Line Following

These rules were created by the Portland Area Robotics Society (PARTS) for their annual PDXBOT. The Seattle Robotics Society (SRS) has made adjustments to the qualification criteria for the race categories, but otherwise the rules are identical.


Robots will follow a line from a starting location to a finish line. The robot that accomplishes that goal in the shortest time is the winner.

Race Description

The Line Following course is a 3/4″ non-crossing line with curves no tighter than 6″ in radius.

  • The course is a circular or oval course with some waviness.
  • This course requires no special hardware to be added to the SRS Robot kit.
  • This course requires no special hardware to be added to the Mark III kit other than a device to prevent the scoop from catching on track joints.
  • LEGO and other kit robots, such as the Parallax BoeBot or Sumo Bot will work well also.


Robot Specifications

Robots must be autonomous. Data links to off-board computers are allowed, but no wetware (human) operated remote controls will be permitted.

The length, width, and weight of a robot are not specified in this contest. The only requirement is that the robot must remain on the course during the event. It is the designers’ responsibility to design the robot to accomplish its task.

The maximum robot height is not applicable for the Line Following course, but no robot that is deemed by race officials to be harmful or damaging to either people or the course will be permitted.

Track Specifications

  • The track surface is a minimum of 11.5″ (292 mm) wide.
  • The track surface is white. This year’s course will be cut from Collegewood brand “polar white” melamine coated hardboard, available in 3’x7’x1/8″ sheets from Home Depot and other sources. This is the same surface that is used in Portland Robotics’ PDXBOT.
  • The track surface is assembled from 11.5″ (292-mm) wide sections.
  • The track surface may have discontinuities, not to exceed 1/10″ at segment joints.
  • The course line is 3/4″ wide +/- 1/16″ for Line Following course. It will be made of standard 3M vinyl electrical tape, 3M splice tape (thicker and stretchier for curves) and/or 2″ Pro-Pak plumbers tape on curved sections (tests show little or no difference in reflectance between these tapes). Plumbers’ tape usually has white writing on its surface. This can be easily removed by wiping the tape with a rag dampened with acetone.
  • The course line may have discontinuities, not to exceed 1/10″.
  • The course line may be curved, with a minimum centerline radius of 6″ for the Line Following course.
  • The robot must deal with the lighting conditions as they appear. That is, room lighting and window drapes will be set as desired by the judges and will not be modified for individual contestants. Also, flash photography and IR focusing cameras will be allowed, unless the judges deem such activities as interfering with the ability to hold the event in general.
  • Note: figure 1 is just an example — the courses will be different the day of the event.

Race Operations

A sample track will be available for “test drives” prior to the competition, to perform testing and calibration.

All robots must be ready to run at the start of the contest. 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. The contestant starts a match by pressing a start button. Timing of the run will begin when the robot crosses the “START” line.

Once a match has started, no contestant or official may touch the track or interfere with the robots in any way except to reset a robot as stated below. Resets are done only by the race official.

If time permits, after all robots have made one run, robots may make a second run. The score for each robot will be the better of its two scores. No robot modifications are permitted between runs!

Race Scoring

Races may be run in matches of two robots, on separate tracks of equal length, or they may be solitary timed events.

Each race is timed; the robot with the lowest total time wins the match.

If the track is open-ended, the time is to the end of the line. If the track is a closed loop, the time is to the start/end line after the specified number of laps.

After the initial start, a contestant may not operate a robot. All manipulation of the robot is to be done only by the tournament official.

A machine that has no part of its structure over the course line, or is clearly not steering in response to the course line, is no longer tracking the course line.

An official may reset a machine that is no longer tracking the course line.

Resetting a machine onto the course incurs a 5-second penalty (plus how ever much time it takes the official to replace it). Placement is to be at the previous turn or hazard.

Decisions regarding whether a machine is tracking the course line are made only by a track official.

A robot’s run ends when it has completed the course, or it is deemed by the official to be unable to track the line, or at the end of 3 minutes.

Final scoring

Accuracy in completing the event is ranked above speed.

Final scoring shall be as follows:

  1. Entries that have completed the course with no penalties shall be ranked in order of fastest time.
  2. Entries that have been assessed penalties shall be ranked in the order of lowest combined time and penalty points.

If no robots complete the course, the robots shall be ranked by total distance traveled before the first reset, as determined by the match official.


  • Make some effort to shield the sensors from camera lights and IR focusing cameras. A flexible skirt around the sensors may help.
  • Get a piece of white Melamine, some tape, and PRACTICE.
  • Make sure you can calibrate your sensors at the event. Lighting conditions are sure to be different than in the Bat Cave.
  • Have a look at previous PDXBOT courses in the archives at the PDXBOT Gallery.Pictures there will give you a very good idea of what to expect. The actual course layout will be different, but the course will be largely composed of similar course pieces.

More Information

Questions or comments about these rules should be directed to the Seattle Robotics Yahoo Group.

———————- New content as of 7-14-2022

Liability – Each contestant is fully responsible for any damage to person or property caused directly or indirectly by his or her robot.  The SRS, the event organizers, judges and other entrants are not responsible for damage caused by any competing robots.  Each contestant must sign the waiver of liability form prior to the competition.  A minor must have a guardian present to sign their waiver.

Please reference a copy of the waiver here that each contestant will need to sign in-person before competing.

Code of Conduct – All builders, handlers and spectators are expected to comply with our organization’s code of conduct, please reference these SRS rules here.

These SRS rules also apply to all event staff. Please keep the event fun and light-hearted for all, including the organizers and humans.