IMUVar - VarIoNav - Analysis of Various Integration Methods of GNSS and Inertial Measurement Systems with Respect to Different Scenarios of Georeferencing

The main objective of the project VarIoNav is a scientifically based and comprehensive investigation of the integration of Global Navigation Satellite Systems (GNSS) and inertial measurement systems (IMS).

Short Description

Regarding the high value of GNSS/IMS fusion within integrated navigation, the integration analysis is performed against the background of the challenging trajectory determination for a mobile exploration system (e.g., imaging sensors) and the subsequent direct georeferencing of the sensor and its output.

In the field of navigation, integrated navigation is an upcoming technique. This means that trajectory determination of a moving object is performed via sensor fusion. Sensors with different operation principles and characteristics complement each other in such a way that disadvantages of the one sensor are compensated by advantages of the other and vice versa.

In the case of mobile platforms (terrestrial or airborne), the integration of satellite-based positioning and inertial measure- ment systems is gaining in importance today. GNSS, such as GPS or the future Galileo, represent absolute positioning (absolute coordinates of long-term accuracy), but in the sense of radio navigation, they are non-autonomous systems. In contrast, inertial navigation (use of gyroscopes and accelero- meters) is self-contained, but is indicative of relative positioning (small coordinate differences of short-term accuracy). Therefore, the importance of such a sensor integration is obvious: an inertial measurement system overcomes shadowing effects of GNSS, while GNSS compensates the IMS-typical drift behaviour.

Within the scope of the project VarIoNav, a science-based and comprehensive investigation of diverse types of GNSS/IMS integration is performed. For this purpose, GNSS receivers and inertial measurement units (IMU) of three different quality and price classes (low, middle, and high) are to be compared in a lot of possible combinations.

The type of integration not only depends on the quality of the involved sensors but also on the coupling method within signal processing. Due to the used filtering technique, an uncoupled, loosely coupled, and tightly coupled integration of GNSS receivers and IMUs can be performed.

As a primary result of the investigations, a classification of the integration types with respect to usability, accuracy, and reliability is expected. The two latter quality measures are related to positioning and attitude determination. For the purpose of direct georeferencing, the methods of GNSS/IMS integration are based both on simulations and experimental tests for measurement and imaging platforms.

Project Partners


Graz University of Technology, Institute of Navigation and Satellite Geodesy - Prof. Manfred Wieser


  • JOANNEUM RESEARCH Forschungsgesellschaft mbH, DIGITAL Institute for Information and Communication Technologies, Remote Sensing and Geoinformation - Karlheinz Gutjahr

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