My Other Robots

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This robot was built a few years ago for the San Diego Robotics Society which has a contest requiring a robot to navigate around a large area (15 by 30 feet, more or less).  The contest was to navigate around the outside edge of the area and return to the starting point as accurately as possible.  Options were to circle several pylons on the way around; and to search for "mines" on the floor.  (small magnets taped to the floor)

The robot is based on an RC car chassis from Radio Shack.  It uses the existing H-bridge and motors and adds circuitry to sense the robots speed from the back EMF of the motor and PID style equations to control speed.  Using this speed signal, it could calculate distance traveled within 5 or 10 percent.

It was controlled by an Adapt912 processor card from Technologicalarts.com.

The contest area was enclosed within wooden walls 12 inches high.  The robot navigated using the Polaroid sonar sensor mounted in the project box above the RC servo in front.   The servo would look right to navigate at a fixed distance from a side wall, and look straight ahead to decide when to start a turn to end up traveling along the next wall...as well as to judge when it had returned to the starting point.

This is my version of the Ebot whose construction is described elsewhere on this site.  As usual, it is controlled by an Adapt912 microcontroller card.   The motors are driven by RC servos modified for continuous rotation.  The distance traveled is measured by small encoders mounted outboard of the wheels.  These encoders, sometimes available from gateway electronics for about $5, measure only 16 clicks per revolution; but, were good enough for this purpose.

The bottom view shows the robot was powered by 4 C cells for motor power and a 9v battery (missing in the center) to drive the processor and encoders.