Author Topic: major robot noob...help  (Read 17564 times)

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Offline airman00

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Re: major robot noob...help
« Reply #30 on: January 16, 2008, 06:19:35 AM »
Maybe it says futaba only because they're are different connector types http://www.servocity.com/html/connector_types.html
Or maybe different brand servos have different pulse ranges

Buy a package of transmitter and receiver -- it'll make your life easier and you'll be sure that it works

I think that companies have begun to sell continuous servos now, but I would still modify it , its much cheaper!

it's a little complicated because im not exactly lifting the object, im pushing a box up from the box's bottom so the box can tip over back to its original orientation. so i'm not really lifting the box off the ground or anything. what am i doing wrong?


What do you mean by that, explain that more . Maybe upload a diagram ;)
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Offline SmAsH

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Re: major robot noob...help
« Reply #31 on: January 16, 2008, 03:52:44 PM »
yea ive gone and bought 2 76 mhz for a chopper and they were slightly off..really annoys me.


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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #32 on: January 16, 2008, 05:41:28 PM »
sorry i wasnt clear.
so i want to tip the box over, then after doing some other task, prop the box back to its original orientation.
ok i drew a diagram but i have no idea how to put it as a post here. anyway, i have a thin arm (as suggested) that can rotate 180 degrees (like a car wipers) with a shape at the end of it so it can hook onto the the top of the box (bottom and top sides of box are open). when i get close to the box, i can rotate the arm around and ill have to practice, but get the hook to just loosely latch on to the top edge of the box (ill make the hook big so its easy to make it latch on). then, i could just drive backwards (does servo reversing enable this?) and the box will tip over (open ends pointing horizontally) since it's a carpet surface. also, i could just try to rotate the arm downwards after i drive backwards a little, maybe that'll help. after that, ill have the hook designed so that once i lower the arm, i can drive forward a little bit and a thin part of the plastic/metal can dig into the bottom of the box, then i can start lifting a bit, and then drive forward for the box to tip back over into its correct orientation. i hope thats a little clearer so you guys can help me?
« Last Edit: January 16, 2008, 08:04:30 PM by tjpark1111 »

Offline SmAsH

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Re: major robot noob...help
« Reply #33 on: January 16, 2008, 05:50:37 PM »
maybe you can get a shovel attachment and slide under to tip back up...


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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #34 on: January 16, 2008, 08:05:32 PM »
i was actually thinking id have the arm up front and a passive shovel (just a piece of metal, or i could just buy premade) in the back to round up all the stuff (tennis balls, index cards, etc.) into the box. also, i posted this in the electronics section, but "the newbie guide tells me to double the torque that i THINK i would need, but im really worried that'll ill get TOO MUCH power and whenever i try to use my arm itll just go from 0 to 180 degrees rotation in like 1 second so i have no maneuverability at all. how can i get my robot to operate like the wall climbing robot that the admin made, where all the movements are smooth, nothing jerks because something is too fast/powerful, etc." ive seen video where a simple differential drive robot (like the $50 one on this site) steered a little too much everytime the throttle was applied so in a small robot playing field, it was hard to maneuver the robot at all. how can i take care of this issue if im using RC? if i get a weak servo im afraid i wont have enough power since 1/4" plexiglas 30x30x30cm box with aluminum/steel reinforcements in the corners could be quite heavy to tip over/move.
« Last Edit: January 16, 2008, 08:08:44 PM by tjpark1111 »

Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #35 on: January 18, 2008, 06:42:34 PM »
btw im still confused about the servos. do servos only turn clockwise? does that mean itll only turn an arm around clockwise and the only function after it has reached the turning limit it's just to bring it back to neutral position, not anywhere in between?

Offline SmAsH

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Re: major robot noob...help
« Reply #36 on: January 18, 2008, 06:55:01 PM »
yea generally servos do only go clockwise but they can be modified to go anti-clockwise, i dont know how but some companies sell modified servos. as for the power cant you get speed control for them or is that only for dc motors. idk. to your other question you could just get a plate that goes up and down. and get a capasatator to steady the current. well good luck.


