The Bottom-mounted ocean-observation platforms installed on the seabed have been used for marine environment analysis. The role of the observing platform is to collect precise observation data without human’s assistance for 2 weeks. However, the dynamic environment in underwater, such as ocean topography and current is very unstable and unpredictable. Furthermore, their working environment is very harsh so the typical device can't afford to provide easy accessibility for faulted or missing problems during their working period. So the existing bottom-mounted ocean-observation platforms have been difficult to collect the continuous observation data. By now, the developed Bottom-mounted ocean-observation platforms operated in very limited conditions in undersea. So, this paper suggests a new ocean-observation platform for precise measurement of the marine environment. Firstly, their structure is designed as the form of a two-axis gimbal type with a level control system including two IMU sensors. The plate uploaded on inner gimbal part has a room for Acoustic Doppler Current Profiler (ADCP) to send ultrasonic sound to find the environmental factors around the proposed robot. The prototype model is fabricated by the authors in house. It includes two DC motors to manage the angle of rotational motion toward the sea level. It also has a small computer to send control commands to motors and collect data from sensors. The difficulty of the waterproofed process is ignored, so this paper only focuses on the possibility of the proposed platform. To regulate each axis of gimbals on the developed system, the suggested platform uses PID control method to be applied for error compensation of each axis of gimbal. PID gains on each axis are obtained in trial and error. To verify the system, the experiment was carried out in the air with the external force applied to this system and shows the performance result of the body posture controller. Tracking control on each roll and pitch of the proposed system results in the appropriated results to be applied in the real sea condition; each error existed between 0 and 3 degree, measured from IMU for the targeting angles. In the future, these authors will redesign the current robot with the waterproof version based on the performance of the robot in the preliminary experiment result that tested in air condition. Next, the newly design robot will be tested underwater condition. The next control approach will be concentrated on LQR optimal control. Finally, these authors will carry out the simulation for the proposed platform under the sea.


Development of Prototype of Two Axis Gimbal-Type Platform in Underwater

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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