Choosing parts for a simple obstacle avoider or line follower robot

I'm a teacher and I'd like to build a very simple two wheel robot as a continuation of an Arduino introduction in a high school course. So far we've used Arduino with LEDs only. I'd like to get into something more exciting like driving motors and using sensors to either avoid obstacles or following a line (btw which is easier?).

We already have Arduino boards (and wifi shiels) but no mechanical parts. I'd like to build a cheap prototype with my students this year and, if all goes well, build some more next years.

I made some research and found there is no "mainstream" cheap kit in that field and I don't know exactly what my requirements are. I guess I need:

  • a motor shield
  • two gearmotors
  • some chassis with wheels
  • sensors

Could you recommend me some of these parts?

I've also been looking in some kits like:

  • DFRobot 2WD(turtle) mobile platform
  • Dagu Rover5
  • Sparkfun Magician Chassis
  • Sparkfun Protosnap Minibot kit

Should I go for some of them instead?

Thanks!

btw which is easier?

Detecting obstacles is easier than sensing a line.

Using the data to avoid the obstacle or to follow the line is about the same level of difficulty. In one case, you run the motors until a value (distance to obstacle) increases. In the other, you run the motors until the value decreases (distance from line).

I guess I need

A good list.

Could you recommend me some of these parts?

Start with the chassis. Get motors to fit. Get a shield to work with those motors.

The sensors depend on what you want the bot to do (avoid or seek).

Should I go for some of them instead?

In my opinion, part of the fun is choosing the components and assembling them. A premade bot or kit takes some of that away.

I could build a chassis from wood - or even better reuse some toy parts - but the focus of this project should be on electronics (sensors, data and programming) and I can't spend much time on mechanical parts. That's why I looked into kits also.

Anyway what about this choice: - arduino motor shiled rev3 - tamiya double gearbox kit (IIRC you can choose ratio when assembling)

Any recommended sensors setup for line following? And for obstacle avoiding? IR or ultrasonic?

Thanks again!

Hi, a few pointers based on what I have messed with:

Chassis/Motors: You mentioned Dagu products, from different suppliers. Dagu information and the manuals for most products are here: https://sites.google.com/site/daguproducts/ (Thanks to Russell Cameron, who designed many of these, and the great Magician controller boards)

Take a look at: http://goo.gl/uBg9K (Disclaimer below) for some Robot stuff I have tried out..

The Robot 7-way Multi Tracking Sensor works well and is versatible for line following. The Ultrasonic sensors are best for obstacle avoidance. Putting one on a "Sensor Pan-Tilt" head allows the robot to look around while travelling ahead.

Sometimes Servo-based motors/wheels make it easy to get started with a robot. Simple 3-wire connection, built-in H-Bridge. But not highly powerful. Fine for travelling on a typical floor/carpet.

If you're going to use DC motors, the Micro magician controller has good FET-based H-bridges built in, plus an accelerometer to know when you hit something or fell off a cliff... And separate Servo power connections. Russell has thought a LOT about all this.

Keep narrowing in on what you really want/need...

Other: If you're doing a course, check out the ArduinoInfo.Info WIKI for class materials, like http://arduino-info.wikispaces.com/Arduino-What-IS-it and http://arduino-info.wikispaces.com/YourDuinoStarter

DISCLAIMER: Mentioned stuff from my own shop...