Implementación de un sistema de posicionamiento en interiores para robots móviles

Abstract

The purpose of this project is to select a suitable technology for the implementation of an indoor positioning system. For this, a review of the state of the art was carried out, where Wi-Fi, Bluetooth low energy and ultrasound technologies were highlighted. Later, more detailed investigations of these works were made, to deduce which would be the most appropriate, taking into account tests and final results. In this way, ultrasound was selected mainly for achieving errors in the order of centimeters and also for its ease in capturing and processing the signal. Additionally, radio waves were chosen to be taken as a reference, for estimating the relative distance between nodes. For the hardware of the system, six nodes were implemented, a transmitter node to send an ultrasound signal and a radio frequency signal, four receiver nodes to receive both signals, calculate the time difference between these two, then estimate their respective distance and send it to an end node. This final node is made up of a computer and the coordinating Xbee module. This node receives the four corresponding distances and subsequently estimates the final position of the mobile node in third dimension. To obtain the relative position with respect to the system, it was necessary to use the linearization positioning technique with spherical trilateration. It should be mentioned that in this case there were singularities in the nodes of the system, because they are nodes that are in the same plane. These singularities were solved by applying the singular value decomposition in the system of equations.