Fric is a small, STAMP powered, autonomous robot. It's inspiration comes from EPFL's ALICE robot and DIDEL's SWIBOT. These are tiny robots built using SWATCH stepper motors. These motors draw a fracion of the power that DC motors draw (15 to 20mA compared 75 mA for a pager motor) and can be run directly from the STAMP module without intervening circuitry. This means you can make a robot with very few components, basically, a CPU, the motors and a power supply. Fric's specs: size: 7 cm long by 9 cm wide by 2 cm tall. Electronics: Stamp BS2 and a 74hc164 shift register motor: 2 SWATCH bipolar stepper motors power suply: 9v battery sensors: IR detector and 2 emmitters for obstacle detection cost: $20 for the SWATCH motors, $49 for the STAMP, $5 for the rest. I used a shift register to actually run the motors. Originally I ran it directly from the STAMP, but that uses 6 pins. The hc164 only uses two pins. I had to experiment with different famillies of chips before I hit on the "hc" familly, the others couldn't sink or source enough current to drive the motors effectively. There are two problems with using these SWATCH motors. Unlike a DC motor, the CPU has to be an active participant in driving it. With a DC motor and an H-bridge the CPU sets the control pins and goes it's merry way. With stepper motors the CPU has to constantly change the state of the control pins, AND it has to do that rather quickly. The stepper motors won't move otherwise. This means that the CPU spends most of it's time moving the motors. The other problem is that these motors deliver very little torque. That is the trade off for using very little current. Fric's environment is my linoleum floor or table top. It can't handle rough surfaces. Part of the problem is the gear ratio of 1:180. I found that by adding another gear train the torque can be improved significantly. The price is, however, speed. The fastest you can move the steppers is 600 degrees a second, 100 RPM. So, adding gears slows it down to a snail's pace. Future plans are to complete Fric's brother, Frac (he is awaiting a brain), finding a lighter power supply (the battery amounts to half of Fric's weight) and trying smaller CPU (I figure I can make a robot about a quarter of the size of Fric). Email: mwalimu@sbcglobal.net