Observer design for underwater vehicles with position and angle measurement

Abstract

In this paper we propose a new observer system for underwater vehicles. The main design objective behind this strategy is to reduce the destabilizing effect of the Coriolis and centripetal forces and moments in the observer. Especially for low cost vehicles with limited measurement equipment, these forces and moments represent a significant challenge for automatic control when the forward speed is sufficiently high. However, by explicitly utilizing an estimation of the current velocity in the observer, this paper shows that a high degree of robustness related to environmental disturbance and measurement noise is achieved. This is related to the estimation of the destabilizing Coriolis and centripetal forces and moments. UGES is proven for the observer error dynamics. Furthermore, this observer scheme has shown to be tolerant to large error in the position measurements, which is a common occurrence in underwater navigation.