Acessórios anti-derrapagem para lagartas Technic / Mindstorms

[oracid]

One more effort and you will reach 90 °. Look here at 2'35 : https://youtu.be/dP3WeFkbWRA

[CyberX]

[quote="oracid"]
One more effort and you will reach 90 °. Look here at 2'35 : https://youtu.be/dP3WeFkbWRA
[/quote]

Yes, I saw that. My kid almost got same situation (no video proof) but it's not climbing, it's just "standing up".
I've been reading some things about military tanks, seems like most «datasheets» state only 60% slope (that's less than 31º). So it turns out this 50º is already a very good mark.

[pt]
Estive a ler algumas coisas sobre tanques militares, parece que a maioria foram desenhados para inclinações de apenas 60% (não chega a 31º). Afinal estes 50º já são um grande feito e eu nem sabia.
[/pt]

[AVCampos]

Yeah, 50° is 111%, which is almost impossible in large scale. For such inclinations, I believe the only option would be suction cups in the treads...

Sim, 50° é 111%, o que é quase impossível em grande escala. Para essas inclinações, acho que a única opção seria ventosas nas lagartas...

[CyberX]

A Páscoa foi em casa dos meus sogros. Como têm quintal levei o My Little Tank para um teste no mundo real (eu moro num 6º andar).
[Easter was at my parents-in-law house. As they have a backyard I took My Little Tank with us for a real-world test (I live in a 6th floor) ]

A «suspensão» não rebentou / The «suspension» didn't brake


Mas o comportamento com degraus foi horrível / But the performance against steps was horrible:


[pt]
Fiquei admirado, cada vez que tentava subir algum degrau ou mesmo rampa a conexão com o Sbrick caía, coisa que nunca aconteceu em casa.
A razão: como as pilhas já estavam fracas troquei-as: tirei as 6x Energizer AA MAX e coloquei 6x Energizer AA Ultimate Lithium, como têm menor resistência interna (cerca de 80%) deveriam dar mais potência.
Asneira.
Os 2 motores PF-XL passaram a puxar demasiada corrente e a caixa de pilhas LEGO PF passou a cortar a corrente e desligar o SBrick.
De volta à mesa de desenho para repensar a bateria.
[/pt ]

[en]
I was baffled, each time I tried a step or even a slope the SBrick connection dropped, that never happened at home.
Reason: as batteries were weak, I changed them: took off the 6x Energizer AA MAX and put 6x Energizer AA Ultimate Lithium, as they have lesser internal resistance (about 80%) I should get more power.
Bad mistake.
The 2 PF-XL motors now consume to much current so the LEGO PF battery box now cuts the power and turns off the SBrick.
Back to drawing board to remake the battery.
[/en]

[oracid]

[quote="CyberX"]
Mas o comportamento com degraus foi horrível / But the performance against steps was horrible:[/quote]
I think you should put the D joint on each side of the track elements and not alternate.
Also, you should put the adhesive part (after removing the adhesive) on the front of the elements.
And you should use 4 motors, because your tank is at least 1.5kg. But in any case, it rotate well.

[CyberX]

[quote="oracid"]
[quote="CyberX"]
Mas o comportamento com degraus foi horrível / But the performance against steps was horrible:[/quote]
I think you should put the D joint on each side of the track elements and not alternate.
Also, you should put the adhesive part (after removing the adhesive) on the front of the elements.
And you should use 4 motors, because your tank is at least 1.5kg. But in any case, it rotate well.
[/quote]

[en]
Yes, I will add a second D-joint to each track link. But that means cutting almost 200 pieces more... I'm a lazy guy.
And one day I will try moving the adhesive part to the outer side of the track. But that means moving almost 400 pieces and also taking the adhesive off... did I say I'm a lazy guy?

Now the 4 motors is much more appealing... but I'm also a stubborn guy so first want to try a better battery that doesn't cut at 800 mA. Then I'll try 2x 9V RC Buggy motors (5292) instead of the 2x PF XL motors. And then will try 4 motors, both 4x PF XL and 4x 9V RC. And maybe a fire extinguisher for the battery
[/en]

[pt]
Sim, hei-de duplicar o número de juntas-D. Mas implica cortar quase mais 200 pedaços e sou preguiçoso.
E um dia destes hei-de virar as juntas-D de forma a ter a parte do adesivo para fora, mas isso significa reorientar quase 400 pedaços e tirar o adesivo a eles todos... já disse que sou preguiçoso?

