Update 12/27/10:

      
I have made considerable
      changes to the drive system since last report. The modified Servo
      drives were really bad, and I couldn't keep both motors running
      an even speed or even make the robot run straight on a perfectly
      smooth surface! So I stripped out the servos, shaft encoders
      and its shaft encoder board, and put in two high efficiency precision
      gear head motors, new hard rubber wheels and completely rewrote
      the software for the motor driver PIC's to work with DC motors.
      The robot goes perfectly straight now without having to adjust
      the motors speeds to match.

      
On driving straight
      in a household environment...

      
As I discovered
      with the servo motors, just making the wheels move exactly the
      same speed did not make the robot go straight in the home. Bumps
      in the tile floor, carpet, moldings and small obstacles on the
      floor always make the robot veer off straight after only a matter
      of 3 - 6 feet. So this aspect will not be used in the new motor
      drive design. What is most important is to make sure the motors
      are matched in quality and have the wheels similar in size. The
      robot will have to use navigation correction to go a straight
      path from one end of a room to another. The optical encoders
      I am now making will indicate in 10 degree increments on the
      wheels and with a .2 inch resolution on the ground, will be more
      accurate than the rough floors it will have to traverse in the
      home. Measuring approximate distances, and making accurate angular
      turns will be the primary goals here.


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