TrotBot's Leg Mechanism Simplified
A couple of things I learned from teaching my walking robot class are that TrotBot's build instructions are too long, and also that sometimes the students built legs that weren't straight, causing the linkage to bind and jam. Hopefully these leg-only instructions will help!
1. You only need to build one type of leg, and make 6 or 8 of them. TrotBot doesn't need both "left-facing" and "right-facing" legs to walk well, and either orientation will work fine. These instructions cover building the above "left-facing" leg, which works for all 6 legs of Hexapod TrotBot, and for all 8 legs of TrotBot Ver 3 and Mindstorms TrotBot (Versions 2 and 3)
2. If leg parts are connected to other parts in the wrong plane, then the leg will be twisted and the linkage will bind or jam. To avoid this, these instructions show how to build the leg in stages, one plane at a time:
Part List for One Leg:
Here are a few more views of how this leg should look when finished:
These instructions build the leg one plane at a time, starting with Plane 1:
Next, add Plane 2:
If you don't want to cut one hole off of a 7-hole beam to make a 6-hole beam, then below is another option.
Next, add plane 3:
If you don't want to cut one hole off of a 9-hole beam to make an 8-hole beam, then below is Catweazel's alternative.
Finally, add the 4th plane:
The next step would be to attach cranks to both sides of the leg's axle, and then add the frames of the version of TrotBot being built.