First Arduino + Servos, what to buy?

Hi !

I've been lurking at tutorials, projects, .. concerning Arduino for a long time now, and I'm finally buying one. I'm an experienced developer so I don't think software will be a big issue; but I'm completely new to micro-controllers and mechanics.

This is what I'd like my robot to do, simplified: - I turn it on. - I push START, it records the position of the wheels (=the rotation of the servos). - I drive my robot a little further. - I push STOP, it records the position of the wheels (=the rotation of the servos). - I push PLAY, it comes back to the starting place, and plays back the movement. (=it moves back to START, and drives to STOP).

Here's my basket at sparkfun.com: - Arduino Starter Kit - Arduino Protoshield Kit - Tool Kit - Beginner - Beginner Parts Kit - Serial Servo Controller - Servo - Full Rotation (2 - pour les roues) - Serial enabled 20*4 LCD - Potentiometer knob - Rotary encoder

Are there missing or unnecessary things? The LCD + potentiometer would replace the three buttons in my example (Start, Stop, Play).

Do you think it can be done with these components? Also, could my robot take a bend, like this?

Thanks :)

The LCD + potentiometer would replace the three buttons in my example (Start, Stop, Play).

Buttons hold shirts closed. Switches can be open or closed, and can communicate information to the Arduino.

An LCD is used to display information. A potentiometer is used, with an Arduino, as a voltage divider device. The center tap will, therefore have varying voltage levels, depending on where the shaft is positioned. The varying voltage can be read by the Arduino, and the changing level can be used for controlling PWM outputs, for instance.

How do you intend to use an LCD and potentiometer to keep your shirt closed? Or did you mean switches? In which case, how will an LCD and potentiometer substitute for 3 switches?

Sparkfun's site is down for me, so I can't be really sure, but I think that the potentiometer can act as a push button as well, so, by rotating the potentiometer you would switch between "record start position", "record stop position", "replay movement" and "erase positions". by pushing the potentiometer, you would accept (if I'm wrong, I could add a "OK" push button)

by rotating the potentiometer you would switch between "record start position", "record stop position", "replay movement" and "erase positions".

For your first project, do yourself a favor. Use the switches that come in the parts kit. Yes, you could use a pot this way, but it does not include a push button capability, as you implied, so getting from "replay movement" back to "record start position" will involve going through "record stop position". The stop position will be recorded many times while you're fiddling with the pot.

How do you intend to use an LCD and potentiometer to keep your shirt closed? Or did you mean switches?

From Wikipedia:

A push-button (also spelled pushbutton) or simply button is a simple switch mechanism for controlling some aspect of a machine or a process.

Less "arsey" and more "helpful" wouldn't go amiss.

Andrew

The stop position will be recorded many times while you're fiddling with the pot.

Ok, I get it. Now, can you tell me if I am missing parts / if with all this in hands an experienced arduinist could build exactly what I'm looking for? That's what I'm most curious about :P

You’ve got the stuff needed for the brains and motion part of the robot. A chassis and some wheels would be useful. Other than that, though, you’d be fine.

great ! thanks, a lot I think I'll build the chassis myself once everything starts to work as for the wheels... at sparfun they were like $13, I think I'll find them for cheaper or free somewhere else. again, thanks ;)

Oh, I almost forgot I don't know how vehicles "turn", I think the wheels are supposed to rotate on the Y axis? Can servos control it? Where can I find some basic information about this?

You can run the servos at different speeds. Make the left side turn faster and the robot goes right. Make the right side turn faster and the robot goes left. Make them turn the same speed to go straight.

One thing to think about is how you will press the stop button when the robot is racing away from you.

lol, ok ! ;D

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You have a poorly designed web page. Bottom products on left bottom of page can't be seen on some small computer screens. They keep moving off screen when trying to scroll down to see them.

I didn’t see a portable power source for your robot. :slight_smile:

Maybe you want to get one of these to power the Arduino using a 9V battery.

You may also want to get a separate battery holder to power the motors (maybe you can power them using rechargable batteries).
http://www.sparkfun.com/commerce/advanced_search_result.php?keywords=battery+holder&x=0&y=0&search_section=products

Sounds like a cool project, please keep us posted here.