The Linkage simulator works great when there are a lot of links that all chain together into some interesting complex movement. But one place I didn’t do much work on is related to links that just sort of hang on and move with others. Look at the picture below:
Links 4 and 5 are not needed for the mechanism to work. Or links 5 and 6. Any two of the four vertical links can be completely removed and the location of link 1 can still be simulated just fine. And that’s what happens; the simulator calculates the position of J then uses J and E to figure out the location of A. Then any one of 3, 4, or 5, can be used to calculate the location of link 1 and all of it’s connectors.
The problem is that two of those vertical links are not simulated since both ends are already known. And that’s where the simulator fails.
Would someone design a mechanism like this? Absolutely. Links 3, 4, 5, and 6, might all have another connector that moves some other parts. But if this basic foundation of the mechanism cannot be simulated, the other parts fail too.