Three Point Turn

Time limit

5 minutes

Control method


Aim of the challenge

The robot must be autonomously programmed for this challenge which takes place inside a course measuring 1.22m by 2.44m with various markers. A picture of the course is shown on the right (click for a larger version).

The robot will:

  • start in the middle of the course surface, behind the white "start line".
  • proceed forward and cross the second white line ("CROSS THIS LINE").
  • turn left by 90 degrees (either on the spot or in-motion).
  • drive forward and touch or cross the 'top' black edge line.
  • drive backwards in a straight line and touch or cross the 'bottom' black edge line.
  • drive forwards to the middle of the turning area.
  • turn left by 90 degrees.
  • return to the starting box.

The measurements of the course as shown in the diagram are correct and will be measured as such when the course is marked out. The distances of travel required within the turning area will, of course, vary according to the length of your robot - it is up to you to prevent it from leaving the course surface.

Ranking and points

Robots will be ranked according to how quickly they return to the starting box after having completed all turns and movements correctly. The fastest will be ranked first. Points will be awarded to the top ranked robots like so:

  • 1st: 40 points
  • 2nd: 32 points
  • 3rd : 25 points
  • 4th : 18 points
  • 5th : 15 points
  • 6th : 12 points
  • 7th : 10 points
  • 8th : 8 points
  • 9th : 6 points
  • 10th : 4 points
  • 11th : 2 points
  • 12th : 1 point

Additional points:

  • 10 points will be awarded to any robot that finishes the three-point-turn successfully and completely crosses the white start line on its return.
  • 20 points will be awarded for any robot that finishes the three point turn successfully and finishes with any wheel inside the starting box.



  • Any rescue of the robot will incur a 20 second penalty.
  • Only 2 rescues are allowed before the challenge is abandoned.
  • If the robot's wheels go beyond the perimeter of the course, this will incur a 15 second penalty in addition to the 'rescue' penalty.


3 Point Turn


3 Point Turn driven


26 thoughts on “Three Point Turn

  1. Hello, this looks interesting.
    Will the green start line and the red line be detectable lines on the course?

  2. Hi,

    I assume the black line in the middle of the turning area is 0.37m in, is this correct?

    How far in from the boundary are the two black lines at the edge of this area?

    Looks like a fun challenge!

    1. That’s correct on the 0.37m – it’s slap in the middle of the ‘third sector’.
      The two short black lines in the third sector towards the outer edges weren’t measured last year, but if it helps they were about 10-15cm in.
      It certainly proved to be on of the most interesting challenge last year – autonomous operation is very challenging!

  3. Could you clarify which line is the red line please? Is it the first dimension at 0.81m from the left or the halfway dimension at 1.22m? Or the start of the second 0.81m line?

    1. Hi Mike. Apologies. I think me and Tim have our wires crossed on colours. I’ll get back to you with clarification.

  4. Sorry for so many questions 🙂 Hope I’m not taking things toooo seriously 😉 The course instructions above say the course is 1.8m by 2.2m. The course diagram says the course outline is 1.22m x 2.44m. However the 2.44m dimension is also subdivided in to 3 x 0.81m sections which is 2.43m 😉 Just wondering which are the correct dimensions 🙂

    1. You’re right of course. Diagram is correct. It’s 1.22 x 2.44, which is a standard size of hardboard. You’ll forgive us the rounding error 😉 (I have no idea why it’s subdivided into 3 apart from to give the turning area a size)

    1. It’s okay, David. Three Point Turn is always a bit of a mind-bender. I’ve changed the description and the diagram of the course to make it clearer. Your diagram is not correct. You’ve turned right at the top when you should turn left.

      1. Hi Mike – nice new diagram! 🙂

        That makes it loads clearer – going to be a tricky challenge this one methinks.



  5. Thanks for clarifying the red line issue.

    A couple more clarification points please:

    1). You now refer to white lines for the start and turn line but the Additional points state “10 points will be awarded to any robot that finishes the three-point-turn successfully and completely crosses the green line on its return.” Should that read “10 points will be awarded to any robot that finishes the three-point-turn successfully and completely crosses the White Start line on its return.”

    2) Additional points also state “20 points will be awarded for any robot that finishes the three point turn successfully and finishes with any wheel inside the starting box.” Could you explain how the Starting box is marked out please? A Black tape outline? A purple rectangle as shown? How big is it?

    1. Right. Yes, it should be the white start line. The starting box will be outlined in black tape. (It won’t be purple, that’s just to show the max size of robot)

  6. Sorry Mike. Just a final clarification.

    After the first turn the robot moves forward to touch or cross the top black line. Am I right if I assume that if part of the robot extends beyond that line then that counts as crossing it? i.e. If you look at the robot from above the front has gone beyond the line.

    If the bot must touch the line then KEITH needs to move forward much further as the tracks have a limited contact area on a flat floor…


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.