[Madison]

This has been a fantastic build season for our team and we're proud to present our 8th robot, X8: The Ocho.

Overall --

• Achieves all game functions - hurdle, herd, possess, remove from overpass and place on overpass.
• 118 lbs., 58" tall
• Bumpers cover 68% of perimeter
• Remains upright until tipped to approximately 60* off horizontal in all directions -- with ball and elevator extended to maximum height.
• Physically incapable of violating <R16>
• We've had approximately 20 hours of drive testing, 10 hours of elevator testing.
• Most sophisticated sensor package in team history
• IR-based hybrid functionality

Drive System --

• 6WD
• 4" Traction Wheels in the center, custom-built 4" omni wheels on each corner for fantastic maneuverability
• 3-speed, shift-on-the-fly Dewalt XRP transmissions
• ~12 ft/sec top speed
• 24:1 low-speed gear ratio
• Screw-based chain tensioning system

Inclinator --

• Inclined at 15* to move trackball mass above robot as its height increases
• ~74" travel
• PID-based position control with three preset positions -- bottom, "descore" and top -- and fine adjustment.
• Electronically controlled braking slows descent
• Cascade-style cable rigging moves each stage simultaneously, maximizing overlap for best support possible
• Driven by two CIM motors through AndyMark Toughbox transmission at 12.75:1 ratio. Inclinator is powered both up and down by 3/32" steel cabling tensioned by turnbuckles.
• Redundant cabling increases reliability
• Linear bearing surfaces are a hybrid of custom-made HDPE linear slides and 80/20 system nylon rollers on oil-impregnated bronze bushings.
• Pneumatic tubing take-up reel insures proper management of tubing to Ball Manipulator
  

Ball Manipulator --

• Simple forklift-inspired design
• Can be used as a secondary mechanism to remove ball from overpass
• Pneumatically-actuated tipping action secures ball against Inclinator
• Can pick up ball on the fly
• Passive hurdling action requires no coordination between operator and driver, increasing scoring efficiency
• We have prefabricated two spares with more on the way

Sensor Package --

• Encoders in line with drive system for PID-based position and velocity management. Accuracy is +/- 1" over 24'.
• Encoder mounted to winch drum for PID-based position and velocity control
• Brake/Coast settings on Victor 884 Speed Controllers driving winch are controlled by encoder-based position feedback and allow faster-than-gravity descent of Inclinator while minimizing sudden impact at the end of travel.
• Limit switch at bottom of Inclinator travel zeros encoder value to eliminate drift and acts as safety override in case of encoder failure.
• Limit switch at top of Inclinator travel acts as safety override in case of encoder failure.
• IR-board is mounted to bracket with two degrees of freedom that gives flexibility in starting position while maximizing signal readability.
• Pressure switch allows automatic control of compressor power.

Controls --

• One XBox 360 controller each for driver and operator
• Driver has control of motion and gear shifting; operator controls Inclinator position and Ball Manipulator position
• Software intelligently switches between simulated "Ackerman-style" steering and rotating in place, allowing fast lap times and fine control for ball retrieval.
• IR-based hybrid controller tells The Ocho which Overpass position contains our trackball; fourth function is "abort".
• Matlab-based trajectory generation software takes way point and heading information and generates hybrid movement code automatically.
• "Crossing" macro releases and retrieves ball while crossing the finish line, adjusting timing as necessary based upon robot speed and direction.

Video --

Early test of Inclinator with abandoned claw.

IR-controlled autonomous mode knocks trackball off overpass.

Hurdling demonstrated during driver tryouts.

Hurdling again during driver tryouts.

We're looking forward to competing in Portland, OR, Tacoma, WA and at the Championship in Atlanta, GA.

Please, ask questions! We're enormously proud and would love to talk about all of the amazing features this robot contains. How many other robots can say that they have a functioning tailgate, after all?