Larry's Blog

LIGHT-SEEKER WORKS!!

It works! The robot LIGHT-SEEKER was completed
and here ii is.

Here is how it works. It rotates around little by little
and checks for a light source ahead of it.
When it finds a light source it beeps and proceeds
in that direction. After a short distance it checks
if the light source is still there. If so it continues ahead,
otherwise it rotates again and seeks a light source.

Thanks to Bob Neidorff of NEMES for help with
293 H-bridges which worked well with
my DC motor control. However things did not go smoothly until
I put in the diodes to curb the spikes
from the motor coils, etc.

A NEW ROBOT

This new robot is pictured on the right. It is called
STEPBOT and is powered by stepper motors.

I am coming to grips with problems of torque. The wave pattern
is the easiest to drive a stepper. These are unipolar stepper
motors. So I went to a half-step pattern which should give me
more torque - I hope. There is still another pattern that I can look into.
With the DC motors there seems to be no problem with torque.

Stepper motors for locomotion do have some advantages.
To reverse direction, I just send the patterns in the opposite
sequence. To stop, I just stop sending the signals.

An example of wave pattern is as follows:
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1

Each of the one's represents energizing one of the coils
in the stepper motor. You just repeat sending this pattern over and over
and the motor steps ahead. The pattern for the half-step
is more complicated, but basically energizes 2 coils
on some of the patterns.

Of course, I am sending these patterns to 2 stepper motors,
so I can make one stop or go in reverse while the other
goes forward.

TWO ROBOTS !

Here they are ! 2 robots
the one on the right I call the SQUARE.
It goes in a straight line and turns to the right.
It repeats this, traveling in a square.

The robot on the left is called the LIGHT-SEEKER
It will rotate and search for a light source. When it finds it, it will beep and flash and head toward the light