Beacon-based Robot Navigation System
Using a scanning IR detector a robot can lock on and navigate toward a beacon. Once at the beacon the robot turns and navigates to the next beacon. By using multiple beacons you can mark out any path you desire. The robot can reliably traverse this path over and over again very much like a night watchman would make his rounds.
The beacons are simple 38 kHz IR LED emitters. If you don’t want to build your own beacons you can reuse iRobot Roomba Virtual Walls as beacons.
Located on the robot is a simple IR detector (PNA4602) mounted on a servo. The detector is enclosed in a narrow tube that makes it very directional. By scanning left to right with the servo the bearing to the beacon can be accurately determined.
The brain of this beacon system is the Propeller chip.
I've implemented this technology on several of my robots including a CrustCrawler QuadCrawler and a Lynxmotion 4WD1 rover as well as the new Night WatchBot published in the Fall issue of Robot Magazine. You can download the source code and schematics directly from the Robot Magazine site.