Relative Localization for Quadcopters using Ultra-wideband Sensors

In this paper a relative localization (RL) system for quadcopters based on ultra-wideband (UWB) ranging measurements is proposed. To achieve the relative localization, UWB modules are installed on the quadcopters to actively measure distances and exchange data package to a hovering quadcopter which is equipped with an identical UWB module. Since instantaneous distanceonly measurements cannot provide enough information for relative position estimate, a combination of nonlinear and linear trajectory is ultilized to fulfill the RL in this paper. To reduce the estimate error, the heading in the linear path phase is designed and chosen online. This intial relative position estimate produced by the algorithm will be further fed to the flight control loop to aid the navigation of the quadcopters. Flight tests have been conducted to validate the performance of UWB based relative localization algorithm.