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Topic: Rover project...Please help me (Read 117 times) previous topic - next topic

Hello guys ... I would like to ask your advice to make a rover like this

http://www.robotshop.com/en/lynxmotion-aluminum-a4wd2-rover-kit.html

Someone could tell me of engines and wheels suitable ( via link ) and could explain how to connect them together? thanks
I apologize for being a true beginner   :D  :D

riesens

Sorry I can't answer that directly as there are millions of possibilities. The most simple is either a kit or stuff from a shop that provides stuff for RC vehicles. As you didn't write where you are from, it is difficult to advise a specific webshop as not every webshop is shipping everywhere....But I can give you some inputs to get your brain started.

Well, to select some wheels you need to ask yourself some questions:

- How big shall the robot be?
- What speed shall it achieve?
- What terrain do you want it to drive?

And for the motors you need to do basically the same.

- What are the physical dimensions of your wheels?
- What payload do you want to add to the robot?
- What size is your robot?
- What power sources are available / What is the power rating of your battery.

And generally:
- What is your budget?

Hope this helps for starters.

Best

Cactusface

Hi,
       I've build a few bots, never done a 4 wheel drive as I think their harder to control and I don't really see any benifits other then perhaps speed and power, which you might need!  Just think about turning it, or it turning..

Why not start with something 2 wheeled even a cheap Chinese kit, just to get you going and and you will learn lots, that you can then put in to a better build.

But if you don't know how to connect together then you have a steep leaning curve ahead, we can help with some of but! Do a bit of googling it all up there!!  read a few tutorials on electronics, etc.

Here's few few of my bots: www.melsaunders.co.uk under electronics.

Get back to us.

Regards

Mel.
Open your mind! But not too far, your brains might fall out.
Also like Photography, model building and my 300+ Cacti and Succs.

cr0sh

Hello guys ... I would like to ask your advice to make a rover like this

http://www.robotshop.com/en/lynxmotion-aluminum-a4wd2-rover-kit.html

Someone could tell me of engines and wheels suitable ( via link ) and could explain how to connect them together? thanks
I apologize for being a true beginner   :D  :D
Not only are you a true beginner, but you also seem either lazy or ignorant about how to figure this out on your own. I'm going to give you the benefit of the doubt here, and assume the latter.

That said - you can basically figure out everything you need from the link you posted. If you go back to that link, you can take a look at the pictures of the platform.

Note how on the 3/4 view of the platform (and other views) there is red writing on the motor, plus a blue-like outline on the label of the motor. Note also on the view of the bottom of the chassis, the motor's output shaft is offset from the center.

Now - open the PDF file "Datasheet" under the "Useful Links" section. Note the following under "Includes":

* Traxxas Stampede Tera (Firm) Tires

* 4x 12vdc 30:1 200rpm (6mm shaft, with rear shaft)

Also note at the product link it says something similar about the motors and wheels, stating it "includes four 12.0vdc 30:1 gear head motors and 4.75'' tires and wheels".

Finally, we know that the manufacturer of the base is "Lynxmotion"; it is very likely then that the platform they sell is made from parts they sell, right? So, go to their website, and look at the motors and wheels.

In their motors section, you can find the following motor:

http://www.lynxmotion.com/p-186-gear-head-motor-12vdc-301-253rpm-6mm-shaft.aspx

Which meets most of the motor requirements - with the exception of the "rear shaft" - I find this odd, as the pictures don't show the "rear shaft", and only the Datasheet mentions it. I don't know why this is, but perhaps one of the other motors Lynxmotion can work.

Each one of the above motors is $29.95; you need four - so for motors, you would need to spend $120.00.

For the wheels, you need the following (same as on the platform):

http://www.lynxmotion.com/p-108-off-road-robot-tire-475d-x-2375w-pair.aspx

Each wheel (pair) costs $25.00; you need two pair (four wheels) - so that's another $50.00. We are up to $170.00.

You also need the mating hubs:

http://www.lynxmotion.com/p-591-12mm-hex-mounting-hub-6mm-shaft-pair.aspx

Which again come as a pair, for $7.95 - so you need two pair again, for an extra $16.00. Now we are up to $186.00.

For the chassis, they use their "Servo Erector Set" - which they refer to as "SES" - they use two "3 inch" aluminum channels:

http://www.lynxmotion.com/p-646-aluminum-channel-3-single-pack.aspx ($6.95 each)

...and two "7 inch" aluminum channels:

http://www.lynxmotion.com/p-755-aluminum-channel-7-single-pack.aspx  ($10.95 each)

I've used the "non-sale" prices - so for that, totaled up, is about $36.00 - so we're up to a total of $222.00.

You need four L-brackets - I think these are the set - two of these, they come as a pair:

http://www.lynxmotion.com/p-328-aluminum-l-connector-bracket-two-pack.aspx ($5.95 each)

You also need four motor brackets - again sold as a pair, so you need two:

http://www.lynxmotion.com/p-842-ses-aluminum-motor-mount-pair.aspx ($7.95 each)

That's an extra $28.00 - so we are up to $250.00.

As you can see, we have spent more money for these parts - the same parts that go into the chassis - and we still haven't added the extra stuff (lexan parts, stand offs, wiring and other stuff as listed in the Datasheet).

But that's not the point. The point here is to show you how you can take what is given, and use that to derive the individual components; in such a case, we can see that the important bits are the motors, and the specs of the motors; they are by far the most expensive component. For this particular robot and wheel combination, it needs motors with specs close to something like the original ones:

Voltage = 12vdc
RPM = 253
Reduction = 30:1
Stall Torque = 138.9 oz-in (10.0 kg-cm)
Outside Diameter = 37mm
Weight = 7.26 oz.

So if you can find motors like that - but cheaper - then you can potentially use those. The only issue will likely be that the shaft size won't be the same, mounting points won't be the same, and you'll have to go custom on everything else. But you can likely do all of this for much cheaper, if you have the tools and time. I can already tell you that you don't have the experience - so you likely don't have the tools, either (for instance, if you found the motors, you could use the same wheels, since they aren't that expensive - and the hubs, but you might have to machine the hubs to fit the shafts of the motors).

Surplus outlets are probably going to be your best bet, but honestly, that's not a bad price for that spec of a motor. Surplus, if you found something similar, you might be able to get it for $15.00 or $20.00 each. For the chassis, use stock aluminum c-channel or similar. For the wheels, there again that price is about what you would be looking at for such wheels, but you might be able to find ones cheaper via an R/C shop or such. Or, maybe you can find an old R/C toy that has large enough wheels. Or maybe repurpose some other kind of wheel? At a certain point, you'll be in up to your neck in trying to figure out how to customize this to fit that, or how to custom build some part to mate two other parts together (the big one would be the wheel hub/shaft adapter for the motors); you have to figure out not only how to do such a thing, but also how to make it as strong as possible for the weight or torque it will bear. Not an easy task, and expect more than a bit of failure until you get it perfect.

Again - if this is your first time with such a project - doing it from scratch very well might cost you more than simply buying the chassis. I also hope that by showing you the steps and how I found the information in the above, that you will be able to do the same in the future. Good luck with your project.





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