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This study presents an untethered magnetic manipulation technique for controlling a microrobot position under high rate laminar flows up to 4.5 mL/min. An increase in flow rate exponentially increases the drag force on the microrobot and negatively impacts its positioning accuracy. Increasing the longitudinal force generated by the microrobot's driving apparatus helps in overcoming the disruptive effects of the fluid flow and increases longitudinal motion stability. To this end, we propose a magnetic configuration with two ring-shaped magnets, one above and the other below the microfluidic channel. This configuration causes the magnetic field lines emanating from the ring-shaped magnets to converge on both sides of the microrobot. Thus, the magnetic trapping forces that hold the microrobot in position are increased. To the best of our knowledge, no prior study exists on investigating the longitudinal motion for high flow velocities (>5 mm/s). Investigating the longitudinal forces (along the x-axis) that affect a magnetically-driven microrobot is a novel research topic that has many potential application areas such as cell research, micromanipulation, and lab-on-a-chip systems. The microrobot's dynamical motion is modeled as a second-order system, and using this model as a guideline, we demonstrate the ability of a microrobot in a square-shaped microfluidic channel 900 m 900 m to follow a linear trajectory with a relative velocity up to 132.6 mm/s. A straight and longitudinal trajectory of 4000 m has been successfully followed in the same and opposite directions to the flow for different flow rates (1-4.5 mL/min) and different robot speeds (10-50 mm/s).

Recent advancements in computational power technology and wide-usage of high qualified electronic hardware allow many engineers to create their control strategies in data-driven and model-free approaches, such as reinforcement-learning, genetic algorithm and other machine learning topics, rather than classical and modern control approaches. In this study, Q-Learning RL algorithm combined with analytic LMI method has been utilized to solve micro-scale vibration isolation problem as energy efficient as possible.

The importance of an untethered microrobotic platform that can operate on high flowrate microfluidic channels for in vitro applications is increasing rapidly. This article presents a method to manipulate a microrobot in a fluidic chip when high flowrates (4 ml/min, 82.304 mm/s) are applied. This method is based on a novel permanent magnet-based diamagnetic levitation configuration. This configuration includes a thin layer of pyrolytic graphite, which is placed just below the microrobot. In this way, microrobot stability and manipulation capability are increased. Also, we aim to increase the longitudinal forces imposed on the microrobot to withstand the drag force proportional to the flowrate. Hence, magnetic field lines are generated more linearly around the microrobot by a different combination of permanent magnets. The proposed magnetic configuration, named “KERKAN configuration,” significantly improves the microrobot’s longitudinal forces. In this configuration, two different ring-shaped ferromagnetic magnets are used. One of the magnets has a smaller diameter than the other magnet. A combination of one smaller and one bigger magnet is placed above and below the microrobot. To validate the advantages of this configuration, analytical and simulation studies are conducted. Their results are then compared with experimental results. Experimental results are on par with analytical and simulation studies. KERKAN configuration has a lower displacement than the next best configuration at the highest flowrate we applied (relatively 3301 μm, %21.8).

In this paper, detailed magnetic force analysis of a 4-pole hybrid electromagnet system providing an advantage of full-redundant levitation is studied. The novel fragmented magnetic equivalent circuit method (MEC) is developed to accurately capture inherited nonlinear characteristics of 4-pole hybrid electromagnet to investigate force characteristics and magnetic field distribution. To confirm this method, two possible scenarios, which are levitation under plain core and levitation under dual-linear motor are composed. As well as, they are examined by both proposed method and FEM analyses. Comparative analyses of both methods revealed that force, inclination torque, and mutual interference can be easily captured with adequate accuracy while at the same time yielding less computation and set up time. Furthermore, the fragmented formulations of permeance functions can be generalized for the analysis and the design of similar devices which specifically involve inclination motions.

This paper presents the electromagnetic and mechanical analysis of an axial flux permanent magnet (AFPM) motor for high speed (12000 rpm) rotor which is vertically suspended by magnetic bearings. In the analysis, a prototype AFPM motor with a double-sided rotor and a coreless stator between the rotors are considered. Firstly, electromagnetic analysis of the motor is carried out by using magnetic equivalent circuit method. Then, the rotor disk thickness is determined based on a rotor axial displacement due to the attractive force between the permanent magnets placed on opposite rotor disks. Hereafter, an analytical solution is carried out to determine the natural frequencies of the rotor-shaft system. Finally, 3D finite element analysis (FEA) is carried out to verify the analytical results and some experimental results are given to verify the analytical and numerical results and prove the stable high-speed operation.

