solenoid vs pnumatic actuator
solenoid vs pnumatic actuator
(OP)
Okay, here's the deal
I'm looking to find a small linear actuator, either a solenoid or a pneumatic actuator triggered by a pic microcontroller and whatever else ends up being necessary.
I need about an inch of stroke, and the force requred is in the ounce range (essentially just needs to move itself plus 4 or 5 grams) but I'm trying to get an actuator that can do this somewhere near 100hz ideally that way when a delay during hold open is taken into account, it can still cycle around 30hz.
If a solenoid can reasonably do this, what kind of information is available to me to design it? And if not, can a pneumatic actuator and solenoid valve reasonable accomplish this?
Could a permanent magnet (rare earth type) be used for the plunger of the solenoid, this way it can be dual action and not need a spring for return (thus reducing force requirements?)
Or is this just not feasible in a cost effective manner?
Thanks in advance for the advice,
Shane Olson
I'm looking to find a small linear actuator, either a solenoid or a pneumatic actuator triggered by a pic microcontroller and whatever else ends up being necessary.
I need about an inch of stroke, and the force requred is in the ounce range (essentially just needs to move itself plus 4 or 5 grams) but I'm trying to get an actuator that can do this somewhere near 100hz ideally that way when a delay during hold open is taken into account, it can still cycle around 30hz.
If a solenoid can reasonably do this, what kind of information is available to me to design it? And if not, can a pneumatic actuator and solenoid valve reasonable accomplish this?
Could a permanent magnet (rare earth type) be used for the plunger of the solenoid, this way it can be dual action and not need a spring for return (thus reducing force requirements?)
Or is this just not feasible in a cost effective manner?
Thanks in advance for the advice,
Shane Olson





RE: solenoid vs pnumatic actuator
On the other hand a pneumatic actuator contolled by a solenoid valve can develop high forces but the combination of the 1 inch travel and 100 hz seems to be a real challenge. I had the opportunity to develop and design fast ON-OFF electro-pneumatic valves with 1 msec up to 4 msec ON and OFF time delays (electrical delay plus mechanical delay) and it was not easy. Therefore, to achieve the 5 msec you need the pneumatic acuator to be extreemly fast and don't forget the pneumatic delay time to fill the actuator inside volume. So the actuator volume should be minimal, on the otherhand it has to be sized to provide the force to complete the 1 inch travel in 1-2 msec.
RE: solenoid vs pnumatic actuator
10m/s/.005s =2000m/s^2
2000m/s^2*.005kg=10N
huh. indeed. maybe I should have done that before..
well, pneumatic it is. difficult but acheivable at least?
thanks again.
any tips?
RE: solenoid vs pnumatic actuator
You should be able to find one with a 1" stroke, and 100 Hz is obviously within their capabilities. Then cut some windows in the loudspeaker cone and you are all set.
At the very least the coil and magnet size would give you a good idea of the required design.
However 1" stroke at 100 Hz is, frankly, an awful lot for an electrodynamic design. I think you'll end up with molten coils. To get that reliably we'd use an electromagnetic shaker that would cost $50000, and have watercooling, and a power amp the size of a fridge.
Cheers
Greg Locock
RE: solenoid vs pnumatic actuator
I'd suggest hydraulic, or even pure mechanical. Cam or crank and linkage.
RE: solenoid vs pnumatic actuator
The rotary voice coils used to move the heads in hard disk drives are capable of 100Hz response; note that they use relatively long lever arms to move milligram loads about an inch, in an arc.
Just as in a disk drive head actuator, your eventual solution will probably involve a mechanical displacement amplifier (e.g. lever arm) designed for minimum mass and high acceleration, and the actual force driver will work over a much shorter stroke.
Along the way, you will learn to design for stiffness, not just for strength. Points of reference; airplanes resonate around 7Hz, buildings a bit lower. Hydraulic fluid compressibility has significant effects well below 100Hz. Air at ordinary pressures is just not going to get you there, and at high pressures it becomes dangerous in at least two ways.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: solenoid vs pnumatic actuator
There is no shortage of hydrauliclly actuated shaker tables that appear to operate just fine from about 5 Hz to well over 100 Hz. What compressibility effects are you refering to?
RE: solenoid vs pnumatic actuator
In a shaker table given pseudo- random excitation, you'd never notice such a thing. I wonder if you'd detect it in a slow sweep.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: solenoid vs pnumatic actuator
Interesting. But it seems tunable by either selecting a fluid with a different density, or changing the volume of the actuator.
RE: solenoid vs pnumatic actuator
Barry1961