplishments - Managerial

• Funding allocated for entire Spring 2003 budget
• Opened new routes for purchasing equipment
• Budget still has small surplus to start future
  work
• Itemized financial records kept up-to-date

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Current Plans

• Implement design plans all finalized
• Final drum weapon
• Gearboxes
• Finalized hub design
• Instantiate radio controls waiting on antennas
• Place components on frame awaiting frame
  completion
• Shield critical components
• Motor controllers
• On-board control logic

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Final Design
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Electrical and Controls Systems

• Led by Jason Harris

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Electrical and Control System

• Electrical and Control teams fused
• Electrical design dictated by control style
• Team goals
• Design and build everything between operator and
  drivetrain
• Successfully integrate with drivetrain and weapon

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Electrical System

• Goals achieved
• Hardware successfully designed and assembled
• Hardware operates to specification
• Software operates to specification
• Goals not achieved
• Radio not functional at this time due to lack of
  hardware

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Hardware Description

• Motors
• Two Bosch 24V 750W motors for drivetrain
• Continuous duty motors that draw a maximum
  current of 150A
• Easily powered by amplifiers and battery packs
• One Magmotor 24V 3,300W motor for weapon
• 3 Minute duty cycle with 550A maximum current
• Weapon has high angular momentum, motor uses only
  4A at no-load has only to overcome friction

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Hardware Description

• Batteries
• Two Hawker 16Ah sealed lead-acid batteries in
  series
• Low internal resistance, can source more than
  300A continuously for 3 minutes
• Weight/Power tradeoff
• All amplifiers and motors optimized for use at
  24V

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Hardware Description

• Amplifiers
• Five OSMC H-bridge amplifiers
• Can switch 160A continuous, 300A peak with little
  loss
• Protection from negative transients built in via
  zener diodes and Transient Voltage Suppressors
• 16 power nMOS transistors have individual
  heatsink, array is cooled by 80mm fan

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Hardware Description

• Controller
• Contains all the hardware required to accept
  human input, communicate via 900MHz radio, drive
  three motor amplifiers and provide feedback to
  the operator
• Provides 8 different voltages (5V, 3.3V, -10V,
  -19V, -26V, and 6VAC) to drive a wide range of
  hardware
• Onboard regulators accept 7V-40V input

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Hardware Description

• Controller
• Based on Atmels 8-bit ATMega128
• 128KB of program memory, 4KB of RAM, 4KB of
  nonvolatile storage and 53 input/outputs provide
  plenty of power
• 24 analog/digital inputs, 16 digital I/Os, 3
  ports directly hardware compatible with
  amplifiers
• Programmable by a PC via serial interface

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Electrical System

• Problems
• Controller board had layout design flaws, but
  they have all been worked around
• Radios invert transmitted signal, but was never
  mentioned in documentation
• Manufacturer late on shipping antennas
• Computer crash destroyed last three weeks worth
  of work

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Drive Train

• Led by Ted Kelleher

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Initial Design Concerns

• Gear Ratios
• Conflicting motor specs
• Connecting motors to wheels and driving
• Gear Boxes
• Frame matching
• Redesign

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Initial Frame Design

• Problems
• Did not match weapons frame
• Motor Mounting issues
• Wheel mounting
• Reversability
• Advantages
• Strength
• Size, weight
• Versatility

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Initial Hub Design

• Cons
• Time to machine
• Meshing with frame
• Pros
• Strong
• Independent spinning
• Holding of wheel
• Axle integrated

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New Hub/Wheel Assembly

• Pros
• Independent Wheels
• Solid Axle
• Each assembly removable and adjustable
• Strength
• Integrated with frame
• Cons
• Expensive bearings
• Multiple bearings

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Overall Design And Issues

• Frame
• Redesigned to accommodate space
• Reversibility, triangular shape with base
• See Adam Duchene
• Wheels and Hubs
• Also redesigned, for new frame
• Bearings, gear boxes design
• New assemblies need time to build

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Framing Concerns

• Led by Adam DuChene

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Initial Frame
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Final Frame
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Weapon Design

• Ryan Connell

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Weapon Design

• Goal
• To create a horizontally driven drum that will
  deliver a large impulse and destroy opponents.
• Components
• Motor
• Driving Mechanism
• Drum
• Axle
• Gripping Teeth

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Motor

• MagMotor S28
• Factors in Decision
• Performance
• 4 ½ hp
• 4500 rpm
• Price
• Electrically Powered
• Size 3 x 3 x 8
• Weight 8 lbs.

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Drum

• Purchased 6 and 8 I.D. steel piping
• Factors in Decision
• Strength
• Weight (approx. 20-40 lbs.)
• Moment (Most material farthest from axis)
• Material
• Strong
• Dense
• Weld Friendly

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Driving Mechanism

• Major Choices Available
• Belt Driven
• Allows Slipping under extreme conditions
• Gear Driven
• Limits placement of motor in final design
• Heavier
• Difficult to design/build
• Does not allow slipping
• Chain Driven
• Stronger
• Heavier
• Does not allow slipping

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Initial Design

• Rotating Axle
• Belt Driven
• Drum welded to axle with steel plates
• Aluminum testing frame
• Team manufactured pillow blocks
• Four ½ steel bars for gripping test objects

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Test Results

• Pros
• Motor worked great
• Belt drive slipped to alleviate the motor
• Aluminum structure did not move from gyroscopic
  forces
• No major vibrations from unbalance
• Cons
• Batteries did not have enough power
• Steel bars were ineffective
• Slight grinding at pillow blocks

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Snowmobile Studs

• Potential Improvement on the steel bar
• Designed to pierce opponents
• Comes in two materials
• Steel
• Carbide Tipped Steel
• Comes in two designs
• Push through
• Screw in

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Second Iteration

• Improvements
• Bushings added to separate drum from pillow block
• Spikes mounted perpendicular to outer face of
  drum
• Results
• Bushings worked great
• Spikes sheared at tip and at threaded base

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Redesign of Spike Application

• Problem spikes were shearing rather than
  puncturing.
• Solution
• Mounted spikes tangent to the drum to decrease
  shear force from attack
• Went to pure steel rather than carbide
• Using nuts rather than threading drum. This
  allows for versatility and easy repair.

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Latest Design

• Three T-shaped members added to the outside of
  prototype drum.
• Upper T is for added grip should the studs shear
  off.

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Outlook

• Most of the final design manufacturing is
  finished.
• Waiting to get results on new teeth design.
• Final Design
• Split drum design centrally driven
• Steel teeth
• 8 drum
• Modular
• Fixed axle

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Robust and Modular Design

• Melody Hung

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Axle and Pillow Blocks

• Two Possible Designs
• Rotating Axle
• Fixed Axle
• Factors in Design
• Interested in being able to remove axle, should
  it fail.
• Developing a shock absorbing addition.