Bu çalışmada, 3 adet doğrusal motorla karma elektromıknatısların bir araya getirilmesiyle elde edilen manyetik yastıklama temeline dayalı bir taşıma aracı, yeni nesil modüler bir taşıma sistemi meydana getirmek için önerilmiştir. Sonlu elemanlar metodu ile manyetik yastıklama kuvvetlerinin 3 boyutlu analizi yapılmıştır. Önerilen sistem doğrusal olmayan dinamiklere sahip olup kontrol açısından kararsız sistem özelliği göstermektedir. Sistemi kararlı hale getirecek denetleyici tasarımlarını gerçekleştirmek için 3-eksende hareket dinamiğine karşılık gelen doğrusal sistem modelleri geliştirilmiştir. Her bir eksen takımı için geliştirilen doğrusal modeller kullanılarak kararlılığı sağlayan ve aynı zamanda verilen referansı takip eden denetleyiciler I-PD denetleyici topolojisi dikkate alınarak tasarlanmıştır. Denetleyici tasarımlarında, muadillerine göre daha kolay tasarım ve uyarlama imkânı sağlayan kanonik polinom yaklaşımı ile katsayı diyagramı metodu kullanımı önerilmiştir. 3-serbestlik derecesinde manyetik yastıklama kontrolü deneysel olarak gerçekleştirilmiş, önerilen kontrol yaklaşımının etkinliği ve başarısı deneysel olarak gösterilmiştir.

Vibration isolation systems based on hybrid electromagnets, consisting of electromagnet and permanent magnet, have a potential usage in many industrial areas, such as clean room design, transportation, semiconductor manufacturing, suspension systems, and robotic surgery due to providing mechanical contact free vibration isolation. Using permanent magnets in the electromagnet structure has some crucial advantages, such as a minimized volume and a more compact structure. Furthermore, the essential force for levitation of vibration isolation stage can be generated by only the permanent magnet(s), which means, by using hybrid electromagnets, magnetic levitation can be achieved with considerably low energy consumption against possible vibrations. This property is called zero-power behavior. However, the main problems of magnetic levitation process are as follows: it has highly nonlinear nature even if it can be linearized; it has unstable pole(s), which makes the system vulnerable in terms of stability. In recent years, linear matrix inequality-based design of controllers has received considerable attention and become very popular due to their ability to satisfy multiobjective design requirements. However, an observer-based H2 controller design for a vibration isolation system having hybrid electromagnets has not been considered yet. Therefore, the linear matrix inequality-based controller is employed to minimize the effect of disturbances on the following objectives, such as vibration isolation, zero-power property, and protection of the levitation gap. The effectiveness of the proposed method is shown with the numerical simulation studies and compared with classical Linear Quadratic Regulator (LQR) approach.

In this study, we present a theoretical and numeric analysis of an untethered microrobot manipulation technique that can be used in a liquid environment. A microrobot, which is levitated on a pyrolytic graphite surface, allows us to achieve high precision positioning (at nano level) and control with lower external magnetic force requirements due to stabilizing manner of its locomotion. Stabilizing microrobot is controlled via a single "lifter magnet" as a driving force that is placed on an automatic micro-stage in order to provide stable-motion about x, y and z axes. The presented microrobot is designed for single cell manipulation and transportation operations in liquid medium. It can be used in different experimental setups such as lab-on-a-chips, petri dishes. Here, a new approach to determine an optimal experimental setup of the diamagnetically levitated microrobot, which provides the most effective and possible microrobot control, is explained with FEM (Finite Element Method) analysis and required background information. For such untethered microrobot control experiments in a FEM program, determination of the size of materials used, selection criteria, required magnetic force effects, and optimum pyrolytic graphite sizes are discussed in detail. To do that, our proposed analysis method suggests how to construct such an FEM model parametrically in COMSOL (R). Before starting the experimental work, the effects of the material and dimensions of each element forming the system on the microrobot are discussed in detail. Moreover, the manipulation technique which revealed the theoretical infrastructure is compared with the numerical calculations and the results are shown to be compatible with each other.

