Strandbeest is a large wind-powered, multi-leg walking machine designed around Theo Jansen's fascinating leg linkage ( http://en.wikipedia.org /wiki/Strandbeest). Numerous videos show the Dutch artist/engineer with his creations walking
along the beach; check out www.youtube.com/watch?
The Strandbeest leg mechanism is somewhat different
from the Spider robot's Klann linkage from last month, but
is another great candidate for hacking into a servo-driven,
differential drive robot. The chassis has a wide stance with
an unusual aspect ratio and geometric look. Physically,
there is plenty of room for adding sensors, LEDs, and other
custom parts, plus numerous unused PICAXE pins to control
The stock kit assembles easily in an hour or two, and is
an enjoyable build. There is much redundancy in building
12 identical legs. I bought two kits: one to leave stock and
one to hack. Mechanically, the main challenge of hacking
this kit is coupling the servos to the two crankshafts.
After modifying two HXT900 servos for continuous
rotation, thread a 3/8" length of 2-56 threaded rod (cut the
head off of a 2-56 bolt) halfway into the servo output
shaft. Drill a 1/8" hole about 3/16" deep into the meatier
end of each crankshaft. Work on one servo/crank assembly
at a time. Use double-stick tape to fasten a servo firmly to a
tabletop with the output shaft screw pointing upward.
Hook up a servo tester so you can rotate and stop the
servo. Fill the crankshaft hole with JB Quick Weld or an
equivalent, then press the crankshaft onto the servo screw.
As the epoxy sets up, rotate the servo and align the
SERVO 04.2014 53
Post comments on this article and find any associated files and/or downloads at
Hack a $10 Theo Jansen Walker Toy into a Programmable Robot
NOTE: This condensed article is a companion to the SpiderBot
construction article in the March issue of SERVO. TheoBot uses
the same servos, sensors, and PICAXE processor detailed there,
so please refer to that article for specific details.
The 2-56 threaded rod; half of 3/8" length in servo hole and half epoxied into drilled-out crankshaft.