Mousetrap Vehicle

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Mousetrap Vehicle

• Bro. Nigel Pratt
• bronigel_at_kellenberg.org
• Dennis Papesh
• papeshdr_at_holyangels.cc

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Goal

• Teams will design, build, and test a vehicle
  which uses one or two single-spring mousetraps as
  their sole source of energy for propulsion.

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Years ago.

• This is basically what you wanted to do
  (1986-1995)
• http//www.youtube.com/watch?vHqc9uexNL64
• The rules were very similar to what we have had
  with Wheeled Vehicle and Battery Buggy in the
  past.
• BUT THIS YEAR EXCITING CHANGES ARE IN STORE!!!

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Parameters

• Only one or two unmodified single-spring
  mousetraps (not rat traps) may be used as energy
  sources.
• Unmodified means that all the original parts of
  the mousetrap(s) remain in place.
• Things may be added to the mousetrap(s), but not
  removed.
• Mousetrap bases less than 6.0 cm x 12.0 cm

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Parameters contd

• All parts of the vehicle must move as a whole,
  i.e. no anchors, tie downs, launching ramps, or
  other separate pieces are allowed.
• If any piece falls off during a run, it is
  considered a Competiton Violation.
• All of the vehicles kinetic energy must
  originate from the mousetrap(s).
• Conversion of the mechanical energy of the
  mousetrap(s) spring is permissible, but any
  additional energy sources must be at their lowest
  states at the beginning of the run.

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Parameters contd

• Reversing and stopping mechanism must work
  automatically.
• The vehicle may not be tethered or controlled in
  any way to guide it, reverse it, or make it stop.
• Recoil is NOT considered reversing.

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Parameters contd

• The vehicle must have a fixed, pointed object on
  the perimeter of the chassis of the vehicle that
  extends to within 1.0 cm of the tracks surface.
• Toothpick, pin, small nail
• Must be easily accessible to event supervisor
  without lifting or moving vehicle
• The tip of this fixed, pointed object nearest the
  track surface will be used as the reference point
  on the vehicle for all distance measurements.

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Parameters contd

• The vehicles wheel base is the distance measured
  parallel to the direction of travel between the
  center of rotation of the front and rear axles,
  and it must be between 30.0 and 34.0 cm.
• The vehicles maximum wheel width is the distance
  measured perpendicular to the direction of travel
  between the outermost side of the left and right
  wheels and it may not exceed 25.0 cm.

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Parameters contd

• Sighting devices which do not use electricity are
  permitted.
• Sighting devices do not have to be permanently
  attached and may be removed before the vehicle
  runs.
• No part of the vehicle, other than the wheels,
  may contact the floor or tape defining the track
  at any time.

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The track

• The competition will be on a straight and level
  lane with a relatively smooth, hard, low-friction
  surface.
• Three quarter or one inch tape will be used to
  define the tracks starting line, a line 3.50
  meters from the starting line (the 3.5 meter
  line), a line 7.00 meters from the starting line
  (the 7 meter line), and a line 8.00 meters from
  the starting line (the 8 meter line)

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The track contd

• The same tape will be used to define the 1.50
  meter lane side boundaries from the starting line
  to the 8 meter line.
• The center of the start line will be indicated
  with an arrow drawn in ink pointing toward the
  inside tape, The 7 meter line will be likewise
  marked.
• The distance between the two arrows will measure
  exactly 7.00 meters.

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The track contd

• Additional space must be provided in all 4
  directions of the lane to allow for the vehicle
  over-running the track.
• At the National Tournament, there will be 0.50
  meters of additional space outside the lane side
  boundary and there will be 2.00 meters of
  additional space beyond the starting line and the
  8 meter line.

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The track contd

• Every 0.5 meters of additional space beyond the 8
  meter line will be marked with tape.
• The additional space requirements for Regional
  and State tournaments will depend on the
  availability of the venue.
• Realize that ALL levels of competition SHOULD
  have a similar set-up.

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The competition

• The students can chose to start their vehicle
  anywhere along the starting line with the
  designated fixed point directly above the
  starting line.
• A target may be placed at the finish line to aid
  in aligning the vehicle, but must be removed
  before starting each run.

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The competition contd

• The vehicle must be able to remain at the
  starting position without being touched until the
  trigger is released using a pencil, pen, dowel,
  or similar device.
• which is not a part of and does not travel with
  the vehicle
• It is considered a run if the vehicle moves any
  distance after the trigger has been released.
• So if it doesnt move. Its not considered a run.

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The competition contd

• The students may not push the vehicle nor will
  they be allowed to constrain the vehicle during
  release.
• The fixed point of the vehicle is to cross the 7
  meter line and return to the center of the
  starting line as quickly as possible in order to
  receive the maximum score.

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The competition (contd)

• Reversing and stopping mechanisms must work
  automatically. The vehicle may not be tethered
  or remotely controlled in any way to guide it,
  reverse it, or make it stop.
• So, you cant do this.
• http//www.youtube.com/watch?vVO_k9Hkz_oU
• Teams will have 10 minutes of Event Time in which
  to get two runs started.

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The competition contd

• The Event Time will begin when the students are
  allowed to place their vehicle on the starting
  line.
• Teams will have 10 minutes of Event time in which
  to get 2 runs started.

