Piezoelectric Actuated Stage Research Articles

Intelligent Tracking Error Prediction and Feedforward Compensation for Nanopositioning Stages With High-Bandwidth Control

In this paper, an intelligent feedforward prediction and compensation scheme to combine with a dual-loop high-bandwidth controller is proposed for high-speed and high-precision tracking control of a nanopositioning stage. Firstly, the dual-loop controller (DLC) consisting of an inner-loop damping and an outer-loop tracking controller is developed with all the parameters optimized simultaneously, which could provide a control bandwidth over the first resonant frequency of the stage. Next, the Gaussian process (GP) machine learning model is employed to capture the dynamic characteristics of the tracking error of the dual-loop controlled plant. Then, a feedforward compensator is constructed to add a compensation term to the initial reference trajectory. Experimental investigations on a self-made piezoelectric-actuated stage validate the effectiveness of the intelligent tracking error prediction method and the excellent performance of the control strategy for high-precision tracking of high-frequency reference trajectories.

Modeling and Identification of Rate Dependent Hysteresis in Piezoelectric Actuated Nano-Stage: A Gray Box Neural Network Based Approach

A modeling and parameter identification method for rate dependent hysteresis of piezoelectric actuated nano-stage is presented in this work. A system level quasi-static hysteresis model is employed to construct a neural network. To better describe the rate dependent behavior of hysteresis in piezoelectric actuated stage, a Nonlinear AutoRegressive Moving Average with eXogenous input (NARMAX) based dynamic model is incorporated with the quasi-static hysteresis model, where the weights of specifically designed neural network corresponds to the model parameters. To handle the multivalued problem of hysteresis, generalized input gradient is proposed to convert multivalued mapping of hysteresis into one-to-one mapping. The parameters of the nonlinear rate dependent hysteresis in piezoelectric actuated stage is identified by neural network training, taking advantage of their universal function approximation capabilities. The proposed scheme is also compared with conventional black box and particle swarm optimization identification based methods, simulation and experimental results demonstrate significant performance improvement with an error of 20.77nm for proposed method whereas 96.56nm and 31.46nm for black box and particle swarm optimization respectively.

Adaptive Tracking Control for the Piezoelectric Actuated Stage Using the Krasnosel’skii-Pokrovskii Operator

In this paper, a discrete second order linear equation with the Krasnosel’skii-Pokrovskii (KP) operator is used to describe the piezoelectric actuated stage. The weights of the KP operators are identified by the gradient descent algorithm. To suppress the hysteresis nonlinearity of the piezoelectric actuated stage, this paper proposes an adaptive tracking control with the hysteresis decomposition on the designed error surface. The proposed adaptive tracking controller dispenses with any form of the feed-forward hysteresis compensation and the unknown parameters of the discrete second order linear equation are adaptively adjusted. Some simulations are implemented to verify the effectiveness of the KP operators, then a series of modeling and control experiments are carried out on the piezoelectric actuated stages experimental systems. The comparative experimental results verify the feasibility of the KP operators modeling method and the adaptive tracking control method.

Two-Dimensional Displacement Control of Piezoelectric Actuator Stage Driven by Series of Current Pulses

Two-Dimensional Displacement Control of Piezoelectric Actuator Stage Driven by Series of Current Pulses

Compensation of the residual error from the charge feedback control of a piezoelectric-actuated stage

Charge control for a piezoelectric actuator is supposedly unaffected by the hysteresis effect; however, the voltage applied to the actuator covers both the effective force-generating voltage and the hysteresis voltage. In this article, this hysteresis nonlinearity is considered an extra disturbance over a linear system. A novel approach entailing the use of the parasitic capacitance charge feedback in conjunction with a Preisach model to estimate the hysteresis disturbance is proposed. The estimated extra voltage enables the controller to augment its effort with an additional term to compensate for this loss. The article also describes the establishment of an adequate Preisach model. The proposed approach applies a low-pass filter and feedforward compensator to improve the tracking performance. Control results under sinusoidal reference and staircase reference tracking confirmed the effectiveness of the proposed compensation in eliminating the hysteresis effect and achieving high-precision control.

