Program a pulsating/reversing

[GreenAce92]

I had an idea for an ornithopter wing drive system using magnets...

All explained in my old thread:

http://www.rcgroups.com/forums/showthread.php?t=1239649

What I need to be able to do is reverse a polarity of a solenoid (coreless) within microseconds or actually about 60hz is good.

Just north south north south like a strobe light.

More details...

I have two solenoids or four they atract and repel in a rhythm that allows the flapping of a membrane/wings like a bird

Normally solenoids are "solid" or I think they are anyways

Wait are electro-magnets and solenoids the same?

Anyhow the image below shows the system that I am trying or was trying to devlop however people told me that it couldn't compare to an electric motor and gears (it takes a gear ratio of at least 80:1 to flap the wings of an ornithopter)

Why can't I embed anything on this website? Is everything mathematics and text? A forum called "Wattflyer" uses the same site generator and they have embedding for videos such as Vimeo, Youtube and also for images and html web pages why not here?...

Here is the image

http://static.rcgroups.net/forums/attachments/1/5/6/3/3/6/a3225763-85-My OWDS.jpg

 

[(*steve*)]

Why can't I embed anything on this website? Is everything mathematics and text? A forum called "Wattflyer" uses the same site generator and they have embedding for videos such as Vimeo, Youtube and also for images and html web pages why not here?...

Because the site owner may decide that he doesn't want to enable these features.

You can always post links to this sort of stuff.

 

[GreenAce92]

I see I see well I best quit my complaining then.

My apologies

 

[(*steve*)]

I'm not sure exactly what you're after, but you mention turning on and off in a microsecond then say that 60Hz is OK. Those are two widely differing timeframes.

If you're looking at reversing the polarity to some device, you probably should investigate H-bridges.

 

[GreenAce92]

See this device that I am trying to make?

A pulsating 'solenoid' will make this magnet which is 'hovering' in the middle to go back and forth at a high rate

This is for a small insect a gram at most weight

But all it has to do is beat really quickly

There are a lot of ball joints so I'm going to have to make the transfer of motion from horizontal to vertical as smooth as possible.

It might be hard to see but the idea is, a rod will go back and forth like a piston, making a bell crank go up and down, with a fixed axle/joint in the center thus making the spar go up and down which will have a wing membrane attached to it, the rest is a matter of the rythm/hz of the wings.

The perspective(s) on the drawing are off so it may be hard to see but the center of the bell crank is attached to a fixed part of the 'chasis' or frame.

 

[(*steve*)]

Then yes, you should investigate H bridges. They are a good way of reversing the polarity to something. And yes, they can operate very quickly.

 

[GreenAce92]

How much is it to build one, I looked at them and the concept seems simple

To me it reminds me of like SPDT switches, as far as the reversing goes but... parts wise... I haven't looked at it yet in great detail but I'm trying to figure out how to actually build a small model of my ornithopter

Also this 'H-bridge' I've been looking at, says you can have either mechanical or solid-state switches for the four switches that operate this said 'H-bridge'

What I don't understand is, will this 'H-bridge' run itself?

What I want to do is have a forward/backwards motion at a high rate which you said can be done through this but does this happen by itself? How would I control the rate?

I obviously need more info as a bunch of these terms like 'MOSFET's' I have no idea what they mean.

But I'm a quick learner and I'll figure it out.

If what I'm trying to build will use a power source of say a 1 cell lithium ion battery rated at 50mA at 3.7 V

What would be the smallest most adequate sizes for things like resistors/diodes etc... how do I figure stuff like that out?

I know I'm just asking for answers and really I should start from stage 1 which I'm going to... I just have trouble with a little thing called 'Patience'

 

[GreenAce92]

I've been working on revising the design

I think I may have a working one but I'm not sure

Now I need to make this project a 'throttle controlled' pulsating solenoid

Where I can vary the amplitude of the wings through the rate of the pulse

Here is a newer revised version of what I'm trying to do, not as 'pretty' as the other but see I'm running into a problem

On birds the upstroke is easier than the downstroke, so my thought was to use a magnets repelling power when pushed against a similar polarity to drive the downstroke

However I think this process may be self defeating

This is how I thought it would run, the magnets would be 'charged' to go together for the upstroke, the magnet is then 'charged' the opposite direction with less current than before since it will just assist the repelling of the magnets to drive the wings.

I know this doens't pertain to you guys but I thought I'd at least show you the perspective of the situation of what I'm trying to accomplish.

 

[Gr3mlin]

Now I need to make this project a 'throttle controlled' pulsating solenoid

I was working on a simple very simple PIC controlled H-Bridge that Interfaced with a standard servo output and responded by pulsing an output connected to either side of the h-bridge. i'll have a look and see if i can find all the info i had on it.
another option of course is a RC motor controller with reverse that does the same thing. just pre-build. and more than likely alot smaller.

I have a look and see if i can find anything on what i was doing, its been a wee while since i looked at it.

 

[Gr3mlin]

Just looked at your drawning. have to tested it yet?
Im just looking at it and, i honestly looks like its going to rattle itself to death.
had you thought of just using a single motor driving like an engine crankshaft? to flap the wings?

 

[BobK]

No, he hasn't, because he is convinced that solenoids are more efficient than motors. Makes me wonder why no one has thought of using solenoids to run electric cars. Think how much farther they could go on the same battery power!

Bob

 

[TBennettcc]

...that sounds sarcastic, Bob.

So I take it motors are more efficient than solenoids? (I don't know about either. Just trying to learn something new.)

 

[GreenAce92]

There seems to be very little innovation these days, it's just the same thing built over and over, better quality mind you but ideas are never pursued... it's easier to say NO as a friend of mine once said.

 

[duke37]

Things tend to stay the same because the laws of physics do not change.

Motors are better than solenoids since they do not have to stop a mass and restart it each time. To get vibration such as a fly or bee does it is necessary to tune the vibrating weight with a spring so that the energy from the moving wing is returned to the wing when travelling in the other direction. I believe that the pumps in domestic refrigerators work in this way, they do not have bearings and are fully sealed so do not lose gas. I will have to chop one apart one day to see what is inside!

An electric motor or solenoid can only produce a small force. Motors are therefore run at high speed and if necessary geared down to get the force required. Your vibrating wing is energised at the base where the force required is high. Have you thought of energising at the wing tip where the force is low. You would need a subsiduary wing to attach the solenoid or another wing to work against.

A most interesting project, keep the ideas flowing.