Micro Sawppy Beta 2

The main objective of MSB1 was to establish that a scaled-down rocker-bogie suspension system could nominally function and expose problems along the way. That objective did not require much of a rover body, so MSB1 only had a minimalist “Scarecrow” box. The main objective of MSB2 was to build upon its established suspension system and add a body with some resemblance to Mars rovers Curiosity and Perseverance.

On top of that body is not a realistic model of a rover camera array. Instead, it has a smiling face, which follows the precedence set by rover illustration JPL used for Mars 2020 “Name the Rover” contest (resulting in Perseverance) and that of ESA’s ExoMy rover. I had contemplated various ideas on how the face can change, maybe small OLED panels or an e-ink display. For this first trial I just drew a face with black marker. (There was also a layer of cellophane tape to block marker ink from capillary action.) I did this during a virtual meet of makers and I was surprised that a simply drawn smiling face made a hugely positive difference on how people perceived my little rover project. Though I probably shouldn’t be surprised: there was a similar change in perception when I added googly eyes to Sawppy V1 after seeing it done by another Sawppy builder. A tiny change makes people smile.

For electromechanical actuation, MSB2 used MG90S metal gear servos from a different manufacturer so I can compare how they perform against the ones used in MSB1. This particular batch were the MG90S that had a mild case of false advertising: only the final output gear was metal (visible as silvery metal) and the remainder were all black plastic. The two batches were bought from the same Amazon vendor on the same product page (*) but they are obviously distinctly different products. One of the differences had a serious impact on MSB2 and changed the direction of the project, more details in a future post.

I originally intended for MSB2 to be up and running in time for launch of Perseverance rover, but as is usually the case, other things happened. All I could do was a short video where I manually moved MSB2’s poseable arm waving a flag cheering Perseverance on. But it became a part of JPL’s official launch tweet, and I’m quite happy with that accomplishment even as I work through MSB2 design problems.


(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.

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