Soft-exoskeleton Part 3: Starting Mid-Term Project (Fagprojekt)

…Continuing from a great 3-week course, this is where the actual mid-term project starts and the team assembles for the first time to start the actual project.

There is literally an incredible amount of stuff that has happened since we started this project. I cannot include them all but I will try to give an insight for those so inclined.

First of all, by random coincidence one of my friends saw a posting for a competition in wearable electronics and forwarded it to me:
While it was a competition targeting electronic/software engineers, the suggested topics hit our project right on the nail so we thought we’d give it a go anyway. They required a team of maximum 5, which we were. I sent them the application while mentioning that we were all mechanical engineering students intending to build an exoskeleton. All seemed good and we got accepted as contestants.

eFactor 2014 - Competition in Wearable Electronics

eFactor 2014 – Competition in Wearable Electronics

The contest revolved around a development kit that all teams were given. The kit included an Arduino Uno and a bunch of other electronics gear which we weren’t quite sure how to include in our project. Nonetheless, we went to the introduction meeting where all the teams were supposed to present themselves, their experience and introducing their project before being handed the kit. The rules for the competition did mention something about 1 of the contestants being allowed to not have prior experience with embedded systems, but having written in the initial e-mail that I was the only one with actual electronics and programming experience and having heard no shouting or other comments on that part, I hoped that they wouldn’t mind.
The meeting was setup with a Skype call to 3 other Universities with teams participating as well. I think we were probably team number 7 in line to introduce ourselves so we had a little time to to enjoy the show. This mainly meant realising how much more experience everyone else had, leaving us increasingly uncomfortable about our presentation.
When we finally went in front of the camera I started by introducing the team, my former experience, that I was a mechanical engineering student but had played around with arduinoes before. However, when the next in line simply said that he was a mech student with no prior embedded systems experience, followed by two more saying the same, the situation got a little tense. When the last guy on our team proclaimed the exact same lack of experience in embedded system the organizer, who was also handing out the dev kits, looked rather confused. None the less he said that he really hoped that some of us had at least a slight idea about what we were doing before handing over the kit. We later heard that many of the other teams watching, had been quite amused by the awkward moment.

Eventually everything was ok though when we spoke to him after the presentation. The competition was about learning electronics and seeing the potential of wearable electronics in particular, so as long as we learned something, he was happy.

That was the signup to eFactor. The finals were on the 5th of April given us about 3 months to come up with something to show, on a project based on a concept that none of us had working with before. Let the fun times begin!

Moving on the the actual mid-term course. As mentioned earlier, the project also included a course in project management. In theory we weren’t really supposed to have a team yet, as we should spend the first couple of lessons analysing our Belbin roles and make our teams based on them. However, as we had locked down our team by signing up to eFactor we were excempt. As it turned out, after analysing our Belbin roles, our team was a completely unintended perfect match. Well done subconcious! or luck… or whatever.. but the fact was that we had a perfect team, in theory. I should mention that we hadn’t at that time worked together all 5 and the team was made based initially on social compatibility and friendship, so it seemed it could work 🙂

– I see that this will be quite a long post. However, I quite enjoy writing it and I don’t even know if anyone is going to read it, so I will continue like this. Sorry in advance if you have reached this point but feel super tired by all the insignificant and boring details that I am providing and just want to find the results. I will not stop…

Anyway. Done with the Belbin stuff, done with the eFactor signup. Moving on the getting some hands dirty. I must admit that I cannot remember everything that happened and when and why and stuff but suddenly we had an office. David Johan Christensen happened to be part of a department at DTU that had moved into a new building, waiting for the old one to be renovated. With him as a superviser we were then allowed to occupy one of the rooms in their old building, as it wouldn’t be renovated before summer. We got a huge room with accompanying solder station and sound studio. Perfect!

The team had many meetings about how to approach the project and given my epxerience from the 3-week couse I started out as project manager. Eventually I would be replaced by someone else more suitable for the role so that everyone would do what they were good at.

