**2.2 Sensor, thrust, and power system**

For underwater vision, there is one colour camera mounted at the vehicle nose. And three range sonar (forward, backward and downward) are mounted on the vehicle. There sonar are designed for obstacle detection and also for assisting vehicle's underwater localization. For P-SURO AUV, we design a relatively simple but low grade of inertial navigation system which consists of AHRS, 1-axis Gyro, 1-axis accelerometer, one depth sensor.

SeaBotix BTD-156 thrusters are selected to steer the vehicle's underwater motion. This is a small size underwater thruster with 90W of average power consumption. For power system, the calculated total power consumption of vehicle system is about 450W. And correspondingly, we design the 1.2kW Lithium Ion battery system, which can support more than two hours of the vehicle's underwater continuous operation. The overall sensor & thrust system for P-SURO AUV is listed in Table. 2.
