This webpage contains a number of designs for robotic platforms which are based on differential adder/subtractors. The first design that I saw for one of these was on Leo's Lego. While these robots are based on the same basic design they have laid it out in much different ways.

• plat - My original design. Closely based on Leo's design.
• dadsdesign - A platform designed by my father, michael@phred.org.
• wanderer.html - A wandering robot based on my father's design. This has the most complete set of pictures.

• LDraw instructions for adder/subtractors - This contains plans for the base of the wanderer and dad's design robots. Look at the bottom of the webpage.
• Cyberia's differtrans webpage - More designs of the same concept.
• Dave Madden's implementation.
• Yet Another Lego Sum/Difference Mechanism