Burf2000

MINDSTORMS TANK : Holds up to 80KG

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I built a new ride on vehicle for Brick 2015 at London Excel. It was super popular and I am so tired now (3 day event, 20,000 + people)

Uses 10 NTX's 22 motors, rotacaster 125mm wheels! Made in 5 evenings powered by RedBull

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WHen I read the name of the topic, I immediately knew it was a Burf2000 creation :laugh:

Really impressive, looks a bit more smooth than the wheelchair :thumbup:

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I have a few spare NXT's at home so no I did not thankfully!

I saw this on youtube the other day. Are they all connected by bluetooth?

It was super popular and I am so tired now.

Uses 10 NTX's 22 motors, rotacaster 125mm wheels!

Hmm NTX's? You must be tired. :grin:

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I use touch sensors to control each NXT as BT would be slow and unstable :(

NTX, told you I needed sleep!

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This tank is quite faster than I expected. Good job!

By the way, your son is starting to look like a mini version of you.

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WHen I read the name of the topic, I immediately knew it was a Burf2000 creation :laugh:

Exact same here....didn't even need to see who posted it, but of course needed to see the monstrosity.

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I presume that the child should be about 20 or 25 kg.

How have you estimated the number of necessary servos.

I see that there are 14, it's a lot!

In my work, here http://www.eurobricks.com/forum/index.php?showtopic=110051&hl=oracid#entry2230918 ,I demonstrate that with a single motor XL, I can move 8 kg.

In fact, I tested with large bottles and it is 12 kg.

By the following realization, http://www.eurobricks.com/forum/index.php?showtopic=117220&hl=oracid#entry2384354 , I realize that the servos lost their position when the torque is too high,which slows them a lot, for this reason I used the XL motor.

Nevertheless, I like your achievement, myself, I'm trying to make a 1m tank, but for now, I do not know where I'm going.

Therefore, what you are doing really interests me.

Edited by oracid

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Hey there. It uses 22 motors! Everything I build I test with my weight (currently 90kg due to xmas and pies). At shows I run with kids so the vehicle last longer. After a while the plastic axels will break.

All motors encoders are off. I did do a go-cart using XL motors

I plan to ride the tank to the shops? worth doing?

Edited by Burf2000

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All motors encoders are off.

Can you tell us how you do that ?!

I did do a go-cart using XL motors

fantastic !

I plan to ride the tank to the shops? worth doing?

Of course ! You have to do !

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Hey dude,

I saw your models up at brick at the weekend, and I you were looking tired on the Saturday afternoon policing that line of kids waiting for a go. It looked like that queue was not going down at all! Real crowd pleaser

Paul

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You can let the motors float / coast instead of relying on the encoder, what software you using?

Big success! Congratulations !

I use the motor block by indicating the time in seconds, nothing more.

I use the LEGO MINDSTORMS Education EV3.

Edited by oracid

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Hey dude,

I saw your models up at brick at the weekend, and I you were looking tired on the Saturday afternoon policing that line of kids waiting for a go. It looked like that queue was not going down at all! Real crowd pleaser

Paul

Sunday I was even more tired, the kids kept coming :)

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On 12/15/2015 at 7:54 AM, oracid said:

In my work, here http://www.eurobricks.com/forum/index.php?showtopic=110051&hl=oracid#entry2230918 ,I demonstrate that with a single motor XL, I can move 8 kg.

In fact, I tested with large bottles and it is 12 kg.

 

One motor might be enough for a turntable like the one you made (maybe even a smaller motor could have worked the same) but carrying a load on wheels or tracks is a very different scenario!

The main difference I guess would be the load applied on the motor driven axle: in your turntable, given the large number of rollers you built, it's taking really only a fraction of those 12 kg. Also, apart from the friction acting against the rollers, there are very little forces opposing the motor's movement, in a wheeled base you would also have to factor in the friction applied by the ground to the wheels creating another opposing momentum( which would just grow with the radius of the wheel).

Once you get to a noticeable load on a plastic axle "freely" rolling in a plastic shell, given that there are no real bearings in LEGO, just the friction forces between the elements start to act as a very effective brake on the driving axle, in that case more than one motor will have to be used just to get the axle moving..

I guess that if you really want to limit the number of motors used you first have to limit the load applied on the driving axle (or axles) by maybe just adding more wheels to the base. Even then however, I think that for some loads, friction would add up really rapidly no matter how many different points you're using to redistribute the load.

I just wanted to point these few things out, having noticed your interest on this topic in a couple of posts:) @oracid

 

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