  This paper presents the development of a system able to estimate the 2D
relative position of nodes in a wireless network, based on distance
measurements between the nodes. The system uses ultra wide band ranging
technology and the Bluetooth Low Energy protocol to acquire data. Furthermore,
a nonlinear least squares problem is formulated and solved numerically for
estimating the relative positions of the nodes. The localization performance of
the system is validated by experimental tests, demonstrating the capability of
measuring the relative position of a network comprised of 4 nodes with an
accuracy of the order of 3 cm and an update rate of 10 Hz. This shows the
feasibility of applying the proposed system for multi-robot cooperative
localization and formation control scenarios.
