摘要 :
This article focuses on identifying and fully utilizing the dynamic capabilities of a nanopositioning system to optimally trace a given trajectory. This work develops a framework for abstracting the capabilities of the piezo-actua...
展开
This article focuses on identifying and fully utilizing the dynamic capabilities of a nanopositioning system to optimally trace a given trajectory. This work develops a framework for abstracting the capabilities of the piezo-actuated nanopositioning systems and a methodology for using these capabilities to generate an optimal trajectory for a particular tool path on a given nanopositioning system while satisfying all the process-related requirements. Several dynamic capabilities of a typical nanopositioning system are identified and modeled as the constraints to drive the optimization problem. First, the velocity and acceleration capabilities of each individual axes are constrained by developing a simplified dynamic model of the performance envelope, which couple velocity and acceleration capabilities of each axis, as a function of displacement. Second, input command bandwidth constraints are introduced to mitigate frequency-related tracking difficulties encountered when traversing sharp geometric features at high velocity. Finally, the accuracy requirement is satisfied by developing a dynamic model of the instantaneous following error to estimate the contour error as a function of the velocity and acceleration at each moment. The above constraints are incorporated into a computationally efficient two-pass algorithm to generate a minimum time feedrate profile for a particular positioning system for any given trajectory. Linear zigzag and cubic spline airfoil trajectories are used to demonstrate the significant improvements in time and contouring accuracy realized through such an approach.
收起
摘要 :
A miniature linear piezoelectric actuator which moves based on inertia- friction theory is described in this paper. The authors discuss its driving principle, dynamic model and experimental results. The piezoelectric actuator incl...
展开
A miniature linear piezoelectric actuator which moves based on inertia- friction theory is described in this paper. The authors discuss its driving principle, dynamic model and experimental results. The piezoelectric actuator includes two piezoelectric elements. Through the sequentially deformations of the two piezo elements, the moving mass slides a miniature displacement. Many strokes will be added to be a large displacement. This type of piezoactuator has advantages in its dimension and motion type, so it can be miniaturized to do micro-manipulation or micro-positioning in microspace.
收起
摘要 :
Dual-servo systems (DSSs) are highly desirable in micro-/nanomanipulation when high positioning accuracy, long stroke motion, and high servo bandwidth are required simultaneously. This paper presents the design and development of ...
展开
Dual-servo systems (DSSs) are highly desirable in micro-/nanomanipulation when high positioning accuracy, long stroke motion, and high servo bandwidth are required simultaneously. This paper presents the design and development of a new flexure-based dual-stage nanopositioning system. A coarse voice coil motor (VCM) and a fine piezoelectric stack actuator (PSA) are adopted to provide long stroke and quick response, respectively. A new decoupling design is carried out to minimize the interference behavior between the coarse and fine stages by taking into account actuation schemes as well as guiding mechanism implementations. Both analytical results and finite-element model (FEM) results show that the system is capable of over 10 mm traveling, while possessing a compact structure. To verify the decoupling property, a single-input-single-output (SISO) control scheme is realized on a prototype to demonstrate the performance of the DSS without considering the interference behavior. Experimental results not only confirm the superiority of the dual-servo stage over the standalone coarse stage but reveal the effectiveness of the proposed idea of decoupling design.
收起
摘要 :
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 structur...
展开
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 $times$ 1 mm and the resolution can reach $pm 0.4 muhbox{m}$. Moreover, the designed micromanipulator can bear a heavy load because of its optimal mechanical structure.
收起
摘要 :
This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography (MSL) process. As a key enabler of high accuracy in this process, a compact desktop-siz...
展开
This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography (MSL) process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis (FEA) was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square (RMS) tracking error of about 80 nm for a circular trajectory. (C) 2017 THE AUTHORS. Published by Elsevier LTD on behalf of the Chinese Academy of Engineering and Higher Education Press Limited Company. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
收起
摘要 :
In the field of nanotechnology, there is a growing demand to provide precision control and manipulation of devices with the ability to interact with complex and unstructured environments at micro/nano-scale. As a result, ultrahigh...
展开
In the field of nanotechnology, there is a growing demand to provide precision control and manipulation of devices with the ability to interact with complex and unstructured environments at micro/nano-scale. As a result, ultrahigh-precision positioning stages have been turned into a key requirement of nanotechnology. In this paper, linear piezoelectric ceramic motors (LPCMs) are adopted to drive micro/nanopositioning stages since they have the ability to achieve high precision in addition to being versatile to be implemented over a wide range of applications. In the establishment of a control scheme for such manipulation systems, the presence of friction, parameter uncertainties, and external disturbances prevent the systems from providing the desired positioning accuracy. The work in this paper focuses on the development of a control framework that addresses these issues as it uses the nonsingular terminal sliding mode technique for the precise position tracking problem of an LPCM-driven positioning stage with friction, uncertain parameters, and external disturbances. The developed control algorithm exhibits the following two attractive features. First, upper bounds of system uncertainties/perturbations are adaptively estimated in the proposed controller; thus, prior knowledge about uncertainty/disturbance bounds is not necessary. Second, the discontinuous signum function is transferred to the time derivative of the control input and the continuous control signal is obtained after integration; consequently, the chattering phenomenon, which presents a major handicap to the implementation of conventional sliding mode control in real applications, is alleviated without deteriorating the robustness of the system. The stability of the controlled system is analyzed, and the convergence of the position tracking error to zero is analytically proven. The proposed control strategy is experimentally validated and compared to the existing control approaches. (C) 2018 ISA. Published by Elsevier Ltd. All rights reserved.