Zero-power micro vibration isolators based on hybrid electromagnets, consisting of coils and permanent magnets, have potential usage in many industrial and academic fields, such as space laboratory operations in orbit, micro-nano assembly, clean room design, bio-engineering, stewart platforms, transportation, semiconductor manufacturing, suspension system design, and robotic surgery platforms etc. due to providing mechanical contact free micro vibration isolation with comparatively low energy consumption. Classical controllers optimized in time-domain do not show satisfying disturbance rejection performance for multi-directional mechanical disturbances varying at different frequencies. To tackle this problem, optimization techniques in frequency-domain are needed. In recent years, linear matrix inequality (LMI) based controllers have received lots of attention and become very popular due to their ability to satisfy multi-objective frequency-domain requirements. However, an experimental research including LMI based H ∞ and H 2 feedback controllers for a zero-power 3-DoF micro vibration isolator has not been conducted so far. In this study, H ∞ and H 2 controller types are employed to minimize the H ∞ and H 2 norms of both ground and direct disturbances for 3-DoF micro-scale vibration isolation with zero-power objective. Moreover, the experimental setup has been designed and manufactured to meet aforementioned goals. The design parameters of the experimental setup are explicitly given. The effectiveness of the proposed LMI structures for 3-DoF micro vibration isolation with zero-power problem is shown with the experimental results.

In this article, we present a microrobot manipulation technique with high precision positional ability to move in a fluid environment with diamagnetic levitation. Untethered manipulation of microrobots by means of externally applied magnetic forces has been emerging as a promising field of research, particularly due to its potential for medical and biological applications. The decreased size of the robots makes them suitable for both in vitro applications such as sorting, moving, filtering micro particles (e.g. cells) within lab-on-a-chip platforms and in vivo applications such as minimally-invasive surgeries or targeted drug delivery inside a human body. Precise (nano) positioning of the levitated microrobot on the pyrolytic graphite is demonstrated in the liquid. Positioning is achieved by the movement of a "lifter" magnet on the sensitive microstage. The suspended microrobot successfully tracked the identified roots. Our study is about controlling the microrobot suspended on the pyrolytic graphite with nano-precision via fixed lifting magnets. The purpose of the presented method is to eliminate the friction force between the surface of the substrate and the microrobot. Thus, high accuracy motion can be achieved.

4-pole hybrid electromagnetic systems have a potential usage in many industrial areas, such as clean room design, transportation, semi-conductor manufacturing due to providing mechanical contact-free operation with considerably low energy consumption. However, the main problem of magnetic levitation process: it has highly nonlinear nature and even if it can be linearized, it has unstable pole(s), which makes the system vulnerable in terms of stability. In this paper, to overcome the instability issue and track the desired references for each degree of freedom, a modified PID controller (so called I-PD) design technique based on coefficient diagram method (CDM) has been proposed. CDM is an algebraic design applied to polynomial structure of the system on the parameter space, where a specific diagram is used to present and interpret the essential data. It is quite simple to apply with a visual support, requires basic mathematical computations for field engineers, and offers a good equilibrium in terms of simplicity, stability, minimum overshoot and robustness, which are crucial specifications for maglev applications. The effectiveness and feasibility of CDM-based I-PD controller have been compared with CDM-based classical PID controller over an experimental set-up.

The conveyance of steel-plates is one of the potential uses of the magnetic levitation technology in industry. How¬ever, the electromagnetic levitation systems inherently show non¬linear feature and are unstable without an active control. Well-known U-shaped or E-shaped electromagnets cannot provide redundant levitation with multiple degrees of freedom. In this paper, to achieve the full redundant levitation of the steel plate, a quadruple configuration of U shaped electromagnets has been proposed. To resolve the issue of instability and attain more robust levitation, a centralized control algorithm based on a modified PID controller (I PD) is designed for each degree of freedom by using the Manabe canonical polynomial technique. The model of the system is carried out using electromechanical energy conversion princi¬ples and verified by 3-D FEM analysis. An experimental bench is built up to test the system performance under trajectory tracking and external disturbance excitation. The results confirm the effectiveness of the proposed system and the control approach to obtain a full redundant levitation even in case of disturbances. The paper demonstrates the feasibility of the con¬veyance of steel plates by using the quadruple configuration of U-shaped electromagnets and shows the merits of I-PD controller both in stabilization and increased robust levitation.

This paper presents the mechanical vibration and stress analysis of an axial flux permanent magnet (AFPM) motor for a high speed (30000 rev/min) rotor which is vertically suspended by active and hybrid magnetic bearings. In the analysis, a prototype AFPM motor with a double sided rotor and a coreless stator between the rotors are considered. Rotor disks of the motor are constructed of two 10 mm-thick steel disks with 6.35 mm-thick permanent magnets which represent around 70% of the total weight of the machine. Firstly, an analytical solution is carried out to determine natural frequencies of the rotor-shaft system. Then rotor disk thickness was determined based on a rotor axial displacement due to the attractive force between the permanent magnets placed on opposite rotor disks. Finally, 3D finite elements analysis (FEA) are carried out to verify the analytical results.

