|Little Brother, the Monitor|
Big Brother watches you. The Monitor watches your robot.
While you focus on navigation and mapping tasks at the host level, there is a collection of tasks running in the background on your Garcia. These tasks are collectively called the monitor.
The monitor checks for the following conditions:
Any one of these may make the robot halt, but the monitor may be reconfigured to check conditions specific to a particular motion. This usually depends on geometry. For example, if the robot is going forward then obstacles behind the robot don't matter.
The monitor also performs some important IO tasks. It provides a host interface for reading the state of an input button and turning range finders on and off. The monitor also initializes all the IO and system constants at power-up.