Introducing the team:

The team - eFactor team Filosoma

The team – eFactor team Filosoma

  • Andreas Körkel: Former carpenter. Good experience in the professional life. Great at quality control and getting things finished as well as talking to people.
  • Peter Hybertz: Great engineering problemsolver with a very analytical and organized approach.
  • Lauge Kongstad: Super organized. Overview of what needs to be done when and an interest in project management (Guess who got to take the project manager role after me?), and good at a range og engineering subjects.
  • Frank Olsen: Former blacksmith and great technical engineering problemsolver
  • Me: I guess my strength is probably in a broad but shallow experience in many subjects touching on both electronics, programming, mechanics, 3D design, professional life / teamwork and idea generation. Also I seem to have a more cowboy-style chaotic approach to rapid prototyping and developent than the rest of the team. We compliment each other very well 🙂

Beyond the mentioned strengths, this obviously isn’t an exhaustive list of talents. Everyone is a super capable engineering student way above my analytical and science skills, so I must say I’m more than happy about the coincidence that brought us together!

Having the funding at hand from Glostrup Hospital we started ordering stock of braided tubing, nuts, bolts, wood, pneumatic components and other misc requirements. Furthermore, having wanted to get a compressor and a 3D printer for myself for quite a while I decided to buy both of them now and dedicating them to the project initially. Justification approved and I could finally get my hands on both…
Andreas put together a huge wooded armature for testing the different muscle designs and shoulder mechanics and we got hold of a bunch of sensors from DTU, giving us a nice little test setup.

Wooden armature with mounted penumatic muscle and sensors

Wooden armature with mounted penumatic muscle and sensors

Given the fairly hacked-together armature it proved impossible to attach the rotation-sensor exactly concentric to the shoulder axis. Oldham couples and a 3D-printer to the rescue and all was good again

Oldham couple connecting the shoulder joint with the rotation sensor

Oldham couple connecting the shoulder joint with the rotation sensor

With everything finally set up for testing, we started out gathering data on a lot of different muscle designs. However, with no emergency relief valve installed yet, we initially had to take several saftety measures when opening the valves:

Initial safety measure

Initial safety measure

However, realising we had a soundstudio just next door, we decided to abuse the situation and perform a few explosion-tests in there. This gave us a better sense of maximum pressure and allowed us to control the flow so that it would never go beyond. Having the sound studio just next door also gave a few benefits in muffling the sound of the compressor a little. Eventually the office looked a little like this:

Despite the late hour Andreas is not sleeping but rather working on a new muscle prototype

Despite the late hour Andreas is not sleeping but rather working on a new muscle prototype. To the left is a makeshift silicone mold made out of cardboard, tape and soap

Workbench art

Workbench art

Starting out with no knowledge whatsoever on pneumatic systems, putting the first bit together was a bit of a struggle. It seemed that pneumatic automation at DTU was no longer an active topic. Despite the plentiful specialists in analytical pneumatics we didn’t manage to find anyone who could tell us anything about the practical application and starting from scratch on that field could get expensive very quickly if we had to buy everything. With a bit of searching about, however, we did manage to find an assistant professor, Casper, who had known the previous professor in pneumatics. The professor had retired but left behind a whole cabinet full of pneumatic elements in the custody of Casper. He then arranged for us to have access to this cabinet and allowed us to use it freely. This was an amazing help! Despite the complete lack of knowledge we now no longer needed to buy everything simply for the sake of testing just to realise that it didnt work anyway. It was like lego. We all digged in and started looking for components matching each other and matching the different ends that we wanted to connect.

One of many boxes of random pneumatic components

One of many boxes of random pneumatic components

When we eventually found some of the needed bricks in the puzzle, we were able to attach the muscle to the first armature (my first test armature from the 3-week course) and test whether it could lift anything.. seems like it worked 🙂


This may look strange and wrong in a few different ways… we know… but it works and that’s just great 🙂

In the masses of pneumatic antiques we also found a few solenoid valves which got the honour of being our first control valves for the system. Following this little victory and the experience it had given us, we could finally sit down and discuss which other components we needed and order them.

