Asked June 12 2014

Community Question

Hi everyone.

I posted a question in regards to reducing the speed of my two 12v motors on the forum last week and I have been pointed in the direction of using motor controllers, and after a response I got from Rich, I found out that it is possible to use two controllers through one EZ-B, so I have ordered two 2.5 amp motor controllers from EZ Robots.

The reason why I need to use two is because the drivetrain for my robot build runs off a 12v battery and has two 12v drive motors that draw about 0.50 amps while running, but can hit about 1.4 amps peak for a split second, so using both channels on the 2.5 amp motor controller with a max peak limit of 3 amps per channel, that takes care of the drive motors.

The drive train also has one 12v steering motor that runs at 0.24 amps with a peak of about 1.3 to 1.4 amps, so apart from needing a third channel I wanted to leave a safety margin, that's why I will require a second motor controller (only using one channel) connected to the EZ-B v4, which I wasn't sure could be done. But as I mentioned above, Rich told me that although it is not done often, it can be done but the second controller would require scripting. So what I would like to ask is...

1.) Has anybody else done this with a similar set up to my example?

2.) Are there any examples of this in action? e.g, controlled via on screen sliders ect.

3.) I'm assuming that I will have to run 2 pairs of power leads from my 12v battery and connect to each L298. Is this correct?

4.) How would to L298's be wired up to a single EZ-B with speed control? I know Rich has a tutorial but I would also like to hear from other members who have done this.

5.) And finally, and this is the main point I am unclear of, one L298 can be controlled through the EZ-B via on screen sliders, smartphone or Wii remote accelerometer movement, voice control ect ect. But I have read that the EZ software will only have these controls for one L298, so how will I be able to control the second L298 for the steering, say for example if I wanted to use it in a "radio controlled" scenario, with both the drive motor control slider and the steering motor slider on one computer/touch screen?

I am waiting for my first batch of EZ goodies to arrive sometime this month, so I am new to all this and only going by what I have read and seen online so far, so any help and/or advice any of you kind people can offer would be gratefully received. There is not that much mentioned about using 2 controllers with one EZ-B on the forum so hopefully any answers or advice given will go towards helping others too. Rich has already offered me help in regards to scripting a second controller which I surly will take him up on, but it this "how will my finished robot physically be controlled Via an iPhone of tablet PC once its scripted" thing I'm scratching my head over.

Thanks everyone.

Steve ;)
October 5 2014
Ok. So I have gone with the HD servo I got from the shop and initial testing seem okay. 1 thing though, when the servo holds position either left or right, it makes quite an annoying buzzing sound. Is that normal? Although it doesn't make the noise when the servo isn't fixed to anything.
October 5 2014
A little buzzing is normal... Just check to see when the servo is left or right it's not binding on anything (pushing against the stops or end of travel)... If it is adjust the servo position until the buzzing goes away or is at least reduced.. Centre position it should not buzz too much...
October 5 2014
No Richard, deffo not being obstructed by anything and I have reduced the end of travel for left and right on a control. It seems the closer it gets to end if travel, the louder it gets. Not excessively loud, but louder than I was expecting. Center position no noise at all.

The new steering set up with the servo and lazy suzan bearing seems to be working great now, even with the weight of the bots chassis and body fitted, So thanks for the advice. Really appreciated. ;)

October 5 2014
That's normal... Glad it's all working for you... One tip (since you're going to add more weight to the bot)... make sure you distribute the weight as evenly as possible... You don't want the majority of weight over the servo... 40/60 front to back might be a good ratio....
October 5 2014
Thanks for the tip buddy. I replanned the equipment layout thIs afternoon so It's been taken care of. ;) . I've lost all the R/C gear which was all located at the front, and have no need for it now, and the main drive battery will be located over the rear drive wheels. When the head is attached to the body this should give me roughly the 40/60 weight ratio you mentioned.