RCX Tank Base One

I've always wanted to be able to make a Lego vehicle with tank treads.
My dream did not come true until Christmas 2001 when my wonderful 
wife gave me the Robotics Invention System.  It has the rubber treads.
At first I was very disappointed, there was way too much friction to
allow robots that could easily turn.  I played with it a bit and
developed the Track Rover in the spring of 2002.  The rubber
treads limited the size of robots one can create, there is barely
enough room for an RCX and the motors, leaving little room for
attachments and sensors.  It was time to move on...

I order 4 sets of "conveyor links" from Spectrum, the Lego Dacta
supplier in Canada.  The result was the RCX Tank Base One.


Features of Tank Base One include:

Remote driving using the Ultimate Accessories remote.

Suspension using ten black spring mounts.

"Equal" forward driving using a 24 gear clutch and axle connecting both
treads.  If both motors drive forward or back the clutch does not slip
causing both treads to move at the same rate.  If the motors are driven
in opposite directions the clutch slips allowing skid steering.  This 
was an alternative to have equal drive to using a bulky adder/subtractor
device.

"Droid Developer Kit squeeze and lift" style hand.  The hand was able to 
lift about half a can of pop.  As you can see in the pictures a full can
of beer caused the base to be lifted.

Enough power to pretty much drive over anything shorter that the height 
of the treads.


Problems of Tank Base One were:

Suspension could barely support the weight of the RCX and motors.  Set it
down gently and the springs stayed uncompressed.  Push down on it and
the springs would not recover.

Skid steering was difficult for the power of the motors on carpet.  The
combined resistance of the slip clutch and friction between the treads
and carpet put significant stain on the motors.

The conveyor links sometimes pull apart when climbing over difficult 
objects.  A partial solution was to tie a thin piece of elastic cording
between the treads.  I helped to hold the treads together and if they
did come apart it made it easier to put them back together.


I am currently working on an RCX Tank Base Two that is bigger with better
suspension, easier turning different style of slip clutch, and some sort
of cool Robot Warriors style of weapon like a chopping axe.  

Roy Nelson