In recent years, linear matrix inequality-based design of controllers has received considerable attention and become very popular due to their ability to satisfy multiobjective requirements. However, an LMI based H2 state-feedback controller, having gap and acceleration parameters as states, for a 3 DoF vibration isolation stage having hybrid electromagnets, has not been researched yet. In this study, this type of controller is employed to minimize the effect of ground and direct disturbances on vibration isolation, zero-power, and protection of the levitation gap objectives. Moreover, the experimental setup used in this study has been designed to meet aforementioned objectives as well. The design parameters of the experimental setup are explicitly given and the effectiveness of the proposed method is shown with the experimental studies.

In this paper, an H ∞ controller is designed for disturbance attenuation of magnetically levitated steel plate. The system contains U-type hybrid electromagnet which constructed by using permanent magnet. A detailed model having nonlinear attraction force of a U-shaped hybrid electromagnet is presented and linearized for controller design purpose. Based on the linearized model, the H ∞ controller is designed to minimize air gap variation under unknown loading disturbances. Thereafter, a set of experiments conducted to compare performance of the H ∞ controller with our previously published I-PD controller on the same experimental setup.

This paper reports a new design topology of 4 pole hybrid electromagnetic levitation system in conjunction with linear synchronous motor. The mover, 4 pole hybrid electromagnet, is levitated underneath of the linear motor with zero power control algorithm. Propulsion and one-dimensional planar motion of the hybrid electromagnet is provided by the vector controlled linear motor. The new design of 4 pole hybrid electromagnet has several improvements over older systems, such as weight reduction and less material usage. Diagonal drive integration of mover and linear motor is proposed and experimental results are presented.

In this study, we propose a knowledge-based approach for detection and isolation of predefined and nonpredefined sensor faults in fault tolerant control (FTC) of a three-tank system. Farthest first traversal algorithm (FFTA) of data mining is used for the first time for the classification of faults in a FTC system. Predefining here means that features of a fault and its effects are known before the fault is seen on the system. Therefore, if a predefined fault is detected on the system, it is isolated into a known fault cluster and predefined action for that cluster can be taken to tolerate the fault. However, in a working system, there may be some other faults, which are not predefined. Those may be inaccurately isolated into available known clusters, since the clusters are determined according to predefined faults instead of non-predefined ones. In our work, we also propose a method for isolating the non-predefined faults that rearranges the clusters of predefined faults, online. In order to show the eff...

In this paper, a motion planning system for a mobile robot is proposed. Path planning tries to find a feasible path for mobile robots to move from a starting node to a target node in an environment with obstacles. A genetic algorithm is used to generate an optimal path by taking the advantage of its strong optimization ability. Mobile robot, obstacle and target localizations are realized by means of camera and image processing. A graphical user interface (GUI) is designed for the motion planning system that allows the user to interact with the robot system and to observe the robot environment. All the software components of the system are written in MATLAB that provides to use non-predefined accessories rather than the robot firmware has, to avoid confusing in C++ libraries of robot's proprietary software, to control the robot in detail and not to re-compile the programs frequently in real-time dynamic operations.

In this study; we present a model based robust controller for a one degree-of-freedom magnetic levitation system with hybrid electromagnets. Nonlinear equations of the magnetic force model have been used to develop the model based controller. The proposed controller can handle parametric uncertainties and only requires air gap and coil current measurements. The output of the controller is the voltage input of the coils and back-stepping procedure have been applied to reach the voltage dynamics over current dynamics. The stability and convergence of the closed loop system have been proved via Lyapunov-type arguments. Simulation results are presented to illustrate the performance of the proposed robust controller.

Ideally, when faults happen, the closed-loop system should be capable of maintaining its present operation. This leads to the recently studied area of fault-tolerant control (FTC). This paper addresses soft computing and signal processing based active FTC for benchmark process. Design of FTC has three levels: Level 1 comprises a traditional control loop with sensor and actuator interface and the controller. Level 2 comprises the functions of online fault detection and identification. Level 3 comprises the supervisor functionality. Online fault detection and identification has signal processing module, feature extraction module, feature cluster module and fault decision module. Wavelet analysis has been used for signal processing module. In the feature extraction module, feature vector of the sensor faults has been constructed using wavelet analysis, sliding window, absolute maximum value changing ratio and variance changing ratio as a statistical analysis. For the feature cluster module, the self-organizing map (SOM), which is a subtype of artificial neural network has been applied as a classifier of the feature vector. As a benchmark process three-tank system has been used. Control of the three-tank system is provided by fuzzy logic controller. Faults are applied to three level sensors. Sensor faults represent incorrect reading from the sensors that the system is equipped with. When a particular fault occurs in the system, a suitable control scheme has been selected on-line by supervisor functionality to maintain the closed-loop performance of the system. Active FTC has been achieved by switch mode control using fuzzy logic controller. Simulation results show that benchmark process has maintained acceptable performance with FTC for the sensor faults. As a result, when the system has sensor faults soft computing and signal processing based FTC helps for the best performance of the system.

