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field road, jupiter creek
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So I just got my shiny new Dagu Rover 5 chassis.


After digging around on the web, I finally found a blog that gave me the adjustment procedure for the motor/gearbox/wheel mounts.
As the bloke pointed out Dagu ship the Rover 5 with the wheels at their greatest extension and the tracks on and like the guy said, it had deformed the main chassis.
Not very much, but the drive arms and wheels were no longer parallel.
I set mine at 45'ish degrees.
2 days later the bend in the chassis sides is starting to come out and the track wheels are almost parallel on each side.

My biggest bitch here is, and it might not be immediately clear why, I got shipped the 4 motor version.

With tracks.

Think about that for a bit while I get another beer.
 smiley

I just spoke to a bloke @the pub who works on 'dozers and other tracked earthmoving  machinery.
He used to work on APC's and tanks in the Australian Army.

I had been thinking about this for the last 2 days, but I had it confirmed tonight!

Having BOTH ends of a track powered is totally pointless!
Worse than pointless.

Not only do you get NO benefit in traction or steering, it is going to use twice as much power.
And probably stretch your tracks as well.

For tracks you only need or want the 2 motor version of the Rover 5.
The 4 motor version is best suited to wheels.

Good thing I ordered 4 Dagu Thumper wheels.

I'll still use the tracks and wheels, but it's going to be a scratch built chassis.

The only bit of Dagu documentation for the Rover 5 tells us the motors are 7.2V with a 2.5A stall current.

So with 4 motors, that is a potential stall current of 10A!
Which rules out using an L298, even if you use 1 per motor!

I ordered one of Sparkfun's Monster Motor Shield's, the VNH2SP30 can handle 30A, the Sparkfun doc says the VNH2SP30 will barely get warm if you keep the current under 6A.

Anyway, I have the 120mm Thumper wheels coming and a motor controller that can handle 10A easy.

The Rover 5 is a great chassis, it feels solid, it's well made, ton of ground clearance.
It doesn't look like it is at all water proof, but that can be fixed.

Before you buy one, make sure you get the right one!

4 motors = 4 wheels

2 motors = tracks




« Last Edit: September 21, 2011, 09:08:20 am by cyberteque » Logged

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Quote
it is going to use twice as much power.

That also means it's going to generate twice as much power.  On a small rover like the dagu, that may not be of any real use, but there are plenty of tracked rovers out there that utilize 4 motors for the additional torque/power.

and the truth is tracked vehicles will need that extra power moreso than wheeled vehicles.  In high traction situations, it takes more power to get the vehicle to turn.

Again, may be unnecessary for a smaller rover, but maybe not.  The 4 motor dagu rover will have a higher payload capacity than the 2 motor version as a result (and I have no idea what either is).  So it's usefulness will depend on what you want to use it for
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field road, jupiter creek
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I have yet to try it with wheels, but unloaded the motors draw 1A more with the tracks than without.

On a surface that had some "give" the tracks might be ok.
On an indoor surface the rubber tracks could get some real traction on that will be way more current.

I want to build an ROV, that I can try out navigation between waypoints, holding a course, that sort of thing.
The whole premise here is the ground is a more forgiving environment than the sea or sky.

The actual Rover 5 chassis is in no way, shape, form or mean water or dust proof when it comes out the box.

It wont be too hard to make it at least dust proof or even moisture proof.

Don't get me wrong, I love it!
My finished ROV will, I hope surprise you.
But this chassis is going with the 4 Dagu thumper wheels.

I have a whole valley to roam in and I get XBee coverage over most of it!
Unless I get antenna tracking happening, I'll have better control coverage than video uplink coverage!

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So I just got my shiny new Dagu Rover 5 chassis.

After digging around on the web, I finally found a blog that gave me the adjustment procedure for the motor/gearbox/wheel mounts.
As the bloke pointed out Dagu ship the Rover 5 with the wheels at their greatest extension and the tracks on and like the guy said, it had deformed the main chassis.
Not very much, but the drive arms and wheels were no longer parallel.
I set mine at 45'ish degrees.
2 days later the bend in the chassis sides is starting to come out and the track wheels are almost parallel on each side.

Yeah - I heard about that issue before; other than that it looked like a nice chassis...

My biggest bitch here is, and it might not be immediately clear why, I got shipped the 4 motor version.

With tracks.

Think about that for a bit while I get another beer.
 smiley

I just spoke to a bloke @the pub who works on 'dozers and other tracked earthmoving  machinery.
He used to work on APC's and tanks in the Australian Army.

I had been thinking about this for the last 2 days, but I had it confirmed tonight!

Having BOTH ends of a track powered is totally pointless!
Worse than pointless.

Not only do you get NO benefit in traction or steering, it is going to use twice as much power.
And probably stretch your tracks as well.

For tracks you only need or want the 2 motor version of the Rover 5.
The 4 motor version is best suited to wheels.

Good thing I ordered 4 Dagu Thumper wheels.

I'll still use the tracks and wheels, but it's going to be a scratch built chassis.

LOL - any way of converting it to two motors?

The only bit of Dagu documentation for the Rover 5 tells us the motors are 7.2V with a 2.5A stall current.

So with 4 motors, that is a potential stall current of 10A!
Which rules out using an L298, even if you use 1 per motor!

A single L298 (D or N, I think) can handle 4 amps in bridged mode (controlling a single motor); you'd probably want a small heatsink on it @ 2.5 amps for each motor, though.

I ordered one of Sparkfun's Monster Motor Shield's, the VNH2SP30 can handle 30A, the Sparkfun doc says the VNH2SP30 will barely get warm if you keep the current under 6A.

Anyway, I have the 120mm Thumper wheels coming and a motor controller that can handle 10A easy.

The Rover 5 is a great chassis, it feels solid, it's well made, ton of ground clearance.
It doesn't look like it is at all water proof, but that can be fixed.

Before you buy one, make sure you get the right one!

4 motors = 4 wheels

2 motors = tracks

I'll definitely keep that in mind - but I doubt I ever will buy one; much cheaper to buy an old R/C toy from Goodwill and mod it, IMHO (not that I need to do that, mind you - my current project is based on an H2 PowerWheels ride-on toy - and an L298 won't run that bad-boy, even in bridged mode - heh)...

Thanks for the review!

smiley
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