Robust and Scalable Multi-Robot Localization Using Stereo UWB Arrays

In environments where robots operate with limited global navigation satellite system accessibility, ultra-wideband (UWB) localization technology is a popular auxiliary solution to assist visual–inertial odometry systems. However, current UWB approaches lack 3-D pairwise localization capability and suffer from rapidly declining localization update rates as the network scales, limiting their effectiveness for swarm robotic applications. This article presents a novel UWB sensor that enables 3-D pairwise localization and a localization scheme that can deliver robust, scalable, and accurate position awareness for multi-robot systems. Our approach begins with calibrating intrinsic UWB errors from hardware deviations and propagation effects, yielding high-accuracy distance and direction measurements. Using these measurements, we perform distributed relative localization through inter- and intra-node cooperation by integrating UWB and inertial measurement unit data. To enable swarm-scale operation, our platform implements the signal-multiplexing network ranging protocol to maximize update rates and network capacity. Experimental results show that our approach achieves centimeter-level localization accuracy at high update rates (100 Hz with UWB only), validating its robustness, scalability, and accuracy for robotic applications.