Crawler tracks

[marcoloca]

(Is it written correctly? )

Hi again,
I need some explanations about the crawlers. As my teacher said, they're absolutely better than normal wheels in moving on an inclined plane, but there are some things I am not certain about.
We (again, I and my team) build it but sometimes they creak and maybe this means that the robot must spend more energy for moving the engines... What do you think?
Of course, as I said, with wheels the robot will never pass the climb...
I don't know, any suggestions?

Thank you all who will answer me soon!

[mattallen37]

Tracks often do introduce more friction than wheels, but are often easier to design for. With tracks, you can easily make a skid-steer, and all motor power can go to driving the tracks (you don't need to waste resources for a steering motor). Wheels often have a large diameter, making them harder to drive (you need torque, which means more tolerance issues).

Tracks can be the best option, but it depends on the surface you will be driving on, and the tracks/wheels/design you have.

[mightor]

At my robotics club we have competitions and the robots with the tracks often find themselves unable to make a pivot turn on the rubber mats due to the friction. I've seen tracks split or just come off the little wheels. Keep that in mind

- Xander

[marcoloca]

Tracks often do introduce more friction than wheels, but are often easier to design for. With tracks, you can easily make a skid-steer, and all motor power can go to driving the tracks (you don't need to waste resources for a steering motor). Wheels often have a large diameter, making them harder to drive (you need torque, which means more tolerance issues).

Tracks can be the best option, but it depends on the surface you will be driving on, and the tracks/wheels/design you have.

Well, I think it's the best option too, because probably (I'm not really sure) the robot will drive on a smooth surface... We already built a track and we need to build the other, but we stopped to think if it's a good choice... It's a track based on three circles (one of them is a bit more high than the others) and it's quite tight [is this a good thing?]

Another thing, do you think we'd better connect all the three "circles" (it's not the right term, I now) to the same motor, or is better to make move only one circle? And if yes, which of the three (anterior, posterior or middle-high)?

At my robotics club we have competitions and the robots with the tracks often find themselves unable to make a pivot turn on the rubber mats due to the friction. I've seen tracks split or just come off the little wheels. Keep that in mind

Sorry, I can't understand what you mean with "on the rubber mats"... You mean that the tracks show problems on a not-smooth surface?

[mightor]

If the mat provides too much grip, the tracks have trouble turning the robot on the spot. There is too much friction and you end up either running the track off the cogs or, worse, snapping them. I've seen it happen.

- Xander

[h-g-t]

Interesting experiment on traction here - http://www.philohome.com/traction/traction.htm

[marcoloca]

If the mat provides too much grip, the tracks have trouble turning the robot on the spot. There is too much friction and you end up either running the track off the cogs or, worse, snapping them. I've seen it happen.

But, as I said, the surface will be smooth and I think the friction won't be I problem... I hope! However, we have an arena (quite the same of the one of the competition) where we can try robots, maybe I'll try and then I tell you how was the performance...

Interesting experiment on traction here - http://www.philohome.com/traction/traction.htm

Thank you! Very interesting!
I think that the performance will be fine, the data are average good (for what we have to do... It's a junior competition, not a professional one!)

[mattallen37]

You don't want the tracks too tight. Whether you are using the track links or rubber tracks, you want some slop in them (but not enough to make them slip or come off).

[hassenplug]

Another thing, do you think we'd better connect all the three "circles" (it's not the right term, I now) to the same motor, or is better to make move only one circle? And if yes, which of the three (anterior, posterior or middle-high)?

The circles are wheel hubs.

Personally, I wouldn't power all three hubs. As long as one hub is turning the track, two or three won't make it turn "more", and adding gearing to connect all three may add friction, which would not be good.

I would connect the motor to the middle hub to give it good ground clearance, but only if the track goes around 90 degrees of the hub. Less than that, and it may slip.

Hope that makes sense.

Steve

[marcoloca]

The circles are wheel hubs.

Personally, I wouldn't power all three hubs. As long as one hub is turning the track, two or three won't make it turn "more", and adding gearing to connect all three may add friction, which would not be good.

Yes, this make sense, thank you! We'll try this, I think...

I would connect the motor to the middle hub to give it good ground clearance, but only if the track goes around 90 degrees of the hub. Less than that, and it may slip.

Sorry, I don't understand "goes around 90 degrees of the hub"...

You don't want the tracks too tight. Whether you are using the track links or rubber tracks, you want some slop in them (but not enough to make them slip or come off).

They're not too tight, of course, just enough I think =)