UWB-Based Localization for Multi-UAV Systems and Collaborative Heterogeneous Multi-Robot Systems: a Survey

I. INTRODUCTION

• GNSS-denied robot navigation requires accurate localization; UAVs add three-dimensional challenges, while onboard odometry and wireless methods have accuracy or robustness limitations.The introduction notes challenges for long-term autonomy with onboard odometry and lower accuracy in most existing wireless solutions.Source: §I · p. 1
• UWB estimates a mobile robot’s position from ranges to fixed nodes at known positions, with reported accuracy from tens of centimeters to centimeters.It may replace more complex, expensive motion-capture arenas when tens-of-centimeters accuracy is sufficient.Source: §I · p. 1
• The survey focuses on UWB localization for UAVs, multi-UAV systems, and heterogeneous multi-robot systems, areas not covered in depth by prior reviews.The authors describe this as a gap amid increasing publication activity on UWB localization for UAVs.Source: §I · pp. 1–2

II. ULTRA-WIDEBAND LOCALIZATION SYSTEMS

• The section covers methods for estimating distances between UWB transceivers and positions of mobile tags relative to fixed anchors.The fixed anchors have known positions.Source: §II · p. 2
• It first describes options for measuring distance between UWB signal emitters and receivers.Source: §II · p. 2
• It then describes localization systems, including cooperative localization methods.Source: §II · p. 2

A. Measurement modalities

• Time of Flight (ToF), or Time of Arrival (ToA), estimates distance from signal propagation time; two-way ranging avoids the clock synchronization required by one-way ranging.Two-way ranging requires communication in both directions and includes Single-Sided and Double-Sided variants.Source: A. Measurement modalities · p. 2
• In Double-Sided Two-Way Ranging, both devices initiate ranging requests, and the flight time is calculated from their timing measurements without prior calibration.The passage contrasts this with Single-Sided Two-Way Ranging, initiated by one device.Source: A. Measurement modalities · pp. 2–3
• Time Difference of Arrival (TDoA) estimates position from differences in signal arrival times across multiple anchors, which must be interconnected or synchronized.The section states that TDoA can improve localization accuracy over ToA.Source: A. Measurement modalities · p. 3

B. Localization System Setup

• Most surveyed multi-robot UWB localization systems use fixed, known-position anchors at constant height, with least squares estimation and Kalman filtering commonly used to track tags.Source: B. Localization System Setup · p. 3
• Researchers have pursued greater localization accuracy by fusing UWB ranging with other sensors, including inertial, vision, and lidar data.Source: B. Localization System Setup · p. 3
• For NLOS transmissions, one described approach uses ray tracing based on the footprint of the area where nodes move.Source: B. Localization System Setup · p. 3

• A mobile reference platform with four known-coordinate UWB modules lets a separate robot determine its position by trilateration, while automatic anchor calibration avoids manually defining anchor coordinates.The calibration calculates anchor coordinates from inter-anchor distances, taking the first anchor as the coordinate-system origin.Source: 1) Mobile Setting for Ad-Hoc Deployments · p. 3
• An extensible network of eight auto-calibrated anchors supports simultaneous robot localization using TDoA, which requires synchronization across the anchor network.A Kalman filter tracks anchor positions over time.Source: 1) Mobile Setting for Ad-Hoc Deployments · p. 3
• A four-module, two-robot setup estimates relative position in real time without communication with a central station or between robots, but anchor placement is constrained by robot size and measurements are noisy.The system uses a Monte-Carlo localization algorithm based on a particle filter to address noisy measurements.Source: 1) Mobile Setting for Ad-Hoc Deployments · p. 3
• The proposed mobile-anchor autocalibration system significantly reduces calibration time and increases anchor-position accuracy compared with Decawave’s built-in process.It was simulated with four anchors and three tags, based on experimental one-to-one measurements with the DWM1001 module.Source: 1) Mobile Setting for Ad-Hoc Deployments · pp. 3–4

2) Collaborative/Distributed Localization:

• Collaborative UWB localization combines synchronization and distributed maximum log-likelihood estimation to reduce the effect of NLOS ranging errors, though solution sensitivity requires further study.The approach uses TWR-TOA and a diffusion algorithm for synchronization; other work reports improved multi-robot localization precision with a collaborative extended particle filter, but its error model remains untested in real time.Source: 2) Collaborative/Distributed… · p. 4
• A distributed signal-strength method lets nodes estimate and broadcast their positions as a mobile anchor moves along a path, with reported scalability in area size and node count.A Kalman filter is used to address noise in the received signal.Source: 2) Collaborative/Distributed… · p. 4

