Expert Line Following Fall 2009

Contest Date: 
Sat, 10/24/2009

Expert Line Following
Contest Rules

Audience: Journeyman Level


Expert Line Following is the ultimate test of a line following robot.  The object is accuracy and speed.  The course while having a “line” loop, the line is distorted and broken through out.

Course Construction

The course will be run on 18” square tiles made from particle board and painted flat black.  The line will be marked by standard width (3/4”), white electrical tape.  The tape is very elastic and every effort will be made to make the tape adhere to the tiles, though tape may have seams, overlaps, and areas where the tape may rise or crease.  The tape marks the center of the course (i.e., the robot is supposed to be positioned over the tape).

The course may be of any length and configuration but all turns will have a radius greater than or equal to 6 inches.

The course may cross itself, but the crossing will never occur at an angle less than 60 degrees.

The course may have sections that are parallel to each other, but they will be at least 12 inches apart.

The following hazards may be found between 6-inch straight sections of track. Several hazards may be placed in succession no closer than 6 inches apart.

·        A right-angle jog to the left or right of no more than 3 inches.

·        A 12 inch zigzag section extending no more than 6 inches left or right of the centerline at angles no less than 60 degrees.

·        A 1-inch to 3-inch break in the line.

·        A gradual widening of the line to 3 inches and back to the standard width over 12 inches.

The course must have turns at assorted radii and will have at least one crossing, one jog, one break, and one zigzag but may have more.

NOTE:  The Spring 2006 expert line-following track was laid out as pictured below.  Do not rely on this exact layout, as the course will be rearranged for each contest.


The course will be comprised of several styles of tile as shown below:


a.         Turns / Zigzags -- The advanced course may contain turns greater than 90 degrees; perhaps implemented as a zigzag.  In prior contests, it messed up a few robots.  One robot stopped, one spun in circles, and one rotated through acceptably (but all the extra rotations slowed down the robot).  However, most robots handled the zigzag well.  Some even smoothed out the oscillations with an optimized path.



b.    Another Zigzag example



c.    Wide Lines / Gaps -- The advanced course may contain wide lines, straight gaps, and offset gaps. In prior contests, all three hurdles stopped a robot or two.  However, most robots drive forward when they lose the line or sense equal floor contrast, and thus are not affected.



d.       Crossed Lines -- The advanced course may contain crossed lines. In prior contests, several robots were heavily confused by the cross. One stopped and the others got turned around to head in the opposite direction.



e        Ramps -- The advanced course may contain one or more ramps.  In prior contests, this stalled more robots than any other course feature.  All but two or three robots were stopped entirely, required a penalty-inducing push.  It was not just the extra torque required from the slope that caused the stall, but also the fact that most robot bodies are not flexible. The robots would either jam their fronts or have their drive wheels lifted off.

Advanced line-following course ramp



f.        Fanout with gap – This is a combination of a gap with the widening of the line



g.       Omega – This obstacle is a combination of the widening of the line and a tight radius curve

h.       Close spacing of a combination of crossing with offset



Robot Construction

This contest follows the Chibots general robot guidelines for line following.

Contest Procedure

Each robot is given up to three chances to run the course, with up to 5 minutes “tweak time” between runs.    The builder may choose to run the robot in either clockwise or counter-clockwise direction, and may choose a different direction for each attempt.  The starting position of the robot is determined by the timing device(s) in use.

All timing will be performed using a digital device located as indicated in the diagram if at all possible.  Otherwise a manual stopwatch procedure will be implemented.

If a course official deems the robot to have failed to navigate a hazard, the builder can reset the robot 4” – 6” prior to the hazard and reattempt it for a 10 second penalty or the builder can start the robot on the line immediately following the hazard and the course official will levy a 60-second penalty.  In such an event the course official will instruct the robot owner to gather their robot and prepare to continue on the line immediately following the hazard.  It is permissible for the robot to be deactivated, placed beyond the hazard, and reactivated when indicated by the course official or the robot may be picked up and held until the course official indicates that it may resume.

The course will be laid out by contest officials according to the rules on the day of the event. 

For a single robot, only the run with the lowest time is to be considered for final scoring.  If a tie occurs the second fastest time will be used to determine ranking.


The lowest time of 3 continuous laps will win the race. 

If a course official deems the robot to have failed to navigate a hazard, the builder has two choices.  The robot can be restarted 4” – 6” prior to the hazard to reattempt the hazard requiring a 10 second penalty.  Alternately, the builder can start the robot on the line immediately following the hazard and receive a 60 second penalty.  It is permissible for the robot to be deactivated, prior to being placed before or after the hazard, and reactivated once in place unless tol d otherwise by the course official.

This page is a rule set for this general contest: