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Tracking control of an underwater vehicle using adaptive back-stepping with tuning function
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 4 , 2005 , Pages 131-138 ; 0791847411 (ISBN); 9780791847411 (ISBN) ; Saghafi, M. M ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
In this article the design and simulation of a velocity and position control for an underwater Remotely Operated Vehicle (ROV) is addressed. The system has a nonlinear dynamic with parametric uncertainties making it a reasonable test-bed for investigating the effectiveness of robust nonlinear control algorithms. The studied ROV can be actively controlled along the 3 Cartesian coordinate directions and rotated about the vertical axis using 4 thrusters positioned on the ROV. The dynamics of the actuator system, consisting of thrusters, is assumed to be a first order linear system with an unknown parameter. To control this system adaptive back-stepping, as a robust adaptive nonlinear control...
Design of a navigator for the optimized path-tracking of underwater ROVs using a nero-genetic fuzzy controller
, Article 2006 World Automation Congress, WAC'06, Budapest, 24 June 2006 through 26 June 2006 ; 2006 ; 1889335339 (ISBN); 9781889335339 (ISBN) ; Saghafi, M. H ; Fathy, M ; Soriani, M ; Sharif University of Technology
IEEE Computer Society
2006
Abstract
This paper proposes a sublime-optimum soft- computing based controller to follow a desired path with a desired velocity by mobile robots with identified dynamical behavior. This method consists of a fuzzy controller where a trained Neural Network sets its membership functions values in On-line mode. Training of the Network is done by a Genetic Algorithm for various vehicle initial positions and different path convexities in Off-line. After the training of the network, during vehicle motion, it retrieves sub-optimized fuzziness values and sends them to the fuzzy control algorithm according to the vehicle position. Meanwhile, the influential of the path convexity is considered in fuzziness of...
Magnetron-sputtered TixNy thin films applied on titanium-based alloys for biomedical applications: Composition-microstructure-property relationships
, Article Surface and Coatings Technology ; Volume 349 , 2018 , Pages 251-259 ; 02578972 (ISSN) ; Saghafi, M ; Khamseh, S ; Alibakhshi, E ; Zarrintaj, P ; Saeb, M. R ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Progress in tissue engineering and regenerative medicine necessitates the use of novel materials with promising bio-surface for biomedical applications. In this work, TixNy thin films are applied on biological TC4 substrates in a mixed atmosphere of Ar and N2 via magnetron sputtering system for the protection of TC4 alloy. The effects of N/Ti ratio on the phase structure, growth orientation, contact angle, and the mechanical and corrosion performances of thin films are discussed by implementation of composition-microstructure-property interrelationships. The phase structure of TixNy thin films is changed from amorphous-like to single phase Ti2N structure with increasing N/Ti ratio. In the...