PB-Sandwhichbot . PB-Sandwhichbot is a type of robotic arm that wants to make your peanut-butter sandwhiches! . PB-Sandwhichbot is a very amusing robot that wants to make your peanut butter sand-whiches. Because it can “peanut butter” your bread for you (in theory), you don’t have to do it anymore! Okay, not really. Not wanting to make your own sand-which would be the ultimate in laziness, and pretty soon you would get tired of having to finish the job, but this task does make for an interesting Lego Mindstorms project. The robot is equipped with 3 motors, the only exception to using the RIS set only, which give it 3 degrees of freedom. The 3 motors provide a rotating base, a subassembly that allows the arm to turn at sharp angles, and a “scooper and spreader” assembly which is really a very modified version of the hat arm shown in the constructopedia for the Inventorbot.
In theory, the arm first takes a scoop of peanut butter, turns in the direction of the bread, changes its angle to a lower one to be closer to the bread, and applies the peanut butter to the slice of bread using a special geometry (the one in the constructopedia) on the spreader hand. The heavy knife (heavy compared to Lego pieces) is held in place by a number of rubber bands and a special setup using yellow double pins and connector blocks. After applying the peanut butter, it rotates back to its original height-using a touch sensor to detect the correct position-, then rotates back to its original position again using another touch sensor which is unseen being hidden on the bottom.
In reality, I found real quickly that the program wouldn’t work because of mechanical difficulties and I would have to operate it remote-control-style. Even operating it myself couldn’t gain success though. Apart from obtaining some peanut butter and barely putting it on the bread, it couldn’t do much. It would probably do better as a robotic arm with some modification! Also, I had to hold the peanut butter jar at an angle (and in mid air) due to the fact it was half-gone and that the knife would normally just bump into it because of its length.
For those jelly lovers out there who are wondering why I didn’t make it a PBAJ sand-which maker, I have the answer. I didn’t make it a PBAJ sandwhich machine for the simple reason I don’t like PBAJ sandwhiches! Also, if you try to make one yourself, be prepared to clean your Lego parts from a bit of peanut butter!