Let's Make Robots!

bi-directional speed controller

Hi all.

I am really new to robotics, and only just recently got my arduino uno. i've played around a bit here and there to learn how to control servo's and such, so i figured it's time for me to build my first robot. but in the design, i've come across a few problems:

1: the robot i intend to build needs to be able to haul its approx. 10KG butt around (including motors), so i decided on using 2x 6v 3a motors. this on it's own is a problem, considering the l293d can only handle up to just over 1a. i've considered stacking them to share the load, but then i'd need 14 of them to include 3 servo's aswell (that's if i use 3 per motor/servo. i've estimated the servos to draw 3a each aswell, as they are going to have large loads on them).

2: i need to control the speed of the motors as well as the direction. other than using an ESC, what's the easiest way to do this? also, if i do use an ESC, how do i link it up to be used with an l293d/other motor controller?

3: the arduino doesn't have enough pins for the design i've thought up

4: i'd like to use as few components as possible, in hopes of keeping costs minimal...

can anyone give me some ideas on how to make this work?


thanks for taking the time to read this.

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you could supply about 4A per motor. Your servos will not require h-bridges. You will need to supply about 8 or 9V @ 3+A to feed your motors. You will also need about 6V @ about 3A to supply current to your servos, unless they are really large. Then you will need to be able to supply more current. Saving pins should be easy enough. Using a NOT gate on your motor direction pins will save you 1 pin per motor. You will then only need speed and direction for your motors, and, 3 signal lines for your servos. You really shouldn't need any components beyond motor drivers and a DC-DC convertor to get 6V to drive your servos. A few caps spread around to make sure your motors don't draw too much current and reset your arduino will be about all you should need. Don't forget your sizeable batteries. :D

Thanks birdmun & basile for all the help :-D

i'll google the details and parts. i live in South africa, so parts are hard to find here.

thanks again :-D

thanks oddbot :D with a lil googling, i found the wild thumper motor controller... also, what's the use of doing something if you're not gonna take it head on? ambition is what we live for!!!