LEGO Spot Micro
Awww, isn't he cute? LEGO Spot Micro Ver 1
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The linkage approximated by Spot Micro Ver 2 (see below), using our 6-Bar Walking Linkage Simulator which uses the 3 sides of the lower leg's triangle rather than a knee angle
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Posted by Wade
Spot Micro was developed using our interactive 4-bar walking linkage optimizer, which you can use to modify the linkage here, and below is a video of the simulator in action.
Spot Micro was developed using our interactive 4-bar walking linkage optimizer, which you can use to modify the linkage here, and below is a video of the simulator in action.
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Spot Micro Ver 1 uses the linkage dimensions shown in the image to the right, scaled so that the crank length (bar b1) equals 3 LEGO holes. Some build pictures are at the bottom of this page. |
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Spot Micro's linkage has a fairly consistent foot-speed, which makes it a good candidate for rotating the crank by driving the legs (passive walking), as is done in the following treadmill video:
The mechanism can also be motorized by either motorizing the legs, or by adding motorized wheels (see further down)
Below shows how to make Hiro Labo's compact transmission used to motorize Spot Micro's legs above. I increased the transmission's length to add a second crank, spacing the front/rear legs 5 LEGO holes apart so that their cranks wouldn't collide. And be sure to put the front/rear legs 180 degrees out of phase as described in the video above.
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Version 2 below is slightly bigger and steps a bit higher: |
LEGO Spot Micro Ver 2
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Notice that the below version with a motorized chariot turns more efficiently than the version with motorized legs (see above). The legs are free to rotate at whatever speed the chariot is pushing them, so when turning the wheels the legs on the outside of the turn can rotate more quickly than the legs on the inside of the turn, acting a bit like a differential and reducing how much the feet skid.
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Spot Micro Ver 2 uses the linkage dimensions shown in the image on the right, scaled so that the crank (bar B1) equals 4. It differs from the GIF at the top by shortening the lower leg section (B4) by one LEGO hole so that the front/back feet don't collide when the crank is at 12 o'clock. |
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The following video includes step-by-step instructions for building the smaller version 1:
Regarding the rubber tires used as feet I found dozens of these smooth small tires in one of our LEGO parts bins, but I don't remember the source or part #. Approximate ID is 1.2mm, OD is 1.4mm. Alternatively, you could put pins thru the lower holes and wrap a rubber band around the foot for traction, or use part #45590.
https://www.brickowl.com/catalog/lego-flexible-rubber-axle-connector-45590