From a previous project of mine I had already played around with an EMG-sensor – Namely the Advancer Technologies Muscle Sensor V3. During the meeting with Glostrup Hospital I had been asking around for anyone knowledgable about emg-signals and found that one of the guys at the meeting was a Ph.D in how you can use these signals (Probably wasn’t the official title, but that’s what I remember). Once again it was perfect. He told me that EMG would be an obvious choice for controlling our system and that many other existing exoskeletons were using the technology. With that in mind it seemed that controlling our system with such a sensor would be a solid choice, despite none of us being proficient in the area. It seemed that if ever we got stuck, there would be a huge knowledgebase within our reach, where we could find specialists and get help.
However, as I had previously documented how easily I could control a motor by muscle contractions, we should be able to get something out of it.


Putting together the Arduino Uno from our Dev Kit, EMG sensor (We were allowed to buy additional sensors for eFactor for a predefined sum) and the solenoid valves we managed to get our first muscle controlled muscle to lift a wooden arm, controlled by muscle contraction:


The theory of this definitely worked. The EMG signal in this case was still raw input with a simple threshold  allowing the apply pressure to different degrees. The reason for it relaxing again inbetween applying pressure is in this case due to leakage. None the less I felt like I had pretty good control of when I crossed the threshold and to what degree.
However, the sound of the solinoids was anything but pleasent and they didn’t seem to allow for faster PWM, giving a very uneven flow. After performing this test we starting researching other types of solenoids in the hopes that there would be a less noisy alternative. It seemed though, that solenoids could be the wrong way to go as we found a an article on the subject proposing instead servo actuated valves for more fluent control (Here).

However, after heading back to the cabinet with pneumatics, now looking for an alternative to the solenoid valves, we discovered a manual Festo front panel valve. This valve had a little mounting hole for whatever is normally used actuate it and a little rod in the middle that you push down to change the state. By design the valve was only meant as 2-way, but we realised that by pushing the rod down halfway, you could close all connections at the same time. This was exactly what we were looking for and with the mounting hole being fairly easy to measure we hoped to be able to construct our own mount.

With this all figured out it was merely a matter of playing around in Solidworks for a bit, an encouter with a 3D printer and puff, a servo-controlled valve was made.

3D-printed servo mount for a Festo push-valve

3D-printed servo mount for a Festo push-valve

Figuring out the mapping from servo-position to valve states was then a matter of applying pressure, moving it slightly while listening and then marking the points where it changed from pressure to hold to exhaust.

With all the components for the system now made and tested individually, we could finally put it all together and test the EMG control of pressure/hold/exhaust.


Bam, it was actually working fairly smooth! Next step was to calibrate the EMG-signal from the muscle and map it to the appropriate servo/valve positions for the most intuitive control.

To be continued in Part 4…

Red wine, Tom Waits and a 3D-printer

I recently acquired a 3D printer. This was a day I had been looking forward to for quite a while. In a way I guess I kinda needed one. It simply seems to fit too well 🙂

Initially I tried justifying the investment by the fact that we can benefit a lot from faster turnaround on prototyping for our exoskeleton project, but I guess it only had very little to do with it. Eventually I would have to get one and it was only a matter of time. Now it happened and I’m super happy!

The printer is of the type Wanhao Duplicator 4x and is an extension upon the MakerBot Replicator 1. I did my share of research, asked around at DTU, different online communities. At a point I found a danish reseller that could show it in action and that convinced me. I can’t really say if it’s THE BEST out there at the moment, but for what I’ve found so far, it seems like a super machine compared to the price.

It has been sitting at DTU for a while as I had it shipped there for an immediate helping hand while we were pushing towards the finishline of the eFactor competition. Now it’s done and I’m off on easter break so I brought it home to play around.

After bringing it back I’ve had 3 super nerdy nights alone with a box of red, Tom Waits on the stereo and a 3D-printer to befriend. I love this… but I know it’s nerdy… but I LOVE this!