A nonlinear fuzzy modelling and control strategy, having merits of linear control theory and TSK (Takagi-Sugeno- Kang) reasoning algorithm of fuzzy logic, is proposed for active vibration control systems under maglev actuation and the effectiveness of the approach verified via comparative experimental results.

Generally, it is very difficult to assess the true operating cost of an electrical power unit in the countries where there is little or no operational experience. Since Turkey has no experience on operating a nuclear unit, operating costs of a nuclear unit is uncertain for use in generation expansion planning (GEP). Furthermore, there is a disagreement of whether it is cheap or not. In this study, an acceptable level of operating cost of nuclear units is determined for Turkey's power system. It is aimed to find a numerical value for nuclear operating cost at which nuclear is able to compete with other energy sources. Seven types of units are chosen as candidate units to the power system. Mixed-integer programming (MIP) is used as a mathematical model of generation expansion planning. The model consists of the cost function that minimizes the construction and operating costs and the reliability constraints. Adaptive simulated annealing genetic algorithm (ASAGA) is used for optimization algorithm to determine the types, times, and number of candidate units which meet forecasted demand within a pre-specified reliability criterion over the planning horizon from 2006 to 2025. In the case studies, a high level of nuclear energy operating cost is taken and then the cost is gradually lowered. Optimizations are made for each level of nuclear operating costs within four different scenarios and the quantities of nuclear capacity selected by optimizations are recorded. It is determined that, nuclear energy is able to compete with other energy sources when the operating cost is less than 210$/kWh yr or 2.4cent/kWh.

In this study, a flexible conveyance system driven by linear motors and hybrid magnets for magnetic levitation is proposed. For modelling purposes, nonlinear analytic models are derived and extended to 3 axis of movement and controlled with those nonlinear equations. For energy efficiency, each pole is controlled with voltage driving zero power levitation method. Since the system only has displacement sensors for feedback, to fully control and understand the systems characteristics and disturbances, all axis are observed by disturbance observer and integrated to controller algorithm for better response and robustness, which is achieved multiplying the disturbance observer's output with system gain and feedforwarded. The proposed system and control algorithms are well confirmed by numerical results.

In this paper, a flexible conveyance system consists of 4 pole hybrid electromagnet and linear synchronous motor is introduced. Firstly, modeling of 4 pole hybrid electromagnet was derived based on well -known magnetic circuit principles. Then, the control method in which the currents converge virtually to zero is called as “zero power control” is applied to hybrid electromagnet to stabilize the system and provide levitation against gravity. Secondly, PM-LSM, which enables to move hybrid electromagnet horizontally, is modeled. According to modeling basis, I-PD controller is designed to provide moving action in a desired position reference. Simulation and experimental studies of position control for both levitation and horizontal motion verify validity of the proposed methods.

Bu calismada, 4-kutuplu karma elektromiknatisin dogrusal motorla birlestirilmesi ile elde edilen esnek tasima sisteminin, manyetik yastiklama kuvvet ve moment karakteristikleri 3 boyutlu sonlu elemanlar yontemi kullanilarak incelenmistir. Ortaya cikan sonuclar dikkate alinarak sistemin 3 eksende hareket dinamigine karsilik gelen dogrusal sistem modeli turetilmistir. Karma elektromiknatis yapisi geregi dogrusal olmayan bir karakteristige sahiptir ve kontrol edilebilirlik noktasinda kararsizlik gostermektedir. Sistemin kontrolunu saglamak amaciyla her bir eksen icin gerilimle uyartim durumu dikkate alinarak durum geri beslemeli integral denetleyicileri kutup atama yontemi kullanilarak tasarlanmistir. Denetleyici kutuplari katsayilar diyagrami yontemi (Kanonik polinom yontemi) kullanilarak belirlenmistir. Manyetik yastiklama sistemi sadece hava araliklarini olcen algilayicilar icermektedir. Sisteme iliskin diger durumlarin olculebilmesi amaciyla her bir eksen takimi icin durum ve bozucu girisi kestirimini gerceklestiren bozucu giris gozlemcileri tasarlanmis ve kontrol cevrimine entegre edilmistir. Gozlemlenen bozucu giris degerleri uygun donusturme kazanci ile carpilarak kontrol yoluna ileri beslenmis boylece sistemin gurbuz kontrolu saglanmistir. Deneysel sonuclar onerilen kontrol yaklasimlarinin etkinligini basarili bir bicimde gostermistir.