high speed actuators

hi
there are two companys selling cheap high speed actuators
they could be great for sfgt ,r&r,joy ride.
http://www.firgeliauto.com
www. progressiveautomations.com
regards Ad

Re: high seed actuators

http://www.firgelliauto.com/

Re: high seed actuators

Anyone that can compare the following to the SCN5?

http://www.firgelliauto.com/product_inf ... cts_id=230

Re: high seed actuators

There isn't much of a comparison.

The SCN5 has a stepper motor, controller, optical feedback and a high duty cycle.

This actuator has a DC motor, no feedback mechanism and only 20% duty cycle! Is is also nearly half the speed of an SCN5.

I would have to disagree with the statement that these are suitable for a simulator.

Re: high seed actuators

There isn't much of a comparison. - Seems biased and a good way to turn people off right away from your response, IMOP

9 Per sec speed (230mm/sec)
isnt the scn5 250mm/sec?

Were looking for options to be more affordable, I totally get checking out the figs.

Can you explain the half the speed?

Feedback I can get wtih POT

Re: high seed actuators

Whats the duty cycle of the scn5? Please explain what this means too if you can, woudl be helpful when looking for alternatives.

Re: high seed actuators

Duty cycle means how much you can use the actuators.
100% means you can run them continuously, without stopping.
20% means you have to let the actuators rest 8minutes after every 2 minutes of use.

After you add the electronics, feedback mechanism and your build time, these actuators will be in the same price rage as SCN5 actuators.

There is no bias here, I have to agree with Bernard. They are pretty much useless for anything that could be called a simulator. Maybe for a garage door they work great!

p.s. SCN5's are 400mm/s compared to 230mm/s

Re: high seed actuators

I got you, that duty cycle certainly does kill it unless you want to do Drag Race all the time! Good to know, thanks for the help. Gonna stick wtih wiper motors for the first go round

Re: high seed actuators

Hi
2x jrk12v12=198,00
2x high speed actuator=238,00
total =436,00
1 scn5 100 mm=425,00/1 scn5 150mm=505,00
there is lots of room left fore 2 poti,s
steppermotors torque drops fast, pmdc dont
this means ,they are even as strong @ there beginning and 4 times stronger @ there top speed , because there dropping torque scn5 dont get 230mm/sec
@ full load they become faster above 75mm/sec,they are stronger!
scn5 duty cycle unknow!

Re: high seed actuators

I've seen the SCN5's run for 1 month of non-stop use with a simulated 250lb driver load.

I've also seen them run for full 8-hour stints at trade shows with very small breaks for driver changes. My personal set is about 3 years old.

I think it's safe to say that the duty cycle is not an issue with the SCN5.

You're also looking at 230 mm/sec vs 400mm/sec and discounting the ability of the stepper to make the important rapid direction changes that result in a proper road surface feel.

Re: high seed actuators

adgun you have valid points, but the numbers really don't mean anything until it is put to the test.

The actuator might be strong enough for the application, but that is only one factor in the equation. You should consider:

-Durability. How long will these last at ~80% duty cycle for 3-4 hours continous. SCN5's are proven to be durable.

-Positioning accuracy. How are you going to mount the potentiometers? The jrk controllers have 10bit analog resolution (1024 counts for the full pot travel) , which is affected by noise.
The SCN5's have encoders, unaffected by noise and about 20x more precise (~20000 counts for 150mm of travel).


If anyone feels that these actuators are worth a try, please go ahead and test them out. If they prove to be worth their money they will be a welcomed option!

Re: high seed actuators

hi
i made a mistake
@ full load (10kg)scn5 stand stil and these actuators are making more than 100mm/sec

@ bernard
about motor dynamics i disagree
driver/controller is playing a roll allso,but accelelating, braking,reversing is only a matter of force
steppermotors have a stall torque when they are driving ther torque is falling
pmdc motors capable to ask the forces they need ,with peak currents
they are more dynamic than steppers
when you look @ an scn5 he is far more dynamic than a sfgt with wipermotors
BUT DONT FORGET WIPERMOTORS ARE REDUCED 50 TIMES, THIS MEANS THE MOTOR WORKS 50 TIMES FASTER THAN WAT YOU SEE(50 TIMES MORE DYNAMIC THAN YOU SEE ON LEVER ARM)THE REDUCTION MAKES THEM SLOW.

@FRAKK
thanks fore youre honnest reply
on top off the actuator there are screw hols ,and this actuator got a square pushrod
so a simple rubber wheel on the pot and a holder could do the yob
but there are better solutions
about the scn5 encoders i heve never seen them,and dont know of the are working in oper ore closed loop

Re: high seed actuators

I have spoken to Firgelli several times by phone. I own these actuators. Firgelli does not recommend them for simulation use due to the duty cycle and heat concerns. One engineer suggested that there may be issues with ball-screw temperature also. He said that they are intended for momentary use, such as opening an observatory door, etc..

