Читать книгу Pedestrian Inertial Navigation with Self-Contained Aiding - Doruk Senkal, Andrei M. Shkel - Страница 13

Pedestrian navigation has been of great interest in recent years for path finding, personal security, health monitoring, and localizers for first responder systems. Due to the complicated environment in which a person may need to navigate, self‐contained navigation techniques are fundamental for pedestrian navigation. An example of the self‐contained navigation technique is inertial‐only navigation of pedestrians, which became recently a popular topic. Most pedestrian navigation systems rely on inertial sensors and inertial navigation techniques in their core, just as any other navigation applications. However, the pedestrian navigation poses much stricter requirements on the size and weight of inertial instruments, or IMUs, due to the limitation of human carrying capacity, and the inertial‐only pedestrian application was technologically not feasible until recently.

Thanks to the development of Micro‐Electro‐Mechanical Systems (MEMS) technology in the past 20 years, MEMS‐based IMUs have become smaller in size and more accurate in performances, and as a result, pedestrian inertial navigation has been made possible [10]. MEMS‐based IMUs with a size on the order of millimeters have become widely available on the market, and they can be installed in portable devices that can be easily carried around, such as mobile phones, smart watches, or devices that are small enough to be carried in a pocket. Figure 1.3 compares the IMU that was developed for the Apollo missions 50 years ago and a current commercial MEMS‐based IMU. This is an illustration of technological advances in size, and it should be acknowledged that performances of the two systems are still not the same. Note that a gimbal inertial navigation was implemented for the Apollo mission, instead of the more commonly used strapdown inertial navigation systems in these days. The IMU for the Apollo missions had a volume of 1100 (or ) and a weight of 42.5 [11], whereas the volume of the shown MEMS‐bases IMU is 8.55 and the weight is on the order of tens of milligrams. Six orders of magnitude of reduction in both volume and weight has been demonstrated over the past 50 years, though to achieve the matching performance is still an on‐going area of research. Such a great technical advancement in the miniaturization of IMUs started enabling the pedestrian inertial navigation. Along with the size reduction, the performance of inertial sensors is continuously improving. The use of miniaturized sensors in these new applications inspired the development of new algorithms and new approaches for solving the challenges of navigation. These approaches are discussed next.

Figure 1.3 A comparison of (a) an IMU developed for the Apollo missions in 1960s.

Source: https://en.wikipedia.org/wiki/Inertial_measurement_unit

and (b) a current commercial MEMS‐based IMU.

Source: https://www.bosch-sensortec.com/products/smart-sensors/bhi160b/

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