C E R B E R E S
Small 3-wheel ROBOT with PIC16F84 brain & Infrared eyes.
Cerberes is a small three wheel robot that avoids obstacles which it senses with its active
Each rear wheel has its own motor, the single front wheel is not powered. The robot steers "like
a tank" by rotating the rear wheels in opposite direction.
The sensors are built with infrared LEDs which are running at 36kHz and two 36 kHz remote
control receiver modules.
When the 36 kHz infrared light from the LEDs is reflected by an object, one of the receiver
modules will be triggered, and the PIC16F84 µController will steer the ROBOT away from the
objects by reversing one of the motors.
Two electric toy ducks were sacrificed for this project.
The motors, axes and axe-holders from the toy ducks are glued on a piece of circuit board which
acts as a base plate.
The rotation speed of the motors is reduced by the "worm-wheel" of the motor axes which drive
the cogs of the wheel axes.
The circuit is built on another piece of circuit board which is identical to the base plate.
The circuit is placed on top of the base plate.
The 3.6 Volt battery pack (from a cordless phone) is also glued to the base plate.
The circuit behind CERBERES can be divided in 3 parts:
A double motor drive to drive two small electric motors forward / reverse / full stop.
Two infrared emitters and receivers to sense objects.
A "brain" which is a PIC 16F84 µController which will drive the motors in reaction to the
The Motor Drive circuit
Both motors are driven by an identical full bridge
circuit. The circuit of Motor1 will be used to explain
Motor1 is driven by a full bridge built with transistors
Q1, Q2, Q3 and Q4.
This full bridge is able to drive the DC motor forward
backward and full stop by driving the base
connections of Q1/Q4 and Q2/Q3 as in the table