General Help

[SciOlyStudent]

Hi, I'm new to this website and the concept of building robots.  I'm looking to participate in a competition where I have to build a robot that can move objects (batteries, index cards and tennis balls for a few) into a box.  I have read some of the tutorials, but I have to say I was a little overwhelmed with all of the the information and I have NO IDEA  about some of the stuff they talk about... Just to start, how would I go about making a RC robot that has differential drive?  What parts and building are required?  Thanks for any help in advance!

[nottoooily]

Buy an up-market RC car with a diff, sellotape some plywood over it, and you're finished.

[SciOlyStudent]

Thanks, but even though I am a beginner, I'd like to make something myself.  I am going for simplicity, but that doesn't mean that I do not want to be challenged.  Thanks again anyway.

[nottoooily]

How much do you know about electronics?

The mechanical parts are usually just common sense, what in particular is confusing you?

For example, you could buy two gearmotors, bolt them to a chasis, fit wheels to them, solder up motor drivers to switch the motors, solder up a microcontroller to control them, make a regulator to power the chips, stick some batteries in, program the uc and drive away.

What part(s) of that are confusing you? Or is it the overall design that you're not sure of?

A lot of the design decisions can come down to what tools you have and what parts you can get cheaply enough.

[Admin]

Can you tell us more about your requirements?

A good place to start is to write a list of requirements, then searching one item at a time for what you can do to fulfill that requirement.

For example, if you need a motor, then look up stuff like where to buy one, how to select for torque, how to control a motor, how much power would it draw, etc.

Its also a good idea to read about other robots to get ideas.

even though I am a beginner, I'd like to make something myself.

You must decide what your limit is on buying vs making stuff. Do you want to buy capacitors or make them? Do you want to coil your own motors or buy them?

I prefer to buy everything if possible, only making what I can't buy. And I'm definitely not a beginner!

There is a lot to absorb for your first bot - if you decide to make everything on your first try, you're in for a long long journey

[SciOlyStudent]

To answer some of your questions, for the most part the parts do not confuse me, its the connection process.  I think a big part is not understanding the reason behind the certain parts too, because I am just like that (hard for me to learn without having a reason as to why it works like that).  And to the admin, I do not really know what I need in this robot and I want a "cheapish" robot but at the same time I DEFINITELY do not trust myself to make the parts.  I guess to rephrase the question here, how do I link my robot to my remote control and be able to make it go straight, and if you could please explain why certain things are needed because if I can understand the workings of this then it will be much easier for me to carry out the other parts of my robot (mainly an arm to grab objects).  Also, is there anyway to control this without using a micro controller and programming?

[Admin]

This remote control tutorial might answer a few of your questions:
http://www.societyofrobots.com/remote_control_robot.shtml
(no microcontroller interfacing required)


And this is a good read to understand how to build a robot step by step:
http://www.societyofrobots.com/step_by_step_robot.shtml

[Robotboy86]

also we call admin "Mr. god sir lord master king of all"


That probably wasn't in the 50$ robot tut..

[Admin]

lol . . . but I ask for help in my own forum as much as you guys do

[SciOlyStudent]

Yes, I have taken a look at those tutorials, and if I was just starting my robot career for a hobby, then they would be great, but I need to build a different type of robot.  In essence, I'm trying to "skip" the beginner stage by trying to understand what makes the robot work, not just how to put it together... sorry if I'm being vague.  What I really need to know is how to make an RC robot that I can move around.  If I follow the tutorial on making an RC robot, how do I know what on the controller does what, for instance.  WHAT makes it possible for the remote control to drive the robot?  I'm looking for understanding, not just a list of parts and an instruction manual.  Maybe hard to understand, but could you please explain Mr. god sir lord master king of all?

[nottoooily]

Yep, I would never copy somebody's design for that reason. If I knew why the various parts were there I'd have designed it myself in the first place.

I recently entered a competition where I didn't know how I should design it. So I started with an idea that seemed like it might roughly work, and I told myself I would make a first version, tweak it as much as possible, then discard it and build a new one starting from where that left off, and repeat that till I ran out of time.

With that mindset, I never had to worry about what's the best way to do something, the main thing was getting it to work, any optimizations could come in later versions. So the first one was powered by a cordless drill, that was just enough to test that the tracks worked and could climb the obstacles. I then went through several different drivetrains until finally settling on a good one.

I think once you start building, the things you need to know will present themselves as brickwalls and it'll be blindingly obvious what you need to find out to solve each problem in turn. You might find you have to tear it apart and start again. Accepting that as inevitable makes things move much faster.

To answer some of your questions, for the most part the parts do not confuse me, its the connection process.  I think a big part is not understanding the reason behind the certain parts too, because I am just like that (hard for me to learn without having a reason as to why it works like that).  And to the admin, I do not really know what I   Also, is there anyway to control this without using a micro controller and programming?

[Admin]

I second what nottoooily said . . .

I'm more in the engineering camp, meaning I only try and understand what I need to so that I can get it to work. Over the years I've learned a lot on the way, so now I can do a ton of optimization before even my first prototype . . .

I think the best way to learn is to start with something someone else built/designed, then start experimenting on it. This way you have something that works, and you can take it from there. Try adding a new sensor, or upgrading motors, or attempt to mod the algorithm. The $50 robot I made is meant to be heavily modded. There is quite a lot to understand in robotics, with a very sharp learning curve, so just take it piecewise and work your way up.

WHAT makes it possible for the remote control to drive the robot?

I'm not quite sure what you want to know here, so I'll give a quick rundown.

The controller takes the inputs from the joystick and converts it into a radio signal. This signal travels wirelessly and is recieved by the reciever. The signal is decoded, and appropriate servo command signals are then sent to each port of the reciever. The servos get these servo signals and then actuate appropriately.

[SciOlyStudent]

Ok, thanks for all the input.  And the RC question was more supposed to be, what would determine which input into the controller would do (joystick up/down), but from what you said I am assuming you have to use a micro controller to make the process possible.  Thanks again for all of you help.

[Admin]

It depends on how you configure the RC controller. They have buttons to change settings. Plus, each joystick controls a different channel, so you can decide which channel controls which servo.

Its actually really easy and self explanatory.