This paper presents the optimal design, fabrication, and control of a novel compliant flexure-based totally decoupled XY micropositioning stage driven by electromagnetic actuators. The stage is constructed with a simple structure by employing double four-bar parallelogram flexures and four noncontact types of electromagnetic actuators to realize the kinematic decoupling and force decoupling, respectively. The kinematics and dynamics modeling of the stage are conducted by resorting to compliance and stiffness analysis based on matrix method, and the parameters are obtained by multiobjective genetic algorithm (GA) optimization method. The analytical models for electromagnetic forces are also established, and both mechanical structure and electromagnetic models are validated by finite-element analysis via ANSYS software. It is found that the system is with hysteresis and nonlinear characteristics when a preliminary open-loop test is conducted; thereafter, a simple PID controller is applied. Therefore, an inverse Preisach model-based feedforward sliding-mode controller is exploited to control the micromanipulator system. Experiments show that the moving range can achieve 1 mm t 1 mm and the resolution can reach ±0.4 μm. Moreover, the designed micromanipulator can bear a heavy load because of its optimal mechanical structure.

Optimal Design, Fabrication, and Control of an $XY$ Micropositioning Stage Driven by Electromagnetic Actuators

Displacement devices comprise a stator and a moveable stage. The stator comprises a plurality of coils shaped to provide pluralities of generally linearly elongated coil traces in one or more layers. Layers of coils may overlap in the Z-direction. The moveable stage comprises a plurality of magnet arrays. Each magnet array may comprise a plurality of magnetization segments generally linearly elongated in a corresponding direction. Each magnetization segment has a magnetization direction generally orthogonal to the direction in which it is elongated and at least two of the magnetization directions are different from one another. One or more amplifiers may be connected to selectively drive current in the coil traces and to thereby effect relative movement between the stator and the moveable stage.

Displacement devices and methods for fabrication, use and control of same

MEMS actuators for biomedical applications: a review

This paper presents a 2-degrees of freedom flexure-based micropositioning stage with a flexible decoupling mechanism. The stage is composed of an upper planar stage and four vertical support links to improve the out-of-plane stiffness. The moving platform is driven by two voice coil motors, and thus it has the capability of large working stroke. The upper stage is connected with the base through six double parallel four-bar linkages mechanisms, which are orthogonally arranged to implement the motion decoupling in the x and y directions. The vertical support links with serially connected hook joints are utilized to guarantee good planar motion with heavy-loads. The static stiffness and the dynamic resonant frequencies are obtained based on the theoretical analyses. Finite element analysis is used to investigate the characteristics of the developed stage. Experiments are carried out to validate the established models and the performance of the developed stage. It is noted that the developed stage has the capability of translational motion stroke of 1.8 mm and 1.78 mm in working axes. The maximum coupling errors in the x and y directions are 0.65% and 0.82%, respectively, and the motion resolution is less than 200 nm. The experimental results show that the developed stage has good capability for trajectory tracking.

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A novel voice coil motor-driven compliant micropositioning stage based on flexure mechanism

In this paper, a Lorentz force-based $XY$ positioning stage with a stack of four electromagnetic linear motors in parallel configuration is presented. The overall design of the positioning stage consists of a mobile and a fixed part separated using a four-point contact technique. The uniqueness of the proposed positioning stage lies in its light design with the ability to perform variable strokes at short $( m) and long range (millimeter level) with preembedded auto guidance feature. The analytical modeling and experiment have been realized. The open- and closed-loop performance of positioning stage in linear and nonlinear trajectories have been tested and good agreement is observed between experimental and analytical results. The positioning stage is able to perform variable strokes up till 2 mm in the $xy$ plane. In closed loop, the maximum precision errors in short and long strokes are found to be 0.031 and 0.451 μm, respectively. The maximum travel speed is 12 mm/s in open loop.

/pdf/a-long-stroke-electromagnetic-xy-positioning-stage-for-micro-vr0uxuckc9.pdf

A Long Stroke Electromagnetic $XY$ Positioning Stage for Micro Applications

In this paper, a parallel-kinematics-based micropositioning system prototype driven with four electromagnetic motors is presented. The optimal design characteristics of the system incorporate its long-range displacement capability with submicrometer level positioning precision suitable for numerous microapplications. In order to achieve a compact design with micrometer level component assembly tolerances, the movable mechanical structure of the experimental prototype has been microfabricated in the silicon material using inductively coupled plasma etching process. The 80 mm  $\times$  80 mm footprint of the prototype is able to perform millimeter level displacement strokes along both axes in the horizontal plane. The experimental results demonstrate that the micropositioning system is capable of delivering variable strokes up to 2.5 mm in the $xy$ -plane. In closed-loop control the system is able to perform repeatable displacement of 2  $\mu$ m with a positioning precision of 24 nm. In addition, the proposed micropositioning system design is able to carry 17.3 g of additional load during planar motion in the $xy$ -plane.

Design and Assessment of a Micropositioning System Driven by Electromagnetic Actuators

This paper presents a planar electromagnetic conveyor for a microfactory. The uniqueness of the conveyor design lies in its arrangement of overlapped two-dimensional mesh coils in matrix configuration that enables to drive a mobile part over long strokes. The conveyor architecture includes a fixed part, which consists of 5×5 matrix design that has been fabricated on a multilayer printed circuit board. An analytical model that takes into account the electromagnetic and friction effects has been developed. A conveyor prototype has been fabricated and experimentally characterized in open-loop control. Linear and planar motions, positioning repeatability error, straightness error, and rotation have been experimentally measured. From experimental results, the proposed architecture enables long linear displacement strokes ( $\leqslant$ 70 mm) and rotation ( $\leqslant \pm$ 12.37 $^\circ$ ). In addition, a 12 mm/s speed can be achieved for the mobile part at a nominal current of 0.8 A.

Design and Development of a Planar Electromagnetic Conveyor for the Microfactory

In this paper, the concept of a two layer coil based electromagnetic actuator for planar motions is presented. The actuator is composed of two pairs of fixed overlapped 2D electric drive coils and a mobile part consists of permanent magnets arrays which perform motions in xy plane due to the generation of Lorentz force. A multi-layer printed circuit board is used for the two layers of drive coils. An electromagnetic model of the actuator has been developed in order to compute the electromagnetic force exerted on the magnets arrays. A prototype of the device has been manufactured and tested. The mobile part displacement along the two displacement axes have been shown and determined using image processing method.

A planar electromagnetic actuator based on two layer coil assembly for micro applications

This paper presents a planar digital actuator based on hexagonal design. The actuator is comprised of a Mobile Permanent Magnet (MPM) surrounded by six Fixed Permanent Magnets (FPMs). The originality of the proposed actuator lies in its ability to reach six discrete positions in xy-plane with different stroke sizes (along x-axis: 0.50 mm and 1.00 mm; along y-axis: 0.86 mm). An analytical model has been developed to compute the electromagnetic and magnetic forces exerted on the MPM. Using this model, the design parameters of the actuator have been selected. A prototype has then been realized using the rapid prototyping manufacturing techniques. Through experiments, the motion behavior of the actuator has been verified. The driving current impact on the MPM displacement has been observed. For an MPM switch between two discrete positions, the obtained 10% settling time is between 10 and 20 ms.

Muneeb Ullah Khan

Papers

A Long Stroke Electromagnetic $XY$ Positioning Stage for Micro Applications

Design and Assessment of a Micropositioning System Driven by Electromagnetic Actuators

Design and Development of a Planar Electromagnetic Conveyor for the Microfactory

A planar electromagnetic actuator based on two layer coil assembly for micro applications

Development of a six positions digital electromagnetic actuator