System-Level Algorithm Design for Radionavigation using UWB Waveforms

Abstract

A radiolocation/navigation system is considered in which mobile nodes use ultra-wideband (UWB) radios to obtain inter-node ranges via round-trip travel time (RTT). Each node is also assumed to contain an inertial measurement unit (IMU) which generates 2D position estimates subject to Gaussian drift and additive noise errors. The key problem in such a system is obtaining 2 or 3-D position estimates from the nonlinear UWB range measurements and fusing the resulting UWB and IMU estimates. The system presented uses a Steepest Descent Random Start (SDRS) algorithm to solve the nonlinear positioning problem. It is shown that SDRS is a stable algorithim under a realistic communications reciprocity assumption. The SDRS estimates are then treated as measurements by the navigation Kalman filter. The navigation filter also processes separate IMU-derived position estimates to update node position/velocity. Simulation results for an urban corridor are given showing < 6 m. rms position errors.