Drag Racing tasks
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Here is a list of things you need to be able get your robot to do.
For Drag Racing.

1) detect start sensor, and light a LED
   this is an extra sensor detecting a white slip of paper.
2) display the line sensor readings and remember the upper and lower values.
   display can be on the LEDs and/or via debug.
4) Use maths to calculate the two motors speeds directly from the sensor reading 
   (or the "corrected" derivative reading).
5) Adjust the "Proportion" ratio
   (This is the ratio of sensor reading change to motor speed change).
   Adjust it to suit the speed and the maximum curvature required to get round the track.
6) Adjust the "Derivative" ratio 
   (This is the multiplication factor of the reading difference to be added)
   Adjust to bring stabilty to the robot.
7) make the overall speed depend on the distance travelled
   you can make it extremely fast at the very beginning - the first meter or so,
   then slow to something stable.
8) use side sensor to stop the robot at the end of the track.
   this will can be the white line to be seen on one side only!
   ignore the starting white line however!
9) Make it continue to steer (and stay on the line) when stopping
   it's not good enough to just set the motor speeds to zero, as the robot will swing right or left
   make the motor speeds still depend on the snsor reading, but their sum should be zero.

 Finally
   tune it all up so that it gets along the course as quickly as possible!
   
 Easter Egg
   Make the robot return to the start, after the race is run.
   - this can be by spinning, and following the line back,
   - or be reversing down the track (extra sensor needed)
   
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J Fisher 20/1/20