Nice! I'm glad you succeded with the construction and coding!
- if there is an obstacle in front of the bot, don't back up. Start turning like 5 degrees (turn for 10 ms or so) then check the sensor. Turn a bit more, just to be sure the side of the bot won't hit the obstacle, then drive straight.
- if you keep turning left until you reach something like 90 degrees, turn 90 degrees back (to the right) and start turning to the right a few degrees at a time to find an opening on the right side of the bot. You can continue turning this time for more thatn 90 degrees.
- add a third servo, unmodified, mount the sensor on it and scan for openings, then after you found it turn the robot that way and escape.
- after you have the scanning sensor, try to have the bot drive using a map. Use cereal boxes, books, furniture and build a small room, have the robot start in a fixed position, then go and map the room. To measure distance traveled, make a program that will drive the servos forward for 10 pulses and stop. Measure the distance, divide by 10 and you have the traveled distance per servo pulse. Now you can measure distance (not very acurate, but good enough for experimenting). Change the program so the robot turns in place, repeat the experiment and see how many degrees the robot turns per pulse. Create a map of the place and have the robot drive and find an object that is not stored on the map, then return to the base. This is good for Search and Rescue. If you attach a piece of velcro to the back of the robot, use a small teddy bear as the foreign object, have the robot turn 180 degrees when it finds it, then drive backwards to touch the teddy bear and grab it with the velcro and drag it to the base.