I was wondering if anyone had more information about the GHM-04 motors.
Firstly are these the motors which are on the 4WD-1 Kit? It looks like this is the case but I’m not sure.
Secondly, I will need to build my own motor driver as it is a requirement for my class. I have looked at the Scorpion motor driver and also the Sabertooth 2x5 controller to get an idea for what kind of power I need to design my motor driver to handle. Would one scorpion driver be enough to power all 4 motors on the 4WD-1? I wasn’t sure because on the spec sheet for the motor it was showing that the motor could draw up to 3.8 A each if it were stalled.
Would you think that a 2 channel driver with 4A/channel (continuous) and 6A/channel (spike current) would be good enough, too little, or overkill?
I would assume that you were using the 2 x 10 to drive 2 motors per channel right?
From what I can tell of the motor specs, I need to be able to supply at least 4 amps of non continuous current per motor, is that about right?
Also I was thinking about just having 2 powered wheels in front and making the rear wheels free spinning. The amount of weight the robot will need to carry is not that great but I love the look and form factor of the 4WD1 especially since I must design and build most of my own boards (motor drivers, main controller, etc) as a requirement for my class and hand soldered protoboards tend to be quite a bit bigger than the premade modules.
Right now, I’m trying to decide whether I should buy a 4WD1 and make the two rear wheels free spinning or to buy an octobot kit and modify it to mount the 2 of the GHM-04 motors using the GHM motor mounts. What do you think is the better way to go?
I don’t think the passive rear wheel idea is a good one. The motor controller does not need to be able to supply the full stall torque. If you were building a sumo or other fighting bot I would design for it. But a rover will not get anywhere near the stall torque in normal use.
Will the Sabertooth 2x5 handle two pair of GHM-04 motors without any problems on a four wheeled rover? Should I be going with a 2x10 instead to be sure I have enough power to handle them?
I ask because I am getting ready to order another motor controller for a redesigned W.A.L.T.E.R.
I presently have a Sabertooth 2X5 RC on a 4WD1 and it works just fine with the mini-ABB and an Atom 28.
However, I have it mounted on a 3"X3"X1/4" chunk of aluminum with some Artic Silver thermal compound for good thermal conduction.
So far, no problems.
If you purchase the RC version, like me, be sure to clip the red power lead on each of the three pin connectors so the +5v power supply on the 2X5 RC will not try and buck the +5v regulator on the mini-ABB or the servo battery if you are driving more than the 2X5 RC on one of the mini-ABB servo headers.
I also have a Sabertooth 2X10 that I am saving for Jim’s new 6WD Rover!
I am thinking about just going ahead and spending the extra money and getting the Sabertooth 2X10 Regenerative Dual Channel Motor Controller (not the R/C version), simply because it could be used with more combinations of motors. I’d rather not have to purchase another controller right away if I got the Sabertooth 2x5 and it would not work with two pairs of GHM-04’s.
Of course, if I end up eventually going with full four wheel independent control and steering, I’d need two motor controllers anyways. That would be quite a ways off though. I want to take this in small steps. A pair of GHM-04’s is just going to be too much torque and speed for a two wheeled W.A.L.T.E.R., and I would like something that could potentially run outdoors as well as indoors.
