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Sawppy the Rover; Hobbyist-level rover for $500
Topic Started: Jul 13 2018, 11:21 PM (1,306 Views)
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Hello everybody!

I was on the team for SGVHAK Rover, one of the beta rovers built as a test run for JPL's Open Source Rover build documentation. We enjoyed bringing a rover to life, but during its construction we also lamented at its $2,500 price tag. It's within reach for large group projects but on the high side for an individual hobbyist project. Out of all the ideas that were tossed around to reduce the price of admission, one caught my attention: a 3D-printed rover using RC hobby servo motors should be possible for $500. I really liked the idea and decided: Challenge Accepted.

After our SGVHAK rover was up and running, I switched my attention to building a rover for $500. Obviously, some sacrifices had to be made. The top two changes were:

  • Motors: JPLOSR uses powerful gearmotors controlled by sophisticated Roboclaw controllers. They're really good but they're also expensive. To hit the $500 price point, we have to downgrade to something like serial bus servos that are less powerful but also a lot less expensive.
  • Structure: JPLOSR metal structure is built using Actobotics construction system. They are strong, and gives great flexibility for experimentation with different rover chassis designs. But that flexibility also comes at a cost. To hit the $500 price point, we have to build the structure differently like using 3D-printed connectors for aluminum extrusion beams

I started my rover project with the acronym SAWPIFE = Servo Actuated Wheels, Printed Interconnect For Extrusions. SAWPIFE evolved to become a much friendlier nickname "Sawppy".

Everyone, meet Sawppy the Rover, seen here exploring my back yard.

Posted Image

Though to be honest, $500 only covers the motorized chassis. Additional accessories visible in this picture, like the cameras on top of the camera mast, pushed my rover above $500.

The project is currently documented across several resources:

Sawppy's control software is nearly identical to what I wrote to run SGVHAK rover, with only configuration changes to work with the LewanSoul serial bus servos instead of Roboclaw used in JPLOSR.

As of this writing, Sawppy is at version 1.0: mechanical design is mature enough to take a pause in physical evolution. In the immediate future I'll focus on improving the software.

And to anyone who builds their own Sawppy: please post pictures (or link to YouTube videos) here. Sawppy would love to see some siblings running around!
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