WallFollower

Wall Follower was one of those “proof-of-concepts” robots. The intent was to build something small and compact that was fast and versatile. Wall Follower can navigate around a room, on a table, in a maze, whatever. It is built from one of the basic robot platforms in the Mindstorms Contructopedia. Motion is done by 2 motors, each of which can steer by removing power to one. The main sensor is the DIRPD sensor (grey) mounted on the front. Through programming, the sensor can detect 3 distance ranges, near, far and too-close. The NQC program has a few main tasks. They are:
1) To follow the wall and avoid obstacles without hitting anything using the DIRPD sensor.
2) If it gets stuck, a routine will get it out of the situation
3) If it reaches an area where there is no wall and a drop-off is present. Detect an avoid.

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Wall Follower is outfitted as follows:

DIRPD Sensor – Allows for wall following and object avoidance.
Light Sensor – detects drop off of floor area.
Touch Sensor – detects if Wall Follower is hit from front or top.
Motors 1 & 2 – left and right drive motors.

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A bottom view shows the drop off light sensor (left), the touch sensor mechanism and the two motors.
A close-up view of the front touch sensor mechanism. Two #6 axles are used to trigger a single touch sensor. The purpose of using two axles was to have a carrier for the entire touch component so that it could “float” so that it would freely trigger when touched.