Search for: variation-of-extremals
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    Optimal control of human-like musculoskeletal arm: prediction of trajectory and muscle forces

    , Article Optimal Control Applications and Methods ; Volume 38, Issue 2 , 2017 , Pages 167-183 ; 01432087 (ISSN) Sharifi, M ; Pourtakdoust, S. H ; Parnianpour, M ; Sharif University of Technology
    Optimal trajectory and muscle forces of a human-like musculoskeletal arm are predicted for planar point-to-point movements using optimal control theory. The central nervous system (CNS) is modeled as an optimal controller that performs a reaching motion to final states via minimization of an objective function. For the CNS strategy, a cubic function of muscles stresses is considered as an appropriate objective function that minimizes muscles fatigue. A two-DOF nonlinear musculoskeletal planar arm model with four states and six muscle actuators is used for the evaluation of the proposed optimal strategy. The nonlinear variational formulation of the corresponding optimal control problem is... 

    Optimal robust control of drug delivery in cancer chemotherapy: A comparison between three control approaches

    , Article Computer Methods and Programs in Biomedicine ; Volume 112, Issue 1 , 2013 , Pages 69-83 ; 01692607 (ISSN) Moradi, H ; Vossoughi, G ; Salarieh, H ; Sharif University of Technology
    During the drug delivery process in chemotherapy, both of the cancer cells and normal healthy cells may be killed. In this paper, three mathematical cell-kill models including log-kill hypothesis, Norton-Simon hypothesis and Emax hypothesis are considered. Three control approaches including optimal linear regulation, nonlinear optimal control based on variation of extremals and H∞-robust control based on μ-synthesis are developed. An appropriate cost function is defined such that the amount of required drug is minimized while the tumor volume is reduced. For the first time, performance of the system is investigated and compared for three control strategies; applied on three nonlinear models...