Expected Speed of a Linear actuator.

[aero_storm]

No Re-introductions here - I posted a short one in the General section;

So, what kind of speed would the actuator of a typical lifter operate ate? And does it change anything that the Robot will be based more on Speed and power, and that the actuator would be rather secondary?

I currently have my eye on this:

http://www.firgelliauto.com/COMPACT%20A ... e%2005.pdf

However, as you will see, there are four different models to choose from. Any help as to which one, or even if the four of them are suitable for a Robot, would be highly appreciated.

Thanks all,

Alex R

P.S Hi again.

[Metal Demons]

It varies - the information's all available on the datasheet. Which actuator will or will not be suitable for a lifter I can't tell you, as that depends entirely on the actual design of your mechanism as to what input force is required to apply the required force to lift their robot. Work out what kind of shape you're aiming at, then what the mechanism will be to apply the required motion (whether a 4 bar mechanism or a simple hinged lifter, or whatever else) - then how much force you need to apply where in order to lift them.

Overvolting your lifter will increase speed significantly though, which you can get away with for low duty cycles.

[aero_storm]

It is supposed to be a simple hinged lifter. The plan was to over-volt it, but I was warned against it on my last stint in these forums.

To the original question; Can anyone give me the speeds of any linear actuator they use, or any that they know is in use, so I can get an idea for the typical speed. Or, I suppose to put the direct question at you, is 2.8 cm/s too slow, because it seems it to me.

Alex R.

[Metal Demons]

I'd want to shoot for something significantly more than that - I would aim to have the system fully extend in ~1 sec in order to make sure you can actually get hold of them before they get off the lifter.

[RogueTwoRobots]

For an actuator, 2.8cm/s is a pretty decent speed. I've got one that moves at 3.5mm/s, so by comparison, I'd be happy with 2.8cm/s. If the actuator is quite highly rated force-wise, you could configure your system with a ratio in such a way that the lifter moves a large degree for a relatively small movement of the actuator.

If you want something much faster but still want a high level of force, you're gonna be looking at lots of £££ on an extremely high-quality actuator, or custom-built system. The time Nick mentions of ~1 sec isn't really viable with off-the-shelf actuators. It's certainly achievable for a lifter; Storm 2's lifting arm was devilishly fast for an electric system, but no actuator in sight there - there you're talking about a Magmotor running through a custom-made gearbox setup.

Bear in mind also that your lifter doesn't have to be fast to be effective. If your lifting arm is under a robot and moves, say, about 10-20% of its total travelling distance, the chances are your opponent's wheels will be off the ground and you'll have broken their traction. They're now at your mercy (until you lower your lifter or they fall off) to do with them as you please
So if your lifter takes 10 seconds to go from down to fully up, that doesn't mean it'll take you 10 seconds to lift your opponent up to immobilise them. You could probably manage that in 1-2 seconds

[Metal Demons]

If you want something much faster but still want a high level of force, you're gonna be looking at lots of £££ on an extremely high-quality actuator, or custom-built system. The time Nick mentions of ~1 sec isn't really viable with off-the-shelf actuators. It's certainly achievable for a lifter; Storm 2's lifting arm was devilishly fast for an electric system, but no actuator in sight there - there you're talking about a Magmotor running through a custom-made gearbox setup.

Cheapest way to do it right is to use the mechanism from an existing actuator (Acme thread or ideally ball-screw) driven off a more powerful motor: the dinky little motors powering the actuators you stated will only pull ~35w at peak, whereas you could, with minor modifications, use something far more powerful like a DeWalt hammerdrill motor - that'll give you plenty of grunt to lift robots quickly. Feel free to buy an off the shelf high speed actuator for the low gear ratio - but you'll probably need to jam the clutch mechanism on it if there is one so as to be able to take advantage of the increased torque given by your new motor.

Off the shelf actuators that get picked up from Ebay or other surplus sources are primarily limited by the fact they're usually designed to open window blinds, move beds, aim Sky dishes, and such like - therefore they don't really need to move fast and can get away with an itty-bitty motor (run at a very high gear reduction). That's something which can be sorted out easily and without going to the extent of a custom mechanism.

[aero_storm]

Hi Nick,

I am afraid, my friend, that I am a 14 year old, with little or no technical knowledge. I've read up on Robots, I've done as much research as I can, yet I am afraid the only words of the last post that I understood was Drill and and.

The way I see it is thus:

You want me to buy an actuator, take a hammer drill and some how use the hammer drill motor to power the actuator? And, even if this is what you suggest I do, please could you give me some tips on how to achieve it?

Thanks,

Alex R

[daliad100]

A word of advice.

Hammer Drills are a pain to pull apart (might just be the one I took apart) because of the extra bit that does the hammer action.

I would suggest using a normal drill as it can't slip into hammer mode and start to reciprocate whilst using it in your robot.

[dragonmaster_1]

Hi you can get very powerfull linear actuators but they are not cheap got one on a feather crusher

this is now going into another bot as a lifter mech 10000 nu of force.

[daliad100]

You want me to buy an actuator, take a hammer drill and some how use the hammer drill motor to power the actuator? And, even if this is what you suggest I do, please could you give me some tips on how to achieve it?

To answer your question, what was meant by using a hammer drill was to remove the motor (and gearbox) and coupling this to a threaded rod. A nut on this threaded rod will travel up and down it when the motor is turned on.

If you look at a nut and bolt being tightened or the insides of a glue stick (a twist one) then you should see what I mean properly. However, for it to work you will need to make sure that only the nut or rod is turning.

http://robowars.org/teams/rotwang/blade/

Take a look at some of these pictures. They contain the same mechanism as above.

Finally, wikipedia is your friend the animation should help if you still don't get it

http://en.wikipedia.org/wiki/Linear_actuator