Please Help Me!?

Question

i need a science fair project idea quick! It needs to do with something electronic with circut boards (i love soldering) and im kind of a starter..... ive only built 1 circuit board b4 and that was with instructions but im catching on quick. I LOVE ROBOTS! so please throw out some ideas and links!

Answer 1

I'm thinking a small vehicle moved forward by two motors, one driving each back wheel. A spdt micro-switch on each of the two front corners. a dpdt relay for each motor. Since I cannot graphically draw a diagram I will try to verbally draw it.
Here is the operation of the left motor.
There are two sets of contacts for the left motor relay .
The positive wire from the battery goes to the power switch terminal one, and terminal two is wired to the comon pin of contact set one, the negitive wire from the battery goes to the comon pin of set two.
The positive wire to the motor is wired to the NC (Normaly Closed) pin of set one, and the NO (Normaly Open) pin of set 2.
The negitive to the motor is wired to the NC pin of set two, and the NO pin of set one. I'll tell you why in a minute. Now, the positive wire from the battery is wired to the common pin of the right microswitch. The Normally Open pin is wired to the positive terminal of the relay coil, and the negitive of the battery is wired to the negitive of the coil.
The right motor is wired in exacly the same way to the left mictoswitch.
Circuit operation (where I try to explane why it was wired this way)
When the power switch is turned to the on position, power flows throught it to the comon pin of the left relay, out through the NC contact to the positive wire of the motor, causing it to turn in the forward direction. The same is happening with the right relay and motor. Since both motors are turning in a forward direction, the vehical moves forward.
If the left microswitch encounteres an object, it closes, sending a voltage to the coil of the right motor relay. The right motor relay closes. Now the positive voltage, which previously had been applied to the positive terminal of the motor, is now applied to the negitive terminal (the relay contacts transfer, and what was normally open is now closed, and what was closed is now open)the voltage is applied to the motor oposite to what it was originally, and the motor turns in the oposite direction. What we see on the vehical is the right motor now operating in reverse, turning the vehicle away from the object that made contact with the left front microswitch.