As Frakk suggested, you can give them a try and let us know how long they last.

With regard to the rapid direction changes, I understand your theory, but I have driven the difference with 3 different controller options. I am yet to see a DC motor solution that matches the SCN5 performance for rapid direction change and road surface detail. There is a reason why the majority of commercial sims are using the SCN5 actuators

What would be interesting is to understand why there is such a noticable performance difference. One theory suggested by Frakk is related top the mass and diameter of the motors themselves, although I suspect there is more to it than just that.

Re: high seed actuators

Hi
@bernard
Frakk is right there is a big difference between a high dynamic motor(long and thin)
and a pancake motor (short and thick) it,s a story about massinteria
it cost more energy to stop a rotating 1kg short thick drum,than a 1kg long thin drum
working vertical with non self locking actuators ,you need a continius working area
for locking you,re actuator (this have every thing to do with heat)
There peak current makes them more dynamic than steppers
look @ www.servo2go.com
About ballscrews, a ballscrew isnt a screw its a ballbearing converting rotary movement to linear movement for overheating you must overload them
regards Ad

Re: high seed actuators

Before we start comparing the two actuators, let's go back to the basics and clear up this whole open/closed loop mistery first.. What is the difference between open and closed loop?

This is not true. You can test how dynamic a DC motor is by driving it full power from a battery, and keep reversing it at full speeds. This will show you the absolute fastest deceleration of that particular motor. As you would observe, it will not happen very fast because of the fast speed and mass of the armature in the DC motor.
As you said, the driver/controller is playing a role, in fact the most significant role. The PID loop has significant impact on motion response and positioning.

Steppers in theory accelerate/decelerate faster because they have far less armature mass, and more torque at low RPM's (comparing them without gearing). The trade-off is the torque at higher speeds.

Have you actually measured the current draw of a DC motor vs Stepper motor (in a time scale where you actually see these peaks and how long they last)?
I don't see how peak currents would effect the overall performance..

Re: high seed actuators

As I mentioned earlier, there is nothing to compare

The JRK was suggested as a controller because the Firgelli actuator does not have one. Now if adgun would like to suggest a feedback mechanism since this actuator does not hasve that either, then I will make the comparison since I already have these actuators and several controller options. However, what I keep trying convey here is that I already know the end result. The motor is not the only cause for the 20% duty cycle.

If for some reason, my results aren't satisfactory vs a theory, then perhaps you would consider the results from egoexpress. In the early days, he had some different 20% duty cycle actuators from Firgelli. I believe that he stopped using them in favor of the SCN. Maybe he can explain his issues to your satisfaction.

You should consider that noobs may see this post and believe that this is a good use of their money and will have a good result, but this is not the case!

Re: high seed actuators

Hi
i admire you,re work greatly bernard
I,am not able to tell if there 20% duty cicle will do the yob
i started this tread with ,it could be a cheap solution
i,am not waiting for egoexpres reply
you are the only commercial guy @this not commercial comunity
who is using this community fore cheap recearch often
speaking about existing scn dof 6/wronly advicing someone who wants to convurt his RenR/grand canaria inventid the thirt axis,because it isnt a seatmover you can legaly screem
its your design and patend it
DONT TURN THE WORLD AROUND

That's hilarious.

What does my being commercial have to do with you being wrong about the suitability of these actuators for simulation use? It seems you're bothered by being wrong and then go on a personal attack.

I derive almost nothing here, but I contribute alot. BTW, the rear traction loss axis was done here first and documented as such. That being said, I shared a drawing of it in these forums and explained how it worked for the DIY crowd.

The only world that is turned around is yours.

Call Firgelli yourself to ask about the duty cycle and simulation use. You say that they would be good for sfgt, RNR, etc.. but THEY ARE NOT SUITABLE! You are attempting to convince people that they are and you have not even tried them!

adgun: You are presented with technical information and pure facts about the actuators.
COMING FROM THE MANUFACTURER: THESE ACTUATORS ARE NOT SUITABLE FOR SIMULATOR USE.

If you want to prove that they suitable, please do so. I would be very happy to see these actuators in a simulator!
Unless you have proven it, please don't advise other's to waste their hard earned money on them. After all we are looking for actuators that are cheaper, but more importantly actuators that work...

ps. How many commercial companies do you see giving personal advice to individuals on their personal time?
For the matter of fact, commercial companies lurk these forums, taking whatever they can, without making a single post and return nothing to the community.

It is in our best interest to keep these few companies around, that actually care about the community..

hi,
frakk: i agree with you.bernard spend many privat time for x-sim.
for a simulator you mast have 100% Duty Cicle.
but we have talk over the Firgllie years befor.
adgun:Firgelli say dont use it on a simulator.than you dont have garanty.
i mean we can beend the trade befor any guys lose money by order Firgllie actuartors