Red, Waits and Printer

With all fine mechanics, such a printer needs calibration. The manufacturer can only go so far in making it work out of the box and the rest is a matter of compensating for all the ever so small differences from production tollerances.

The out-of-the-box experience was fair. I started it using ReplicatorG and the default firmware. First print we needed for the project was a box for the electronics. It made a great print but I guess the geometry was quite forgiving as well. It turned out though, that the scale was slightly off and it seemed it extruded a little too much material so it had room for improvement.

I’ve now updated the firmware for Sailfish 7.6 and spent the first 2 nights tryning to figure out how to correct the small issues. ReplicatorG – based on Skeinforge – allows for an amazing range of tweaks, really. Way too much to take it all in at once. Changing one parameter is furthermore likely to change the impact of another parameter at another place and looking at the billions’ish og numbers you can put in and change and stuff, it’s quite a mouthful. My first 2 night went ahead and I didn’t really feel I got anywhere. I was learning loads though, getting to know many new terms involved with 3D-printing and how many features have been made to compensate for a lot of particular difficult situations when printing special shapes.

At a point I even thought I was going backwards on my tweaks, having made decent prints earlier but now suddenly they were coming out much worse and I couldn’t seem to find my way back.

Final result after spending 2 nights tweaking ReplicatorG for my printer. Not good at all

Final result after spending 2 nights tweaking ReplicatorG for my printer. Not good at all

Finally, today, I decided to look into alternative software and found Simplify3D. It seemed to have been recommended by several people online and was supposed to make your life much easier for printing. It did come with a pricetag of $140 though, so I guess it’s something to consider. Anyway, I decided to give it a go, both because I want to support the community of people development software for 3D-printing and because I wanted to get the basics right with my printer, before digging into tweaking it myself.

So, I bought Simplify3D, started a print using only the presets and out came an amazing even and smooth print.

First print after switching to Simplify3D. Super smooth and even print. Very few inconsistencies apart from small holes in top surfaces. That can be fixed easily.

First print after switching to Simplify3D. Super smooth and even print. Very few inconsistencies apart from small holes in top surfaces. That can be fixed easily.

Lets just say that the money seems well spend. With this as a basis I am definitely able to print decent objects and Simplify3D seems much easier to handle when putting in custom values anyway.


Simplify3D side 1

Simplify3D side 1


Simplify3D side 2

Simplify3D side 2


ReplicatorG side 1

ReplicatorG side 1


ReplicatorG side 2

ReplicatorG side 2

Finally, after quite a lot of browsing around for working presets for the Duplicator 4 machine, I haven’t really found much. I don’t know if the machine is simply too new just yet and havent built up momentum but I’m planning on putting up whatever I discover on that part, if there should be more people out there looking for info.

Cheers and good night

Carls first sign of life

I finally got around to finishing the eye mechanism so here is the dude looking around for the first time!

It’s currently controlled manually by 2 potentiometers driving an Arduino Diecimila and 2 standard servos. Maybe one day it will be procedurally controlled or something.

Eyebrows are shit and probably needs redesign before I get more into that, but I’m still proud of him!

First draft of 3D-printed animatronic face

I’m now just about 2 weeks into my 3-week course of doing a 3D-printed animatronic head and it’s progressing in a nice direction… not too quick though but progressing nonetheless.

It’s a whole lotta fun to work with despite having verified that I know nothing on this subject 🙂 but then again that’s what studying is for.
I’ve certainly learned a quite significant amount about mechanical design and 3D-printing in a very short time.

Anyway. As I only hinted at this project last I wrote, I’d better explain it a bit.

Basically it’s what the subjet says. It’s a 3D-printed animatronic face that I’m working on.
It’s a school project where and my supervisors are the two guys managing the Fablab at DTU (where I work as well)
I wanted to do stuff that moves and I wanted to use 3D-printing for it. They wanted a mascot for their Fablab to showcase what they’re capable of. We started chatting and suddenly we were setting up a custom course on just that.

