View Full Version : Servos - How much can they lift?
John JediMaster
17-01-2004, 14:39
Okay my team is considering using some servos for our robot. But we need to know how much at best they could lift. Note. I'm in charge of strategy for our team so if I say something that is technical nonsense, please correct me.
Thank you.
Okay my team is considering using some servos for our robot. But we need to know how much at best they could lift. Note. I'm in charge of strategy for our team so if I say something that is technical nonsense, please correct me.
Thank you.
The servo provides 42 oz/in peak torque and rotates with a speed of .16sec/60 deg.
Let me know if you need help figuring out what those two specs mean.
Greg McCoy
17-01-2004, 17:29
Probably about as much as you can lift with your pinky finger ;)
Probably about as much as you can lift with your pinky finger ;)
Servos are much more stout than that ...
Jay Lundy
17-01-2004, 23:13
Servos are much more stout than that ... Going by GregT's numbers I doubt it.
If you placed something 2 inches from the base of your pinky, and your pinky had the same torque as the servo, then it could lift 21 oz (about 1.3 lbs).
If anything I bet your pinky is stronger than that.
Of course there are different kinds of servos with different torques.
Going by GregT's numbers I doubt it.
If you placed something 2 inches from the base of your pinky, and your pinky had the same torque as the servo, then it could lift 21 oz (about 1.3 lbs).
If anything I bet your pinky is stronger than that.
Of course there are different kinds of servos with different torques.
The numbers I posted refer to the Kit of Parts servo. And yes, its less then your pinky finger can lift.
Greg
OneAngryDaisy
18-01-2004, 01:50
Whatever you do, I would not reccomend using servos for something that requires uh... strength or consitency.. In 2001 we used a servo, or should I say 'attempted' to use a servo to latch on one of the goals. lets put it this way, we literally had to replace the servo after every match, and this was a 4v0 game with no robot interaction with eachother.
Moral: Servos inhale audibly
Joe Ross
18-01-2004, 12:00
The servo provides 42 oz/in peak torque and rotates with a speed of .16sec/60 deg.
In past rules books, FIRST has said that servo manufacturers typically inflaste their specs by 2x. So, don't count on more then 20 in/oz of torque.
The servo is not designed for high torque applications. Start using it for such and you'll strip the gears. I can't think of many instances its appropriate to use the servo to interact with the "outside world" (ie grabbing a goal or ball).
I just quoted quoted the FIRST KOP manual on those servo stats. If this number hasn't been correct in past years and you are depending on more then 20 or so oz/in you should probably measure the torque yourself.
Greg
In past rules books, FIRST has said that servo manufacturers typically inflaste their specs by 2x. So, don't count on more then 20 in/oz of torque.
I have never heard that before. Could you be thinking of r/c speed controllers? Does anyone remeber what servo they are. I believe last year the were hitech servos.
Whatever you do, I would not reccomend using servos for something that requires uh... strength or consitency.. In 2001 we used a servo, or should I say 'attempted' to use a servo to latch on one of the goals. lets put it this way, we literally had to replace the servo after every match, and this was a 4v0 game with no robot interaction with eachother.
We used servos to control our forward and rear goal hook in this game ... and they both worked flawlessly every time.
I'd leave a servo for a small task, just to be safe. For the past two years, and perhaps this year, servos have been the essential component to 25's <sarcasm>elaborate</sarcasm> braking system.
I've never seen a servo in recent years do anything besides simple tasks (such as switching transmissions in the drill motors). They simply do not have enough torque.
Everyone is telling you servos will not work for lifting, but no one is telling you what to do instead.
Use pnuematic cylinders! They are designed for lifting, you can get whatever size you need, and (new for this year) you can use as many as you want.
Skip the servos and go with pnuematics.
correction, you can't use as many as you want, you're limited to 4 if memory serves.
Greg Needel
18-01-2004, 18:22
correction, you can't use as many as you want, you're limited to 4 if memory serves.
nope that was in previous years...this year you get as many as you want
Joe Ross
19-01-2004, 09:20
nope that was in previous years...this year you get as many as you want
In the past, a servo has been considered a motor. I don't see anywhere in the rules where this was specifically changed. In that case, I would ask FIRST, however, I would expect that they would say that you can't use more servos based on the fact that they said you can't use the EDU bot "motors" which are basically servos.
In the past, a servo has been considered a motor. I don't see anywhere in the rules where this was specifically changed. In that case, I would ask FIRST, however, I would expect that they would say that you can't use more servos based on the fact that they said you can't use the EDU bot "motors" which are basically servos.
I think that comment was in reference to the pneumatic cylinders.
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Does anyone know if we are allowed to purchase additional servo motors and use them at the same time as those we were supplied with by the kit?
Katie Reynolds
20-01-2004, 15:38
Does anyone know if we are allowed to purchase additional servo motors and use them at the same time as those we were supplied with by the kit? If you're looking at buying a different brand/kind of servo than those provided in the kit, the answer is no (see the Part Use Flowchart).
<R70> Specific items NOT allowed include: ...electric motors different from or in addition to those in the kit.
Like Joe Ross said before, FIRST considers servos to be motors. I would say you can't use more than what you're provided with.
just to clarify, when I said you can use as many as you want I was talking about pneumatic cylinders. as for motors, you are limited to those in the kit, including servos (as everyone has already said).
Joe Ross
21-01-2004, 16:25
In the past, a servo has been considered a motor. I don't see anywhere in the rules where this was specifically changed. In that case, I would ask FIRST, however, I would expect that they would say that you can't use more servos based on the fact that they said you can't use the EDU bot "motors" which are basically servos.
Well, FIRST changed their defintion this year (which is why I suggested asking FIRST).
Q: Are servos treated as electronics (in which case we can have an unlimited number of them) or are they treated as motors (in which case we are limited to 2)?
A: Electronics.
ark_1230
21-01-2004, 20:27
correction, you can't use as many as you want, you're limited to 4 if memory serves.
In past years yes, this year no.
Refer to rule R54 third bullet in the robot section of the manual:
"There is no limit to the number of solenoid valves, air cylinders, and connecting fittings you may use on your robot. They must, however, be “off the shelf” pneumatic devices rated by their manufacturers for pressure of at least 125psi. Besides the “free” pneumatic components listed on the Pneumatic Components Order form, you may use additional air cylinders or rotary actuators, however, they must be identical to those listed on the Pneumatic Components Order form, and obtained from a Bimba or Parker Hannifan distributor."
Just wanted to get thing straight :D
Joe Ross
31-01-2004, 19:03
Well, FIRST changed their defintion this year (which is why I suggested asking FIRST).Q: Are servos treated as electronics (in which case we can have an unlimited number of them) or are they treated as motors (in which case we are limited to 2)?
A: Electronics.
See Team Update 6, since FIRST corrected themselves again. You may only use the 2 servos in the kit.
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