Welcome to our new FLL team blog

Our team, "Veni Vidi Roboti" has been going strong since this summer, when we decided to work our way through LEGO MINDSTORMS NXT: The Mayan Adventure . The kids had fun making robots to traverse tomb tunnels and swing on vines across deadly spike-filled caverns, ala an Indiana-Jones-style adventure. Here's just a few of the imaginative solutions they came up with for a vine-traversing robot. The robot had to somehow make its way along a vine strung across a large cavern while carrying a pebble. When it reached the opposite wall of the cavern, it had to drop the pebble into a jar and return to get the next pebble. When the jar reached a certain weight, a door into the next tomb opened. We simulated the cavern and vine with a rope strung across our living room.
The kids took some time to test out a variety of different designs to traverse the vine, from clawed hands to gears to a single gear system like a gondola. Eventually they concluded that the triple-gear system worked best for propulsion along the vine, especially as the vine swung upwards towards the final attachment spot. One gear gripped the vine and the other larger gears kept it from slipping off
Next it was time to devise an attachment that would hold a pebble without dropping it as it moved across the vine, and be able to drop it with precision into a bucket at the other end, via connection with a motor. Here's their final design for the pebble attachment, it tips downward with the rotation of the motor to release the pebble.

And here's their final design for the robot, without the attachment of the ultrasonic sensor that allowed it to know when it was finally approaching the wall.


Here's a video of the final robot in action, after they finished programming it (sorry for the poor quality, it was taken with a Blackberry). They decided to use an ultrasonic sensor to detect the approaching wall. The robot moves forward for a long ways, then begins moving in shorter increments which are separated by taking in data from the ultrasonic sensor. When it is the appropriate distance from the wall, it pauses, as the kids discovered that if it didn't pause, it would drop the pebble while it was still swinging and the accuracy would be off. Once it has stopped swinging, it drops the pebble and returns to the other side of the chamber to be re-loaded with the next pebble. They tested 8 pebbles in a variety of shapes and sizes and were able to drop them in the small jar with 90% accuracy. Extremely exciting for a few hours of work!