Abstract: An inertial system is provided. The system includes at least one inertial sensor, a processing unit and a plurality of Kalman filters implemented in the processing unit. The Kalman filters receive information from the at least one inertial sensor, and at most one of the plurality of Kalman filters has processed zero velocity updates on the last cycle. The plurality of Kalman filters is used to optimize system response and performance during periods of intermittent motion.

Abstract: A speed responsive control device is useful for preventing a dangerous overspeed condition of a propulsor. The device begins governing before the dangerous overspeed condition occurs through the use of an acceleration responsive mechanism which actuates the spool of a governor pilot valve. The spool is also actuated by a speed responsive mechanism in the form of a flyweight governor. The control device thus anticipates dangerous overspeed conditions to make necessary adjustments such as blade pitch corrections, to prevent a dangerous overspeed condition.

Abstract: A first laser beam is modulated at a modulation frequency and focused on a first point in the proximity of a connection being tested so as to generate a photothermo elastic wave thereat, and a second laser beam is focused on a second point in the proximity of the connection, which second point is separated from the first point. The second laser beam is scattered at the second point. A detector detects a modulation-frequency component of the scattered second laser beam, so as to detect a propagated level at the second point of the photo-thermo elastic wave from said first point based on the detected modulation-frequency component of the scattered second laser beam. The propagation of the elastic wave depends on the strength of the connection and the detected level of the elastic wave indicates strength of the connection.