Accuracy of TWR-Based Ranging and Localization in Mobile Acoustic Underwater Networks

Underwater robots require location information for autonomous navigation and even remote control. [3–1]Acoustic communication is the natural choice to cater for distance information to anchors with known position in an underwater environment. Additionally, it does not require the use of extra hardware, making it useful in cost-sensitive applications. Unfortunately, the acoustic channel is slow, adding considerable, but typically ignored, errors to distance measurements and, as a consequence, location estimates. Quantification of errors in realworld scenarios and field tests is difficult, if not impossible, unless expensive, special equipment is available. Therefore, we derive a detailed, yet comprehensible, mathematical model to obtain distance of a moving robot to one or many anchors and its real position. We identify the influencing factors and study the error of both distance measurements and self-localization. Our results indicate that compensation of robot movement is required for accurate self-localization.