Robo Sweeper

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Initial starting position

Figure 1 Initial starting position

Though Robo Sweeper can be solved many different ways, we like to use Robo Sweeper to introduce robot teams to target finding.

Mission Objective

Build an autonomous robot that will sweep an area clean of yellow balls.

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.
The robot is placed in the center of the challenge area facing a pre-determined direction.
When commanded, the robot driver will press the green “run” button and the clock will start.
The robot must push all of the yellow balls out of the challenge area while staying in the challenge area.
Each robot’s run is timed from the time the run button is hit to the time the last ball is swept out of the challenge area.

Robot Construction

The robot must be less than 11 inches long including any extensions.
The robot must be less than 10 inches wide including any extensions.
The robot must use pieces from a standard Lego Minstrom Robotics Invention System 1.5.
One extra light sensor is allowed for this event.
The robot must be programmed using RCX code programming.
Once started, the robot must be completely autonomous.

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.
Losing pieces while the robot is running.
Leaving the challenge area.

Minor infractions

None.

Determining the winner

The robot with the shortest time 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

Materials

A large table or flat ground with consistent coloring.
White or black tape, whichever has more contrast against the playing surface.
4 or 5 yellow or white balls. You can use any type of ball as long as the robot can detect it and push it. The yellow balls from the RoboSports expansion are ideal.

Construction

Layout a closed area using white or black tape.
In this area, place 4 or 5 balls for the robot to sweep.
The balls should be placed consistently between runs so that every robot competes on the same layout.

Sweeping a yellow ball

Figure 2 Sweeping a yellow ball

Hints:

There are many ways to solve this problem. Experiment to find the best solution.
Placing a light sensor close to the ground is a good way to detect balls in the challenge area.
Sometimes you can get lucky by using a little random behavior in your robot’s program.