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LEGO Robot Attachments – Part 3: Hooks

In RePlay (2021), one of the missions required the robot to lift itself up, on a transverse bar, under which another mission also required the robot to be able to complete pass. So we combined these two missions, making the robot first go forward under the bar, completely, and then backing up, but with its arms both lifted just enough that grabbers set at the top of the arms manage to get a hold of the bar.

These grabbers are not fixed, but, similar to the one of the tire, and even more so, they can flip one way, almost completely. They come back once free, thanks to the rubber band. Their role being to help the robot lift itself, it is ok to have them flip one way, as long as the other way they firmly remain vertical. The fine adjustments had to do with the exact dimensions of the grabbers, to allow for a tight grip of the bar, since they have a 90 degree angle. Also, the robot has its center of mass very close to the vertical underneath these grabbers, so when hanging it would not rotate too much. The rack-and-pinion mechanisms are strong enough to lift (both at the same time) the whole robot.

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