Latent oscillator frequency estimation for ranging measurements

US10948584B2 · kind B2 · utility

Assignee

• THE REGENTS OF THE UNIVERSITY OF MICHIGAN · US

Inventors

• Edwin Olson · Ann Arbor, US
• Sean M. Messenger · Ann Arbor, US
• John Mamish · Ann Arbor, US

Key dates

• Filing date: Mar 14, 2018
• Grant date: Mar 16, 2021
• Expiry date: Sep 19, 2038

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S13/767
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Time of Flight ranging using double-sided two-way ranging (DS-TWR) is a conventional method of ranging with ultra-wideband (UWB) radios and has been shown to have ranging accuracies on the order of tens of centimeters. This approach requires several transmissions for each range measurement, which does not scale well for multi-agent robotics because of the bandwidth needed for ranging measurements. This disclosure proposes a latent model for clock frequencies using a factor graph that enables greater consistency of clock synchronization and increases the rate of useful range measurements. This model is an effective and robust improvement to conventional DS-TWR that can leverage shared information from a network of robots. An increase in the rate of range measurements of 232% was obtained as compared to DS-TWR with the same hardware and transmission rate, and with a mean square error of range measurements of 20 cm.