Designing an intelligent controller for landing phase of a jet transport aircraft in presence of ... more Designing an intelligent controller for landing phase of a jet transport aircraft in presence of different wind patterns, in order to expand the flight safety envelope has been considered. There are some dangerous conditions like gusts and downbursts which may occur rarely in service life of aircraft, though, aircraft must be tested for these dangerous conditions. Then it is desired to design a controller that not only acts well in usual conditions but also has an acceptable performance in those hazardous conditions. Four different types of controllers have been designed named PID, Neuro, hybrid Neuro-PID and Anfis-PID (Adaptive Network-based Fuzzy Inference System) controllers. Simulation results show that the Anfis-PID which its inner loop is PID and outer loop is Anfis satisfies desired conditions in presence of very strong gust, however, the performance of Neuro-PID is also acceptable. To evaluate the performance of controllers two level of performance have been defined named level I (desired) and level II (acceptable). Also, in comparison with JFK airport gusts two strong wind patterns named strong and very strong winds have been applied.
In this paper, a Robust adaptive neural network controller (RANNC) based on variable structure sy... more In this paper, a Robust adaptive neural network controller (RANNC) based on variable structure system for robotic manipulators is proposed to alleviate the problems met in practical implementation using classical variable structure controllers. The chattering phenomenon is eliminated by substituting single-input single-output radialbasis-function neural networks (RBFNN's), which are nonlinear and continuous, in lieu of the discontinuous part of the control signals present in classical forms. The weights of the hidden layer of the RBFNN's are updated in an online manner to compensate the system uncertainties. The key feature of this scheme is that prior knowledge of the system uncertainties is not required to guarantee the stability. Moreover, a theoretical proof of the stability and convergence of the proposed scheme using Lyapunov method is presented. To demonstrate the effectiveness of the proposed approach, a practical situation in robot control is simulated.
Genetic approach to pole placement by static output feedback
Proceedings of the 2002 Congress on Evolutionary Computation. CEC'02 (Cat. No.02TH8600), 2002
In this paper, a new approach for solving the problem of pole assignment, using static output fee... more In this paper, a new approach for solving the problem of pole assignment, using static output feedback, has been proposed. The proposed approach is based on genetic algorithm where it can place all the closed-loop poles at desired locations with a high accuracy, provided that there exists a solution to the problem. It is also shown that how some known difficulties of static output feedback like order of system, multiplicity of the desired poles and the need for having closed-loop poles to be distinct or different from the open loop poles have been solved. Numerical examples at the end of the paper illustrate the applicability and the performance of the proposed method
Computing bidding strategies in oligopolistic electricity markets using an analytic approach
This paper presents a new method to compute bidding strategies for generating companies (Gencos) ... more This paper presents a new method to compute bidding strategies for generating companies (Gencos) in electricity markets. The proposed scheme, which is based on an analytic approach to supply function models, is simpler computationally compared with conventional approaches, while the uniqueness and existence of its solution is also guaranteed. Furthermore, it is shown that it can also be applied to Cournot models. Simulations prove its effectiveness, and its analytic nature opens way for strategies to be analyzed more thoroughly.
Presented is a novel approach for online trajectory modification of joint motions to transfer a f... more Presented is a novel approach for online trajectory modification of joint motions to transfer a free open kinematic chain, undergoing flight phase, from a specified initial configuration to a specified final configuration. Formally, it is assumed that a nominal trajectory, computed offline, can reorient the kinematic chain (reconfiguration problem) for a given angular momentum on a time interval. A modification algorithm of body joints, based on optimal control, is developed such that for different angular momentums and time intervals, the same reconfiguration problem can be solved online. This approach can be utilised for space robotics applications and online computation of planar running trajectories during flight phases.
Two-level optimal load–frequency control for multi-area power systems
International Journal of Electrical Power & Energy Systems, 2013
ABSTRACT In large-scale power systems, classical centralized control approaches may fail due to g... more ABSTRACT In large-scale power systems, classical centralized control approaches may fail due to geographically distribution of information and decentralized controllers result in sub-optimal solution for load–frequency control (LFC) problems. In this paper, a two-level structure is presented to obtain optimal solution for LFC problems and also reduce the computational complexity of centralized controllers. In this approach, an interconnected multi-area power system is decomposed into several sub-systems (areas) at the first-level. Then an optimization problem in each area is solved separately, with respect to its local information and interaction signals coming from other areas. At the second-level, by updating the interaction signals and using an iterative procedure, the local controllers will converge to the overall optimal solution. By parallel solving of areas, the computational time of the algorithm is reduced in contrast to centralized controllers. This approach is applicable to any interconnected large-scale power system. However, for simulation purposes, a three-are power system is presented to show advantages and optimality of the proposed algorithm.
International Journal of Electrical Power & Energy Systems, 2014
Supply function equilibrium (SFE) is often used to describe the behavior of generating companies ... more Supply function equilibrium (SFE) is often used to describe the behavior of generating companies in electricity markets. However, comprehensive analytical description of supply function models is rarely available in the literature. In this paper, using some analytical calculations, a novel direct approach is proposed to compute the Nash equilibrium (NE) of the supply function model under uniform marginal pricing mechanism. An explicit mathematical proof for its existence and uniqueness is also presented. The proposed methodology is then generalized to accommodate practical market constraints. In addition, a new concept of robust NE is introduced and calculated based on this approach. Finally, numerical simulations demonstrate the applicability and effectiveness of the proposed solution scheme.
On the application of fuzzy predictive control based on multiple models strategy to a tubular heat exchanger system
Transactions of the Institute of Measurement and Control, 2010
Page 1. http://tim.sagepub.com/ Measurement and Control Transactions of the Institute of http://t... more Page 1. http://tim.sagepub.com/ Measurement and Control Transactions of the Institute of http://tim.sagepub.com/content/32/4/395 The online version of this article can be found at: DOI: 10.1177/0142331209345153 February 2010 2010 32: 395 originally published online 18 ...
Fuzzy multiple models predictive control of tubular heat exchanger
2008 IEEE International Conference on Fuzzy Systems (IEEE World Congress on Computational Intelligence), 2008
In this paper, a new strategy for control of tubular heat exchanger system has been presented. Th... more In this paper, a new strategy for control of tubular heat exchanger system has been presented. The proposed approach is realized using generalized predictive control (GPC) scheme and multiple models method. By using the multiple models approach, different operating environments of the system are first modeled. Then in each instant of time, the best model of the system is identified
A case study for fuzzy adaptive multiple models predictive control strategy
2009 IEEE International Symposium on Industrial Electronics, 2009
... Now, the inner tube temperature should be adjusted by commanded valve pressure; Pv , on the s... more ... Now, the inner tube temperature should be adjusted by commanded valve pressure; Pv , on the shell tube. ... 3, pp. 2936-2937, 1994. [21] MHR Fazlur Rahman and R. Devanathan, "Modeling and dynamic feedback linearization of a heat exchanger," in Proc. ...
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