power concern

Hey all first post here and first major project on my own with Arduino.
Below is a link to a motor that i plan to be running on my project. There will be 2-4 of them (having decided 2wd or 4wd)
Link to motors

I plan on running a 12v battery linky link <----

Motor control board that i plan on running (unless i find a better version or am suggested other wise)

My question is will the be to much for the Arduino to handle? This is one of the few robotics projects I’ve ever attempted. Not trying to fry the board before i even get to use it.

It appears they draw about 7.5A in normal operation - I can’t find the rating of that control board in the Amazon ad, but I think you’ll be better off to build your own H-bridges with suitable MOSFETs. It doesn’t look like it’s designed for high currents.

Then, did you see that stall current? Such a battery may very well be able to supply that current - even if all four motors get stuck at the same time. I’ll leave it to you to think of what will happen to your board (and your battery).

You have motors that will run at about 20A each and at several thousand rpm and you haven't mentioned any gearing. Your motor controller can deliver less than 1A per motor. The battery is heavy and will not like trying to deliver 4 x 20A.

Everything is badly mismatched. Perhaps you could start by saying what exactly you are trying to build. Then people round here may be able to suggest a more suitable collection of parts.


essentially i'll be making a wagon that will be rc controlled or setup for following a human that way around the yard to put things like vegetables from teh garden to small twigs and such that fall nothing to heavy. maybe the weight of a push mower at worst

would this work?

kamonso: would this work?

100USD?- jeez, you have deeeeeeep pockets.

You're working back-asswards here. You need to figure out the mechanical side first, mass and speed and all that cr@p, to arrive at a suitable motor, which in turn will inform the power and driver requirements.

would this work?

Yes, if motor off/full forward/full reverse is all you want.

You should learn by making a small cart as a model before trying the real thing.

Getting any robot to go where you want, and especially to follow something else, is a major challenge.

Well, yeah, for your motor it may work. But is your motor even suitable?

Why don't you start with say a small golf cart, and modify that? Then at least you know you have suitable motors, the gearing is taken care of, you have a steering mechanism and a matching battery. Saves a lot of work.

And do remember to include some form of fail safe as the last thing you want is being run over by your own cart.

Or, to start small as suggested in #6 (which is a good idea indeed), a kid's car.

Those motors are more powerful version of a power wheels motor. I figured they were cheap and could hold the weight. I can't afford a golf cart motor at 400+ ea new. I have a few family members I'm doing this project for so new parts are what I'm aiming for. Used parts are to scarce in my area

Or would two of these

24 Volt 400 Watt MAC® Brushless Motor with Built In Speed Controller (gotta look on the page for it)

Be a better option?

With those I’d switch to a track system since it’s not reversible

Better link to the above motor with wiring diagram to see if it could work

How much power and speed do you want your cart to have? What gearing will you use? Answer that, and you can tell whether the motor is suitable for the application. it seems to have some form of control but I don't see how that can easily be interfaced with an Arduino.

speed 1-2 mph cruise speed 5 mph peak. Not sure what you mean regarding gearing.

Gearing... from motor (high RPM) to wheels (low RPM). What RPM will your wheels spin at for your speed, and then what RPM does your motor have to spin at?

Also consider the roughness of the terrain including speed bumps and thresholds at doorways, the maximum incline you may encounter, and with it the torque needed to overcome those obstacles with maximum load on the cart (plus of course the considerable weight of the cart and its batteries).

kamonso: Not sure what you mean regarding gearing.

wvmarle: Gearing... from motor (high RPM) to wheels (low RPM).

Just like in your car.

kamonso: essentially i'll be making a wagon that will be ... setup for following a human

jremington: Getting any robot .... to follow something else, is a major challenge.

Did around the forum: I do recall one example, but not a trivial thing at all

wvmarle: the last thing you want is being run over by your own cart.

If it's big enough and fast enough, it may literally be the last thing....

kenwood120s: [follow-me robot] Did around the forum: I do recall one example, but not a trivial thing at all

Makes it sound like a fun challenge to me (albeit not in the scale OP suggests).

The hardest part I think is in the positional awareness of the robot: knowing where it is in relation to its master (distance & direction). Making the robot move to that point should then be fairly straightforward.

wvmarle: The hardest part I think is in the positional awareness of the robot

Some kind of beacon thing....

For example ottomh, an infrared 38kHz carrier modulated with a specific "I am me" message, that a TSOPxxx style receiver can look for.

But where will that beacon be? The gardener will be standing, kneeling, crouching, walking, facing this way or that, partly obscured by cabbages. Strapped to the ankle maybe?

Very challenging project: but that of course, is the whole point of a hobby isn't it? No mad rush like client deadlines, no H&S inspector (bless 'em) lurking behind those cabbages, no large scale production implications to address. Just something that "works for me".

How to get a distance and direction to such an IR beacon? AFAIK the TSOP receivers are designed to have a very wide detection angle, and definitely have no idea of distance.

I said it was ottomh. Will need say an IR or ultrasonic sensor to measure the distance, once the robot knows it's pointing at the person through some other means. Could always try a sleeve on the tsop to narrow it.

Point is, it needs to know that the thing it's pointing at is the right human, so the cart doesn't go wondering off after the dog.

I just did some Googling on the subject, and most posts talk about using a camera and image processing software to identify the master. Even so this is not straightforward as the master still needs something uniquely identifying, and facial recognition is out as the master will normally look away from a follow-me robot.

IR sensors are used for simpler such robots. Use two (or more) sensors, see which one gets the stronger signal, turn in that direction until both have the same strength. Works until there is no line of sight, and the robot turns towards the wall with the strongest reflection. It would be easy to add sensors and make it omnidirectional, so it can easily detect a master that’s behind the robot. IR sensors and sunlight are not the best friends, though.

So back to OP: best you do is get two smallish motors, and use that to build a two-wheeled robot. Get this robot to follow you first, after that’s working you’ll have gained a year or two experience and you’ll be much better prepared to decide what you need for building the full scale version. Sensors are basically the same, control software is mostly the same (some parameters different mostly).