Creative uses for servos?

[dddriveman]

If anybody has any creative uses or has any good ideas on how to use servos on a robot please share them here.

[Cory]

shift the drill gearboxes with them

Cory

[dddriveman]

I"m not sure how you would do that! :confused:

[sanddrag]

Well, you would need to fabricate a servo mount and a custom shifting linkage.

Another good use for servos is to mount sensors on to scan back and forth for HP stacks or other reflective tape.

[jon]

Originally posted by dddriveman
I"m not sure how you would do that! :confused:

Attach them to the shaft collar on the drill motors, so that when the servos are rotated, the collar shifts positions.

Though, this is not longer very original, anymore.

[dddriveman]

thanx for the idea sanddrag

[sanddrag]

Check the white papers for the servo shifting. There are a couple designs in there.

[dddriveman]

I'll check the white pages for Servo shifting. Thanks again sanddrag

[Mike Schroeder]

we used servos to engage.. disengage our brakes

[Sully]

Clever use of a servo motor

In Houston I found one team using a servo as a vacuum release mechanism for their suction cup. The servo was used to close or pinch off a piece of tubing thereby keeping their suction cup fully engaged. If necessary the servo would open the tube - releasing the vacuum. A clever and simple release mechanism.

Often servos are used as release mechanisms at the beginning of matches so that a robot can expand outside its constrained envelope.

[dddriveman]

I found a way to flip down the motor the powers the flashing lights on our robot. THE motor is spring loading so you can make the light spin or not spin . Useless but, fun:)

[Ian W.]

just don't do that in an official competition ;)

[dddriveman]

I know. But when you are not in competition it is fun to do.:]

[JLambert]

Originally posted by dddriveman
I found a way to flip down the motor the powers the flashing lights on our robot. THE motor is spring loading so you can make the light spin or not spin . Useless but, fun:)

Also, if you wedge a small disc on between the pinion (like, say, a small piece of a glue stick), the light will turn at a little over 2x the normal speed. Again, not legal, but fun to mess with when you have nothing else to do.

Not that our team would ever be sitting around, or ever be doing ANYTHING like that...

[Rickertsen2]

you can also short the resistor in the light to make it go faster. Again not legal but fun anyway. Its also interesting to hook it up to a speed controller. lol

Anyway i'm not sure if this counts but i made this (http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=5267) from the FIRST provided servos.

[Al Skierkiewicz]

We have several...
Over the years we have used servos to activate a microswitch on the robot for a program branch jump, to drop an anchor to hold us on a ramp, release a magic tongue and this year we used servos to brake the drive mechanism for our wings (that is what holds them up at the end of the match!) Sometimes you don't need a lot of power, just the will to move.

[Sully]

At one of the regionals in 2003 I noticed one team (I don't recall the no.) that was using a servos to interface with the Victor 884. The servo was used to activate a switch that was wired to the brake / coaster jumper on the Victor. This enabled the team to actively change the drive system from a dynamic brake system to a coast system. I am not sure what their reasoning was but it was a very clever way to overcome a problem. Simply put the servos can be used to activate switches of all types to suit the needs of the robots.

[James114]

In 2001 my team used a servo to wave a small American flag back in forth

[Veselin Kolev]

My team has never used the servos, but we will next year...

Anyway, you can use it to shift gears as many say, or do useless stuff, but I saw one team that put two servos on their lamp and raised or lowered it every time they had to go under the bar. The only problem was it took too long to move one time, and they broke their lamp. You can buy servos withing a huge range of power, from about 5 oz/in of torque to about 1000 oz/in.

