Notes: Some pictures are taken from the link directly. Some pictures are taken from my model.
I will show a video at the end.
Motion of the robot main body
The main body is connected to a red link:
This red link base is a square that sit and fits tightly between the cams. Notice that the cams are tilted 20 degrees.
Due to the tightness of space, the tilting of the cams, and finally how the red link passes through a hole to connect with the main body:
The red link is forced to alternatingly rotate to the same orientation that the cams has from the top view.
Motion of the legs
The legs are connected with this blue linkage through the green flap located at the upper green follower.
The blue linkage has a flap that is pasted on the ground, making it to pivot around that point.
The coin acts as a counterweight to pull the left green follower to be constantly at contact with the cam.
The cams are circular but pivoted eccentrically so that it pushes either of the green followers when the longer length reaches them.
Together they act like this:
- First, The cam longest part will push the upper green follower to create a vertical motion of lifting leg.
- Then the cam contacts with the lower green follower and pushes forward the entire blue linkage to rotate around its pivot, and this causes the forward arc-like motion of the leg.
- Once the cam longest part no longer touches both, due to the coin's weight, it pulls the leg backward to its initial position.
For the legs to walk in different direction, the cams are phased 180 degrees and the green lower followers face opposite to each other, so they gets pushed in difference direction.
(In the second image which is my model, I made a mistake of not phasing the cams)
Video of my model and from the creator
Note: The pasting of the blue linkage to the ground for the pivoting has to be extremely well-done and kept without any damage in order to keep the blue linkage to not pivot sideway. (Which causes the leg to not work anymore)
I made two attempts and my best attempt only made one leg work due to the difficulty. Here it is: (Click on the video to play it)
- Notice that the upper part of the blue linkage has some kind of compliance so that it doesn't fall. I have ignored this effect in my analysis as it makes it much complicated and contributes only to keep the leg not move too much downward.
- The red link rotating motion is faster through halfway of the motin, and when it reaches the angle limits it is slower.
- The leg motions are better displayed on the creator gif.