Independent position control of two identical magnetic microrobots in a plane using rotating permanent magnets

2021 ◽  
Author(s):  
Masoud Yousefi ◽  
Hossein Nejat Pishkenari
Keyword(s):  
Permanent Magnets ◽  
Position Control ◽  
Magnetic Microrobots

scholarly journals Design of a magnetic encoder using Hall effect

2019 ◽  
Vol 13 (2) ◽  
pp. 254-261
Author(s):  
William Alejandro López-Contreras ◽  
José Danilo Rairán-Antolines
Keyword(s):  
Hall Effect ◽  
Relative Motion ◽  
Direct Current ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Linearization Method ◽  
Acquisition Process ◽  
Voltage Variation ◽  
Hall Sensors

We present the design of a magnetic encoder to measure angular position. The proposed encoder includes two Hall sensors in quadrature in a fixed platform. In addition, and over the sensors, there are two permanent magnets in a shaft. The relative motion between the fixed and the movable components generate a voltage variation in the sensors, which serve to generate the approximation of the angular position. We detail the acquisition process and the linearization method, because we consider that these are the most important contributions of this work. Lastly, we show the application of the encoder in the position control of a direct current motor to show the performance of the encoder estimating fast and slow angular position changes.

scholarly journals Cogging Torque Reduction in Brushless Motors by a Nonlinear Control Technique

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2224 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Permanent Magnet ◽  
Electric Drive ◽  
Feedback Linearization ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Control Technique ◽  
Electrical Machine ◽  
Brushless Motors ◽  
Cogging Torque

This work addresses the problem of mitigating the effects of the cogging torque in permanent magnet synchronous motors, particularly brushless motors, which is a main issue in precision electric drive applications. In this work, a method for mitigating the effects of the cogging torque is proposed, based on the use of a nonlinear automatic control technique known as feedback linearization that is ideal for underactuated dynamic systems. The aim of this work is to present an alternative to classic solutions based on the physical modification of the electrical machine to try to suppress the natural interaction between the permanent magnets and the teeth of the stator slots. Such modifications of electric machines are often expensive because they require customized procedures, while the proposed method does not require any modification of the electric drive. With respect to other algorithmic-based solutions for cogging torque reduction, the proposed control technique is scalable to different motor parameters, deterministic, and robust, and hence easy to use and verify for safety-critical applications. As an application case example, the work reports the reduction of the oscillations for the angular position control of a permanent magnet synchronous motor vs. classic PI (proportional-integrative) cascaded control. Moreover, the proposed algorithm is suitable to be implemented in low-cost embedded control units.

A Study on Semi-Active Magnetic Bearing Position-Controlled by Piezoelectric Actuators

2011 ◽  
Vol 5 (4) ◽  
pp. 594-600
Author(s):  
Jung-Ho Park ◽  
◽  
Hu-Seung Lee ◽  
Young-Bog Ham ◽  
So-Nam Yun
Keyword(s):  
Permanent Magnets ◽  
Position Control ◽  
Control Method ◽  
Piezoelectric Actuators ◽  
Magnetic Bearing ◽  
Repulsive Force ◽  
Active Magnetic Bearing ◽  
Test Results ◽  
Magnetic Forces ◽  
Hybrid Bearing

This paper investigates non-contact hybrid bearings that use permanent magnets for repulsive force and piezoelectric actuators for position-control. A structurally-improved hybrid bearing is presented. First, the concept of the hybrid bearing is briefly introduced along with previous test results. Then, the newly devised bearing with a decreased gap between rotor and stator is designed and analyzed with FEM to optimize the magnetic forces. Finally, a prototype bearing using the proposed mechanism is fabricated and a control method is discussed.

