Contents I. Introduction
Mobile robots and especially quadcopters offer new possibilities in research and in commercial applications. Exemplary applications include their use as a mobile sensor platform, in search and rescue [17], exploration tasks and in logistics [1]. For indoor navigation, ultra-wide band (UWB) based time-difference of arrival (TDoA) measurements [3], [12], [18] and potentially optical flow and laser-based altitude measurements [5] can be used by quadcopters to position themselves within an indoor environment. A major advantage of the UWB measurements is that these signals have good penetration capabilities, so positioning is possible within obstructed environments. For a higher accuracy in navigational performance, motion capture system (MoCap) or the Lighthouse Positioning System [15] are also a possibility. However, these types of systems are constrained to applications with non-obstructed line-of-sight contact to their transmitting devices. For applications such as multi-agent path coordination in obstructed environments, a satisfactory navigation performance is of crucial importance, but line-of-sight contact to the transmitting devices can not be guaranteed. Therefore, it is of importance to improving the UWB-based navigation performance.