[sanddrag]

Originally posted by Veselin Kolev
You can buy servos withing a huge range of power, from about 5 oz/in of torque to about 1000 oz/in. You can buy wheelchair motors with a huge range of power that doesn't mean you can use them. Servos not provided in the kit are illegal since they have a motor inside. Sorry. :(

[WakeZero]

Rookie power ;)

This is really a neat and compact design. We used the plastic drill motor mounts and mounted them to our steel frame. We then added a little L shape piece of aluminum on all four sides to serve two purposes:

1) Mount four small muffin fans to cool our motors down

and

2) Support the servo mounts

The airflow was superb, we didn't overheat once after they were installed, and being able to switch from high to low gear allowed us to have a quick/precise autonomous mode followed by a powerful low gear. It all worked out nicely =)

I would also like to point out that it was one of our wonderful students who designed that little gear-shift mechanism. Hope the picture helps :)

[WakeZero]

Oh, one more use I forgot about! Some of you may remember Gila III from 2000 (Team 64). We used a servo to release the gate that let out all of the balls in our basket into the trough.

The RED arrow is where the servo is mounted (I know its not very visible) and the BLUE arrow is what it was actually moving. There is another BLUE arrow thing on the opposite side, and it works almost exactly as the gear shifting mechanism in my post above. BTW, that is Mike Rush in the picture... my personal hero, and the man responsible for me being so involved with FIRST :D

[Veselin Kolev]

Originally posted by WakeZero
Rookie power ;)

The airflow was superb, we didn't overheat once after they were installed, and being able to switch from high to low gear allowed us to have a quick/precise autonomous mode followed by a powerful low gear. It all worked out nicely =)



Quite impressive transmission. Even more so for a rookie team. But on the subject of motor cooling, we never did it. You think it would help, but not really. Blowing air on the motor doesn't do much. The motor doen't have enough surface area. Even if you make a custom heat sink and use silicon thermal gel, you still won't do much. You'll cool the outside of the motor, so you'll cool the magnets. You don't really cool the wire windings, and that's what you want to cool. Even if you manage to cool the wires, you won't lower the temperature too much, so you won't really improve the conductance enough to ever notice. Cooling works, but not with fans. For example, team 254 injected liquid oxygen (or something like that, i forgot exactly) from a can into their motors right before competing. This cooled the wires to about 250 kelvin (-23 C) or so they say, and I think that is close. This gives their robot a hugh advantage during autonomous mode, since they can really shoot up the ramp. But after a minute the motors heat up again.

[sanddrag]

We used a heat sink and heat sink grease on each of our drill motors. This lowered the temp on the surface of the can nearly by half. They worked really great and we never had any overheating problems. Here's where you can buy them and a pic. (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXTG83&P=7) You should also be able to find them at any quality hobby reatailer such as Hobby Town USA.

As for the colling spray, it is canned air that you buy from Office Depot or Staples or Fry's. When the can is turned upside down, the compressed gas comes out as an ice cold liquid spray. This works very well for cooling the CAN of the motor between matches. It is also very useful for cooling breakers before matches to ensure that they don't trip as much.

The reason I'm telling you all this is from something Andy Baker said that I agree with: There are so many advantages to giving these designs out. We as a team
feel that giving these designs to other teams “raises the bar” of FIRST robot designs and all of
FIRST benefits.

Last, I would strongly advice against cooling any part of the motor except for the can. You can accidentally freeze the thin insulation off the armature windings or even more easily crack a brush. If you absolutely must spray the inside or endbell at all, do it on a room temperature motor.

PS. Sometime hopefully before the end of the summer I will have a little white paper made of "Tips, Tricks, and Field Side Fixes" that will cover the things above and much more.

[Veselin Kolev]

Originally posted by sanddrag
We used a heat sink and heat sink grease on each of our drill motors. This lowered the temp on the surface of the can nearly by half. They worked really great and we never had

Yes, note the word "surface". It's inside that you want to cool. Anyway, we never use cooling and we never have problems. I frequently touch the motors to check their temperature. I do it right before we lift it out of the field, and they're never very hot.

