Precise navigation indoor

Indoor positioning can be of great interest for a number of applications including those in robotics and automation. Today positioning outdoor is very successful using satellite navigation systems, such as GPS and GLONASS and can routinely achieve centimeter level accuracy. Indoor positioning in many respects is different from typical GPS positioning outdoors. It comes up against number of obstacles. For instance, although the error budget indoor doesn't include atmospheric and orbital errors, it suffers from a potentially high multipath component. However, the main challenge in indoor positioning is to find an appropriate algorithm for positioning. Even in the case of pseudorange positioning, a solution for a classic system of nonlinear equations can present a significant challenge. In the conventional approach, the initial position error plays a critical role, because nonlinear pseudorange equations require linearization close to the true position. The positioning with carrier phase data encounters even more obstacles. First of all it requires a rather good initial position estimation, delivered usually by pseudorange positioning. The other problem is that pseudolites are fixed in the space, which doesn't allow to implement conventional ambiguity resolution technique without imposing some conditions on the rover receiver movement, which is not always acceptable from the practical point of view. The other way to implement the conventional technique is to start from a known location. This technique is not always acceptable in real life. Therefore we developed a special methods and algorithms to overcome the above obstacles. It allowed us to achieve centimeter-level positioning indoors in low multipath environment. The developed procedures don't require knowledge of the initial rover receiver position, and don't impose any restrictions on rover receiver dynamics. The proposed technique uses specially developed two reference station approach. This approach allows to resolve ambiguities indoors without applying any restriction to the rover movement.