line following

Official Contest Rules

Revised 8-10-2025

The following changes have been made starting with SRS Robothon 2025:

  • A two contest Categorizes \ Tiers design will be implemented for robot designs

    • These Tiers are characterized by the robot counting (or not) it’s number of times around the loop (based on the “Start \ End Line”).

      • “No Loop Counting” – the robot does not need to detect nor count it’s “passing” of the “Start \ End Line”. For this Tier of a contest run, the officials will NOT specify a certain number of loops that the robot must navigate; instead by default it is a lap count of 1.

      • “Loop Counting” – the robot does need to detect and count it’s “passing” of the “Start \ End Line”. For this Tier of a contest run, the officials will specify the number of loops the robot must navigate with STOP motion on the “Start \ End Line”.

  • Clarifications to the previous version of Rules

    • Elimination of Open-Ended Course being an option.

    • All Contests going forward will use Closed-Loop designs.

    • Added course specifications for “Start \ End Line” & “Direction Arrow” used.

    • Even though two distinct Tiers for entrants exist, only ONE Course will be setup\used during the contest: with the “No Loop Counting” Tier running first.

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

Object

Robots will follow a line from a starting location given a circular or oval Closed-Loop Course to the race official defined finish goal. The robot that accomplishes that goal in the shortest time is the winner.

Race Description

The Line Following course is a 3/4″ wide non-crossing line with curves no tighter than 6″ in radius. The “Start \ End Line” is a randomly “marked” perpendicular to the course itself with a piece of 1/4″ wide tape of random length. There is also a “Direction Arrow” that is placed on the inside circumference (random location) of the course to make traversal (clock-wise or counter-clock-wise) direction clear to all.

  • The course is a circular or oval with random waviness and straight sections.

  • The “Direction Arrow” is of no particular size other than being large enough for the general contestant and audience to view it clearly. Neither the placement of or its location is of importance to a successful robot design – since it’s included only for visual information; the robot does not need to sense it.

  • The course requires no specific overall size of a robot design. Popular choices are a SRS Robot kit, Parallax kit, your custom platform design or other smaller platform robot kit.

  • The primary hardware addition to most robot platforms are an “array of line following sensors” plus a scoop design to shield them from external light sources.

  • A secondary hardware modification is a device\design to prevent the scoop from catching on track joints.

Sample Course

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. The course is 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 was 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 Black 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 “Start \ End Line” is a randomly “marked” perpendicular to the course itself with a piece of 1/4″ wide Black tape of random length. The race officials decide on it’s location when designing the course.

  • There is a “Direction Arrow” that is placed on the inside circumference (random location) of the course to make traversal (clock-wise or counter-clock-wise) direction clear to all. The race officials decide on it’s placement when designing the course.

  • The robot must deal with the lighting conditions as they appear. That is, room lighting 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 course 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.

In general, the “No Loop Counting” tier is run before “Loop Counting”.

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.

Before any robots race, the official announces: the direction of travel and for the “Loop Counting” tier indicates the number of laps the robot must navigate and then stop.

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 with their robot BEHIND the “Start \ End Line”. Timing of the run will begin when the robot crosses the “Start \ End 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 multiple runs. The recorded score for each robot will be the “the best of” from all its runs. No robot modifications are permitted between runs!

Race Scoring

Races are held on one course track; same used for both Tiers.

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

For the “No Loop Counting” tier, the time is for one loop as the robot crosses the “Start \ End Line”.

For the “Loop Counting” tier, 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.

Hints

  • 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.

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.

Detailed view of “Start \ End Line” & “Direction Arrow”