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Article

Precise Underwater Gliders Pitch Control with the Presence of the Pycnocline

by 1,†, 2,†, 3, 1 and 3,4,*
1
College of Information Science and Engineering, Ocean University of China, No. 238 Songling Rd., Qingdao 266100, China
2
Qingdao West Coast Development (Group) Co., Ltd., 2567 Binhai Avenue, West Coast New District, Qingdao 266100, China
3
College of Engineering, Ocean University of China, No. 238 Songling Rd., Qingdao 266100, China
4
Institute for Advanced Ocean Study, Ocean University of China, No. 238 Songling Rd., Qingdao 266100, China
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editor: Alessandro Ridolfi
J. Mar. Sci. Eng. 2021, 9(9), 1013; https://doi.org/10.3390/jmse9091013
Received: 21 August 2021 / Revised: 9 September 2021 / Accepted: 10 September 2021 / Published: 15 September 2021
(This article belongs to the Section Ocean Engineering)
Glider-based mobile currents observations are gaining increasing research attention. However, the quality of such observations is directly related to the pitch accuracy of the glider. As a buoyancy-driven robot, the glider will be strongly disturbed during the passage through the pycnocline. The pycnocline refers to the oceanic phenomenon where the density of the seawater changes abruptly with respect to depth. The presence of the pycnocline influences the pitch of the glider and consequently affects the quality of the observed currents data. In this work, we propose an actuator constrained active disturbance rejection controller (ACADRC) to improve the accuracy of the pitch angle control when gliders move across the pycnocline. For this purpose, the dynamical model of the glider is first derived. Then, the longitudinal plane motion model of the glider considering the density variation is analyzed. Based on that, we discuss three typical types of pycnocline encountered during glider profiling, which are the pycnocline, the inverted pycnocline and the multiple pycnocline. To alleviate the low accuracy of bang-bang control and proportion integration differentiation control, and furthermore, to mitigate the disturbance of pitch by sudden density changes, we propose the actuator constrained active disturbance rejection controller in conjunction with specific glider pitch actuator hardware constraints. Simulation results show that the proposed method has significant improvement in pitch control accuracy over the comparison methods. View Full-Text
Keywords: underwater gliders; pycnocline; pitch control; ACADRC underwater gliders; pycnocline; pitch control; ACADRC
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MDPI and ACS Style

Zang, W.; Chen, M.; Guo, T.; Luan, X.; Song, D. Precise Underwater Gliders Pitch Control with the Presence of the Pycnocline. J. Mar. Sci. Eng. 2021, 9, 1013. https://doi.org/10.3390/jmse9091013

AMA Style

Zang W, Chen M, Guo T, Luan X, Song D. Precise Underwater Gliders Pitch Control with the Presence of the Pycnocline. Journal of Marine Science and Engineering. 2021; 9(9):1013. https://doi.org/10.3390/jmse9091013

Chicago/Turabian Style

Zang, Wenchuan, Ming Chen, Tingting Guo, Xin Luan, and Dalei Song. 2021. "Precise Underwater Gliders Pitch Control with the Presence of the Pycnocline" Journal of Marine Science and Engineering 9, no. 9: 1013. https://doi.org/10.3390/jmse9091013

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