Inertial reference unit

About: Inertial reference unit is a research topic. Over the lifetime, 1306 publications have been published within this topic receiving 22068 citations. The topic is also known as: IRU.

Methods and apparatus for detecting, measuring, and mitigating effects of moving an inertial navigation device's cradle

Abstract: Methods and apparatus for detecting, measuring, and/or mitigating effects of moving an inertial navigation device's cradle are provided. In an example, provided are methods and apparatus to mitigate cradle rotation-induced inertial navigation errors. In an example, a method for mitigating an inertial navigation error includes receiving inertial sensor data and processing the inertial sensor data with a first navigation algorithm having a non-holonomic constraint (NHC). A second navigation algorithm, lacking a NHC, also processes the inertial sensor data simultaneously with the first algorithm. A cradle rotation is detected by the second navigation algorithm. A first navigation algorithm result, produced from the inertial sensor data generated during the cradle rotation, is discarded. The first algorithm can be computationally realigned, based on a second navigation algorithm result produced from the inertial sensor data generated during the cradle rotation.

Inertial Navigation System Tests having Improved Observability of Error Sources

Abstract: Optimal filtering of simulated inertial navigation system (INS) test data is used to evaluate alternate laboratory and flight test echniques, which are intended to determine the value of each significant source of navigation error. Tests of both gimbaled and strapdown systems are evaluated. The major problem preventing more accurate determination of the dozens of sources of error in an INS is the high correlation between the contributions of many of the sources of error. Laboratory test sequences and flight test trajectories are presented that reduce these correlations and improve the observability of the individual sources of error. Parametric studies include the effects of flight duration and distance, multi directional flights versus straight out-and-out flights, frequency and direction of maneuvers, and supersonic flights vs subsonic flights. The effects of the range instrumentation (reference system) accuracy and measurement frequency are demonstrated.

Utilization of fiber optic gyros in inertial measurement units

Abstract: Fiber optic gyro technology has been developed to a point where these gyros are now being introduced into advanced engineering models of the next generation of inertial measurement units (IMUs). This paper covers the operating principles of the interferometric type of fiber optic gyroscopes, together with a brief comparison against ring-laser gyroscopes. Recent flight test data of an IMU employing fiber optic gyro sensors are presented. Finally, the unique characteristics of the fiber optic gyro are discussed, with particular emphasis on the role they will play in future fault-tolerant IMUs.

Bounding inertial drift with human gait dynamics for personal navigation

Abstract: The integration of inertial measurements to estimate position and orientation is limited in its accuracy by the biases in the inertial instruments. The gyroscopes and accelerometers used in personal navigation systems do not have extremely high fidelity. The drift in position estimates grows as the cube of time elapsed without absolute measurements such as GPS to bound it. However, one source of inertial aiding has largely been overlooked, which is the unique dynamics of gait for each individual. Based on the record of inertial measurements in walking or running, the relationships between stride length and stride interval for individuals is developed. We designed an integrated system with corrected human gait model to limit the drift of inertial integration with the assistance of this relationship. Analysing in individual step and corrected with gait model can effectively minimize the error of position estimating.