Rollie by Bill Sherman

ROLLIE has only two wheels to roll on; each wheel is a pair of CD discs with a foam center.  The
foam center conforms to the surface and helps provide traction with the floor.  The robot's battery
pack is toward the bottom and lowers its center of balance.  Rollie can move forward, backward, stop
and turn upon its center.

A 16F84 PIC, running at 20 Mhz is the brain for the robot.  Programming can be downloaded "in
circuit" using a serial link with a PC. 

Each wheel is driven by a servo modified for continuous rotation.  The servos can be powered down
using a Mosfet under software control.

IR emitting LEDs and receiver modules are used to avoid obstacles with very little interference from
other light sources.

A separate 38kc receiver is used to receive command instructions and detect an IR beacon for
location purposes.  To prevent interference from the IR emitting LEDs, the 38kc receiver is read
between avoidance routines.  A PIR  motion sensor is used to detect people or hot objects. 

Four "AA" alkaline rechargeable cells provide power for about 2 hours before recharging.

Rollie's autonomous behavior can be interrupted using a IR remote control to help guide the robot
out of dangerous situations.  A switch is used to cycle the robot through different behaviors.

Rollie's primary mission is to move forward and avoid obstacles, find people and move toward them. 
A blue LED flashes and a beeper sounds at different times to alert people of its presence.  If
Rollie cannot find obstacles, people or the IR beacon, the robot will power down to "watch dog mode"
and wait for stimulus.  Future additions: replace foam wheels with conductive foam to allow charging
through the wheels in contact with a "charging pad".  An IR beacon at the pad will guide Rollie when
charging is required.


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