SRS Line Maze


Each robot gets four attempts to find the fastest possible route from the start to the end of a maze using line following techniques. The robot that solves the maze in the shortest time is the winner.

Related Files

Robothon Line Following Algorithm
Presentation by Lloyd Moore at the SRS meeting May 19, 2012

The Maze

The maze will consist of a series of black, intersecting, 1/4″ lines on a white arena. The white space will be relatively glossy and the black space will be relatively flat. No line will be closer than 6″ to any other (parallel) line and there will always be a minimum of 6″ between any two intersections. All intersections will be at right angles. There will NOT be loops in the maze, resulting in a single route from beginning to end. A solid, black, 6″ diameter circle marks the finish point. Dead ends are not marked; the line simply terminates. The starting point is marked with a 2″ wide tee and robots must begin their run with some portion of the robot over the tee.

Figure 1 – A small, sample maze showing the starting tee, the ending circle, and various intersections types.

The maze will be no larger than 8′ by 8′ and no line will be closer than 6″ to the edge of the maze. There is no guarantee that intersections will be exactly 6″ apart, however. Although every effort will be made to keep the maze as flat and level as possible, contestants must be prepared for irregularities in the surface such as where two sections of the maze adjoin.

The maze layout will not be known until after all robots have been registered and presented to the contest judge. However, a small sample maze will be available before the contest for calibration and testing. The test maze will be made of the same materials as the full-size maze and will be placed in similar lighting conditions.

The Robot

The robot must fit inside of a 6″ x 6″ x 6″ square cube. There is no weight restriction. The robot cannot expand beyond these dimensions at any time during the event.

The robot is permitted to sense lines other than the one it is traveling on as long as those sensors do not extend beyond the above-mentioned dimensions. In other words, a camera arrangement can be used to glean information about the maze, as long as the camera is mounted wholly on the robot itself and within the 6″ cube.

The robot must be completely autonomous and self contained; external computers are not allowed. Robots may not leave any trail or markings. They also may not split into separate robots. The robot may not leave the maze at anytime. If it does, the attempt will be terminated and the robot will receive no score for that attempt. The robot is considered to have left the maze if no part of the body is over the line it was traveling along.


Prior to the maze being unveiled, all competing robots must be placed in a designated location in the competition area. After the maze is revealed, no modifications of any type may be made to the robots, including changes in software or strategy (this includes changing settings via switches).

The order of running will be randomly assigned. Before the contest starts, all contestants are invited to examine the course. Any issues the contestants have with the course (smudges, uneven surfaces, etc.) must be brought to the attention of the judges at this time.

When it is his or her turn, a contestant may perform a quick calibration (e.g. metering black and white) before starting the run. To begin a run, the contestant places the robot with some portion of the robot over the starting tee, then starts the robot.

Each robot is given three minutes to find its way to the termination point of the maze. Timing starts when the robot starts moving and ends when any part of the robot touches the finish circle. The robot may continue to explore the maze after it finds the termination point but must shut itself down prior to three minutes after the run begins. If a robot continues to operate past the three-minute point, it will be stopped manually and receive a 30-second penalty.

The robot will be given four attempts to solve the maze. Robots are permitted (and encouraged) to remember the maze geometry that they have explored and use that information on subsequent runs. No modifications of any type may be made to the robot between attempts. Each attempt will receive a score equal to the time to complete the course plus any penalties. The lowest score will be recorded as the final score for the robot.


The robot with the lowest score is the winner. Robots who have completed the maze are ranked from lowest score to highest. Then, robots are ranked based on distance remaining to travel to the end (along maze lines); this determination will be made by the judges.

Clarification: The “distance remaining to travel” is determined by the shortest distance from the end of the maze, along the maze path, to any point along the path that the robot traveled along during any of its 4 runs.


Other clubs and non-commercial organizations may use these rules and the name “SRS Line Maze” provided:

  • The SRS is notified of any upcoming contests.
  • The rules are not changed.
  • The SRS is credited (using the full name “SRS Line Maze” is sufficient).

It is the intent of the SRS to keep these rules fresh as robot capabilities progress. Changes will be announced once per year, shortly after the SRS Robothon. Questions or comments concerning these rules may be submitted to the Seattle Robotics Yahoo Group.