Abstract: Systems and methods for reducing vibration-induced bias errors in inertial sensors are disclosed. A system for reducing bias errors in an inertial sensor operating within an environment may include a vibration detector for sensing vibration changes within the environment proximate to the inertial sensor, and a Kalman filter for computing an estimate of the navigational error produced by the inertial sensor due to a vibration-induced bias shift detected by the vibration detector. The vibration detector can be configured to measure an accelerometer output of the inertial sensor over a Kalman filter cycle, and then use the standard deviation of such output to obtain a statistical measure of the vibration within the environment. In some embodiments, the inertial sensor may include an inertial measurement unit (IMU) connected to an error compensation unit and strapdown navigator, each of which can be fed navigation corrections determined by the Kalman filter.

Abstract: A navigation system includes an inertial navigation unit. The navigation system also includes a Kalman filter that generates corrective feedback for use by the inertial navigation unit. The Kalman filter generates the corrective feedback as a function of at least one of GPS/DGPS information, sensor information, user input, terrain correlation information, signal-of-opportunity information, and/or position information output by a motion classifier.

Abstract: An apparatus and method for improving the safety of railroad systems of the present invention includes a system for navigating a railroad vehicle over railroad tracks. An attitude sensor is used to dynamically sense the attitude of the railroad vehicle as it travels over a set of railroad tracks. By sensing the attitude of the railroad vehicle, a determination of the condition of the railroad tracks can be made. The apparatus also sensed the position of the railroad vehicle in real time to correlate the sensed attitude with a precise position along the railroad tracks. The navigation system is capable of determining a highly accurate position of the vehicle in real time. The position of the vehicle is also used to navigate the railroad vehicle.

Abstract: An apparatus and method for improving the safety of railroad systems of the present invention includes a system for navigating a railroad vehicle over railroad tracks. An attitude sensor is used to dynamically sense the attitude of the railroad vehicle as it travels over a set of railroad tracks. By sensing the attitude of the railroad vehicle, a determination of the condition of the railroad tracks can be made. The apparatus also sensed the position of the railroad vehicle in real time to correlate the sensed attitude with a precise position along the railroad tracks. The navigation system is capable of determining a highly accurate position of the vehicle in real time. The position of the vehicle is also used to navigate the railroad vehicle.

Abstract: A navigation/guidance system uses a dead reckoning navigator with periodic GPS fixes to correct the drift of the inertial system. The navigation system primarily uses speed sensed by Doppler radar and attitude and heading sensed by a set of gyros. The navigation system uses various processes to compensate for any sensor errors. The system uses attitude data to compensate for GPS leverarm errors. The system can be used on a land-based vehicle to economically and accurately provide navigation data.