Nonlinear robust integral sliding super-twisting sliding mode control application in autonomous underwater glider

1016-1027The design of a robust controller is a challenging task due to nonlinear behaviour of the glider and surround environment. This paper presents design and simulation of nonlinear robust integral super-twisting sliding mode control for controlling the longitudinal plane of an autonomous underwater glider (AUG). The controller is designed for trajectory tracking problem in existence of external disturbance and parameter variations for pitching angle and net buoyancy of the longitudinal plane of an AUG. The algorithm is designed based on integral sliding mode control and super-twisting sliding mode control. The performance of the proposed controller is compared to original integral sliding mode and original super-twisting algorithm. The simulation results have shown that the proposed controller demonstrates satisfactory performance and also reduces the chattering effect and control effort

Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)

This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases

Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)

904-913This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases

EFFECT OF RUDDER DESIGN ON HYDRODYNAMIC FORCES OF AUTONOMOUS UNDERWATER GLIDER

An autonomous underwater glider (AUG) is a vehicle with fixed-wing. They move through the ocean by changing the buoyancy to follow a “Saw-tooth” pattern of motion. In this project, a part of AUGs which is rudder design is studied. Specifically, the relationship between rudder design and lift and drag of hydrodynamic forces is investigated. The comparative study is done between conventional rudder and schilling/ fishtail rudder. For the modelling works, SOLIDWORKS is used to create the model. ANSYS code "Fluent” is used to do analysis on hydrodynamic performance such as lift force of AUGs. The numerical simulation is done at various angle of attack from 0°- 20°. The result from the simulation shown that the fishtail rudder has higher lift coefficients and can produce better maneuvering performance compare to conventional rudder

Pemahaman pelajar tingkatan lima katering terhadap bab kaedah memasak dalam mata pelajaran teknologi katering

Bab Kaedah Memasak merupakan salah satu bab yang penting dalam mata pelajaran Teknologi Katering. Faktor terpenting adalah memastikan pelajar menguasai serta memahami konsepnya adalah melalui proses pengajaran dan pembelajaran yang betul. Tinjauan awal di Sekolah Menengah Teknik yang menawarkan Kursus Katering, menunjukkan bahawa kebanyakan pelajar sukar untuk menguasai dan memahami bab tersebut. Berdasarkan hasil tinjauan , pengkaji ingin mengenalpasti pemasalahan dalam memahami bab tersebut. Di samping itu juga, pengkaji ingin mengenalpasti adakah pencapaian pelajar dalam PMR, minat, motivasi dan gaya pembelajaran mempengaruhi pemahaman pelajar, Kajian rintis telah dilakukan terhadap 10 orang responden dengan nilai alpha 0.91. Ini menunjukkan kebolehpercayaan terhadap kajian di jalankan adalah tinggi. Responden adalah terdiri daripada 30 orang pelajar Tingkatan Lima (ERT) Sekolah Menengah Teknik Muar, Johor. Keputusan skor min keseluruhan menunjukkan pelajar berminat dan mempunyai motivasi ynag baik dalam bidang ini. Namun begitu, gaya pembelajaran yang diamalkan tidak sesuai dan antara pemyebab wujudnya pemasalahan dalam memahami bab Kaedah Memasak. Ujian kolerasi menunjukkan bahawa tidak terdapat sebarang hubungan signifikan antara pencapaian PMR pelajar dengan pemahaman bab tersebut. Sementara minat, motivasi dan gaya pembelajaran membuktikan ada hubungan signifikan dengan pemahaman pelajar dalam bab Kaedah Memasak

EFFECT OF TRANSVERSE, LONGITUDINAL AND VERTICAL SEPARATION ON DRAG FOR A FLEET OF AUTONOMOUS UNDERWATER GLIDER

Land vehicle platooning has shown positive result in improving its fuel efficiency with decrease in drag. In this work, platooning of an autonomous underwater glider fleet is investigated. Specifically, the effect of transverse and longitudinal separation of the glider on the drag for a “V” formation is studied. An alternative 3D configuration for “V” formation which requires less foot print space is proposed. Besides that, the effect of transverse, longitudinal and vertical separation of glider for the 3D “V” formation on the drag will be studied. The number of glider in the fleet will be limited to five gliders. The project is a simulation study using ANSYS Fluent with Re-Normalization Group (RNG) k-epsilon model with non-equilibrium wall function as the turbulence model. Based on the simulation, the drag of the alternative 3D configuration is relatively similar to the drag of the drag of “V” formation. This shows that low drag can still be achieved with a more compact formation

