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  #196   Spotlight this post!  
Unread 31-03-2011, 09:07
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Re: Minibot climb rate

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Originally Posted by WileyB-J View Post
meet richard.
What's the blue broom-hook thing at the top made of ?


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Unread 31-03-2011, 22:05
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Re: Minibot climb rate

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Originally Posted by Ether View Post
What's the blue broom-hook thing at the top made of ?

if you're referring to the clip, its actually blue pvc pipe!
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Unread 31-03-2011, 23:57
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Re: Minibot climb rate

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Originally Posted by WileyB-J View Post
if you're referring to the clip, its actually blue pvc pipe!
are you using the stock 52:1 gearbox? and are those 4" wheels ?


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Unread 01-04-2011, 01:12
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Re: Minibot climb rate

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Originally Posted by Ether View Post
are you using the stock 52:1 gearbox? and are those 4" wheels ?
Based on a quick comparison in proportions to the opening in their deployment system, my guess is they are 4.6 inch. It looks like they are made of PVC and wrapped with surgical tubing.
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  #200   Spotlight this post!  
Unread 02-04-2011, 19:00
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Re: Minibot climb rate

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Originally Posted by Ether View Post
are you using the stock 52:1 gearbox? and are those 4" wheels ?

Quote:
Originally Posted by billbo911 View Post
Based on a quick comparison in proportions to the opening in their deployment system, my guess is they are 4.6 inch. It looks like they are made of PVC and wrapped with surgical tubing.
Stock gearboxes, I modded some gearboxes to 10:1 but I didn't invest much thought into them after. The wheels are actually around 5.5", the picture angle is misleading. They use a 4" to 3" PVC pipe fitting for the wheel rim and its 3/8's surgical tubing. Im pleased with the way they came out, and can safely say its a unique design (unlike many little screamer bots out there).
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Unread 02-04-2011, 20:04
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Re: Minibot climb rate


pi*5.5" wheel diameter = 17.3" wheel circumference.

90"/17.3" = 5.2 wheel revs to climb pole

(5.2 revs)/(2.2 seconds)*(60 seconds/minute) = 142 rpm

At that speed, the motors are generating virtually no torque.

Somebody please check my math.



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Unread 02-04-2011, 20:37
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Re: Minibot climb rate

Quote:
Originally Posted by Ether View Post

pi*5.5" wheel diameter = 17.3" wheel circumference.

90"/17.3" = 5.2 wheel revs to climb pole

(5.2 revs)/(2.2 seconds)*(60 seconds/minute) = 142 rpm

At that speed, the motors are generating virtually no torque.

Somebody please check my math.
He noted in passing that he modded the gearboxes to 10:1. Which probably puts him on the wrong side of peak power, but makes a little more sense.
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  #203   Spotlight this post!  
Unread 02-04-2011, 22:24
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Re: Minibot climb rate

Quote:
Originally Posted by Kevin Sevcik View Post
He noted in passing that he modded the gearboxes to 10:1. Which probably puts him on the wrong side of peak power, but makes a little more sense.
OK, is that what he meant? I thought that was an aside. The way I read it, he modded some gearboxes but then decided to use stock (as-is) ones.

Your interpretation makes more sense I guess.



  #204   Spotlight this post!  
Unread 03-04-2011, 01:25
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Re: Minibot climb rate

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Originally Posted by Ether View Post
OK, is that what he meant? I thought that was an aside. The way I read it, he modded some gearboxes but then decided to use stock (as-is) ones.

Your interpretation makes more sense I guess.



I also took it to mean that the gear boxes on this bot were the original 52 to 1 ratio.

The 10.4 to 1 boxes, based on our experiences and pile of smoked motors, won't work with a 5.5" diameter wheel. We ended up with ~3" wheels with our 10.4 to 1 gear boxes.

The math doesn't add up to a 2.2 sec time with 52 to 1 boxes either, unless that bot's weight is less than the total of the battery and motors, let alone the wheels and frame, again based on our experiences.
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Unread 03-04-2011, 09:13
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Re: Minibot climb rate

We used stock (52:1) gearboxes on the minibot. The average time was 2.2-2.3 seconds from bottom of the pole to the top. It weighs around 4.5-5 pounds.

If this helps:

Last edited by WileyB-J : 03-04-2011 at 11:29.
  #206   Spotlight this post!  
Unread 12-04-2011, 13:04
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Re: Minibot climb rate

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Originally Posted by jskene View Post
We were consistently getting ~1.2 seconds. We got our minibot measured by team 1279 at the DC regional and got a higher accuracy measurement:

Our deployment arm, when it was working properly , was taking ~0.2 seconds to get the bot on the pole, so total time was ~1.27 seconds.

Below is a photo of the bot, which uses a cnc machined chassis. Our goal was to use only the minimum of materials necessary to hold the components in place. Weight came in at 2.5 lb.

Very Impressive. What type of switch are you using for the trip down?
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Unread 12-04-2011, 16:50
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Re: Minibot climb rate

Our minibot had a 3.5 second climb. Unlike a lot of robots that I saw that used magnets to hold on to the pole. Our magnets were located in our wheels and then covered in electrical tape for traction.

I have attached a picture of one of the early forms of the minibot. the magnets are underneath the thin layer of black electrical tape.

We had some problems with deployment early on, mainly due to the fact that the robot was driving down the pole, but other than that it worked reasonably well.
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  #208   Spotlight this post!  
Unread 12-04-2011, 17:01
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Re: Minibot climb rate

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Originally Posted by Garret View Post
Our magnets were located in our wheels and then covered in electrical tape for traction.

I have attached a picture of one of the early forms of the minibot. the magnets are underneath the thin layer of black electrical tape.
Is there any gap between the magnets, or are they butted right up against each other?

How did you secure them to the wheel?

Did you alternate them N/S ?


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Unread 12-04-2011, 17:05
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Re: Minibot climb rate

Late in the process we got a 1.7s minibot working with 1/4" tubes covered with surgical tubing. I never understood why everyone thinks magnets are necessary. If you center the minibot's mass left to right and balance the top to bottom mass difference by angling the minibot a bit, magnets are not necessary. Sure the minibot is not trying to climb straight up but it is also not trying to pull the magnets up with it - and its simpler.
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Unread 12-04-2011, 17:14
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Re: Minibot climb rate

Quote:
Is there any gap between the magnets, or are they butted right up against each other?

How did you secure them to the wheel?

Did you alternate them N/S ?
The magnets are butted right up against eachother and are alternated. To stick them to the wheel we took electrical tape and made a loop to make it act like double-sided tape. Then we used a layer of electrical tape on top of the magnets to hold them to the wheel. Overall the minibot worked well, the main issues were silly mistakes made when hooking the battery up or when setting it up before a match (forgetting to set it to turn on). but overall when we didn't mess up before the match the minibot worked well.
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