Waist Plate, Donut and support rings

Building a fully mobile robot has some challenges that static robot builders do not usually have to deal with. For example, the donut (a fiberglass ring that sits between the torso and the waist plate) has to be able to withstand the impact of bumps and jolts of a greater magnitude and for longer periods of time than a stationary robot or it will split or crack. In addition, my donut is connected to the torso and will disconect at the waist plate. I have designed my robot to disconnect from the lower portion of the donut to the waist plate by a twist lock method. I have seen other builders make the donut secured on the waist plate and the torso seperates from the upper part of the donut via screws from the inside of the torso via the side vents. What I have below are a few pictures of the underside of the donut. Look carefully at the grooved “twist lock slots” on the donut.

To handle this situation, James (my machinist) came up with a way to insert a large delrin ring inside the donut that would mate with the delrin twist lock plates to provide compression support to prevent the donut from being crushed. Standard aluminum spacers would not provide adequate/contiguous support for the donut. I would of made a titanium donut If weight and cost wasn’t an issue.