Naked Science Forum

General Science => General Science => Topic started by: albert on 28/02/2007 03:38:10

Title: Can you help with my project...
Post by: albert on 28/02/2007 03:38:10

I project I have in mind requires an array of actuators to provide rapid fore/aft movement. They don't need to be powerful, but they do need to be small and preferably to have proportional control.

I've bought a handful of micro-servos to prototype with, but they are far too big and expensive for the product I have in mind.

Does anyone have any experience of working with flexinol/nitinol? From what I've read it can be quite slow to expand/contract when heated. Is there anything else in the pipeline?

A few years ago there were battling star wars figures that had a range of movements. I should have bought one from the bargain bin just to dismantle to see how the actuators worked - I'm guessing that they were some sort of solenoid. I've researched this for several years but haven't found a solution and wondered if any micro robotics boffins could help.

thanks

Albert

Title: Can you help with my project...
Post by: ROBERT on 01/03/2007 10:55:17

Solenoids (UK source)
http://www.maplin.co.uk/family_free_delivery/Solenoid.htm
Servos (same UK source)
http://www.maplin.co.uk/Module.aspx?ModuleNo=3739 (£10)

Title: Can you help with my project...
Post by: albert on 01/03/2007 23:41:12

Thanks Robert,

I've already got ten of those (ebayed from Hong Kong - much cheaper) but they are far too big.

I see there are developments in the field of electroactive polymers which might offer a solution...

Albert

Title: Can you help with my project...
Post by: ROBERT on 02/03/2007 15:21:57

What about "air muscles" Albert ...

(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi24.photobucket.com%2Falbums%2Fc23%2FSUEDONIM%2Ffig2.jpg&hash=838bdbd0da14c7253a584ee03e8f5aaf)

Quote

Air muscles have applications in robotics, biorobotics, biomechanics, artificial limb replacement and industry. The principle reasons experimenters and hobbyists will like air muscles are ease of use (as compared to standard pneumatic cylinders) and simple construction. Air muscles are soft, lightweight and compliant, have a high power to weight ratio (400:1), can be twisted axially and used on unaligned mounting and provide contractive force around bends, (see robot wars near the end of this article). Air muscles may also be used underwater.

http://www.imagesco.com/articles/airmuscle/AirMuscleDescription01.html

Title: Can you help with my project...
Post by: daveshorts on 02/03/2007 21:33:26

If you don't have a power constraint or need very quick movements you could use the muscle wire stuff which changes shape when it heats up. I don't know what sort of cost you are talking about though.

1 limited have some very interesting piezo based actuators which would possibly do what you want, but I doubt that they are very cheap. Although if you wanted the ones they are mass producing for a digital camera, they are probably not too pricey.
http://www.1limited.com/tech/helimorph/index.html

Title: Can you help with my project...
Post by: ROBERT on 06/03/2007 14:19:45

Plastic syringes could be used lightweight hydraulic actuators.
At about 20 pence each they are cheap...
http://www.mutr.co.uk/prodDetail.aspx?prodID=374


Also ready-made "air muscles" from the same UK source...
http://www.mutr.co.uk/prodDetail.aspx?prodID=379

Title: Can you help with my project...
Post by: albert on 06/03/2007 14:53:11

Thanks for your input guys.

Muscle wire (aka nitinol / flexinol) seems the most suitable until electroactive polymers hit the streets.

If I ever get a patent and a prototype made you'll catch me making a fool of myself in the Dragon's Den. Any venture capitalists reading - feel free to throw some money at me... £50,000 gets you 0.5% (I think that's the usual ratio hoped for).

Albert

Title: Can you help with my project...
Post by: Bored chemist on 06/03/2007 19:22:44

If I had a spare £50000, I'd have better things to do than surf the net.

Title: Can you help with my project...
Post by: albert on 06/03/2007 23:20:18

Me too ... first stop ... the curry house!