High-Performance Scan-Type Stage for Large Substrates

2007 ◽  
Vol 1030 ◽  
Author(s):  
Ohno Takashi ◽  
K. Azuma ◽  
T. Mizutani ◽  
H. Kobayashi
Keyword(s):  
High Performance ◽  
Permanent Magnets ◽  
Position Control ◽  
Substrate Surface ◽  
Vertical Direction ◽  
Linear Motor ◽  
Steady Increase ◽  
Scan Time ◽  
Acceleration And Deceleration ◽  
Better Than

AbstractDue to the steady increase in substrate sizes for low-temperature poly-Si devices and LSIs, there are strong demands for larger substrate handling, more accurate positioning and shorter tact time for many processes such as laser crystallization scan exposure, [3], and dopant activation [4] and so on. In order to satisfy such demands, we have developed a high-performance scan-type stage for large substrates. In this paper, we describe the outline of the mechanical structure and also the performance of this stage.The XY moving stage was installed on an air slider of planarized granite. Stroke sizes of the stage were more than 920 mm and 730 mm for scan and step directions, respectively; the stage size was matched to the large glass substrates (4th generation). The stroke in the vertical direction was more than 32 mm, and the stage could rotate for more than ±0.3 degree for alignment.The stage is driven by a newly introduced shaft-type linear motor, which consists of a fixed stainless-steel pipe shaft and a moving cylindrical coil rounded around the shaft. There are thin annular permanent magnets stacked inside the shaft. Since this coaxially aligned structure of permanent magnets and the coil is a nearly ideal configuration for efficient magnetic coupling, this motor could generate a stronger driving force; this enabled rapid acceleration and deceleration of the stage. Since stacked magnets generate parallel and uniform magnetic field along the shaft surface but slight field for transverse direction, electromagnetic force slightly fluctuated along the shaft, independent of the pitch of the magnet plate. This introduced another important advantage of the shaft-type linear motor that cogging, which has a serious impact on processing, was almost eliminated. This fluctuation was further reduced by introducing a real-time feedback system. The shaft-type motor, however, had been said to have the serious difficulty of elongation since its own weight bends the shaft. This problem was solved by using new magnetic materials and an optimized design of physical dimensions of the motor.Experiments have been conducted under stabilized temperature conditions. The maximum scan speed of the stage was more than 500 mm/s with a speed stability of 0.03%, about one order of magnitude better than the reported value of about 0.5%. Acceleration and deceleration times from the halt condition to the constant velocity condition and vise versa were 1.0 s; the scan time was as short as 1.8 s for a 920 mm stroke. The “straight extent” was always better than ±0.5 mm Projection optics is commercially available for shaping a 30-mm-long excimer laser light beam on a sample surface. If we combine this stage and such optics, the whole area of a 4th-generation substrate surface can be scanned within a little more than 1 minute; that is, extremely high throughput can be expected. For example, to grow arrays of large Si grains, two-dimensional position control is the most important subject.

scholarly journals A Sensorless Wind Speed and Rotor Position Control of PMSG in Wind Power Generation Systems

2020 ◽  
Vol 12 (20) ◽  
pp. 8481
Author(s):  
Ahmed G. Abo-Khalil ◽  
Ali M. Eltamaly ◽  
Praveen R.P. ◽  
Ali S. Alghamdi ◽  
Iskander Tlili
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Permanent Magnets ◽  
Position Control ◽  
Synchronous Generator ◽  
Power Converter ◽  
Support Vector ◽  
Rotor Position ◽  
Wide Range ◽  
Full Power

Currently, among the topologies of wind energy conversion systems, those based on full power converters are growing. The permanent magnet synchronous generator (PMSG) uses full power converter to allow wide speed ranges to extract the maximum power from the wind. In order to obtain efficient vector control in a synchronous generator with permanent magnets, it is necessary to know the position of the rotor. The PMSGs work over a wide range of speed, and it is mandatory to measure or estimate their speed and position. Usually, the position of the rotor is obtained through Resolver or Encoder. However, the presence of these sensor elements increases the cost, in addition to reducing the system’s reliability. Moreover, in high wind power turbine, the measured wind speed by the anemometer is taken at the level of the blades which makes the measurement of the wind speed at a single point inaccurate. This paper is a study on the sensorless control that removes the rotor position, speed sensors and anemometer from the speed control. The estimation of the rotor position is based on the output of a rotor current controller and the wind speed estimator is based on the opposition-based learning (OBL), particle swarm optimization and support vector regression.

