Intake actuation

so we want to actuate our intake over the bumper. and initially we thought use pneumatics, but it seems like a waste of space and weight as that is currently the only thing we have in mind for them at the moment. so, wanted to know about others experience with linear servo actuators. have you used them? are they any good? whats your overall experience with them?
would it possibly be beneficial for us to use them instead of pneumatics?

Our 2020 robot used pneumatics just for the intake solely (2 cylinders total on the robot).

It was much easier then we thought, and went smoothly. I think it would be a good idea to start using pneumatics with only a few cylinders.

Never used linear servo actuators, looked into them in 2019, but decided against them. Cost wise they seem more expensive though.

Also can’t tell you about weight, it does add up, but it’s not much heavier if you are going to use linear actuators anyways. The pump is the main add-on weight, the tanks don’t weigh much.

right, we know pneumatics would be good, but the weight of the pump seems silly for just intake actuation.
so thats why im looking at these too.

If you wanted to get creative, you could use a motor to rotate the intake out. There’s a few possible ways to do that; the primary issue is reducing the motor’s speed enough to not slam the intake in/out.

For example, a light winch set up as a pull/feed could do the job with a loop of line. (Or chain/sprocket the intake.)

Linear motion is not the only way to move intakes…

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If we went that route, we would probably try to use a regular motor somehow. We used the Andymark linear servo, and thry are amazing, but fragile. I would be wary of the kind of impact an intake will take.

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Look at the power it takes to move the intake up and down. Pneumatics are neat in that you can store the energy from a small motor (part of the compressor) running over a long time, in a tank, as compressed air. Then you can use a bunch of that energy very quickly, to move a load, using a pneumatic cylinder.

You can also put the heavy stuff down low in the robot, and have the light cylinders mounted in places where you don’t want a heavy motor, and the complexity of a gearbox and chain or belt or whatever.

Cylinders are also very easy to attach, a bolt and a couple nuts is all you need.

One downside is that you have to consider how long it takes to build pressure back up. And the work you can get out of it in a match is limited.

Small motors like window motors don’t have much power, and take really careful mechanism design to make them work satisfactorily.

A larger motor and appropriate gear/chain/belt speed reduction is a good way to go, but it takes good design to make it work well.

One thing we’ve done a few times is have an intake just drop down at the beginning of the match, and stay there. No actuation required. There are several downsides to this approach, though.

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we have also gone the drop down at the start of the match route. some years its ok, this year i dont think it will be.
and we lack in the “good design” category. im the one design mentor and not very experienced. and my students aren’t either. both are in their first build season. so if the chain and sprocket drop down takes good design that may not be best for us lol.

We have also used the linear servos and found them to be very fragile.

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Great point that linear motion is not the only way to move things. Almost all of our intakes actually pivot at a point and use rotational motion instead. We usually use pneumatic cylinders for this which is converting linear motion into rotational motion

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well thats kinda our intention with it, the whole 4 bar linkage intake idea, turning linear actuation to make rotational motion

It is possible to use rotary motion to drive a 4-bar linkage–done it before, can go digging for details if asked.

Actually… leadscrew it. Leadscrew on a motor, leadscrew nut on the intake. You’ll need to figure out how to pivot at least one of those mounts, though…

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Also look into having some help lifting the intake up…gas springs, lengths of surgical tubing, or other things like that can greatly reduce the load on a pair of pneumatic cylinders. We’re planning to use this method to make ours, which will hopefully be able to score in the low goal, and pick up off the floor, repeatedly through a match. Depending on how well we can get the prototype to work, of course!

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Have not applied the linear servos, but I have been hands-on enough to know I wouldn’t want them leaving my frame perimeter.

I’d say to take the L and run the pneumatics with one small tank and the teeny-tiny AutomationDirect hardware. You can certainly get slick with code if you’re worried about compressor power drain.

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i think this is where im leaning at this point. pneumatics add weight, but theyre easy and reliable.
thanks everyone!

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I was thinking about how I’d do this if I didn’t have the resources to do major building and I came up with the answer of “rod end”. If I did it right I’d only need one.

On the intake: a bolt sticks out, goes through the hole of a rod end. The rod end is attached to 1x hole on a leadscrew nut. (Advanced build: Make an adapter plate for the leadscrew nut to the rod end.) Leadscrew goes back to the motor/gearbox and coupler to the leadscrew; this assembly is mounted on a pivot.

Catch is, that’s pretty much a linear actuator, just custom-built.

Pneumatics are pretty much your best option, but I’d actually suggest using spring-return cylinders in this particular case. They don’t use as much air as the usual setup, so you can use fewer tanks (not that you’d need all that many anyways).

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Do you ever plan to retract your intake after the match starts? Sometimes you can forego the actuators and just let gravity (and a short burst of drivetrain acceleration) do the work. We did this on our 2020/2021 robot.

we already asked…

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I somehow missed that on my first read. Sorry to restate the obvious.

Carry on!

Any thoughts on why it wont work this year? Are you thinking it get in the way during the climb?

I don’t know what team 342 is thinking…but in our case, we are using a robot design that requires the intake to lift up pretty high, to deliver Cargo to the low goal (no conveyor, shooter, etc).