[Jeff Waegelin]

Originally posted by Veselin Kolev
Yes, note the word "surface". It's inside that you want to cool. Anyway, we never use cooling and we never have problems. I frequently touch the motors to check their temperature. I do it right before we lift it out of the field, and they're never very hot.

True, but the surface temperature is usually an indicator of the internal temperature. If it's hot, the inside surely is, and if it's not, the inside is probably cool (relatively speaking).

[sanddrag]

My post above got posted without being complete :p, it's all edited and finished up now. :)

[WakeZero]

Originally posted by Veselin Kolev
Quite impressive transmission. Even more so for a rookie team. But on the subject of motor cooling, we never did it. You think it would help, but not really. Blowing air on the motor doesn't do much. The motor doen't have enough surface area. Even if you make a custom heat sink and use silicon thermal gel, you still won't do much. You'll cool the outside of the motor, so you'll cool the magnets. You don't really cool the wire windings, and that's what you want to cool.

First, thanks for the compliment =)

As for the cooling fans, I forgot to mention that they are all pointing in the same direction. So you have:

Fan --> Motor --> Fan

The arrows represent the airflow, and the left fan brought in the cool air while the right fan sucked out the hot air. I can see your point about just blowing cool air onto the casing, but we actually took the hot air out ;)

It may not have made a huge difference, but we did notice that after we installed them we never overheated like we did a couple times before :yikes:

[Veselin Kolev]

Originally posted by WakeZero


It may not have made a huge difference, but we did notice that after we installed them we never overheated like we did a couple times before :yikes:



Wow, our motors never came close to overheating. Maybe it's because you guys used the drills and we used drills+chippies. Looks like they help each other out enough so that they don't overheat. Cool!

[sanddrag]

Originally posted by Veselin Kolev
Wow, our motors never came close to overheating. Maybe it's because you guys used the drills and we used drills+chippies. Looks like they help each other out enough so that they don't overheat. Cool! And let's not forget about gearing and wheel size. Those both play an important part in current draw and heating.

[Veselin Kolev]

Originally posted by sanddrag
And let's not forget about gearing and wheel size. Those both play an important part in current draw and heating.

Yes, except that most teams gear the motors to be running at full power while pushing other robots.

Or maybe our motors didn't heat up because we never liked to get into pushing fights with our top-heavy stacker. We're afraid. :)

[sanddrag]

Originally posted by Veselin Kolev
Yes, except that most teams gear the motors to be running at full power while pushing other robots. I'm not sure I understand what you are trying to say. See, gearing is a relationship between on torque and speed. As one goes up, the other goes down, and the power stays constant. Your statement is very unclear. Motors can be geared low (a high number to one) or high (a lower number to one.) Low gearing will give you lot's of torque resulting in a large force applied by the wheels. High gearing will give you more rotations per time resulting in a higher linear speed of the vehicle.

[Not2B]

Some of that canned "air" is really a refridgerent known as R152a (difluorethane). When it is released it expands, and that is what does the cooling. Works just like your AC at home, except it's a different refridgerant.

By the way, even though it is not classified as "flamable", it burns like crazy when you light it. I've done tests... my "lab" wall has burn marks to prove it.

[Veselin Kolev]

Okay, let me rephrase my idea.
My original comment was that our team's motors didn't heat up because we used the drills + chippies. And that they help each other out to not overheat.

Most robots draw the most current while pushing other robots, and more current results in more heat. They draw even more current because their wheels stop spinning sometimes if they only use the drills. We used 4 motors, and if you run the robot into another, (or into a wall) the wheels will burn away freely at the ground, preventing the motors from stalling out and drawing crazy current. Meaning that if you used more motors, they provide enough power together so they can never stall out.

Gearing this kind of system for speeds upward of 15 ft/sec could result in stall since they aren't geared for power at such low speeds. But few teams actually did use similar gearing.

[Dan Richardson]

If you do it just right you can attach a q-tip to the end and use them to clean your ears..

wow.. he said creative