scholarly journals Design of an Observer-Based Architecture and Non-Linear Control Algorithm for Cogging Torque Reduction in Synchronous Motors

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2077 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Control Algorithm ◽  
Permanent Magnets ◽  
Position Control ◽  
Deterministic Model ◽  
Initial Conditions ◽  
Angular Position ◽  
Observer Design ◽  
Control Technique ◽  
Servo Drive ◽  
Cogging Torque

The problem of cogging torque is due to a magnetic behavior, intrinsic to synchronous machines and due to the presence of permanent magnets themselves. Cogging torque is a significant problem when the servo drive is used for applications where high precision in terms of position control is required. In this paper we present a method of cogging torque reduction by means of a control technique based on mathematical modeling of the cogging phenomenon itself in order to exploit this knowledge directly in the controller design. The mathematical model is inserted in the dynamic model of the synchronous machine in order to exploit the feedback linearization, providing an expression of the control law in which the contribution of the deterministic knowledge of the phenomenon is directly present. The cogging phenomenon physically depends on the angular position of the rotor, as well as the deterministic model we use to define the control vector. This makes it interesting and innovative to determine whether the control algorithm can be inserted within a sensor-less architecture, where rotor position and angular velocity measurements are not available. For this purpose, we present the use of an extended Kalman filter (EKF) in the continuous-time domain, discussing the advantages of an observer design based on a dynamic motor model in three-phase and direct-square axes. Results are presented through very accurate simulation for a trajectory-tracking problem, completing with variational analysis in terms of variation of initial conditions between EKF and motor dynamics, and in terms of parametric variation to verify the robustness of the proposed algorithm. Moreover, a computational analysis based on Simulink Profiler is proposed, which provides some indication for possible implementation on an embedded platform.

scholarly journals Magnetically Guided Micromanipulation of Magnetic Microrobots for Accurate Creation of Artistic Patterns in Liquid Environment

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 697
Author(s):  
Xingfu Li ◽  
Toshio Fukuda
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Permanent Magnets ◽  
Magnetic Field Gradient ◽  
Morphological Structure ◽  
Space Distribution ◽  
Magnetic Flux Density ◽  
Liquid Environment ◽  
Magnetic Microrobots

In this paper, a magnetically guided micromanipulation method is proposed to accurately create artistic patterns with magnetic microrobots in a liquid environment for tissue engineering. A magnetically guided device is developed depend on symmetrical combination of square permanent magnets and array layout of soft magnetic wires, which changed the space distribution of magnetic field of conventional permanent magnet and generated powerful magnetic flux density and high magnetic field gradient. Furthermore, the morphological structure of the magnetic microrobot is flexibly adjusted via precise control of the volumetric flow rates inside the microfluidic device and the magnetic nanoparticles are taken along to enable its controllability by rapid magnetic response. And then, the spatial posture of the magnetic microrobot is contactless controlled by the magnetically guided manipulator and it is released under the influence of surface tension and gravity. Subsequently, the artistic fashions of the magnetic microrobots are precisely distributed via the dot-matrix magnetic flux density of the magnetically guided device. Finally, the experimental results herein demonstrate the accuracy and diversity of the pattern structures in the water and the developed method will be providing a new way for personalized functional scaffold construction.

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

1990 ◽  
Vol 48 (4) ◽  
pp. 990-991
Author(s):  
Mahesh Chandramouli
Keyword(s):  
Electron Microscope ◽  
Liquid Phase ◽  
Permanent Magnets ◽  
Phase Distribution ◽  
Energy Dispersive Spectrometer ◽  
Nucleation And Growth ◽  
Liquid Phase Sintering ◽  
Domain Wall Energy ◽  
Oxide Phases ◽  
Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

Sign in / Sign up

Export Citation Format

Share Document