Since Sawppy the Rover is a one-man show and not a rigorously designed project, head-scratching things happen from time to time. One such instance occurred up when designing and building a test steering mechanism for the tricycle test gear. Sawppy will be using ten identical LewanSoul LX-16A serial bus servos for all its wheel actuation duties. Six acting as drive actuators and four as steering actuators. All ten will be coupled to 8mm steel shafts for their respective duties.
So when assembling the tricycle test rig, I noticed that I had used identical shaft couplers but different mounting brackets for these servos in their different roles: one bracket for driving, and a different bracket for steering. This was not a deliberate decision. I just drew up a bracket as I went and failed to think about the big picture.
Once I stopped and gave it some thought, I noticed a lot of commonality beyond the obvious fact they’re holding identical servos. In both cases, they don’t need to take up any part of rover’s structural load. That is taken up by the bearing + shaft assembly. All a servo has to worry about is putting torque on that shaft. This meant the workload is similar from a servo’s perspective and hence all servos can use the same bracket.
Using a common servo bracket for all roles mean we can print ten identical brackets instead of keeping track of several different types. Using a common mounting mechanism also means it’ll be easier to adapt Sawppy to use a different servo in the future: we only have to design one bracket and print ten copies.
Once this “aha” moment struck, it was fairly easy to reconfigure related components to accept a common servo bracket. Fortunately this insight occurred before full scale rover construction had commenced. Now we have increased ease of build, simplified parts inventory, with no noticeable loss in functionality.
Here’s a picture of the new mechanisms using a common servo brackets (left) versus old mechanisms using distinct drive and steer brackets (right).