2009 FIRST Robotics Team 1212 By: Bernard McBryan Boeing Technical Fellow 7 January 2009

Points Available 2 points for each moon rock (max 120->240) 2 points for each empty cell (max 8 -> 16) 15 points for each super cell (max 8 -> 120) Total: empty cell removed if team score was > than 2x opponents 2 empty cells removed if team score was > than 3x opponents Penalties: Empty Cell launched over the glass -10 Re-entry of an exchanged Empty cell -10 Super cell launched before last 20 sec -20 Robots handling more than 1 Empty cell -10 Must pick up game pieces with tongs -10 Robot will not extend across wall or be disabled

Constraints Must use low coefficient of friction wheels! –Can use any number of wheels –Must be flat, Rotate axis must be parallel to floor –Static coefficient = - Dynamic = Always pulling a trailer (cannot modify trailer in any way) Restricted size constraints throughout the match: –28” width x 38” Length x 60” Height (cannot violate this space constraint) Weight Battery (12.5) + bumpers (18) = 150 lbs. Max Power available = 12volts * 120 Amps = 2 HP Motors: –4 CIMs (1/3 hp) = 4/3 HP2 Window Motors (.1 HP) =.2 –2 Fisher Price (1/3hp) = 2/3 HP1 Heavy Window Motor (.1 HP) =.1 –2 small motors & servos 2 globe motors (.1 HP) =.2 Pneumatics: Up to 4 air tanks Must use bumpers: 2/3 perimeter, placed 1-7” above floor Items in RED above were determined to be “game Changers” by the veteran FIRST personnel

Tasks Robot Stores Balls (start with up to 7 in basket) Robot Picks up Balls (from floor) Robot Receives Balls from Outpost (catch) Catch Balls? Robot passes balls into airlock. Robot shoots balls into competitor’s trailer Robot dumps balls into competitor’s trailer Human shoots Ball (into trailer or basket) Maneuver under low gravity while pulling a trailer –To transport fuel cells- To disrupt transporters –To retrieve balls- To block herders –To Catch robot for dumping- To avoid being dumped on –To get in range for a good shot - To avoid being easy target

Herding or picking up balls The robot can’t expand out of its footprint, even to put out herding arms (example 1 below) Thus, probably need a U-shaped robot. Since the length is wider than the width, probably should use the width as the front. –This will also help turning with differential turning.

Maneuver under low gravity Multiple Wheels helpful? Friction Force = Cf*Normal Force (i.e. weight) Increasing the number of wheels, e.g. going from 4 to 8 looks like it will double the friction force, but it also halves the Normal Force. Thus, the friction force is approximately independent of surface area.

Maneuver under low gravity Maximum Acceleration? Friction Force = Cf*Normal Force (i.e. weight) Inline: Static 0.06Dynamic: 0.05 Transverse: Static 0.14 Dynamic: 0.10 Friction Force =.05*150lbs (1kgrams/2.2lbs) = 4 Newtons? F= m*a Ke = ½ m v**2 Max Speed? Max Gear Ratio for CIM? 5000 RPM * 1Min/60sec = 83 Rev/Sec Current Gear Box Ratio: 12:1 12:1 Gearbox => 83/12 = 7 Rev/Sec * 1.5 ft = 10.4ft/sec

Maneuver under low gravity Eliminate Wheel Slippage Friction Force = Cf*Normal Force (i.e. weight) Inline: Static 0.06Dynamic: 0.05 Transverse: Static 0.14 Dynamic: 0.10 There is a 20% increase in friction if can keep wheels from slipping. Limit speed before slipping. -Wheel counters and speed schedule -Measure speed with undriven wheel -Measure speed with accelerometer -Measure current*voltage (with current sensor) -Radar Sensors or optical mouse? (on chief delphi)

Maneuver under low gravity Vertical Flywheel Vertical Flywheel will cause a heading torque if rotated about its axis. Should be able to steer robot with flywheel and rotate basket on a dime. Spin up flywheel with Fisher Price (located at back of robot) Energy is proportional to Mass, R**2, and W**2. Not sure of impact when rammed or hit wall. Might be able to resurrect robot if falls tips left or right.

Maneuver under low gravity Horizontal Flywheel Horizontal Flywheel will cause a heading torque if rotated about its axis. Should be able to increase weight of the robot, thus, increasing driving force. Spin up flywheel with Fisher Price (located at bottom of robot) Energy is proportional to Mass, R**2, and W**2. Not sure of impact when rammed or hit wall. Might be able to resurrect robot if falls tips forward or back, but the trailer should have prevented this.

Candidate Designs Herder/retriever gets balls to human Retrieve balls and dump them Retrieve balls and shoot them Try to make a robot that can do two or all three? Team needs to determine strategy early and prioritize most important tasks to work Veterans agreed that designing for all three above is very ambitious. Suggested that teams strive for doing one or two well, rather than all three poorly. Good strategy is to select one or two above and do the best you can given our 6 week time limit.

Maneuver under low gravity Differential Chain Drive Three wheels: Four wheels: Six wheels: Eight wheels:

Maneuver under low gravity Individual Steering Drive Three wheels: Four wheels: Eight wheels:

Shooting Catapult: –Small pneumatic –Rotational pneumatic –Fisherprice Windmill

Ram Dump Ram Trailer, – while lowering front wall –Raise dump (if reserve height).