Autonomous Mobile Robots and Multi-Robot Systems

5GNSS and Robot Localization

Roi Yozevitch and Boaz Ben‐Moshe

5.1 Introduction to Satellite Navigation

A mandatory demand for any mobile robot is to know its exact location in space. The Global Navigation Satellite System (GNSS) is the most famous and spread‐out system for mobile localization outdoor. This chapter is devoted to satellite navigation and its application for mobile robots.

GNSSs enable an Earth‐located receiver to determine its absolute position in space. This is done by measuring the receiver's distance to the navigation satellites and extracts its location from those distances. The most famous (and oldest) GNSS is the US global positioning system (GPS), which became operational at 1980. Nowadays, almost every receiver uses a GNSS, including the Russian system – GLONASS. Other GNSSs are the European GALILEO and the Chinese BeiDou2. Although not all GNSSs work exactly the same way, the principle is the same. But how does GNSS actually work?

5.1.1 Trilateration

Both GPS and GLONASS are navigation systems based on the trilateration method. As opposed to triangulation, trilateration is based on measuring the distance (not angle) between the receiver and three beacons at known location. The accuracy using this method is determined by the receiver’s ability to measure the distance involved. The distances are calculated by means of the time of arrival (ToA) method. Each navigation satellite is equipped with four atomic clocks. When a signal is received, the arrival ...