III. UWB IN MULTI-UAV SYSTEMS

• UAV localization adds challenges beyond UGV localization, while motion-capture systems use high-speed cameras and reflective markers but require expensive hardware for real-time visual processing and offer relatively fixed, limited-area coverage.The passage describes UWB as a more flexible option for UAV and multi-UAV localization, potentially with lower accuracy than motion capture.Source: §III · p. 4
• A two-way time-of-flight UWB system used an EKF estimate and nonlinear regression for simultaneous localization of four UAVs.The passage introduces this work as a multi-UAV positioning system.Source: §III · p. 4

A. Formation Control

• Formation control is the design of multi-robot control systems for spatial coordination.Source: A. Formation Control · p. 4
• Formation-control schemes often use distance measurements, while many require relative positioning between robots.Source: A. Formation Control · p. 4
• Some formation-control algorithms do not require accurate localization, and collision avoidance is often part of the control scheme.Source: A. Formation Control · p. 4
• Distributed formation-control schemes use UWB ranging and communication to estimate UAV relative positions, distances, and relative speeds in two dimensions.Source: A. Formation Control · p. 4
• One reported UWB formation flight used three UAVs, while another demonstrated a two-UAV leader-follower formation.Source: A. Formation Control · p. 4
• The two-UAV leader-follower work compared outdoor UWB positioning with GPS and concluded UWB met relative-positioning requirements for formation control at a similar level to GNSS sensors.Source: A. Formation Control · p. 4

B. Application Scenarios

• The survey identifies UWB-and-UAV applications across industrial scenarios, search and rescue, and entertainment shows.Source: B. Application Scenarios · p. 4

• Industrial UAV use cases include warehouse management, coal-mine inspection, environmental mapping, metric reconstruction, logistics, and forest-fire prevention.Source: Industrial Applications · p. 4
• 5 cm positioning accuracy was reported for a multi-technology UWB localization MAC protocol designed to optimize anchor-node energy consumption for UAV inventory management.Source: Industrial Applications · p. 4
• The UWB system was validated for automatic drone navigation in inventory management and for positioning runners on an indoor track without infrastructure.Source: Industrial Applications · p. 4
• For building reconstruction, a UAV-mounted tag ranged to eight anchors fixed at different heights, supporting image fusion and a 3D model validated against terrestrial laser scanner data.Source: Industrial Applications · p. 5
• UWB radar experiments showed high accuracy under harsh underground coal-mine conditions, while a separate simulated radar sensor used an environmental map to extend its applications,.Source: Industrial Applications · p. 5

Shows/Entertainment:

• Indoor UAV formations for entertainment have used UWB localization for precise positioning and control, including the MAKS human-machine dance.Verity Studios also uses undisclosed UWB technology for indoor multi-UAV spectacles.Source: Shows/Entertainment · p. 5

Search and Rescue:

• A search-and-rescue patent uses UWB transceivers to locate survivors and relay their positions to a command center over a separate data link.UWB localization may also help in post-disaster poor visibility, while a separate UAV system combines UWB radar and RTK positioning for underground imaging.Source: Search and Rescue · p. 5

Surveillance/Monitoring:

• A UWB-and-GPS system reduced outdoor relative-position error between devices under test from 6 m to 10 cm.Another system uses machine vision and UWB positioning to track UAV trajectories in real time.Source: Surveillance/Monitoring · p. 5
• A UWB-radar drone detected the boundary between two liquids in a tank with an average square error of 1 mm.The system was designed to study underground layers and solid and liquid media.Source: Surveillance/Monitoring · p. 5

IV. UWB IN HETEROGENEOUS MULTI-ROBOT SYSTEMS

• Multiple UWB transceivers on each robot can estimate both relative position and orientation, supporting sensor fusion and target-relative localization.Nguyen et al. demonstrated this approach with an extended Kalman filter, using UWB for both ranging and communication [61].Source: §IV · p. 5
• UWB localization supported an autonomous UAV approach to a mobile UGV docking station, while onboard vision and known markers handled the final docking maneuvers.The reported mobile platform measured 2 m by 1.5 m.Source: §IV · p. 5
• UWB transceivers have been used for global localization in a deep-reinforcement-learning multi-robot collision-avoidance scheme [63].Source: §IV · p. 5
• A ROS-based localization platform that accommodates different robot types was later extended for formation control.Source: §IV · pp. 5–6

V. UWB LOCALIZATION FOR ROBOTICS DATASETS

• The most extensive dataset identified includes multiple anchor settings and manual and autonomous flights, whereas an earlier UAV dataset contains one flight with one anchor setting.The survey also describes a dataset analyzing one-to-one distance measurements and a study of UWB-inertial fusion for three-dimensional localization.Source: §V · p. 6

VI. CONCLUSION

• The survey describes fixed anchors as predominant for estimating mobile-tag positions, alongside distributed cooperative localization, and concludes UWB has potential for relative positioning and ranging in multi-robot systems.It reviews applications including multi-UAV formation control and cooperative actions such as UAV docking on a mobile platform.Source: §VI · p. 6