An automatically guided agricultural vehicle with multiple sensors is disclosed. The automatically guided agricultural vehicle includes guidance parameter identification using multi-sensor data fusion for real-time vehicle guidance. To insure robust navigation, a map-based guidance and sensor-based guidance are disclosed and integrated because no individual sensing technology is ideally suited for vehicle automation under all modes of use. The appropriate sensor and operational mode will depend on the field status of time or operation. A fiber optic gyroscope (FOG) and a real-time kinematic GPS (RTK-GPS) and machine vision are added to the guidance system in order to improve reliability of the system for vehicle guidance. The navigator includes key functions of selecting control mode, correcting position by vehicle roll/pitch inclinations, Kalman filtering, and calculating a steering angle.