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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #37 on: January 19, 2008, 08:18:46 AM »
so after it turns fully clockwise (let's say 180 degrees), the only function the servo has is to return back to 0 degrees? tahts ALL i need to know. if i know that, i can order parts right now. servocity.com sells counter clockwise for a bit more money.
also, do the 1/4 scale servos have teh same connection types and pulse width ranges? i found that high torque servos in 1/4 scale are a lot cheaper and i just want to know if i can use them with RC receivers.
« Last Edit: January 19, 2008, 08:32:54 AM by tjpark1111 »

Offline Trumpkin

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Re: major robot noob...help
« Reply #38 on: January 19, 2008, 11:38:14 AM »
does the ballon have to be out of the box? you could just build an arm with a thumb tack attached to the end so you could reach inside the box and pop it.
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Offline dunk

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Re: major robot noob...help
« Reply #39 on: January 19, 2008, 01:45:33 PM »
Quote
yea generally servos do only go clockwise but they can be modified to go anti-clockwise, i dont know how but some companies sell modified servos. as for the power cant you get speed control for them or is that only for dc motors. idk. to your other question you could just get a plate that goes up and down. and get a capasatator to steady the current. well good luck.
Smash, please refrain from giving advice if you don't know the answer.

Quote
btw im still confused about the servos. do servos only turn clockwise?
hi tjpark1111,
standard servos can turn both ways. they can only rotate 180 degrees total.
you can control which direction they point by altering the pulse width of the timing pulse you send them.
radio control receivers generate these pulses without you having to know anything about how it's done. you can also generate pulses like this with a microcontroller and control servos that way.

it is possible to modify servos by disabling the built in feedback pot so they continuously rotate (either clockwise or anticlockwise).
you can vary the speed by again altering the pulse width of the timing pulse you send them.

dunk.

Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #40 on: January 19, 2008, 11:17:26 PM »
thanks so much!
i know i asked this in the other electronics thread, but:
can i use a 6V battery to power my receiver? (and therefore my 3 ultra high torque servos?)  the how to build a robot guide said a receiver is powered by ~5V and said to use a y harness to use more voltage for the servos which i still don't understand how it works.. what power do you guys recommend? would 2300mah suffice? i have a 300+ oz/in 1/4 scale servo, and 2 80+ oz/in servos.
my other question, and idk if any of you know, what size screw do i use to attach stuff to the servo horn/wheel that the servo comes with? the tutorial on this site just shows pretty pictures and not actual information about how to mount it (like screw size).

Offline SmAsH

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Re: major robot noob...help
« Reply #41 on: January 20, 2008, 12:02:47 AM »
well you could glue it. jk lol well dont servos come with screws these day...*sigh* anyway the are standard 1" screws usially fit dont they?


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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #42 on: January 20, 2008, 12:05:36 AM »
no but they aren't long enough for my applications. size meaning like 5-40.

Offline SmAsH

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Re: major robot noob...help
« Reply #43 on: January 20, 2008, 12:17:16 AM »
well that just sucks!


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Offline airman00

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Re: major robot noob...help
« Reply #44 on: January 20, 2008, 12:22:36 AM »
well that just sucks!


~smash

LOL , that made me smile  :)


@tjpark1111

i actually needed the screw size last week but forgot it ...  anyway I searched google for a while to find the size . I'm really tired now so I'll be heading off to sleep , but I'll check tomorrow in the afternoon for you.

Check out servocity.com for extra long servo screws  , they actually sell them .
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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #45 on: January 20, 2008, 12:24:17 AM »
yeah i was planning on that too its just idk the size.
are there any instructions on how to modify a servo to 180 degree rotation?

Offline airman00

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Re: major robot noob...help
« Reply #46 on: January 20, 2008, 12:27:59 AM »
my last post of tonite


yeah i was planning on that too its just idk the size.
are there any instructions on how to modify a servo to 180 degree rotation?

well here it is

attach another bigger gear to the servo gear so that a turn of 90 degrees on the servo gear is a turn of 180 degrees on the bigger gear connected to the servo

ill let someone else on the forum explain this to you if you dont understand
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Offline SmAsH

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Re: major robot noob...help
« Reply #47 on: January 20, 2008, 12:29:55 AM »
planning to set evil robots on Eric or google the screw size? anyway check the tutorial on this site  for how to modify servos. i would find the link for you but im just to damd lazy!


