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Author Topic: My first robot frame!  (Read 5065 times)

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Offline h3roTopic starter

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My first robot frame!
« on: September 07, 2007, 04:52:05 AM »
So now I have ordered the electronic needed to start to build simple stuff, but I need a frame to attach it to, right? ;)

I, like 99% of other people think tracks are really cool. But after reading around everyone say that tracks are very very hard to do good. Even after reading this I think of building a frame with tracks.

So I was wondering, what is the really difficulties with using tracks? Also, will it make much easier if I use lego tracks like the ones belove and attach a technic gear to a servo instead of re-inventing some kind of track driving?


The robot I plane to build is the all famous 50$ Robot, but as I have way to much time at hand right now (and next week) I might as well try to pimp the frame up a bit (If the track idea is not to hard.)
« Last Edit: September 07, 2007, 04:56:58 AM by h3ro »

Offline Rebelgium

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Re: My first robot frame!
« Reply #1 on: September 07, 2007, 09:30:26 AM »
Lego tracks are cool, but very small. So it's good (cheap!) to use lego's for beginner robots. :)

I personally like to have more than enough ground clearance for all my robot's (distance from the frame to the ground) but the lego tracks have very limited ground clearance...
But for indoor use this is of little importance.

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Offline h3roTopic starter

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Re: My first robot frame!
« Reply #2 on: September 08, 2007, 12:33:02 PM »
Here is my frame so far:


It is made out of stuff I found at home. Mostly old R/C parts and Lego.
The Lexan polycarbonate (I think thats the English name for it?) I got for free at a shop which sells windows to cars and houses. Places which work with plastic/metal/ wood and so on normally have a lot of left overs which they never can use as it to small for them so they are more then happy to give it away for free. I got two 40x40cm sheets for free and was more then welcomed to come and get more if needed.

Right now I'm a bit concerned of the speed of the thing, but time will tell I guess. If its to bad I will just remove the tracks and replace them with some wheels.

Offline HDL_CinC_Dragon

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Re: My first robot frame!
« Reply #3 on: September 08, 2007, 03:57:33 PM »
Yeah speed is never really a super strong point for tracked vehicles but that really is only limited by what motors you use.
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Offline h3roTopic starter

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Re: My first robot frame!
« Reply #4 on: September 08, 2007, 05:33:47 PM »
Just a quick question,

Will it course any problems to use a 4.8V battery ? Thats the only thing I had, thats not the size of a NiCad  battery.

Offline HDL_CinC_Dragon

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Re: My first robot frame!
« Reply #5 on: September 09, 2007, 09:15:29 AM »
yeah You need at least 6v I think
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Re: My first robot frame!
« Reply #6 on: September 09, 2007, 02:50:49 PM »
Quote
Will it course any problems to use a 4.8V battery ?
For the microcontroller you will need at least 6V, as HDL_CinC_Dragon said. You could always use a 9V battery for it. I give that option in the $50 robot tutorial.

For the motors, 4.8V will work. But . . . ignoring all mechanical problems that tracks cause, there are energy efficiency problems. Tracks have very high friction, meaning they are much less efficient than wheels. This means less torque, and a higher drain on batteries.

So . . . a higher voltage battery gives you higher torque. Perhaps important . . . I'd just test out the 4.8V and see how things go before making the investment :)

Anyway, if you are going to use tracks, you are required to post video of your robot going through rough terrain ;)

Offline h3roTopic starter

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Re: My first robot frame!
« Reply #7 on: September 11, 2007, 12:03:16 PM »
Finished my frame today! Added one more servo to the front, so I can attach my sharpIRs to it later on.

Got my parts from digi-key today as well. Just waiting for the prototype board from sparkfun so I can start.

Quote
Anyway, if you are going to use tracks, you are required to post video of your robot going through rough terrain
With a 1.5 cm ground clearance I guess it will suck badly:P

Quote
For the motors, 4.8V will work. But . . . ignoring all mechanical problems that tracks cause, there are energy efficiency problems. Tracks have very high friction, meaning they are much less efficient than wheels. This means less torque, and a higher drain on batteries.

So . . . a higher voltage battery gives you higher torque. Perhaps important . . . I'd just test out the 4.8V and see how things go before making the investment
I made my own battery :D
"I made" sounds so cool, but all I did was attach one more battery to an other battery pack I had. The good part is that its made up of 1600mAh batteries, so they should last a bit when charged. (I hope)

If the tracks turn out to be to bad for this im just going to rip them off and put on some wheels. But tracks are soo much more fun the wheels.

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Re: My first robot frame!
« Reply #8 on: September 11, 2007, 12:52:31 PM »
be careful that the battery you added is exactly like the others . . . if not bad stuff could happen . . .

Offline h3roTopic starter

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Re: My first robot frame!
« Reply #9 on: September 11, 2007, 12:56:01 PM »
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be careful that the battery you added is exactly like the others . . . if not bad stuff could happen . .

Its not. How bad is bad stuff in this case?

4 of the batteries are 1.2V and 1600mAh and the last one is an other brand with 1.2V and 1000mAh. Does that mean that I did something stupid?

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Re: My first robot frame!
« Reply #10 on: September 11, 2007, 01:00:28 PM »
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4 of the batteries are 1.2V and 1600mAh and the last one is an other brand with 1.2V and 1000mAh. Does that mean that I did something stupid?
YES! lol

what will happen is the batteries will unevenly discharge, and some batteries will waste energy recharging the other type of battery. if you are lucky your batteries will just have reduced lifetime and waste energy. if you arent lucky, possibly chemical leakage and/or fire . . .

you shouldnt even connect batteries that are exactly the same with different charge levels . . .

Offline h3roTopic starter

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Re: My first robot frame!
« Reply #11 on: September 11, 2007, 01:09:04 PM »
Fire kind of sucks. Guess I have to unsolder the extra battery again. (Or are all the batteries destroyed now, as they have been connected and charged for a while now? Yes, I attached them to my charger :P)

What do you recommend? Using a old 9V or getting a new 6V? There is a RC shop fairly close to me, so I can get one for a decent money.

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Re: My first robot frame!
« Reply #12 on: September 11, 2007, 01:22:49 PM »
hmmm id say the batteries are still useful . . . just reduced lifetime now :P

if you dont have a 6V NiMH battery pack yet, and you plan to build bots in the future, i highly recommend getting one. consider it a long term investment (they will last for many years).

Offline andy b

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Re: My first robot frame!
« Reply #13 on: September 16, 2007, 08:29:39 AM »
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For the motors, 4.8V will work.

Is that 4.8V per motor/servo or for all 3 of them?

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Re: My first robot frame!
« Reply #14 on: September 16, 2007, 03:02:16 PM »
4.8V for all three (all motors sharing the same battery)

 


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