The deal was to spend 3 weeks building as much of an actuated face as possible, using as many different printing techniques as possible.
Obviously it’s a fairly complex game to play, especially with so little time and so little knowledge, but I’m beginning to understand now, slowly. Initially I wanted to find a good design to go for, so that I could have a nice 3D model shell and place whatever mechanics inside of it, just like I’ve seen on so many animatronic showreel.

The primary design ended up being based on an old model I had lying around from a speed modeling challenge. this dude:


After cleaning up the mesh a bit, I managed to convert it to IGES and import it into Solidworks, where I intended to do the mechanical design.
I’ve now sliced up the model into different bits and pieces, hollowed it out and started building new parts that can be 3D-printed.
I’ve done quite a few different tests and gone through a lot of iterations on many ideas as I felt I had to reinvent the wheel a bit, in order to understand it.

I finished up a working prototype of an eyeball yesterday, which you can see below. I’ve mounted a 2-axial gimbal on the inside which is all printed in 1 piece on an Objet 30 Pro 3D printer. It’s amazing to be able to print hinges that couldn’t otherwise be assembled like that and I’m trying my best to make use of it, but it’s not easy. As the Objet can’t do color, I’ve printed the Iris on a different printer – ZPrinter 650 – which prints in plaster. The eyeball is designed with a little indent on the front, where the Iris part slips into and sticks.

As for the other piece on the image below, that’s the eyebrow. It’s quit difficult to show it’s full potential on film like that, but the more I play with it, the more I realise how it can be used.
It’s a basic design that’s been used a lot in animatronics – and probably also many other places – but I find it quite amazing how much motion you can get out of it, only using 2 strings. Also, depending on how you thread it, you can get a lot of different results. The thread can change distance from the centerline along the length of the part and it can skip through the centerline, suddenly pulling in a different direction on part of the length. You can also put stops on it (You can see 2 on this part) where the structure can only bend a certain amount for that particular joint, and so on.
Currently I’m trying to get an overview of brow movements, what’s required, what I can live without and how best to achieve it.

2013-06-20 20.05.30


Finally, here’s a preview of the current state of my design. There’s still much to be done, many features to test, design, implement, print etc. but I love it!
Almost before I started these 3 weeks, I conlucded that I probably wouldn’t be able to produce anything fully functional in 3 weeks time. Luckily, my supervisors agree, so the point of this is simply to get a better understanding of the process and establish a few basics. Before next friday I’ll have to hand in a 4-5 p assignment describing the process, what I learned, what it can be used for and so on, but I do hope to have something moving by that time as well.

The assignment is going to contain a section with related research along with a discussion on the usefulness of the subject. Currently I’m digging into the research conducted by Paul Ekman, who’s an american pshycologist and a pioneer in the study of emotions related to facial expressions (His research was a key factor in the development of the facial animation system for Gollum in Lord of The Rings).
Furthermore I’m looking into the field of Human-Robot interaction, where the ability for robots to convey emotions through facial features is a big factor in how willing humans are to interact with Robots.
I think the assignment may end up slightly longer than 5 pages…


Animatronic Head Draft 1

New Job – 3D printing assistant

After about a year into my new studies I’ve now managed to sneak in and get a job at a newly started 3D-printing facility at the University where I study (DTU – Fablab).

This not only supports me financially but I get to spend time in the lab, helping out with printing, setting up stuff, fixing, launching new prints and generally just learning loads about 3D printing. Even better still is that I’m allowed to print whatever I feel like on some pretty amazing printers… whole new world is opening up now 🙂

Obviously my first print isn’t gonna be amazing or anything but it’s a great feeling to see a model all the way through from design to print. I decided to try my luck on an old model of a girl. For the sake of simplicity and the otherwise NSFW print I only printed her arm but it turned out great! Fingers need a little extra love but the surface on the arm itself is really good.

Arm from an old model made many years ago

First 3D-print. Modeled in Maya, printed on an Ultimaker

Further advancement will follow.

As a side note I may be spending 3 whole weeks in June on a really exciting Uni project involving animatronics and 3D-print. More info on that later.