oribotics [network]

Prototype waterbomb flower

In this video you can see the prototype oribot, handmade mechanics, being actuated through the firgelli micro linear actuator.

VHB 9473

oh boy, I just got some super sticky tape from the US. Its called VHB (Very High Bond) tape made by 3M. Varieties of this tape is so strong its used in aircraft and buildings. Kind of amazing to think that sticky tape has become one of the strongest bonding agents. Well its not just sticky tape. Anyway I wrote to 3M and they advised me that the tape I need is the VHB 9473 tape, its 0.25mm thick, and is double sided and bonds aluminium, stainless steel, and plastics together. It takes a few days for the bond to acquire full strength. I can wait to try it out. Its kind of fun to think of doing away with screws in favour of this stuff!

I searched high and low for an Australian distributor of 3M tapes, talked to guys on the phone, only to find that I have to buy cartons to get a single roll, its too specialised and no one sells it by the roll, at least the VHB 9473… So I went to the US, and found CPC, rang through an order last Saturday morning, and it arrived today, very happy. I love making art, you get to try out so much cool stuff.

new design for leaf/flower petal

Folding Metal

I’m modelling the current generation of oribots, and have prototyped a new design and am going to make the parts from aluminium with some folds.

Ok. so I haven’t folded much metal before, and while I was modelling with my favorite modeller blender I was struck by the idea that metal has a thickness that needs to be considered when folding! Of course it does! My modelling prior to this point was all about aesthetics not about accurate measurements for laser cutting.

I’m trying to determine where to mark the fold on the aluminium so that the outside edge of the fold ends up at a precise location. By outside edge I mean if you have a sheet of paper on the table, and you make a valley (concave) fold then the outside egde is the bottom side of the paper.

So how do you calculate the radius of a fold (or bend radius)??? Well thanks to this Sheet Metal Bending Calculator I found some answers, which I am yet to test…

The following are my illustrations to help educate my train of thought on the matter.

I’m going to use the following values calculated using the Sheet Metal Bending Calculator.

1mm Aluminium
bend radius 1.591mm
outer radius 2.566mm
length of fold 4.037mm
length before 90º outside egde of fold 2.566mm (same as outer radius)

2mm Aluminium
bend radius 5.132mm
outer radius 3.183mm
length of fold 8.061mm
length before 90º outside egde of fold 5.132mm (same as outer radius)

Flexbond

I’ve been searching for a technique to bond fabric and plastics. Why? The most recent oribot prototypes have been made with plastic and fabric laminates. Basically the crease pattern is cut out of thin plastic with a gap at the creases to allow for folding, and then sandwiched between two layers of fabric. The result is a highly flexible and durable oribot, unlike the original paper bots which tended to ‘wilt’ in time (a fact which I liked as it added to the fragility of the work - but technically I was not happy, as I think a bot should be strong enough to perform its actions).

These guys look like they have what I’m after, according to them it remains extremely pliable and strong even as the materials bend and deform - we’ll I can certainly put that to the test.

http://www.rosco.com/australia/scenic/flexbond.asp

Folding Robot project

While googling around on the subject of origami hinges, I came across this project that developed (well almost) a walking origami robot. The concept seems sound enough, but the interesting thing is their approach in using servo motors as actuators for folding. I have had similar ideas, to use tiny tiny mobile phone motors, which I soon discovered come in a minimum order of 2000 units - a few to many - and they supply to large companies. I think a smaller cylindrical motor would actually work very well. I’m keeping this for a later evolution. I’ve decided I really like the simplicity of the current system using wires to create tension. And at the moment, the thought of mounting tiny motors on each joint is a bit too daunting - not to mention the extended prototyping period required…

Anyway after that rant, here is the project.

http://www.medphys.ucl.ac.uk/teaching/undergrad/projects/2005/group_05/projectstages2.htm

Muscle wire on hold

Well, I’ve exhausted the ideas I have for muscle wire right now. It can contract up to 5% of its original length, and I’ve tried multiple ways of attaching the muscle wire to a basic fold. Increasing the leverage, and it still only yields about 40 degrees of movement. This is not satisfactory. I am shifting to a more fundamental aspect of the project, which is design of the flower bots.

Though it must be noted that this avenue of exploration is very valuable, as the idea of muscle like actuation of folds is central to the future idea of pure oribotics. I hope some technology will emerge in the not too distant future to aid this aspect of the design. But for now the muscle wire exploration is on hold.

We really need muscle paper ^_^ Paper that folds you!

One tiny step forward

I’ve been plugging away at this idea to replace the motors used in oribotics with SMA - Shape Memory Actuators - otherwise known as BIO METAL. It’s been about 5 days work just to relearn basic electronics (all that high school education was useful), finding parts in Akihabara, and then inventing a mechanism which could actually perform the action of folding.

Well, after so many days of pure research and scribbling on paper, the first successful experiment bore fruit. A tiny folding mechanism can be activated by the touch of a button. It’s very primitive, only unfolds, and actually doesnt work well enough for production, but at least I can see a way forward. The next steps are to improve the mechanism. When I get something worthwhile showing, I’ll make a small video and post it.

The beautiful thing is that I can see it working, and if the technique can be refined, it would make oribotics truly beautiful, and one tiny step closer to the dreams of pure oribotic paper.