EFFECT OF TRANSVERSE, LONGITUDINAL AND VERTICAL SEPARATION ON DRAG FOR A FLEET OF AUTONOMOUS UNDERWATER GLIDER

Land vehicle platooning has shown positive result in improving its fuel efficiency with decrease in drag. In this work, platooning of an autonomous underwater glider fleet is investigated. Specifically, the effect of transverse and longitudinal separation of the glider on the drag for a “V” formation is studied. An alternative 3D configuration for “V” formation which requires less foot print space is proposed. Besides that, the effect of transverse, longitudinal and vertical separation of glider for the 3D “V” formation on the drag will be studied. The number of glider in the fleet will be limited to five gliders. The project is a simulation study using ANSYS Fluent with Re-Normalization Group (RNG) k-epsilon model with non-equilibrium wall function as the turbulence model. Based on the simulation, the drag of the alternative 3D configuration is relatively similar to the drag of the drag of “V” formation. This shows that low drag can still be achieved with a more compact formation

Towards basin-scale in-situ characterization of sea-ice using an Autonomous Underwater Glider

Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2020.This thesis presents an Autonomous Underwater Glider (AUG) architecture that is intended for basin-scale unattended survey of Arctic sea-ice. The distinguishing challenge for AUG operations in the Arctic environment is the presence of year-round sea-ice cover which prevents vehicle surfacing for localization updates and shore-side communication. Due to the high cost of operating support vessels in the Arctic, the proposed AUG architecture minimizes external infrastructure requirements to brief and infrequent satellite updates on the order of once per day. This is possible by employing onboard acoustic sensing for sea-ice observation and navigation, along with intelligent management of onboard resources. To enable unattended survey of Arctic sea-ice with an AUG, this thesis proposes a hierarchical acoustics-based sea-ice characterization scheme to perform science data collection and assess environment risk, a multi-factor terrain-aided navigation method that leverages bathymetric features and active ocean current sensing to limit localization error, and a set of energy-optimal propulsive and hotel policies that react to evolving environmental conditions to improve AUG endurance. These methods are evaluated with respect to laboratory experiments and preliminary field data, and future Arctic sea-ice survey mission concepts are discussed.Support for this research was provided through the National Science Foundation Navigating the New Arctic Grant #1839063 and the NASA PSTAR Grant #NNX16AL08G. Additionally, this research was supported by the Walter A. Rosenblith Presidential Fellowship

In-situ characterization of sea state with improved navigation on an Autonomous Underwater Glider

Submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2022.This thesis presents an Autonomous Underwater Glider (AUG) architecture with improved onboard navigation and acoustics-based sensing intended to enable basin-scale unattended surveys of our Earth’s most remote oceans. Traditional AUGs have long-been an important platform for oceanographic surveys due to their high endurance and autonomy, yet lack the operational flexibility to operate in many regions of scientific interest and the sensing capability to capture scientific data at the air-sea interface. Particularly of interest is the marginal ice zone (MIZ) in the Arctic and the Southern Ocean, as both are vitally important to understanding global climate trends, yet prohibitively expensive to persistently monitor with support vessels. To fill this observational gap, the sensing, navigation, and adaptability of AUGs must be improved. This is possible by employing onboard acoustic sensing for sea state observation and navigation, as well as incorporating vehicle improvements targeting maneuverability and intelligent adaptability to evolving environmental states. To enable persistent monitoring of both the water-column and air-sea interface, this thesis proposes an improved vehicle architecture for a more capable AUG, a real-time DVLaided navigation process that leverages ocean current sensing to limit localization error, and a subsea acoustics-based sea state characterization method capable of analyzing wave spectra under-ice and with zero surface expression. These methods are evaluated with respect to extensive laboratory experiments and field data collected during in-situ implementation.Support for this research was provided through grants from the National Science Foundation (NSF) Navigating the New Arctic Grant (NNA #1839063) and the National Ocean Partnership Program (NOPP) Enhanced Propulsion Integrated Capability - Deep Autonomous Underwater Glider (EPIC-DAUG) grant (NA19OAR0110408)