I posted a very hard puzzle here and challenged the Internet to solve it. It’s quite a hard puzzle and it took about a day from originally posting it for someone to solve it. That someone was Mark Ivey (
@zovirl). I asked him to write a quick description of his solution and he did up a very nice little post which I thank him for. Here is Mark Ivey’s solution to my puzzle:
The Solution to the BirdBrain Puzzle by Mark Ivey
Overview: A down-and-left circuit moves the birds to the first & last yellow pellets. A decaying memory circuit bounces the birds up off the red ball. Since this loop decays over time the birds will go down again after clearing wall #2.
To bounce up, the birds have to hit the ball from the top. If they hit the side, they’ll bounce at the wrong angle.
The right signal is slightly stronger than the down signal to make sure the birds get over the ball before hitting it.
Decaying Memory Circuit
Bouncing up requires reversing the ball signal. Keeping the birds moving up after they hit the ball requires a memory loop. When a bird hits the ball, the ball signal gets injected into the loop. The 2 neurons in the loop keep the signal alive even after the bird leaves the ball. Then the signal is reversed (repel from the ball instead of attract to it) and passed to the wings.
Don’t want the birds to keep going up forever, just want them to go high enough to clear wall #2. This means the memory of hitting the ball has to decay. A sidetrip out through the 1/2 neuron does this. To keep the signal from decaying too quickly, more connections are added between the 2 memory neurons. This dilutes the effect of the 1/2.
If the bounce signal has to fight against the down signal, the birds move too slowly. To prevent the bounce from having to fight the down signal like this, a bunch of parts of the bounce circuit send suppression signals to the down-and-left circuit.
Once the birds are moving in a nice down-up-down motion, it took some tuning to get them to just barely clear wall #2 before going back down to the 3rd pill.
Tuning #1: The memory decays slower if there are more connections between the 2 memory neurons (this dilutes the effect of the 1/2 signal). About 5 connections in each direction worked well.
Tuning #2: The suppression lines are doubled in a few places to suppress the down signal even more.