The detectors are positioned at a specific distance from the center. If the ball interrupts the light at any of the three detectors, it drops the logic level to a LOW. This means, for example, if it moves to the right detector and switches the logic level, the system remains in this state until the ball returns to the center position. This operational sequence tells the microprocessor whether the right or left detector has been triggered and subsequently whether or not it has returned to the center. The only case when it functions as a simple tilt indicator is when there are no turning forces involved. During a turn in a vehicle (car or aircraft), the centrifugal/centripetal forces come into play as well. This is how a skidding condition is detected: The microprocessor first observes which way the aircraft is banked and then compares that with the observed direction of ball movement. If the bank angle is to the left, for example, but the ball has moved to the right, that's a skid. If they're in the same direction however, it's a "slip", which, in the intended application, is much less important than a "skid".
