Let's Make Robots!

Controlling a bots turning movements

Im thinking of implementing something like whats shown below. The bot scans from left to right, in increments of say 20 degrees, storing each value recorded. Then based on these readings, moves in the direction where there is no obstacle. Now here lies my problem. I cant figure out how to get near precise control of the bots turning movements. I can, say make it turn 90 degree left or right; but how do i make it turn to an arbitrary angle from a halted position? Is this possible, or am i being over enthusiastic?

Programming help, sharp IR mounted on servo


I am trying to control my bot using a sharp IR sensor mounted on hitec servo with arduino mega. The pseudocode i have so far is as follows:

1. Set servo at 90deg and read IR sensor value
2. If val > 200, then stop the bot for a second
  a. Turn servo 0 deg completely and read ir val
  b. if val < 200 then turn bot left
  c. else turn servo 180 deg and read ir val
  d. if val < 200 then turn bot right
  e. else if cant turn right or left, reverse a bit and then turn the bot 180 degree and go straight.

Seeks light, then bangs into a wall
Using a
  A update of the bot put up here : http://letsmakerobots.com/node/9163   Just to save reading two similar posts, i'll brief what i've done:   Read more

The challenge of building a 1st bot..


I got my arduino mega in the post a few days back and having been playing around lighting up LEDs. Thought id get started with constructing my 1st bot. Hence i rigged up 2 motors, a dual mc33887 motor driver, a 6v supply and the mega board. Uploaded a sample code to see if it would turn the motors. Voila!! Nothing happens. Nothing whirring, no sound, no ecstasy. No nothing. 

Its quite obvious that my bot wont perform with stationary wheels.

Still trying to find a solution. Images of connection, mc33887 truth table and sample code below.

Suggestions on choosing motor


Im considering on buying the following motor for my project.


Quick specs : 12V, 150 RPM, 195 oz-in torque, 67:1 ratio

Beginner robot..suggestions please!! (Axon and VEX for the bot)


Im envisaging on building my first robot, so would greatly appreciate any advice.

About me > I've some basic programming skills through GW-Basic and QuickBASIC which i learnt nearly 10yrs back. I suck at C programming, and am not well versed with microcontrollers/electronics, although im sure i can learn (maybe not C!!). Mechanically, im sure i can conjure up something fairly decent, if not pathetic!