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Up the Garden Path


Garden Gnomes have rearranged the path in your garden and you get lost every time you go out there! You must find the route to your shed to continue your Raspberry Pi adventures.

Aim of the Challenge

To complete the maze as fast as possible using one of the methods available.

Control Method

Remote control or Autonomous.

Time Limit

5 minutes.

Example run


  • The maze course will be provided to you electronically. It will fit within the 1500mm x 1500mm walled arena. It will be possible to print the course onto paper and measurements will be given if you wish to mark it out some other way (for example with 19mm electrical tape).
  • The colour of the course is up to you. For instance, if you already have a black floor, you can mark out the course with white tape. You could even have a green floor and mark out the course in red if you wanted to!
  • The red lines are to indicate the end of the six elements of the course (see the notes on points for how these are used). Anything in red should not be marked/printed – see the second version below:


  • Please note, especially, the start position marked with the small black mark and the size of the “shed”.
  • Roboteer Mark Mellors has created this highly-detailed technical drawing of the course. It clears up some of the measurements and flaws in the diagram above. We are happy, however, for your version of the course to be “approximately correct” as long as you make your best effort to recreate the overall shapes.
  • You can run the maze as many times as you wish. However, you should only submit the video of your fastest run, which will be used for ranking purposes, and that single run must be completed within the five minute time limit.
  • There are multiple ways of completing the course. You must choose only one method for your run. These are in order of difficulty:
    1. You can use only a remote control to manually navigate the maze.
    2. You can use pre-programmed moves (aka dead reckoning) to navigate the maze autonomously on a pre-programmed route.
    3. You can use line following sensors to follow the course and autonomously navigate the correct path. You may optionally use audio commands to direct the robot should it need assistance at any point.
    4. You can use a camera attached to the core Raspberry Pi to follow the line autonomously using image recognition. Alternatively, you may use a camera to recognize shapes or markers on the walls of your arena in order to navigate. You may optionally use audio commands to direct the robot should it need assistance at any point.
    5. You can issue purely audio commands such that your robot listens and behaves accordingly. We suggest these instructions should be limited to simple commands such as “forward”, “back”, “left”, “right”, “stop” etc. You may use any method of getting audio commands to your robot, for example a paired Bluetooth headset or even just shouting the commands at your robot! 
  • Each control method will be worth different amounts of points, depending on the complexity of the method.
  • A successful run requires staying over the path and not getting muddy feet. (i.e. your robot must keep to the line of the maze without wandering off!)
  • You must finish inside the “Shed” (marked on the course diagram). Timing of your run will finish when any part of your robot is inside the Shed.

Ranking and Points

  • Competitors will be ranked according to the single shortest time taken to drive the course across all their attempts. The robot with the shortest time will take first place. Points will be awarded according to the Formula Scoring System. Only robots completing the whole course will qualify for these ranking points.
  • For each of the six elements (marked in red in the above plan) passed by the entire chassis, you will be awarded points, dependent on the method chosen:
    • Completely remote control – 45 points.
    • Dead reckoning – 55 points.
    • Line following using line following sensors – 80 points.
    • Navigation using a camera – 150 points.
    • Audio commands only – 150 points.
  • Additional points for navigating the entire course, depending on the method chosen are as follows:
    • Completely remote control – 50 points.
    • Dead reckoning – 75 points.
    • Line following using line following sensors – 100 points.
    • Navigation using a camera – 200 points.
    • Audio commands only – 450 points.
  • If you use audio commands together with either the Line following method or Camera method, you will gain an additional 250 points. You must use at least three audio commands to score these points.


  • If a rescue of your robot is necessary, place your robot back at the start of the course and try again as this will be classed as “getting muddy feet”. There is no penalty for resetting your robot as you will very likely not be submitted that video anyway.


  • Once you’ve chosen your method, stick to it.

Ask Questions and Discuss

You can discuss this challenge and the general rules with fellow competitors on our Discord chat. If you have questions for the organisers, please contact us through the website.