Need some help and advice on building first robot

Community General Discussions
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Hello everyone, I am currently researching into building a robot but have become a bit confused about what actual specifics I need to get everything to work.

Basically I want to build a tracked robot that moves a decent speed and can go forward/reverse and can turn. It would also be programmed by a microcontroller to do a set list of tasks. Sounded easy to me but actually figuring out what I need has been rather confusing.

So what I need help with is deciding what I need to make the project work this way I can decide whether or not I have the funds to begin the project at the moment.

Now as I said I want to make a tracked robot so I was thinking of getting the tri-track chassis kit and then adding everything else I need. I could purchase tracks and motors etc. separately and attempt to construct something similar but I think this might be more trouble then it is worth in my situation.

So assuming I use the tri-track kit what else will I need to be able to program the robot to move in certain directions? From what I have gathered I need a motor controller of some sort and then some sort of microcontroller. As well as a battery pack to power everything. Is this all that will be required?

If this is all I need then would you be able to recommend some certain components that I should use, if not could you tell me what else I will need? As I guess I have made obvious I am quite new to robotics but am willing to spend some time learning, that includes new to electronics and programming as well.

So just to reiterate I just want to be able to program the robot to move forward, backwards as well as being able to turn. Which would be done by only turning one of the tracks I assume. It will also need to carry a bit of weight but very little so it doesn’t need to be considered.

Sorry for the long post I just wanted to be as specific as possible, if you need me to give any more information or clear anything up please ask.

Thanks!

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Well, the basic configuration would be to use :

-Motor contoller (sabertooth, choose one)
-Micro controller, (Basic Atom is a possibility to program in BASIC)
-Controller board (on wich the micro controller goes, I have the mini ABB and it works suberbly well).
-Tri-track chasis.

I believe, since you are new to robotics, that the biggest of youre difficulty will come in programing the electronics. Electronics are already made (don’t have to create your own boards). Mechanics are (well, I’m talking for myself, but a rover isn’t that complexe). you can use snipets of code and you will be just fine to make it go foward backard and turn. If you want to go (later on) in more developed robots, then you should get some more info on programing more behavior like robots.

Have fun with your bot, don’t hesitate to ask for help if you have difficulty with something.

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Welcome to robotics!! Your first pre-requisite was that you be willing to learn and experiment, and I think you said you have that, so this is good.

First, I want to make sure you are choosing the right technology for your job. When you say you want a tracked robot, what type of environment are you planning on running in? If you are starting off indoors, on the carpet, tracks probably aren’t the best option. If you are starting outdoors, and have lots of stuff that is loose, like gravel, sand, etc, then tracks are perfect.

Of course, if you want tracks simply because of aesthetics, well, :smiley: That I can understand too, as your robot following your vision for it is pretty important too.

Lets assume you keep with the Tri Track kit. I think Jim has said that it can carry up to a few pounds of payload, so as long as your payload is small we are ok.

First, look at the Datasheet for the motors that come with the Tri Track kit. You need to know two things for the motors, what voltage they are rated for, and what current (Amps) they are going to stall at. This will help you size your drive electronics. So, down in Section III, we see a line that says “Rated Voltage 12V”. Ok, stick that in a corner of your mind. Then, go to the graph in the middle of the page. Look for the green line that is labelled Amps, and find the right most end of it. Trace the y coordinate of that end to the value on the left. This shows us that the maximum current that the motor will draw is a shade under 1.6A.

So, you have a motor that draws 12V at 1.6A. Your next step is to find a motor controller that is rated to handle that. Lets start out with the smallest of the two channel motor controllers that Lynxmotion carries, the Sabertooth 2x5. It is a dual motor controller, which means it will handle both sides of your robot. It has a voltage range of 6V to 18V. Your 12V motors are inside this range, so that is good. It has a continuous current rating of 5A, which is greater then the 1.6A your motors will draw worst case. So, if you wanted too, you could use LM’s smallest motor controller. Of course, then, the choice falls to you if you want to buy a bigger one or not. Oversizing your motor controller won’t hurt, and will allow you to use it on future bots with bigger motors.

Then we have to look at batteries to power your motors. Lynx has a small 12V battery pack. Of course, if you are just getting started, that means you will also need a Battery Charger. And of course, unless you want to do some soldering and hacking on the battery and chargers connections, you also need a Connector to hook the battery into your motor controller.

Ok, Battery, Motor Controller, and their related stuff out of the way. Time to get the logic portion of the robot. If you want your robot to do stuff by itself, you will need to put in a microcontroller. I would say go ahead and get the Basic Atom Pro, as its the most capable one that Lynx sells, and there is only a negligible price difference. Of course, you will need somewhere for that processor to plug in, so you need to get a Carrier Board to go with it. You will also need to provide power for your carrier board. If you look at the carrier board’s Manual, you will see it accepts between 6 and 9V. That means you can’t use your 12V battery to power it, as you will burn something up. The easiest option to use the carrier board is simply to have a 9V battery. (So, go grab one from your closest store.) The board comes with a 9V battery wire. Then of course, you will need some way to get data from the carrier board to the motor controller, so you might need A connection kit. As the last piece of the puzzle, you will need a way to get data from a Windows computer (which runs the Basic Micro software, free download) to the carrier board / microprocessor. If you have a serial port on your computer, you can use that. Otherwise, you will have to search these forums for which USB to serial adapters work.

And Viola, I think that is enough to get you off the ground! Good Luck and have fun!

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Thank you both very much for all that information! That is precisely what I was looking for and I very much appreciate the detailed explanations!

That should definitely be enough information for me to continue my research and hopefully start building in the near future. If I have any more questions I will post here again.

Thanks again for your help!

EDIT: Actually I just did think of one more question that I forgot to ask. Now this probably seems a little silly but how would I go about turning it on and off. Do I just buy a switch of some sort to put in between the batteries and one of the components. Or will one of the other components listed have an on/off switch on it?

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I think the kits come with one wiring harness. Wiring Harness which connects easy to bot board and NI-MH batteries.

What it seems is you get one harness with the tri track set and will have to buy another if you wish to add scc-32 servo controller.