Autoland controllers are prevalent for both large and small/micro unmanned aerial vehicles, but very few are available for medium-sized unmanned air vehicles. These vehicles tend to have limited sensors and instrumentation, yet must possess good performance in the presence of modeling uncertainties and exogenous inputs such as turbulence. Quantitative feedback theory has been reported in the li...

This research deals to introduce a new method for generalizing the well-famed Quantitative Feedback Theory (QFT) in granting robustness of Feedback linearization on nonlinear systems. In this new scheme, first applying feedback linearization, with selecting operating points in domain of system parameter's variations, nonlinear systems replaced with linear systems, then robust controller is desi...

researchers have suggested that interactional feedback which is between teacher and learner during their writing is associated with l2 learning because it prompts learners to notice l2 forms. this paper reports a classroom-based study that investigated the role of feedback in socio-cultural theory. in this study, 12 efl learners performed on three writing tasks and were provided with a three-st...

This paper examines the feedback design possibilities for uncertain plants where the underlying parameterisation is described by a probabilistic rather than a deterministic set membership. The design perspective is Horowitz' quantitative feedback theory.

This paper represents the design of a Quantitative Feedback Theory (QFT) based controller for an unstable system with some desired performance specifications [1]. Here a controller and prefilter has been designed so that the given performance specifications like robust stability and robust tracking criterions can be achieved. In order to implement that, different algorithms have been used and t...

Temperature control of tank reactors with exothermic reactions is an acknowledgedly difficult task because of complex interacting phenomena, several nonlinearities and unstable dynamics. Traditionally, simple control functions are implemented, implying poor control performance and small operating windows. However, many advanced control schemes have been published, though in many applications th...

Most of the practical systems are characterized by high uncertainty which makes it difficult to maintain good stability margins and performance properties for closed loop system. In case of conventional control, if plant parameter changes we cannot assure about the system performance hence it is necessary to design robust control for uncertain plant. Among the various strategies proposed to tac...

Quantitative feedback theory (hereafter referred as QFT), developed by Isaac Horowitz (Horowitz, 1963; Horowitz and Sidi, 1972), is a frequency domain technique utilizing the Nichols chart in order to achieve a desired robust design over a specified region of plant uncertainty. Desired time-domain responses are transformed into frequency domain tolerances, which lead to bounds (or constraints) ...

An important statement in Quantitative Feedback Theory(QFT) is that the nominal plant can be chosen arbitrarily whether or not it is a member of the plant set. Based on this statement, a design method for non-minimum phase and unstable plants proposed by Horowitz is to choose the stable minimum phase plant as the nominal plant. This report shows this statement is incorrect by several counterexa...

This paper evaluates a new and simple controller design method based on QFT (quantitative feedback theory) for a two-link manipulator whose first link is rigid and the second is flexible. A piezoelectric patch is attached to the surface of the flexible link for vibration suppression of it. This system is modeled as a nonlinear multi-input multi-output (MIMO) control systems whose inputs are two...