The Vexmen of Brandywine Robotics

Blog Post

Vexmen 2014 Spring Classes Progress Report

It’s halfway through the Vexmen spring classes and it’s time to show off some progress.

The Wednesday class is focused on line following and developing more skills in programming your robot. Nine teams are participating in this particular class. We’ve gone over background tasks to keep track of your sensors and logging values to the debug stream for graphing and visualization of what is really happening on your robot. We learned what makes a gyro work and how we can use the gyro to tell if we’re outside the bounds of the line. (If Vex did not run out of gyros we’d be putting them on all the robots now. Instead we will try to incorporate Arduino ones. Oh boy! Soldering!)

Vexmen Line Following Class Maze

Vexmen spring line following course

Along the way, we’ve been building small squarebots to traverse the maze. Each robot has at least three line followers and two quad encoders. Each team started with the sample line follower code to go left, go right or stay straight. This sample only works so well in a maze or if you want to go fast. So we’re learning how to improve this program and improve their skills along the way.

Team 80C Colossus have made it the furthest and fastest so far. Check their robot action here.

Team 80H Havok roboteers are not far behind right now. Their proportional drive is overreaching right now.

Kids are getting stuck on the cross right now but we’ll be going over strategies for each segment, combining sensor readings to act together, and PID control loops.

We see how far we can get each week in the maze autonomously. As new techniques are added we know more about how the robot operates and can develop new strategies for the maze. The maze gets progressively harder. The first segment has a 45 degree turn between segments. The second has a curve to lead you to the next straight segment. Then comes a 90 degree turn to the right. Then the robots face their first challenge, a T off to the right while straight is a dead end. This is where most line following programs need some more strategies.

Once around the corner it gets interesting. Segment 5 has curves while segment 7 breaks the line into a dashed line. The final run home is a line of a different color (yellow will be replaced as it is too close to white). If you touch an obstacle you lose a point.

Week 2 winner – 80H Havok 2.5 segments
Week 3 winner – 80C Colossus 4 segments
Week 4 winner – 80C Colossus 4 segments

There’s no time limit so some teams have started going really slow and steady. 80Y Cypher takes twice as long as 80H and 80C right now and almost makes it on to segment 5.

Next time, we’ll talk about our Tuesday class learning about structural strength, gear ratios, gear skipping, and friction effects on their drive trains.