Já usar 4 motores é muito mais apelativo... mas como sou casmurro vou primeiro arranjar uma bateria melhor que não corte aos 800 mA. Depois troco os 2 motores PF XL por 2 motores 9V RC (5292) e só depois disso experimento os 4 motores, tanto PF XL como 9v RC. E provavelmente um extintor tb
[/pt]

[CyberX]

Uma foto do meu cunhado, já que é um excelente fotógrafo tenho de aproveitar estas oportunidades raras / a photo from my brother-in-law, since he's an excellent photographer I have to take the most of this rare opportunities:

My Little Tank sees the real world by Jorge Pereira, on Flickr

[oracid]

[quote="CyberX"]
Yes, I will add a second D-joint to each track link. But that means cutting almost 200 pieces more... I'm a lazy guy.[/quote]
Courage !

[AVCampos]

You can try using 4 motors, connected in pairs to 2 IR receivers set to the same channel, and each with its own battery. That should solve the current problem, while ruining outdoor communication. And, for moving on grass, wouldn't it be better to have more ground clearance, which in turn raises the centre of mass and degrades stair climbing ability?
Pull the blanket to cover the head, the feet come out...

Podes tentar usar 4 motores, ligados em pares a 2 receptores IV configurados para o mesmo canal, e cada um com a sua própria bateria. Isso deve resolver o problema da corrente, enquanto prejudica as comunicações em exteriores. E, para andar na erva, não seria melhor ter mais distância ao solo, que por sua vez sobe o centro de massa e prejudica a capacidade de subir escadas?
Puxa-se o cobertor para tapar a cabeça, destapam-se os pés...

[CyberX]

Yep, I was considering something similar: 2 SBricks and 2 PF Battery Packs (I have only one PF IR, I think... somewhere in limbo).
But I'm also considering:
- a LiPo inside an old 9V PP3 LEGO battery case (it's the only LEGO battery case I have without overcurrent protection);
- several PF batteries in parallel [with 3x 14500 LiIon batteries, 2 dummy AA batteries and one dummy battery with a 3A diode in each];
- a LiFeCo2 battery with a custom PF cable and who cares for LEGO purism anyway, I love the Dark Side!

[pt]
Sim, estava a considerar parecido mas 2 SBricks e 2 PF Battery Packs, até porque tenho apenas um PF IR, algures no limbo.
Mas estou também a considerar:
- baterias LiPo dentr de caixa LEGO 9V PP3 (a única caixa de pilhas LEGO que tenho sem circuito de proteção);
- várias caixas de pilhas PF em paralelo [com 3x baterias 14500 LiIon, 2 pilhas falsas AA e uma pilha falsa com um díodo de 3A em casa];
- uma bateria LiFeCo2 com um cabo PF modificado e que se lixe o purismo, eu sou do Lado Negro!
[/pt]

[oracid]

Well, all this seems to me rather complicated. My battery works fine with 4 XL motors.
How heavy is your tank?

[CyberX]

[quote="oracid"]
Well, all this seems to me rather complicated. My battery works fine with 4 XL motors.
How heavy is your tank?
[/quote]

1,1 Kg  [kitchen scale]

You have 4 XL motors with only 1 PF battery and it doesn't activate the overcurrent  protection when climbing high steps... is it because 4 motors distribute the load better than 2? Or am I missing something like track tension, shape... moon phase ?

[AVCampos]

Are you sure the current bottleneck is in the batteries instead of the SBrick? Oracid uses PF receivers instead, perhaps that could be the difference. Also, the V2 receiver can handle more current, it could also make a difference.

[oracid]

[quote="CyberX"]
You have 4 XL motors with only 1 PF battery ....[/quote]
No, I use a lithium battery, 8878.

[CyberX]

[quote="oracid"]
[quote="CyberX"]
You have 4 XL motors with only 1 PF battery ....[/quote]
No, I use a lithium battery, 8878.


[/quote]

That's it!

I took a 8878 from another MOC and used it with the tank (at home, but forced it the most I can) and it never clipped.
But the 8878 and the 8881 have the same overcurent circuit (acording to Philo it's the Bourns MF-MSMF075 that trips at 1,5 A and holds at 750 mA) so why doesn't the 8878 trips?

Since the 8878 is LiPo, the internal resistance should be even smaller than the Energizer Ultimate Lithium I'm using in the 8881 (so it can give even more current)...
... the reason for the difference must be the total voltage: the 8878 is 7.2 V and the 6x Energizer UL is somewhere between 9.0 and 9.6 V when fresh

The downside: the tank is much slower with the 8878 

And [member=85]AVCampos[/member] : The SBrick doesn't cut the current like the PF IR does, remember my experiment one year ago when I melted the plug reaching more than 7 A intake? I wish I could reach 7 A with ordinary AA batteries