The Tilt sensors in the RoboPet are interesting, they are different to those in WowWee's other products, I assume that is because of the size constraints imposed in the RoboPet. Although different, the mechanism of the tilt sensors is the same as in the others. It is a trapped ball bearing, when tilted the bearing closes the circuitbetween two contacts. The board contains two tilt sensors, but this only allows it to detect its basic orientation along one axis.

Tilt Sensor Board Output

Orientation

'R'

'L'

Upright Open Circuit Open Circuit
Rotated Left Open Circuit Closed Circuit with VCC
Rotated Right Closed Circuit with VCC Open Circuit
Upside Down Closed Circuit with VCC Closed Circuit with VCC