~smash


now if you'll excuse me im going to go rip apart some useless r/c car!(will post pics on my site 2morrow!!! and airman better do it aswell!!) and go to freaking bed. god! my robot bugs are getting bored!
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Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #48 on: January 20, 2008, 09:23:17 AM »
theres a tutorial for 360 movement, NOT 180 degree movement...

Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #49 on: January 20, 2008, 10:21:24 AM »
this is my finalized robot parts list, tell me what you guys think:
(2) Hitec 635-HB High Torque 83 oz-in Servos (will modify for continuous rotation) - $60 @ Servocity
1 Hitec 805BB 1/4 Scale Mega Power 343 oz-in Servo (pre-modified 180 degrees) - $50 @ ServoCity
1 Laser 4 75Mhz Ground 4 Channel Receiver Channel 70 - $70 @ ServoCity
1 Hitec DCX 3-Channel Dual Conversion Negative Shift Receiver - $33 @ TowerHobbies
1 75Mhz Hitec Receiver Crystal Channel 70 - $9.50 @ TowerHobbies
1 6V 2700mAh Sanyo HRAUX 5 Cell NiMH Hump Battery - $33.50 @ OnlyBatteryPacks
1 NiMH/NiCad 4.8V-10.8V Fast Charger - $30 @ OnlyBatteryPacks
1 Pair 4" Precision Disk Wheels - $6 @ ServoCity (powered rear wheels)
1 Pair 2" Precision Disk Wheels - $4 @ ServoCity (two in front for stability)
1 3/8" Stainless Steel Shaft 10" long for front wheels - $14 @ ServoCity
1 HDPE 24"x24" White Sheet - $24 @ McMaster
total ~$334 (I know a bit expensive)
5Kg robot lifting a 5lb (approx.) box, differential drive, doesnt need to be fast, for robot competition. do you guys see any part that i could make cheaper?
any glaring problems you guys see? (incompatibilities..?)
btw do you guys really know if servocity has bad customer service? it said so on the parts list on this site.
« Last Edit: January 20, 2008, 10:25:03 AM by tjpark1111 »

Offline Admin

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Re: major robot noob...help
« Reply #50 on: January 26, 2008, 12:58:33 PM »
Quote
my other question, and idk if any of you know, what size screw do i use to attach stuff to the servo horn/wheel that the servo comes with? the tutorial on this site just shows pretty pictures and not actual information about how to mount it (like screw size).
well, I used the screws that came with the servos! but as I understand it now, they are getting cheap and no longer including these extras with the servos . . . a 4-40 screw will be fine.

Quote
1 Pair 4" Precision Disk Wheels - $6 @ ServoCity (powered rear wheels)
1 Pair 2" Precision Disk Wheels - $4 @ ServoCity (two in front for stability)
I prefer foam wheels . . . but it really depends on what you plan to do.

Quote
total ~$334 (I know a bit expensive)
not really. I tell people to budget about $500 for their first custom robot. You won't need to buy these parts again, anyway ;D

Quote
btw do you guys really know if servocity has bad customer service? it said so on the parts list on this site.
I had problems with them in the past, they ignored emails, lost parts, but no problems within the last year . . . anyone else?

ps - Smash, try and stay focused and on topic. Don't reply to a post unless you have something important to add. "lol, so cool!" doesn't count ;D

Offline BANE

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Re: major robot noob...help
« Reply #51 on: January 26, 2008, 01:16:13 PM »
Quote
ps - Smash, try and stay focused and on topic. Don't reply to a post unless you have something important to add. "lol, so cool!" doesn't count ;D

And something like "hmm...yeah that is tricky..sorry cant help you..."  when the question didn't specify it was for you.  It's like "G thanks that was really helpful ::)!!!!!

(sorry, just had to let that one out)

bane

Offline tjpark1111Topic starter

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Re: major robot noob...help
« Reply #52 on: January 26, 2008, 09:04:25 PM »
thanks so much everyone! i ordered all of the parts they're all coming monday. it was around $500 like admin said, including shipping and everything. good to know i have all of my parts and i won't need to buy them again, so i guess it was a good investment.

Offline Trumpkin

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Re: major robot noob...help
« Reply #53 on: January 30, 2008, 03:20:09 PM »
I have also had trouble with servo city i ordered a battery switch from them once and it came with out screws for the switch cover. They don't answer calls either.
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