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The competition contd

• If the second run has started before the 10
  minute period has elapsed, it will be allowed to
  run to completion.
• Time used by the Event Supervisor for measuring
  will not count toward the 10 minute Event Time.

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The competition contd

• Teams may not follow their vehicle down the
  track.
• They must wait until called by the Event
  Supervisor to observe their finish distance and
  pick up their vehicle.
• At this point, the Event Time will resume.
• Students may take any measurements and make any
  adjustments to their vehicle.

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The competition contd

• Measurements made by the Event Supervisor are the
  only ones that will be used as the official
  distances.
• Teams who wish to file an appeal must leave their
  vehicle with the Event Supervisor.

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scoring

• The Run Score shall be the sum of the Distance
  Score Lane Bonus Over-run penalty Time
  Score.
• Negative scores are possible.
• Low score shall be the winner.

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Scoring distance score

• The Distance Score for vehicles that reach the 7
  meter line and reverse shall be the distance
  measured in centimeters (to 0.1 cm) from the
  center of the starting tape to the tip of the
  fixed point.
• For vehicles that travel past the 3.5 m line but
  not the 7 m line and then reverse, a penalty of
  1000 points is added to this distance.

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Scoring distance score

• For vehicles that reverse but do not reach the
  3.5 m line, a penalty of 2000 points is added
• The Distance Score for vehicles which do NOT
  reverse their direction of travel will be the
  absolute value of 700.0 minus the distance
  measured in centimeters (to 0.1 cm) from the
  center of the starting line to the tip of the
  fixed point. These vehicles will be placed in
  Tier 2.

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Scoring lane bonus

• There shall be a -20 point Lane Bonus awarded to
  any vehicle whose fixed point remains inside the
  tape defining the 1.50 meter lane between the
  starting line and the 8 meter line while
  traveling both directions.

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Scoring over-run penalty

• If the fixed point of the vehicle crosses the 8
  meter line, an Over-run penalty shall be assessed
  as follows
• 50 points shall be added for crossing the 8 meter
  line
• An additional 50 points shall be added for each
  additional half-meter of travel.

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Scoring time score

• The Time Score shall be the time of each run in
  seconds, measured in 0.01 seconds.
• The time of the run starts when the vehicle
  begins movement.
• If the vehicle does not reverse within 3 seconds
  after coming to a stop, the total run time will
  be the time of motion plus the three seconds.
• If the vehicle reverses direction, the run time
  will stop when all motion ceases.

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Scoring time Score contd

• At Regional competitions, the Time Score shall be
  added as 1 point for every second.
• At State competitions, the Time Score shall be
  added as 2 points for every second.
• At National competition, the Time Score will be
  added as 4 points for every second.

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Scoring competition violations

• Outlined in Section 5 (The Competition)
• Will result in being ranked in Tier 3

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Scoring construction violations

• Construction Violations are outlined in Section 2
  (Construction Parameters)
• Will result in being ranked in Tier 4

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Scoring - tiers

• Teams will be ranked in four tiers using the
  single run that will give them the best overall
  place where
• 1st Tier A run with no violations and reverses
  its direction of travel
• 2nd Tier A run with no violations but does not
  reverse its direction of travel
• 3rd Tier A run with Competition Violations
• 4th Tier A run with Construction Violations or
  both Competition and Construction Violations

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Scoring contd

• 1st Tie Breaker
• Distance Score of the counted run.
• 2nd Tie Breaker
• The vehicles other run score.
• If the device cannot start at least one run
  within the 10 minute period, or has two failed
  runs, the team will receive participation
  point(s) only.

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Scoring example

• At State competition, the run took 15.8 seconds.
  The fixed point crossed the 8.5 meter line, but
  not the 9 meter line, and ended up with its fixed
  point 18.6 cm from the center of the starting
  line. It stayed within the lane the entire run.
  No violations.
• Time Score 31.6 points (15.8 sec
  15/8 sec x 2 pt/1 sec)
• Over-run Penalty 100.0 points (50 passed 8.0 m
  50 passed 8.5 m)
• Distance Score 18.6 points
• Lane Bonus -20.0 points
• Run Score 130.2 points (31.6 100 18.6
  20)

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So how do you make a good one?

• So for a basic construction
• http//www.youtube.com/watch?vOOobN0bUxqsfeature
  fvw
• Things to consider and discuss
• Dimensions of the vehicle
• Keep in mind KINETIC ENERGY
• Mass, friction, efficiency of energy transfer
• Experienced coach Wisdom re rulers
• Experienced coach Wisdom re axles

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• Wheels
• - 3 wheeled v. 4 wheeled
• Type Rubber, balsa, plastic (DVDs), etc
• Diameter Should both axles have the same size
  wheels?
• Energy Transfer How will you transfer the energy
  of the spring to the axle for maximum speed?
• Directly v. Indirect (spring, rubber band)
• Torque issues are very important here Axle
  thickness
• Do you want to have the energy delivered very
  fast to the wheels and use momentum to travel
  down the course or should the energy be applied
  at a constant (but slow) rate to the wheels?

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• String issues
• entanglement, free string getting caught in the
  axles/wheels
• Type String that stretches or doesnt
• Length of drive arm short v. long
• Please, please forgive us for the following
• http//www.youtube.com/watch?vwZDSfRe5opo
• How will you make it reverse???
• Lets take a brainstorming session..

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• Ideas
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