Introducing the Nomad (working title)

The Nomadtl;dr: I'm building an open-source, 3D printable rover.

What is it?

Now that I have something to show, it's time to share something I've been working on and excited about!

The Nomad is a 3D printable rover that's designed to be an open rover platform for exploring electronic and software systems. These include micro-controllers (TinyDuino, Arduino), companion computers (Raspberry Pi, Chip, Onion), sensors (cameras, LIDAR, GPS), actuators, computer vision, autonomous navigation APM:Rover, orthorectified imagery etc. etc.

My aim is that the Nomad should

  • be 3D Printable. Perhaps if there's demand the parts can be mass-produced, but replacement parts should be 3D printable, possibly with degraded performance (e.g. simplified axial systems).
  • use commercial off-the-shelf (COTS) parts as far as possible. You should be able to buy bearings, servos, motors and the like form your local hobby store.
  • use COTS, open electronics like Arduino and Raspberry-PI as far as possible.
  • use and generate Open Source software.

The suspension, steering and drive mechanisms are based on the NASA Mars rovers, implementing a rocker-bogie suspension with individual motorised wheels. It is not a fast-moving rover, and it should be able to handle uncertain environments to a certain degree. I want it to be able to navigate outside environments like farms, beaches and mines, as well as inside environments (with small steps and obstructions).

I've been concentrating on the suspension, steering and drive systems a starting point, and as you can see the details are way more evolved than the payload body.

The Suspension and Steering

Here's the printed and assembled suspension and steering for one side:

One side

This is the result of a lot of design iterations. Saying that, there's still a long way to go with both the form and function, but it's now at a point where I can attach these to a body and do some work on the basic movement micro-controller software.

The steering system uses a standard micro-servo with a Dubro ball link and a bit of bended 0.032" piano wire. Here you can see a prototype:

Ball link prototype

Excluding the wheels, one side of the suspension can be printed in one go:

Single print

The axes for the steering system and rocker are 3D printed and a RC Car bearing is used, but the 3D printed axis shaft is too weak and easily breaks off at the junction. Another design is required, possibly using metal shafts. Here's a prototype:

Prototype axis

The motors are standard Polulu Micro Metal Gearmotors, and the motor shaft fits snugly in the 3D printed wheel:

Wheel

Zortrax M200

As an aside, I want to wax lyrical about the Zortrax M200. This is an awesome printer. The results are consistent and reliable, and my enthusiasm for low-cost 3D printing has been rekindled.

I've printed these templates to figure out the measurements for a snug fit on the bearings and motor shaft:

Templates

and the printer reliably produces the same result.

Next

The parts for building both sides of the suspension have arrived, so I can produce these, but I'm waiting for some electronics. The first iteration will use TinyDuino and a Raspberry-Pi. I'll design a basic body and determine any problems with the suspension and steering, and if all goes well my next post will show a driving rover!

The design files (Rhino) and STLs for printing are available on github under a Creative Commons license if you're curious.

You can follow @calvinrobotics on Twitter for updates.

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Comments

  • I'll check them out, thanks.

  • @Doug too slow at the moment - too busy with work.

    I'm using 100:1 Micro Metal Gearmotors in the wheels, similar to this:

    https://www.pololu.com/product/992

    I think the ratio is too low and it goes too fast at max speed, so maybe 250/300 would be a better

    Pololu - 100:1 Micro Metal Gearmotor LP 6V
    This gearmotor is a miniature low-power, 6 V brushed DC motor with a 100.37:1 metal gearbox. It has a cross section of 10 × 12 mm, and the D-shaped…
  • @ Ben,

    How goes the build?  I successfully printed all six wheels and the boogie rocker suspension.  I'm now looking at additional parts to assemble my rover.  What driver gear ratio do you recommend for speed of this build?  I'm not looking for a serious rock crawler and would like to be able to still climb objects with a terrain that is + or - 3% grade.  Any suggestions?

  • The video is great.  I like this project enough to consider cloning your design for fun come this winter.  I also have a spare Raspberry Pi and would love to put it to use same as you project.  Looking forward to the outcome of your development.  Keep up the great work.

  • Hi Doug

    It's going well, thanks! The basic microcontroller+servos+motors are working, and I have a short video of that:

    https://vimeo.com/141897265

    There are a couple of mechanical improvements required, but first I want to incorporate the Raspberry PI with the microcontroller and batteries so it can drive around untethered and can be controlled from another computer.

  • @Ben,

    How goes the project.  Excited to see where you are in the development!

  • @Juan nice, would love to hear about any problems

  • very nice. i'm printing just now.

  • @Joshua Great, I will

  • @Ben

    If you ever find some time could you please share this with my Open Source CADDrones.com Community?!

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