Robot Hardware
The robot
Detail showing phototransistors and analog MUX
Mechanical
The robot is constructed from two Lego Technic 8064 kits. Each provided
one 9 Volt electric motor. The two motors are powered by an on-board power
supply consisting of 6 AA batteries. One motor drives the two rear wheels.
The robot can move both forward and reverse. The second motor turns the
front wheels left and right.
Electrical and Control
Signals to and from the controller arrive over a multi-wire bundled
tether. Six digital lines control the motors through a LM18293
Four Channel Push-Pull Driver. The analog motor drive circuitry
was designed by Jeff Cohen.
Sensors
The four corners of the robot are equipped with contact sensors. They are
old computer keyboard keys. The digital value of the sensors is returned
to the controller. Three phototransistors detect light levels forward, left,
and right. The signals are passed into a MC14051 analog multiplexer. Two
digital control signals are used to determine which light level is read.