By: dtengineering
New: 25-02-2007 16:40
Updated: 25-02-2007 20:49
Views: 2604 times

This is the latest entry from team 1346, General Motors Canada and David Thompson Secondary of Vancouver, BC.

We will be competing in Portland and Toronto.

The robot runs on AM mecanums, direct drive from a 12:1 BB planetary and CIM on each wheel. It uses the BB shaft encoders and divider cards for full PID speed control on each wheel. In addition to the CMU cam it has 3 maxbotix ultrasonic rangefinders mounted on the front to help locate the base of the rack. (We tried to use Sharp IR sensors, but the diamond plate was too shiny.) In practice the robot can self-locate to scoring position in auto and telop... can it do it for real? We'll find out soon, but the mecanum's ability to "strafe" makes life much easier, as does keeping the tube roughly parallel to the floor... it lets us take advantage of the curved sides of the spider foot, rather than having to fit perfectly over the flat front.

The arm rotates down to pick up the tube "behind" the robot, then flips up over the top to hold it over the main body of the robot. The lift can elevate the arm to score on all three levels, although there is a bit of unwanted sway at the highest level. When the front bumper smashes into the base of the rack, the centre of the tube should be about 20" out... the perfect position to drop over the spider foot. This "no aiming" approach was inspired by the teams that last year just wheeled up the ramp and "slam dunked" the balls home without really needing to aim.

A very roughly editited series of video clips from our build period (including the robot climbing a 20 degree ramp...) is on youtube at http://www.youtube.com/watch?v=gyn9e0cT3-A

We've still got a few tweaks to do on Thursday at Portland, then it is just a matter of seeing how it all works out during competition. It looks like there will be some great robots to play with there!

Jason

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