Mei Yung Chen

A novel dual-axis repulsive Maglev guiding system with permanent magnet: modeling and controller design

In this paper, we extend our previous result (1999, 2000) on designing a single-axis Maglev guiding system to a more involved task of designing a novel dual-axis positioning system. First, important issues related to construction of the mechanism of the dual-axis positioning system are addressed. Then, the dynamics of the dual-axis Maglev guiding system are analyzed. According to the derived analytic model, which is subject to unknown system parameters, an adaptive controller that can control the carrier at the desired target point of each axis with full alignment is presented. From the experiment results, a good performance in terms of regulation of the guiding-axis and tracking of the positioning-axis is achieved. This validates the design of the system hardware and demonstrates the feasibility of the developed controller.

Modeling and controller design of a Maglev guiding system for application in precision positioning

In this paper, the authors analyze the dynamics of a magnetic guiding system and derive its analytical model with full degrees of freedom (DOFs). Then, an adaptive controller which deals with unknown parameters is proposed to regulate the five DOFs in this system. The guiding system, including sensors and driver subsystems, has actually been implemented. Based on the experimental results, satisfactory performance including stiffness and resolution has been achieved. This validates the design of the system hardware and demonstrates the feasibility of the developed controller.

A New Design of a Submicropositioner Utilizing Electromagnetic Actuators and Flexure Mechanism

In this paper, a novel XY-dimensional submicropositioner, including mechanism, control, and analysis, is successfully presented. The design of the submicropositioner utilizes a monolithic parallel flexure mechanism with built-in electromagnetic actuators and optical sensors to achieve the object of 3-DOF precise motion. From the provided experimental results, there are several main goals that have been achieved in this paper: (1) to integrate the electromagnetic actuator and the parallel flexure mechanism for planar positioning system; (2) to establish the mathematical modeling; (3) to develop an advanced adaptive sliding-mode controller; and (4) to perform extensive experiments to test the realistic performance.

Design and Experiment of a Macro–Micro Planar Maglev Positioning System

In this paper, a new planar magnetic levitation (maglev) positioning system is proposed, which is capable of executing dual-axis planar motions purely involving magnetic forces. Functionally, such a mechanism behaves like a planar XY table with micrometer precision. Specifically, in this system, a new structure with an adaptive sliding-mode control (ASMC) algorithm is described, which aims to achieve the following three goals: 1) a large moving range (millimeter level); 2) precise positioning (micrometer level); and 3) fast response. The system consists of a moving carrier platform, six permanent magnets (PMs) attached to the carrier, and six electromagnets mounted on a fixed base. After exploring the characteristics of the magnetic forces between PMs and electromagnets, the general 6-DOF dynamic model of this system is derived and analyzed. Then, because of the naturally unstable behavior inherent in maglev systems, the proposed ASMC guarantees satisfactory performance of the maglev system. Experiments have successfully demonstrated the feasibility and effectiveness of the overall system.

High-Precision Motion Control for a Linear Permanent Magnet Iron Core Synchronous Motor Drive in Position Platform

The high precision motion tracking controller consisting of a linear permanent magnet iron core synchronous motor (LPMICSM) operating on a positioning platform is proposed. First, we address important issues related to the construction and driving theorem of the LPMICSM. Next the general system dynamic model is derived and analyzed. Then, because of the uncertainties and unknown parameters of the underlying system, a discrete adaptive sliding-mode (DASM) controller is proposed to guarantee system stability for both regulation and tracking tasks. Finally, according to the reported experimental results, the satisfactory performances including step regulation and tracking sinusoid, has been achieved. Therefore, the proposed control method is feasible and effective in high-precision motion control of LPMICSM.

Design of fall detection system with floor pressure and infrared image

Due to the advancement of technology and medicine, people begin to pay more attention to the quality improvement of health care. Many researches show that the fall accident occupies 60% of all accidents in a home. The fall accident may cause the condition of an elder deteriorated or producing complications. As a result, it increases the burden of a family and seriously wastes medical resources from the society. Thus, preventing the fall accident and detect it immediately is one of the important topics regarding the quality improvement of health care.

Modeling and Controller Design of a Precision Hybrid Scanner for Application in Large Measurement-Range Atomic Force Microscopy

In this paper, we have developed a novel large measurement-range atomic force microscopy (AFM) system performing the tapping mode operation. This system consists of a compact/low-cost scanning probe-type sensing system ( z-scanner) and a hybrid xy-scanner. To achieve precision measurement through image scan of given samples, a thorough mathematical modeling is established first, and an advanced robust adaptive controller is then proposed, which can deal with unknown parameters, cross-talk effects, external disturbances, and unknown hysteresis phenomena. The salient properties of the resulting closed-loop AFM system includes long traveling range, high precision, and fast response after integrating two kinds of actuations. To demonstrate and qualify the scanning capability of the proposed system, systematic experiments have been conducted.

Dual-Stage Piezoelectric Nano-Positioner Utilizing a Range-Extended Optical Fiber Fabry–Perot Interferometer

This paper proposes a new modulation scheme using high-order harmonic information to solve the so-called ambiguity problem of interferometry. To start with, we build a fiber Fabry-Perot interferometer to serve as a displacement sensor, which has two operation modes - coarse and fine modes. Integrating the afore-developed sensor, a piezoelectric actuator, and a scheduled proportional-integral/adaptive-sliding controller, we construct a dual-stage nanopositioning system. The experimental results show that the proposed system has the capability to extend the positioning range beyond the limit of the wavelength while keeping the naturally high resolution, plusmn5 nm, of interferometry.

Adaptive sliding mode controller design of a dual-axis Maglev positioning system

A prototype of a dual-axis magnetically levitated positioning platform is proposed and implemented. It is a repulsive Maglev system consisting of two single-axis positioning sub-systems. First of all, the model of the overall system with complete DOFs (degree-of-freedoms) is derived and analyzed thoroughly. Next, an adaptive sliding mode controller which deals with the unknown parameters is designed to regulate the 12 DOFs in this system. From experimental results, the high performance in terms of stiffness and resolution has been demonstrated, which quite matches the theoretical performance.

Precision Sinusoidal Local Scan for Large-Range Atomic Force Microscopy With Auxiliary Optical Microscopy

Atomic force microscopy (AFM) is a powerful measurement instrument which can build 3-D topography image of conductive and nonconductive samples at nanoscale resolution. However, due to the scan method of conventional AFM, the induced mechanical resonance of the scanner and the scan in area of uninterest would strictly limit the scan speed. In this study, we improve these problems with our designed AFM system from three aspects. First, the sinusoidal trajectory is applied to lateral scanning of the AFM rather than the traditional raster trajectory, so the scan rate can be increased without inducing vibration of the lateral scanner. Second, with this promising scan trajectory, the internal model principle-based neural network complementary sliding-mode controller and adaptive complementary sliding-mode controller are designed to achieve high precision scanning and to cope with the system parameter uncertainties and external disturbance. Finally, with the aid of an auxiliary optical microscopy and the scanned information during the scanning process, scan path planning can be adopted to focus the scanning on samples such that the total scan time is further shortened. Extensive experimental results are provided to show the appealing performance of the proposed method.