it is going to use twice as much power.
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. 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 wheels2 motors = tracks