Ugur Hasirci

A Novel Magnetic-Levitation System: Design, Implementation, and Nonlinear Control

This paper concerns the design, implementation, and nonlinear velocity-tracking control of a novel magnetic-levitation (maglev) system for magnetically levitated trains. The proposed system uses only one tubular linear induction motor to produce three forces required in a maglev system: propulsion, levitation, and guidance. Classical maglev systems, on the other hand, contain a separate force-generating system to build each of these three forces. Another benefit that the proposed system offers is that there is no need to control the guidance, and particularly, the levitation forces, one of the most challenging tasks in maglev systems. The system always centers the moving part during operation and eliminates the necessity for control of the levitation and guidance forces. However, the propulsion force strongly requires some control efforts because a linear induction motor has nonlinear system dynamics. This paper gives a condensed design guideline based on the mature theory of electromagnetic launchers, particularly the linear induction launcher type. It explains the implementation process, shows experimental test results, and finally, presents a nonlinear partial state-feedback controller for the proposed system.

Concerning the Design of a Novel Electromagnetic Launcher for Earth-to-Orbit Micro- and Nanosatellite Systems

This paper presents an alternative launcher design for Earth-to-orbit (ETO) micro- and nanosatellite systems. The main goal of the design is to reduce the cost of the launching operation. This paper also addresses the calculation of the energy required for the launching operation and the selection of a power source for the designed satellite launcher. The method introduced here proposes a vertical-takeoff electromagnetic launcher for ETO micro- and nanosatellite systems. The design specifications are 7-km/s muzzle velocity and 30000-gee acceleration for a 10-kg payload. It is expected that the proposed design would present a viable alternative to conventional launchers for ETO systems.

Experimental Performance Investigation of a Novel Magnetic Levitation System

This paper deals with the design, construction, and especially the testing of a new magnetic levitation (maglev) train driven by an air-cored tubular linear induction motor. The proposed new design topology uses only one force-generating system (motor) to produce the three forces required in a maglev system: propulsion, levitation, and guidance, whereas classical maglev trains use separate motors or permanent magnets to produce each of these forces. Moreover, the system eliminates the need for control of the levitation and guidance forces. This paper presents a condensed design guideline, simply explains the implementation process of a laboratory-scale prototype, shows in detail the experimental test results—including the low-damping problem—and then addresses the advantages of the proposed system over existing maglev systems.

Indoor navigation for mobile robots using predictive fields

A predictive field based path planner for mobile robot navigation in indoor areas is described. Predictive fields are used for incorporating moving obstacle information into the navigation function framework. Navigation functions have been limited by geometric restrictions for robot workspaces and cannot easily be used in everyday environments. A methodical description of indoor workspaces such that they follow the constraints of a navigation function based path planner is proposed. Typical use of navigation function based path planners as a gradient based control input requires large scaling factors in practical use. A direction based control input, which eliminates the scaling factor altogether, is proposed and its stability and convergence is proved using Lyapunov-type analysis. The proposed algorithm improves the practicability of navigation functions and makes it possible to envisage a person following mobile robot operating in indoor environments using predictive field navigation.

3-D FEM Analysis of a Novel Magnetic Levitation System

This paper deals with the 3-D finite element method (FEM) analysis of a novel magnetic levitation (maglev) train driven by an air-cored tubular linear induction motor. This new maglev system originates from electromagnetic launcher (EML) technology, especially linear induction launcher (LIL) type. Some 2-D magnetic analyses based on current sheet model or transmission line approach for the LIL type launchers are available in the literature, but this paper provides an alternative way to analyze LIL type of EMLs using 3-D FEM. The analysis examines the variation of propulsion, levitation, and guidance forces induced in the moving part. It is expected that the possible results of this magnetic analysis will lead to some new and important design considerations for the novel maglev system.

Design, fabrication and test of a 250 m/s generator-driven coil launcher

This study deals with the design, implementation and real time test of a generator-driven, full-scale 250 m/s Linear Induction Launcher (LIL). The paper presents a condensed but comprehensive design guideline for such a type of launcher, explains in detail the implementation process, and discusses the test results. Additionally, effects of different materials, different thicknesses, and different lengths of the projectile on the muzzle velocity of the launcher are also examined to obtain a comparison facility for the projectile. The paper clearly explains and experimentally shows step-by-step how a coilgun-type generator-driven EML is designed and fabricated, including barrel design, projectile design, power source and power conditioner design.

Experimental performance investigation of a novel magnetic levitation system

This paper deals with the design, construction and especially the experimental test of a new magnetic levitation (maglev) train driven by an air-cored tubular linear induction motor. Proposed new design topology uses only one force-generating system (motor) to produce the three forces required in a maglev system: propulsion, levitation and guidance, whereas classical maglev trains use a separate motor or permanent magnet to produce each of these forces. Moreover, the system eliminates the need for control of the levitation and guidance forces. The paper presents a condensed design guideline, simply explains the implementation process of a laboratory-scale prototype, shows in detail the experimental test results including the low-damping problem, and then addresses the advantages of the proposed system over existing maglev systems.

An engineering education tool for real-time nonlinear control: Stabilization of a single link robot

Nonlinear control is generally considered as more complex than linear control techniques by graduate students. This is especially because the analysis and design tools for linear systems comprise mature, simple and powerful methods and so almost all undergraduate programs in system engineering provide some linear control classes. But, on the other hand, all physical systems available in nature are inherently nonlinear. Graduate-level education programs in electrical engineering should provide some courses to the learner to make them able to design and implement more realistic high performance controllers to control the engineering systems. This paper deals with the experimental demonstration of the necessity of having a real-time nonlinear control system to be able to design such controllers. Specifically, the paper is designed as a supplementary experimental tool for a nonlinear control class to boost students’ interest and encouragement in this topic. For this aim, a simple tool, a single-link robot driven by a permanent magnet direct current motor, is used to demonstrate the benefits with the real-time nonlinear control systems and to provide replication facility to an instructor. The paper explains in detail the design and implementation of a nonlinear exact-model controller assuming all the system parameters are exactly known, and then, a more realistic case, a nonlinear adaptive controller with full parameter uncertainty. An additional experiment on the effects of a non-real-time system is also presented.

Closed-loop nonlinear smooth robust control of anti-angiogenic tumor therapy

This paper presents a smooth robust controller for anti-angiogenic treatment of a tumor growth. The proposed control algorithm directly aims to drive the carrying capacity of the vascular support network to a desired trajectory that reduces overall tumor volume. For this aim, we present a closed-loop smooth robust controller that ensures the asymptotic tracking of a time-varying carrying capacity profile, despite the model uncertainties. A Lyapunov-based analysis approach is used to determine stability and performance results. Numerical simulation results are presented to demonstrate the performance and feasibility of the proposed approach. Simulation studies also examine some practical issues regarding the clinical application of the proposed dosing algorithm. Finally, the paper provides some basics for real-time implementation of the overall system.

Design, implementation and test of a coilgun-type electromagnetic launcher prototype

This paper deals with the design, fabrication and test of a laboratory scale prototype 50 m/s coilgun-type electromagnetic launcher. It presents a comprehensive design guideline, explains the implementation process, and shows and briefly discusses the test results.