Inertial navigation system

About: Inertial navigation system is a research topic. Over the lifetime, 14582 publications have been published within this topic receiving 190618 citations. The topic is also known as: intertial guidance system & inertial reference platform.

Airborne vector gravimetry using precise, position-aided inertial measurement units

Abstract: Vector gravimetry using a precise inertial navigation system continually updated with external position data, for example using GPS, is studied with respect to two problems. The first concerns the attitude accuracy requirement for horizontal gravity component estimation. With covariance analyses in the space and frequency domains it is argued that with relatively stable uncompensated gyro drift, the short-wavelength gravity vector can be estimated without the aid of external attitude updates. The second problem concerns the state-space estimation of the gravity signal where considerable approximations must be assumed in the gravity model in order to take advantage of the ensemble error estimation afforded by the Kalman filter technique. Gauss-Markov models for the gravity field are specially designed to reflect the attenuation of the signal at a specific altitude and the omission of the long-wavelength components from the estimation. With medium accuracy INS/GPS systems, the horizontal components of gravity with wavelengths shorter than 250 km should be estimable to an accuracy of 4–6 mgal (µg); while high accuracy systems should yield an improvement to 1–2 mgal.

Cooperative Localization and Unknown Currents Estimation Using Multiple Autonomous Underwater Vehicles

Abstract: This letter is on cooperative localization and sea currents estimation using multiple Autonomous Underwater Vehicles (AUVs). Due to sea currents, dead reckoning localization based on inertial navigation sensors results in accumulation of localization error. To reduce the error accumulation, this letter proposes navigation algorithm to allow multiple AUVs to simultaneously estimate their navigation states and unknown sea currents. This letter introduces the fusion of Unscented Kalman filter and linear Kalman filter for joint estimation of the navigation states and unknown sea currents. Suppose that only one AUV, called the leader, is equipped with Doppler Velocity Logs (DVL) and Ultra Short Base Line (USBL) sensors. To improve the localization of multiple AUVs, the leader measures both the bearing and the range of its nearby AUV periodically. As far as we know, this manuscript is unique in considering cooperative localization of multiple AUVs in unknown currents. The effectiveness of this cooperative localization is verified using MATLAB simulations.

FOG-based navigation in downhole environment during horizontal drilling utilizing a complete inertial measurement unit: directional measurement-while-drilling surveying

Abstract: Presently used surveying sensors in directional drilling processes include accelerometers and magnetometers arranged in three orthogonal directions. The magnetometers in these setups are negatively affected by external magnetic interferences induced by various sources. Therefore, expensive, heavy and lengthy protective nonmagnetic collars need to be installed. Fiber-optic gyroscopes (FOGs) in an inertial navigation setup have been proposed as an alternative to magnetometer-based downhole surveying. The present study explored the feasibility of utilizing a FOG-based tactical-grade inertial measurement unit (IMU) as a complete surveying sensor for measurement-while-drilling (MWD) processes downhole. Alignment and real-time navigation under laboratory conditions were demonstrated. Analysis of vibrations and temperature as possible factors limiting the accuracy of the navigation process was performed. Severe vibration effects were reduced using software techniques, and a shock-absorbing housing was suggested. The temperature range of the IMU is limited by the optical components of the device, but dynamic temperature changes within this range did not present a major problem. A downhole sub design demonstrated that the actual integration of the IMU requires only minor changes in the presently used drilling tools. The utilization of a tactical-grade IMU eliminates the necessity of nonmagnetic collars, which results in lower costs and improved accuracy.

The Psi-Angle Error Equation in Strapdown Inertial Navigation Systems

Abstract: A detailed development is presented of the psi-angle vector differential equation as applied to the error analysis of strapdown inertial navigation systems. The coordinate systems involved and the psi misalignment vector are clearly defined. It is proven that apart from a sign change the psi-angle differential equation in the error analysis of strapdown inertial navigation systems is identical to the one used in conventional gimbaled inertial navigation systems.

An Intelligent Multi-sensor System for Pedestrian Navigation

Abstract: In the research project “Pedestrian Navigation Systems in Combined Indoor/Outdoor Environements” (NAVIO) we are working on the development of modern intelligent systems and services for pedestrian navigation and guidance. In the project modern and advanced intelligent mobile multi-sensor systems should be employed for 3-D position determination of a user. Due to the fact that satellite positioning with GNSS (Galileo, GPS, etc.) does not work under any environmental condition (e.g. in urban “canyons” with no satellite visibility and indoor) a combination and integration with other sensors (e.g. dead reckoning sensors, inertial navigation systems (INS), indoor location techniques, cellular phone positioning, etc.) is essential. In our approach a loose coupling of the employed sensors should be achieved and it is proposed to develop a multisensor fusion model which makes use of knowledgebased systems. As far as we can see now knowledgebased systems can be especially useful. Thereby the decision which sensors should be used to obtain an optimal estimate of the current user’s position and the weightings of the observations shall be based on knowledge-based systems. The new algorithm would be of great benefit for the integration of different sensors as the performance of the service would be significantly improved. In this paper the basic principle of the new approach will be described. To test and to demonstrate our approach and results, the project takes a use case scenario into account, i.e., the guidance of visitors to departments of the Vienna University of Techology from nearby public transport stops. The results of first field tests could confirm that such a service can achieve a high level of performance for the guidance of a pedestrian in an urban area and mixed indoor and outdoor environments. Standard deviations in the range of few meters can be achieved for 3-D positioning in urban areas although obstructions cause frequent loss of lock for satellite positioning. Thereby GPS outages of up to 150 m can be bridged using dead reckoning observations with the required positioning accuracy. For indoor areas satellite positioning can be replaced by indoor positioning systems (e.g. WiFi, UWB). Due to the development of advanced sensors it can be expected that such multisensor solutions will be deployed in pedestrians navigation services. We believe that these services will play an important role in the field of location-based services in the near future as a rapid development has already started which is driven by their possible applications.