Strapdown Inertial Navigation Technology (Iee Radar, Sonar, Navigation And Avionics, No 5) Books Pdf

Over the next decades, advances in satellite navigation and inertial sensing technology altered the development of mobile mapping in a different way. The trajectory and attitude of the mobile mapper are now determined directly, instead of using ground control points as references for positioning and orienting the images in space. The determination of time-variable position and orientation parameters for a mobile digital imager is known as direct geo-referencing (DG), which is the core ingredient of modern mobile mapping technology (El-Sheimy 1996). Figure 25.1 illustrates the evolution of georeferencing technology over the past decades.

Cameras and laser scanners or light detection and ranging (LiDAR), along with positioning and orientation sensors, are integrated and mounted on a moving platform for mapping purposes. Objects of interest can be directly measured and mapped from georeferenced images or point clouds. The most common technologies used for this purpose today are satellite positioning using global navigation satellite systems (GNSS) and inertial navigation using an inertial measuring unit (IMU). They are usually integrated to provide seamless time-variable position and orientation parameters for mobile mapping systems. Figure 25.2 illustrates the scope of mobile mapping technology, including components, platforms, and applications, respectively. Figure 25.3 illustrates the example of sensors applied by an image-based mobile mapping system and their functions, respectively.

Strapdown Inertial Navigation Technology (Iee Radar, Sonar, Navigation and Avionics, No 5) books pdf

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The development of the mobile mapping system was highly correlated with the development of strapdown inertial sensing technology. From a DG perspective, there would be no booming mobile-mapping-related industries without the advancement of inertial sensing technology. In principle, an IMU has three gyroscopes and accelerometers, and it provides compensated raw measurements, including velocity changes and orientation changes in three directions of its body frame. Those who require real-time navigation solutions with the use of an IMU require an external computer that has inertial navigation mechanization algorithms. On the other hand, an INS is an IMU combined with a navigation computer to provide navigation solutions in the chosen navigation frame directly in real-time. In addition, it also provides compensated raw measurements. Therefore, the main distinction between an IMU and INS is the ability to provide real-time navigation solutions. The former only provides compensated inertial measurements while the latter can provide real-time navigation solutions as well as compensated inertial measurements. 2ff7e9595c