Theo Jansen style robot leg: prototype #2 and #3
December 29, 2008
I started tinkering with "Theo Jansen legs" again (follow the link first if you don't know what that means).
I am prototyping in corrugated cardboard and trying to come up with a design that could be produced in large numbers (six at least) in plywood.
The left leg (prototype #2) has a "boxy" design. This one holds its shape better, but is so much wider than the other design. The right leg (#3) is eight pieces of cardboard laid flat on the table. It is very wobbly. I improved the lateral stiffness by adding strips of material perpendicular. Yes I used hot glue. The second video shows exactly what I am afraid of in the flat design: buckling in the joints.
The green marking indicates where the weight of the vehicle will rest on the leg. It is one of the four pivots in the parallelogram. The pink markings indicate where the two cranks connect from the crank shaft.
The lower two pictures illustrate another fundamental difference in the two designs. Design #3 cannot fold all the way flat because the linkages in the parallelogram touch each other. Cleverly S-shaped "bones" might circumvent this issue. More scissors and glue tomorrow and then on to the plywood!
update 30 dec:
video by Maneuver
update 1 jan 2009:
Found an interesting interactive animation of a "Theo Jansen Linkage". It lets you tweak the numbers and see the resulting movements.