收起
摘要 :
This paper presents the design and manufacturing processes of a new piezoactuated XY stage with integrated parallel, decoupled, and stacked kinematics structure for micro-/nanopositioning application. The flexure-based XY stage is...
展开
This paper presents the design and manufacturing processes of a new piezoactuated XY stage with integrated parallel, decoupled, and stacked kinematics structure for micro-/nanopositioning application. The flexure-based XY stage is composed of two decoupled prismatic-prismatic limbs which are constructed by compound parallelogram flexures and compound bridge-type displacement amplifiers. The two limbs are assembled in a parallel and stacked manner to achieve a compact stage with the merits of parallel kinematics. Analytical models for the mechanical performance assessment of the stage in terms of kinematics, statics, stiffness, load capacity, and dynamics are derived and verified with finite element analysis. A prototype of the XY stage is then fabricated, and its decoupling property is tested. Moreover, the Bouc-Wen hysteresis model of the system is identified by resorting to particle swarm optimization, and a control scheme combining the inverse hysteresis model-based feedforward with feedback control is employed to compensate for the plant nonlinearity and uncertainty. Experimental results reveal that a submicrometer accuracy single-axis motion tracking and biaxial contouring can be achieved by the micropositioning system, which validate the effectiveness of the proposed mechanism and controller designs as well.
收起
摘要 :
This paper presents mechanism and controller design procedures of a new piezoactuated flexure XY stage for micro-/nanomanipulation applications. The uniqueness of the proposed stage lies in that it possesses an integrated parallel...
展开
This paper presents mechanism and controller design procedures of a new piezoactuated flexure XY stage for micro-/nanomanipulation applications. The uniqueness of the proposed stage lies in that it possesses an integrated parallel, decoupled, and stacked kinematical structure, which owns such properties as identical dynamic behaviors in X and Y axes, decoupled input and output motion, single-input-single-output (SISO) control, high accuracy, and compact size. Finite element analysis (FEA) was conducted to predict static performance of the stage. An XY stage prototype was fabricated by wire electrical discharge machining (EDM) process from the alloy material Al7075. Based on the identified plant transfer function of the micropositioning system, an $H_infty$ robust control combined with a repetitive control (RC) was adopted to compensate for the unmodeled piezoelectric nonlinearity. The necessity of using such a combined control is also investigated. Experimental results demonstrate that the $H_infty$ plus RC scheme improves the tracking response by 67% and 28% compared to the stand-alone $H_infty$ for 1-D and 2-D periodic positioning tasks, respectively. Thus, the results illustrate the effectiveness of the proposed mechanism design and control approach.
收起
摘要 :
This paper presents the mechanical design and control system design of an electromagnetic actuator-based microdisplacement module. The microdisplacement module composed of a symmetrical leaf-spring parallelogram mechanism and an e...
展开
This paper presents the mechanical design and control system design of an electromagnetic actuator-based microdisplacement module. The microdisplacement module composed of a symmetrical leaf-spring parallelogram mechanism and an electromagnetic actuator. The characteristics of the mechanism in terms of stiffness and natural frequencies are derived and verified. Both leakage flux and core inductance are taken into consideration during modeling the mathematic model of the electromagnetic actuator, and based on which, the system dynamic model is established. Due to the nonlinearity characteristics of the system, a dynamic sliding-mode controller is designed without linearizing the system dynamics. A prototype of the microdisplacement module is fabricated, and the parameters of the system are identified and calibrated. Finally, the designed dynamic sliding-mode controller is applied; step response and tracking performance are studied. Experimental results demonstrate that a submicrometer accuracy can be achieved by the module, which validate the effectiveness of the proposed mechanism and controller design as well. The research results show that the electromagnetic actuator-based module can be extended to wide applications in the field of micro/nanopositioning and manipulation.
收起
摘要 :
Piezoelectric actuation micro-/nanopositioning systems have been widely employed in diverse micro-/nanomanipulation applications. This paper presents the design, analysis, and validation of a new control scheme termed input–outpu...
展开
Piezoelectric actuation micro-/nanopositioning systems have been widely employed in diverse micro-/nanomanipulation applications. This paper presents the design, analysis, and validation of a new control scheme termed input–output-based digital sliding-mode control (IODSMC) to suppress the unmolded nonlinearity and disturbance in piezoelectric micro-/nanopositioning systems. The controller is established based on a linear digital input–output nominal model. The scheme facilitates a rapid implementation because the construction of either a hysteresis model or a state observer is not needed. The chattering-free control is capable of achieving an $O(T^{2})$ output tracking accuracy by overcoming the model disturbance. Moreover, the stability of the control system is proved, and its effectiveness is validated through experimental investigations on a piezo-driven micropositioning system. Results demonstrate that the IODSMC scheme is superior to the conventional proportional–integral–derivative control for motion-tracking tasks. Furthermore, it exhibits promising robustness in front of internal and external disturbances.
收起
原文获取