DEVELOPMENT OF A UKF-SLAM SCHEME FOR AUTONOMOUS NAVIGATION OF UNMANNED UNDERWATER VEHICLES
Abstract
Autonomous navigation of unmanned underwater vehicles (UUVs) has gained significance in oceanographic research, underwater exploration, and military applications. Traditional navigation methods like global positioning systems and inertial navigation systems are not fully reliable in underwater environments due to signal attenuation and multipath effects. This work proposes a Simultaneous Localization and Mapping (SLAM) approach based on the Unscented Kalman Filter (UKF) for UUVs equipped with a range sonar system. Unlike Extended Kalman Filter (EKF), UKF can handle highly nonlinear systems and provides consistent unbiased estimates. The proposed SLAM method aims to overcome the limitations of traditional dead reckoning methods, which accumulate navigation errors over time, by using environmental data measured during UUV navigation to obtain ground-fixed relative positioning information. SLAM algorithms have been successfully applied in terrestrial and aerial robotics, but their application in UUVs remains limited, primarily due to the challenges posed by the highly nonlinear motion of UUVs in underwater environments.
In this study, the SLAM based on UKF is presented and evaluated through simulations in tank conditions. The UKF estimates the mean and covariance of the nonlinear system using weighted sums of sampled prior probability density function (PDF) evaluations, known as sigma points, instead of relying on the Jacobian matrix as in the EKF. The proposed method is expected to offer a more robust and accurate navigation solution for UUVs, particularly in highly nonlinear underwater environments.
The simulation results demonstrate the effectiveness of the proposed SLAM based on UKF for UUVs equipped with a range sonar system. The UKF's ability to handle nonlinearities leads to consistent unbiased estimates, making it a promising alternative to EKF-based SLAM for UUVs. The study contributes to enhancing the autonomy and navigation capabilities of UUVs, enabling them to perform critical tasks such as underwater exploration, inspection of ship hulls, and surveying underwater structures.
