The following is an overview of how I went about about creating Hollies unique Robohand.
The first step involved Hollies father creating a series of alginate molds of both her left and right hands. Instructables gives a large number of tutorials on this process, with a number of them being focused on hands.
He then used these alginate molds to make plaster models of Hollies hands.
I then took these plaster models and used a technique called Photogammetry to turn these models into Computer models. The particular tools I used were 123d catch and Autodesk recap 360. These are both free Autodesk products that let you turn a number of photos into a 3D model.
I used a grey paint to bring out the contrast in the hand.
I also added coloured dots to the hand which gives myself and the software reference points to find in 3D space.
The final addition I made used a giant coloured QR code, which the model rests on. The QR code serves the purpose of helping the software know the surface is flat, as well as giving reference points to pick. The colour is also there to help me identify which precise square I’m using as an alignment mark. Trying to identify a black square out of many black squares is needlessly difficult.
The resulting model looks something like this:
Not very useful, so I used another free bit of software called Blender, to edit out the parts of the mesh I don’t need.
Blender gave me some useable models, but photogammetry isn’t perfect and so I used a somewhat less free piece of software called Zbrush to tidy things up further, as well as to re-position the fingers.
Quickly back to Blender to create a printable model,to scale things correctly and to mirror Hollies full hand. Then I printed out the first models on my Lulzbot printer. This gave me a direct comparison to the plaster cast hand to check.
I will describe how I combined the two models to create the fitting hand in Part 2
It’s too late now to go into details regarding the finger tests for Hollies hand. It’s going well though and I hope to incorporate what I’ve learned into the new design.
Below is a video from the test.
I will update about the methods behind the design process hopefully before the weekend.
So first of all I’m not dead! 8 months is a long time, so I have some ground to cover.
Firstly my working relationship with Easton broke down after became too unreliable, and seemingly unwilling to use the strengths that he could have bought to the project. Luckily I managed to get him to finish off the remaining Kickstarter arms. Speaking of the Kickstarter arms they are available either through my shop on Shapeways, or as a download from Thingiverse for those ambitious enough to print one for yourself.
Since I didn’t have a functioning business I had to get a job. Luckily it’s local and I’m working with 3D Printing. It’s given me some breathing room to learn new techniques, such as using iMaterialise Magics software.
In my spare time I’ve managed to make some small designs, which are available on Shapeways.
This involve converting pdb protein structure files into printable models.
Biology inspired art pieces are also available.
I am also updating the website and enhancing my social media profile.
But the big thing is that I haven’t stopped on the robot hand design, although progress has been slow. I’ve been focused on combining 3d scan data with the robohand mechanics. The first and protoype model is being made for a young girl called Hollie. I finished the first stage of the design this weekend and had her try out some elements of it.
I have yet to add the mechanics to the design. My original plan was touse pins and elastic like my kickstarter hand, but this proved time consuming. Instead I am going to take an idea from the Flexy Robohand model. Instead of the filaflex material though I want to engineer an elastic joint straight out of the Shapeways WSF material. I have some experience from experiments with this material and believe it to be possible. As far as I know this is also the first robohand varient made via Shapeways.
You may also have noticed that Hollies right forearm is shorter than her left forearm, requiring me to create a new mechanism to control the fingers.
The copying of her left hand was achieved through a multi-stage process involving making a silicone mold and plaster model of both her hands. I then used Autodesk 123d Catch to turn it into viable models. I then used Zbrush, Blender, Meshlab and Meshmixer to make the above design. I plan to use Autodesk Fusion 360 to make the mechanical parts of the arm.
I hope to have the prototype joints completed this week. To try them out next week, and incorporate them into the design. Hopefully by the end of next month I will have a functioning prosthesis to give her.
Well things have been a bit stressful over here, but progress has been made. I sent out the first of the full working hand rewards on Kickstarter. Yahoo!
I tested it first with the shapeways printed hands, of which I made a video.
As always the hands are available here. I’ve learned a few things from their assembly, mostly how to make assembly go smoother, which I’ll add to the files shortly.
As a short break from all this hand building I decided to mess around with stewart platforms and hexapods.
A video of some stewart platform tests.
The mini hexapod is also online on Shapeways.
Also a pic of its big brother, to come soon.
I’ll be getting back to assembling the Kickstarter hands soon. Easton is back from his speaking tour of South Africa, so hopefully we can get some things out sooner.
Phew the last few months have been hectic. I’ve been doing my end of satisfying the rewards, which meant printing 60 fingers and 10 hands. These weren’t the motorised sort, just the printed and assembled sort. But still they ate up months of time.
Anyway with my end all over I am glad to announce that the hands are available of shapeways.
There are collections of fingers on there also. I also developed a prosthetic finger, which I am looking forward to receiving feedback from.
Easton has been busy, at Nasa and giving ted talks. He will soon begin work on the electronic set of rewards. We also got the hand to be printed at stratasys, whilst Easton visited there.
We have several projects advancing at different rates. We have an upper body exoskeleton, which we are finding and designing components for. We have are on a biped robot, which I hope will share alot of techniques with the exoskeleton. We are working on more advanced hands, which are closer to being used as actual prosthetics.
I hope to add some more info and photos over the next few days.
The Kickstarter was a success. We raised over £12,000!Alas we won’t receive the money until 14 days have passed, so it should be arriving in 5 days. In the meantime I am continuing to refine the design. This mostly involves making it simpler to print and assemble. I have also modified the thumb, to make it more organic as well as easier to position. These designs and test prints have occupied most of my time.
We also plan to open an online shop to take pre-orders. We also hope to make an entire arm, with shoulder joint, available sometime in the next few months.
Ok so we got word back from kickstarter. We needed to change one thing, and then it was ok to go. I also tweaked some elements and improved some information about the project and where we hope to improve the hand in future.
Ooh that launch button is soo tempting!