Otto is a three wheeled mecano platform, that carry 2 servomotors, 2 6 volt battery pack to power the servos and one infrared camera with transmitter , one 9 volt battery, to power the well known pic16f4 microcontroller through a 5 volt regulator and one Autonics, ready to use infrared sensor, to detect objects and prevent colissions. Otto was programmed in Picbasic (microengineering labs) and one of the principal design considerations was to minimize the amount of components on the protoboard. The Autonics sensor has an open colector output that you can connect directly to the microcontroller through a pull up resistor at 5 volts. The Autonics also has a little potentiometer, that let you adjust the detection distance. The overall cost was about U$ 150, if you omit the camera you reduce the cost to U$ 90. Email: rcabes@entelchile.net