Category Archives: Robotics

CAD, templates and a couple of glamour shots

I’ve been working today on the design for Felix,  trying to tidy up the space for the electronics. The new body template is designed to fit an Arduino Uno board and an Adafruit 16×12 servo shield.
I’m trying to get up to speed with Autodesk Fusion 360. It’s great software, but to do this sort of stuff I keep coming back to OpenSCAD.

In order to get some “Fusion time”, I exported the template from OpenSCAD to STL format and uploaded it to Fusion 360. I also downloaded 3D models of an Arduino and a HiTech Servo from GrabCAD.com. Then I spend some time playing with the render:

FelixGlamourShotWhiteFelixGlamourShotTransp

You can grab the OpenSCAD files from the repo:
https://github.com/Traverso/JSFelix/tree/master/Hardware/CAD

and the DXF and SVG templates as well:
https://github.com/Traverso/JSFelix/tree/master/Hardware

I still need to add a license file to the repo, but it’s a regular MIT license.

And speaking of CAD, I recently wrote a post for Makezine: http://makezine.com/2015/04/20/understand-1700-mechanical-linkages-helpful-animations/. It’s a short highlight of Mr. Đức thắng Nguyễn’s YouTube Channel. The channel is an amazing collection of complex animated mechanism he has documented with Autodesk Inventor over the last 10 years.

Dashboard and GitHub Repo

Felix is a NodeBot (http://nodebots.io). A NodeBot is a JavaScript powered robot. One of the benefits of using JavaScript and Node, is that it makes it trivial to create a  web based dashboard for your project. My dashboard has a simple joystick that controls Felix using Socket.io.

You can see a clip of Felix and the dashboard here:

The code is now on GitHub: https://github.com/Traverso/JSFelix
I will add the template files for the design to the repository as well.

Working on the body design

Yesterday I spend sometime at my local #fablab  #fablabnordvest learning to know their Chinese Laser cutter. I used 4mm. white acrylic.

The design was made with #iDraw and exported to SVG (You can download the SVG here Body.svg). But my Chinese friend only speaks DXF or AI. After importing the converted AI file, I realised that I needed to do some cleanup of the path. Some of the patterns appeared twice(?).

Anyhow, it’s always mesmerising to watch a machine do it’s work.

After playing with the assembly, I want to redesign the way the lid is attached and I will like to make a   smaller version for 9g servos. Probably the easiest way to do this is to use OpenSCAD to create a parametric model with the size of the servos as a dynamic variable, and then create a projection which I can export to DXF.

TemplateB

A stand for Felix

IMG_0688 IMG_0689

Today I made a stand for Felix. Like the rest of the parts this is designed as a “2 1/2 D” structure. It should be easy for everybody to cut the parts with at laser cutter, a desktop CNC or easily convert the design to something you can print on your 3D printer.
Or, you can just print it, glue it to plywood and cut it with a bandsaw or jigsaw.
I have used plywood and powertools until now, and done some small corrections with a knife and sanding.
Next week I plan to visit our local fablab (http://fablabnordvest.dk) and laser cut my templates on 4mm. acrylic. I’ll be able to test if everything fits “right out of the oven” or if the design needs some adjustments.  I’ll post the final templates as SVG.

Build and test of the new design

Today I finished the new design for the body. I began to use iDraw for this project, and until now it has been a very positive aquaintance. I used to be a competent Illustrator user, but jumped of the Adobe wagon some years ago. iDraw fells very familiar and stay out off my way.

You can download the pattern here: FelixBodyPattern.svg

To test the dimensions and the range of movements, I cut the pieces from 4mm plywood using the pattern as a template, then put it all together using bolts and washers.The servos are fastened with 3mm. bolts and the knee with 2mm. Below you can se af video of the assembly process.

NodeBots & Johnny-Five

I run a bit out of steam while tinkering with the gaits. The write/compile/upload/test cycle on the Arduino took some of the fun out of it.  For the new leg I have to rewrite the IK and control to accommodate the new servo’s setup. So instead of doing this as Arduino sketches, I decided to give NodeBots (http://nodebots.io)  and Johnny-Five (https://github.com/rwaldron/johnny-five) a try.

This days most of my (professional) projects include NodeJS and Angular, so JavaScript is part of my “mindset”. If a have some spare time during the day I don’t need to “shift-gears” in order to write sketches.

Furthermore Johnny-Five have an Animation module (https://github.com/rwaldron/johnny-five/wiki/Animation) that looks like a perfect fit for managing Felix’s walking cycles.