Sunday April 27th - Touch Sensors

More Touch Sensors

Since it had been some time since we last met, we thought it would be good to review the touch sensor.  We pulled the board out from last year and had the boys use the touch sensor to travel to the other end of it, turn and touch the side wall, and then drive forward until they touched the ambulance.

As usual, we had them start by just programming it to go down to the far wall and touch it and back up a little.  They found that when traveling a long distance, the motors we had were mismatched which made the robot turn a little.  This caused it to run into the side wall.  In order to overcome the turning, they simply turned a little in the opposite direction and managed to get to the other end of the board without much difficulty.

Then they added the rear touch sensor and programmed it to back up and turn to touch the side wall.  We had the boys repeat this several times and mark where the robot touched each time.  Without having put the robot in the same start place, it traveled to the other end and touched the side wall in nearly the same place every time.

It was then simple to make it drive forward until the touch sensor hit the ambulance.

Moving

A few months ago, I found some teaching resources that we have been using loosely during our meetings.  In one of the lessons there was a set of questions around movement and how to figure out how far your robot would move with different move blocks (either rotation or degrees).

We found that our robot was fairly consistent in how far it would move with a small number of rotations (around 4).  We also learned that it was fairly consistent when specifying degrees of rotation.  We talked about how we saw the robot behave differently when the batteries were charged as opposed to when they were dying.

We found out that we can use the circumference of the tires on the robot to determine how far it will move with one rotation.  We learned that 1 rotation = 360 degrees of movement, so we can switch back and forth between the measurements.

Teamwork

We had a little time at the end of the meeting so we decided to try out a little teamwork exercise.  Last year at the competition, the boys were asked to keep a balloon in the air for 1 minute.  They were only able to keep it in the air for about 20 seconds after 3 tries.

At the meeting, their first try was about 20 seconds.  We suggested that when they were going to hit the balloon up, they call it so the others know that they have it.  We also suggested that they call out if another teammate is hitting it too high, or doing something that is making it harder.  When they tried a second time, they were able to keep it up for almost a minute!

Next Meeting

We will probably be building a more robust robot.  The one they have been using is the 5 minute bot, but it is a little difficult to enhance, and it only has two wheels, which makes it very difficult to go over obstacles, and can make turning a little unpredictable.

We will be learning more about how the robot moves and turns, and how we can calculate how far to turn, rather than the guess and check method we have been following thus far.