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Modeling and Control of Flexible Link Manipulators

Dipendra Subedi of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Modeling and Control of Flexible Link Manipulators» and will defend the thesis for the PhD-degree Tuesday 13 September 2022. (Photo: Private)

The thesis aims at presenting a unified understanding of modeling, control, and application of long-reach flexible manipulators. State-of-the-art dynamic modeling techniques and control schemes of the flexible link manipulators are discussed along with their merits, limitations, and challenges.

Dipendra Subedi

PhD Candidate

Dipendra Subedi of the Faculty of Engineering and Science at the University of Agder has submitted his thesis entitled «Modeling and Control of Flexible Link Manipulators» and will defend the thesis for the PhD-degree Tuesday 13 September 2022.

He has followed the PhD programme in Engineering and Science at UiA, with Specialisation in Engineering Sciences, scientific field Mechatronics.

The doctoral work are funded by the Ministry of Education (KD), Research Council of Norway through the centre SFI Offshore Mechatronics (project 237896), and the University of Agder.

Read the summary of the thesis by Dipendra Subedi:

Modeling and Control of Flexible Link Manipulators

Autonomous maritime navigation and offshore operations have gained wide attention with the aim of reducing operational costs and increasing reliability and safety.

Autonomously or semi-autonomously operations

Offshore operations, such as wind farm inspection, sea farm cleaning, and ship mooring, could be carried out autonomously or semi-autonomously by mounting one or more long-reach robots on the ship/vessel.

In addition to offshore applications, long-reach manipulators can be used in many other engineering applications such as construction automation, aerospace industry, and space research.

Some applications require the design of long and slender mechanical structures, which possess some degrees of flexibility and deflections because of the material used and the length of the links. The link elasticity causes deflection leading to problems in precise position control of the end-effector.

So, it is necessary to compensate for the deflection of the long-reach arm to fully utilize the long-reach lightweight flexible manipulators.

A unified understanding

The thesis aims at presenting a unified understanding of modeling, control, and application of long-reach flexible manipulators.

State-of-the-art dynamic modeling techniques and control schemes of the flexible link manipulators are discussed along with their merits, limitations, and challenges.

The kinematics and dynamics of a planar multi-link flexible manipulator are presented.

The effects of robot configuration and payload on the mode shapes and eigenfrequencies of the flexible links are discussed.

A method to estimate and compensate for the static deflection of the multi-link flexible manipulators under gravity is proposed and experimentally validated.

The redundant degree of freedom of the planar multi-link flexible manipulator is exploited to minimize vibrations.

The application of a long-reach arm in autonomous mooring operation based on sensor fusion using camera and LiDAR data is proposed.

 

Disputation facts:

The trial lecture and the public defence will take place on campus in Auditorium C2 040, Campus Grimstad, and online via the Zoom conferencing app - registration link below.

Associate Professor Margrethe Wold, Faculty of Engineering and Science at the University of Agder, will chair the disputation.

The trial lecture Tuesday 13 September at 10:15 hours

Public defense Tuesday 13 September at 12:15 hours

 

Given topic for trial lecture«Force control of robotic manipulators: state of the art and current challenges»

Thesis Title«Modeling and Control of Flexible Link Manipulators»

Search for the thesis in AURA - Agder University Research Archive, a digital archive of scientific papers, theses and dissertations from the academic staff and students at the University of Agder.

The thesis is available here:

https://uia.brage.unit.no/uia-xmlui/handle/11250/3021841 

 

The CandidateDipendra Subedi (16.02.1993, Baglung, Nepal) Bachelor of Engineering (Electrical and Electronics Engineering) Anna University, India (2014), MSc. (Advanced Robotics) I Year - University of Genoa, Italy (2016), MSc. (Advanced Robotics) II Year - Jaume I University, Spain (2017)

Opponents:

First opponent: Senior lecturer PhD Yiannis Karayiannidis, Lunds Universitet, Sverige

Second opponent: Professor Jan Tommy Gravdahl, NTNU - Norwegian University of Science and Technology

Associate Professor Souman Rudra, University of Agder,  is appointed as the administrator for the assessment committee.

Supervisors in the doctoral work were Associate Professor Ilya Tyapin, University of Agder (main supervisor) and Professor Geir Hovland, University of Agder (co-supervisor)