Somewhere Over the Rainbow

Aim of the Challenge

To visit each of the four target areas within the time limit. There are two methods for doing this, so please continue to read.

Your robot will be placed at the centre of a flat wooden course measuring approximately 122cm by 122cm with walls 30cm high. A picture of the course is shown at the top of the page and an animation can be seen above or on YouTube.
A 24cm-radius quarter-circular zone will be marked out in each corner.
At the start of the challenge, coloured balls will be hung from each corner. The bottom of each ball will be 10cm off the floor of the course.
The floor and walls of the course itself will be painted a uniform colour (black) to aid with colour separation.
The course will be lit from four, diffused 10W lamps halfway along each wall. They will be suspended 60cm above the floor and will point towards the balls in the corners of the course.
You must specify which of the two methods below you are using to complete the course.

Your robot must autonomously identify each coloured marker and visit each zone in the following order: Red, Blue, Yellow and, finally, Green.
The placement of the markers will be randomly pre-determined for each team, but will not be pre-advised to competitors ahead of their runs. However, the placement will not be changed between your three runs and it is permissible to have your robot ‘learn’ the route and achieve faster times on subsequent runs.
We will provide a set of coloured balls to be used to “calibrate” your vision sensor. These will be available near the challenge in approximately the same lighting conditions.

If any part of a wheel/track/leg of the robot enters a zone, it is deemed to have visited the zone.
Three run attempts are permitted, and encouraged, during your 7-minute window.
It is not necessary to complete all three runs.
The robot must stop autonomously after visiting the final zone.
If a zone is entered out-of-sequence, it is just ignored – there is no penalty for entering zones out of sequence. However, if a zone is entered out of sequence, it is not deemed to have officially ‘visited’ the zone for the purposes of that run. For example: you enter Red, you enter Blue but then you enter Green. Green does not count because you have not entered Yellow yet. Subsequently, you enter Yellow and enter Blue again, which is permissible but you do need to enter Green again because you entered it out of sequence.
At the end of each run, your robot will be placed back in the centre of the course.
Your robot’s autonomous runs can be triggered by pressing a button on the robot, for example, or by remote control activation.
It is allowed for you to have button(s) on your remote controller that you can press to tell your robot that it has, indeed, visited the zones. This is permitted for both methods described above.
Apart from your “activation” and “visited” controls, no other remote control is permitted.
Up to three rescues per run are permitted, with penalties as detailed below.

15 points for each colour zone entered in the correct order.
No points will be awarded for visiting zones in an incorrect order.
10 additional points for entering all zones in the correct order during a single run.

It is permitted to rescue the robot and place it back on the course at the place where things went wrong once per run without penalty but the clock will not be stopped.
A second rescue is permitted, incurring a 15 second penalty.
A third rescue is permitted, incurring a 15 second penalty.
A fourth rescue is not permitted, instead the run must be abandoned.
Abandoned or non-completed runs will not count towards the shortest run time, however any points accumulated during the incomplete run will count towards the overall score.

If using Method 1, your robot will require some form of computer vision. The Raspberry Pi camera is perfect for this.
A good example of controlling your robot with OpenCV can be found on the PiBorg site. We have modified the code as an example for you to use here.
Lighting conditions on the day may not be the same as where you tested. Your robot should be able to cope with this if possible.

You can discuss this challenge and ask questions on this discussion forum.