Lego – 17cm Stair Tank Climber #10

[oracid]

Lego – 17cm Stair Tank Climber #10
My goal was to climb stairs of real life whose steps have a height of 17cm.
To reach this goal, I thought it had to be a very large tank (81cm) and so very heavy 7.5kg. This was a failure.
So I changed my mind by making a tank, the smallest and lightest as possible.
A final issue exists, it is the nosing that I cannot cross. But it is true that there are all kinds of stairs, each with specific constraints, and want to solve all issues is to risk not to take the first step.
I started by 5cm steps and 10cm and today I crossed steps 17cm.
I think I have reached my goal.
Length: 67 cm
Width: 42 cm
Height: 12 cm
Weight: 1,560kg
4 XL motors

http://youtu.be/hCawhQVRvYI

[phi_qui]

Je ne suis pas adepte trop adepte du thème Technic, mais je viens vous "dire" un grand BRAVO. J'ai bien aimé cette construction, surtout adapter à une situation réelle - escalier sans aucune planche.

[AGarcia]

Amazing!!!

[CyberX]

Amazinh indeed! 
And quite inspiring.

[oracid]

Thank you everybody.

[AVCampos]

That's impressive! As someone who never tried building stair climbers, I believe the hardest part is the first step, where the vehicle must transition from horizontal to tilted. How did you manage it?

[oracid]

[quote="AVCampos"]
That's impressive! As someone who never tried building stair climbers, I believe the hardest part is the first step, where the vehicle must transition from horizontal to tilted. How did you manage it?
[/quote]
Thank you.
When you know nothing about a subject, you have the advantage of not anticipate problems that experts know and where they drown.
I started with rubbers, https://youtu.be/iHyJX5UxPy8, (they have already been used, of course). This video shows the evolution of my progress on the subject. And as I found that it worked well, so I tried to replace rubbers by many sorts of materials.
The D joint, this is my chance card.
One can find also my tests with what did not work in my thread on EuroBrick, http://www.eurobricks.com/forum/index.p ... pic=119844

Today I have one or two ideas to try to cross the step nosing. That's my next step.

[AVCampos]

Thanks for the sequence of videos, they're very instructive! I didn't remember the importance of having enough length to contact at any time the edges of at least 2 steps, and of having a suspension so that there's a greater area of contact around each step edge.

I guess having cleats on the treads, as you showed on one of your videos and like those official from LEGO, would be beneficial for climbing stairs but detrimental for climbing smooth slopes.

Regarding vehicle length, the trade-off of greater length is more difficulty when turning; variable geometry treads should take care of that. For that, the design of PackBot, with two tread "arms", seems ingenious for its efficacy and (relative) simplicity.

[oracid]

[quote="AVCampos"]I guess having cleats on the treads, as you showed on one of your videos and like those official from LEGO, would be beneficial for climbing stairs but detrimental for climbing smooth slopes.[/quote]
I do not understand what you say, can you be more specific?

[quote="AVCampos"]
Regarding vehicle length, the trade-off of greater length is more difficulty when turning; variable geometry treads should take care of that. For that, the design of PackBot, with two tread "arms", seems ingenious for its efficacy and (relative) simplicity.[/quote]
Yes, we must be careful about the length of the tank. I have the intuition that increasing the width we solve the problem of the rotation as the tangent of the track is closer to the perimeter rotation. But I'm not clever enough to demonstrate.
The PackBot solution, I call that "moustaches" is very common and is used in many deminers or other robots. I already said it was a good solution, but it requires a remote control activating or a coded intelligence. If someone finds a purely mechanical solution, it would be more satisfying to me.

Viewing this video, https://youtu.be/tnU_6xU_rq0, I think that's exactly what not to do. While some solutions are interesting.

The code is better when you can do without.

[AVCampos]

[quote="oracid"]
[quote="AVCampos"]I guess having cleats on the treads, as you showed on one of your videos and like those official from LEGO, would be beneficial for climbing stairs but detrimental for climbing smooth slopes.[/quote]
I do not understand what you say, can you be more specific?[/quote]
I mean cleats should be better for stairs than "smooth" tracks because they probably help grabbing the edges of the steps. For slopes, cleats mean there's less contact area, so they should be detrimental.

[oracid]

[quote="AVCampos"]
[quote="oracid"]
[quote="AVCampos"]I guess having cleats on the treads, as you showed on one of your videos and like those official from LEGO, would be beneficial for climbing stairs but detrimental for climbing smooth slopes.[/quote]
I do not understand what you say, can you be more specific?[/quote]
I mean cleats should be better for stairs than "smooth" tracks because they probably help grabbing the edges of the steps. For slopes, cleats mean there's less contact area, so they should be detrimental.[/quote]
What are this cleats you are talking about ?

[CyberX]

I think he means the rubber pads attached to the tracks. "crampons" ?

[AVCampos]

Yes, either the wide red ones that came with the EV3 Expansion Set or the narrow black ones that came with the Fortrex.

[oracid]

[quote="AVCampos"]
Yes, either the wide red ones that came with the EV3 Expansion Set or the narrow black ones that came with the Fortrex.[/quote]

I think you mean that. I have not tested it, I have not enough of them, but I think it's too slippery for stairs and also for the slope. More, it is too expensive for me.

[agadoijo]

This is seriously impressive! Very good work.