Robo Relay Race

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Robo Relay Race builds on the skills learned in Basic Robo Race and introduces communication and coordination between robots. Robo Relay Race is meant as a combined team exercise. Each team will build a robot that is capable of completing the circuit on its own.

Mission Objective

Build the fastest team of two (2) robots to complete a closed circuit. Each robot takes turns running the course.

Relay Robots in the start position.

Figure 1 Relay robots in the start position.

Race Rules

The robot must pass an inspection before the race starts to ensure no construction rules have been violated. The robot team will have a chance to make modifications before the race starts.
Both robots will be placed at the starting location on the track, with the Tail Robot behind the Lead Robot.
When commanded, the robot drivers will press the green “run” button on both of the robots and the clock will start.
The first robot must follow the path until it tags the second robot.
After tagging the second robot, the robot must come to a complete stop and turn off its motors.
A signal must be transmitted to the second robot to get it started.
The second robot must follow the path until it tags the first robot.
After tagging the first robot, the second robot must come to a complete stop and turn off its motors.
Each team will build two (2) robots capable of completing the circuit on their own.
The first robot may only signal the second robot using an infrared transmission, and after it first tags the second robot.
The running time is taken from the time the first robot is commanded to start to the time that the second robot tags the first one and comes to a complete stop.

Robot Construction

The robot must be less than 11 inches long including any extensions.
The robot must be less than 10 inches wide.
The robot must be programmed using RCX code programming.
Once started, the robot must be completely autonomous.
Teams may use any number of Lego sensors and bricks.
The lead robot must have the RCX infrared transmitter facing forward.
The second robot must have the RCX infrared transmitter facing backward.
Neither robot may have sensors located in the rear.

Violations

Major Infractions

When a major infraction occurs, the robot must be restarted from the beginning of the track without stopping the clock.

Once the robot is moving, there can be no human intervention until the robot completes the task.
The robot cannot leave the track during the race.
Losing pieces while the robot is running the race.
If an error occurs and it appears the robot will not finish the race.

Minor infractions

Failing to come to a complete stop when returning home incures a 10 second penalty added to your time.

Premature starting of the second robot will incur a 50% time penalty added to your total time (i.e. Time to complete the race + 50% of the time to complete the race).

Determining the winner

The racer with the shortest time, after violations, is declared the winner.

In case of a tie, the tied contestants are allowed a run-off. The racer with the shortest run-off time is declared the winner regardless of their initial time.

Playfield

See the Track section for help building the track.

Materials

Figure 2 Robo Relay race track.

8-12 white bookshelves, approximately 10”x36”x1/2”. These can be obtained from any local building center.
Black electrical tape, approximately 5/8” wide.

Construction

Layout the bookshelves on a flat surface in any closed pattern.
Lay a strip of tape in a smooth line in the middle of the boards.

Hints:

Use a semaphore to make the trailing robot wait for the lead robot.