A comparison of a mechanically stabilized gyrocompass and a GPS-aided inertial navigation system

The ability to sense ship´s motion accurately is critical to the performance of Naval Oceanographic Office survey missions. Various instruments have been used over the years to provide survey mission equipment with information about ship´s roll, pitch, heading, and vertical motion. Typically the cost and complexity of sensor systems used are directly proportional to the accuracy required. Advances have been made in Global Positioning System (GPS) and inertial navigation system technologies, which can be combined to produce less complex, more reliable, highly accurate sensors. The Naval Oceanographic Office has deployed such a system on its hydrographic survey ships and hydrographic survey launches. This paper presents a comparison of data collected from this system and an MK 29 gyrocompass while both were operating under actual survey conditions. The impact of short-term loss of GPS data on system performance is also explored