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Asked — Edited

Wild Thumper 6Wd

Hi,

What motor controller should I use with the 6WD Wild Thumper platform?

I bought the 2.5 amp H-bridge board but obviously that's is not going to cut it!

There is a dedicated controller board (https://www.sparkfun.com/products/11057) but not sure how one would connect it to ez-robot board?

Has anyone else connect one of these to the ez-robot platform?

Thanks

Paul Clarke


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#1  
Hi Paul. You have a few options and that spark fun controller may not be a good fit. It is both the h bridge and also a arduino microcontroller. You should get two more 298n controllers in the ez robot store and each set of motors would have their own low cost and low heat h bridge. You would just parallel the power, signal and ground wires . One for the right side and the other set of power signal and ground for the left side. That's a 30 dollars cost and you can directly control it with pwm control from ez board. Again because that board is meant to be a stand alone system i do not recommend that one.
PRO
Synthiam
#2  
Josh is super right. I think you were in contact with Alan earlier today. He asked me about the thumper and the 2.5 amp controller. We updated the store description for the thumper to reflect the suggestion that you'll need 3 of the 2.5 controllers. An hbridge (wether sabertooth or not) will require an hbridge per set of motors. Running more than one motor in series or parallel is terrible for power consumption. It's practically impossible to predict the draw of each motor individually and therefore creates an issue.

So affordable low cost controllers for each set of motors is recommended.:)

Btw, they should be connected in parallel (the controllers) to use the hbridge motor control panel on ARC
United Kingdom
#3  
Many thanks Josh and DJ

So just want to check your last point DJ. You are saying that:

1) Each motor should be connected to an individual H-bridge

2) The PWM inputs for the 3 H-bridges for the motors on each side of the Thumper should be connected in parallel and then connected to the EZ-Robot PWM output so that they can be controlled in parallel by the hbridge motor control panel on ARC

Is that right?

Thanks
#4  
I will post one of my low budget illustrations tonight for you;)
PRO
Synthiam
#5  
Before we get Josh's awesome illustration, can you tell us how many volts and amperage your battery source is?
USA
#7  
Did the illustration get posted somewhere?
Canada
#8  
Out of curiosity and of desire to assist others with practical advice, as many have done for me over the years... Why advertise that the Wild Thumper 6WD needs three 2.5A underrated (for this chassis) controllers instead of one properly rated one? (30A MAX recommended for 6WD)

The Dagu Wild Thumper chassis come with motors pre-wired for paralleled use (per side of course :)) And as long as the drive controller is rated (safety wise) for the total stall capacity of all parallel wired motors then all is good! I.e. three 7.2v DC motors, each rated for 6.6A at stall (well over the 2.5A of the recommended controller) will only ever draw 7.2v and total of 20A (assuming ALL stall out simultaneously, more if rapidly changing directions). If just one stalls or is "off" then the remaining two still only draw 7.2v and whatever current they need.

There is no practical need to have separate controllers... I agree that it technically can be done... but, for a new robotics builder, suggesting such actually complicates things not simplifying them.

I do however totally agree with @DJ that wiring drive motors in series is just asking for trouble:( A change in one WILL affect all others, usually to the negative.
#9  
Well gunner the l298n are cheap , though a motor can draw higher amounts of current the l298n itself acts as a bottle neck. If anyone wants to use a pricy controller they can but naturally the ez robot l298n is the go to since there are tutorials to set them up. Ive used a pair of l298n to drive 4 motors in a omnibot 2000 chassis and it easily and smoothly transitions motor speed even when loaded with 60 pounds of weights onboard. The beauty of the tutorials is once they have one h bridge working they only need to splice those wires to connect to the the other two h bridges. So in that respect since the ez robot l298n is supported and has tutorials it is probably easier for a begginer than to try to figure out third party unsupported controllers. Make sense?

Illustration .. woops I thought I posted it ill get that tommorow for you.
United Kingdom
#10  
Hi Gunner,

Out of interest, what controller would you recommend for the Wild Thumper 6WD

The One I listed originally is obviously a complete robotics controller in it's own right and so a bit pointless to try and use that with the EZ-Robot controller

Are there any dumb controllers (rated at 20amps for each side) that you have come across that would interface well with the EZ-Robot controller?

DJ, if the l298n is going to throttle the motors at 2.5 amps, surely that's not going to work terribly well is it?

Thanks

Paul
United Kingdom
#11  
One option I was considering was to use a pair of cheap 30amp ESCs?
#12  
Hi paul - yes if you have a controller on each axle they work great. One of the other members had a video they send me of one running around his house in hardwood floors. It was very peppy. The continous rating is what your looking at when seeing if a controller will do the job. Which for these motors is aprox. 2 amps . Get you three l298n , they are small , cheap , and most important their are tutorial videos here and lots if members who use them. -Josh S
#13  
Yes you can use rc speed controllers but what I don't like about them is they make beeping and buzzing noises to indicate they are armed. L298n does not make any of this racket. You are welcome to buy bigger controllers but then it costs more when we have a great cheap solution ready to go. I don't like spending money on things I don't need to get the job done.
United Kingdom
#14  
Many thanks and sorry for all the questions!

I will give the l298ns a go then
#15  
did the drawing ever got posted?

Noob trying to connect the 6 wheel thumper this weekend:D
#16  
Lol I forgot a drawing ill try to post one tommorow when im by a desktop pc.;)
#17  
looking forward to it:D
#18  
I also had a question re: the 6WD Wild Thumper. What is the gear ratio on the ones in the store? I know they sell 34:1 and 75:1 and I'm wondering which these are.
#19  
75 to 1 , it gives them a higher payload capacity. Its still a quick when you give them some juice. Many use a 7 volt lipo battery but personally I would use a 3s 11.1v lipo because it has a great deal more power. You still control speed with pwm but with the 11.1v 3s lipo you have a lot more acceleration and torque available. ;)
#20  
Awesome, thanks. That is what I was hoping for. To my way of thinking, any serious robotic platform should have more load carying capacity as opposed to speed.
#21  
mine came in and it is the 34:1 ratio! Just FYI
#22  
Thanks ray , whats cool is those dagu chassis have swapable parts.
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