Sawppy the Rover

Motorized model of Mars rovers Curiosity, Mars 2020

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This model's layout and proportion mimics that of Mars rovers Curiosity and Mars 2020. It faithfully reproduces the suspension kinematics of real rovers and is intended to be a hardware platform for future software projects in autonomous operation. Go forth and boldly explore the back yard, Sawppy!

Sawppy Rover was inspired by SGVHAK Rover, a six-wheeled robot inspired by the NASA JPL rovers sent to explore Mars. The major differences between Sawppy and SGVHAK Rover were motivated by a desire to reduce cost and complexity. To accomplish this goal, Sawppy differs in two major design objectives:

  • Motorization: Instead of using gearmotors with encoders managed by RoboClaw motor controllers, moving the wheels will be done with servo motors.
  • Construction Method: Instead of using the Actobotics construction system, Sawppy will be built from Misumi HFS3 aluminum extrusions connected by 3D-printed plastic parts

These two major design goals can be summarized as: Servo Actuated Wheels, Printed Interconnect For Extrusion. The acronym SAWPIFE led to the nickedname "Sawppy".

  • Sawppy Climbs a Backpack

    Roger05/11/2018 at 06:55 0 comments

    Here's a short video clip of the alpha build chassis, showing that the design works.

  • What I Have Isn't Much, But It's Available Now!

    Roger05/09/2018 at 17:43 0 comments

    This project is open and fully intended for others to build their own Sawppy the Rover. The design is not fully baked but as someone who is personally frustrated by many "it'll be shared when it is ready" projects, I'm putting my own project out there in all its incomplete awkwardness.

    What's available today:

    Onshape CAD document: Sawppy is developed in Onshape, a web-based CAD (computer aided design) tool usable on anything from Chromebooks to full power engineering workstations. (You will need a good internet connection.) Hobbyists can create a free account to access public Onshape documents like Sawppy. This is the live development file with all its upsides (latest update!) and downsides (latest update doesn't work!)

    I've already received several requests to release Sawppy CAD data in OpenSCAD format. Sadly my OpenSCAD skill is not good enough to create Sawppy's geometry. If anybody is willing to take my Onshape design and convert it to OpenSCAD, please let me know and I'll be happy to link to your project!

    Github: For those who don't want to create an Onshape account, the 3D printer data files (STL format) exported from Onshape is also available and hosted on Github. This will be a periodic snapshot of designs that have been printed and verified to work on Sawppy. This is good for casual browsing and printing my designs as-is but any editing should be done via Onshape. 

    Build blog: CAD and STL is good for conveying the what of Sawppy, but they won't necessarily cover why. The build blog describes the design decisions behind Sawppy. Each daily blog entry is a short ~300 word story about one specific topic.

  • Construction Technique Shared on

    Roger05/09/2018 at 17:18 0 comments

    After receiving positive feedback about the techniques I used to build Sawppy, I decided it was worth writing up to share on This is a technique I've been evolving over the past few projects (see my profile) and it's been a really great way to bring ideas to reality. It won't be the way to build every project, of course. Use the right tool for the job, etc. And now, this tool is available to more people!

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terence.d.healy wrote 05/17/2018 at 15:18 point

Excellent rover and very nice work.  I'm very interested to hear how you are using the servo motors rather than gear motors with encoders. Can you tell us about the software a bit? Do you use ROS - if so, what computing hardware? 

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Roger wrote 05/17/2018 at 16:29 point

I do have ambition to put ROS on Sawppy and give it some autonomy, but for now I'm still working on the chassis hardware. At the moment Sawppy's brain is a bare-bones piece of software that allows simple tele-operation and runs on a Raspberry Pi. (Translation: right now it's just a very expensive remote control car.) Code is up on Github, search for "SGVHAK Rover"

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John Whitten wrote 05/16/2018 at 19:21 point

Awesome. I am both intrigued and jealous. I applaud your good efforts and eagerly await your next developments. 

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