Modeling and Identification of Piezoelectric-Actuated Stages Cascading Hysteresis Nonlinearity With Linear Dynamics

In this paper, we propose a new modeling and identification approach for piezoelectric-actuated stages cascading hysteresis nonlinearity with linear dynamics, which is described as a Hammerstein-like structure. In the proposed approach, the hysteresis and linear dynamics together with the delay time and higher order dynamic behaviors are obtained with three data-driven identification steps under designed input signals. In the first step, the step input signal is applied to estimate the delay time of the piezoelectric-actuated stages. In the second step, the autoregression with exogenous signal identification algorithm is adopted to identify the linear dynamics using a small-amplitude band-limited white noise input signal. In the third step, with the identified linear dynamics model, the parameters of the rate-independent Prandtl–Ishlinskii hysteresis model are identified by the particle swarm optimization algorithm using a simple low-frequency triangle input signal with different amplitudes. Finally, the experimental results on a piezoelectric-actuated stage show that both the hysteresis and dynamic behaviors of the piezoelectric-actuated stage are well predicted by the proposed modeling method. In addition, we provide the analysis of quantitative prediction errors of the identified model with comparison to experimental data, which clearly demonstrate the effectiveness of the proposed approach.

Output feedback integral control for nano-positioning using piezoelectric actuators

This paper proposes a robust output feedback controller for a piezoelectrically actuated system with only position sensor. This considered piezoelectric actuator (PEA) system is subjected to model imperfection, creep nonlinearity, hysteresis nonlinearity and other external effects. The designed controller employs a second-order auxiliary system and a discontinuous uncertainty and disturbance estimation term to generate filtered error signals and to compensate for the model uncertainties and system disturbance, respectively. The global stability of the proposed controller is proved through Lyapunov-based stability analysis. The feasibility and effectiveness of the proposed control approach are verified experimentally using a PEA stage. Results demonstrate that both set-point and tracking control without/with external loads are realized with good performance and the PEA system with high-accuracy can be achieved. Moreover, the robustness of the controller is verified and analyzed through the sinusoidal tracking with external disturbance.

Structure Design and Stepping Characteristics Analysis of the Biaxial Piezoelectric Actuated Stage Using a Thin-Disc Piezoelectric Actuator

In this paper, a novel thin-disc piezoelectric actuator, 4-9-9-14 piezoelectric actuator, is used to construct and drive the micro/nanometer level biaxial piezoelectric actuated stage. The 4-9-9-14 piezoelectric actuator offers a better balanced capability of forward rotation and reverse rotation than the conventional edge-driving piezoelectric actuator. The biaxial piezoelectric actuated stage structure comprises a base, a V-shaped guide rail, an optical scale measurement system, a preload adjusting structure, and a load-carrying stage. The movement signals of the piezoelectric actuated stage are read and analyzed by means of NI PCI-6115 data acquisition card and LabVIEW software operating in conjunction with a linear optical scale. The new consideration of tuning Ton time is used in place of the traditional method of changing the magnitude of driving voltage to control the stepping distance of the stage. A combined driving signal is based on the sum of a continuous driving signal for Ton time and a DC signal for Ton time; the combined driving signal is continuously output in this manner to form a continuous driving pulse chain. Under a constant driving voltage, the displacement of the stage increases with Ton time and the displacement of the stage decreases with Ton time.

Stepping Experiment and Characteristics Analysis of a Novel Biaxial Piezoelectric Actuated Stage

In this research, our research team used the self-designed piezoelectric actuator to achieve the micro/nanometer level precise positioning biaxial piezoelectric actuated stage through the redesign of stage mechanism. A novel piezoelectric actuator structure - 4-9-9-14 piezoelectric actuator is constructed, and it is made of piezoelectric buzzer to drive the stage. The movement of the piezoelectric actuated stage is read and analyzed by means of NI PCI-6115 data acquisition card and LabVIEW software operating in conjunction with a linear encoder. The new consideration of tuning time Ton is used to place of traditional method of changing the magnitude of driving voltage to control the stepping distance of the stage. Under a constant driving voltage, the displacement of the stage increases with time Ton, and the displacement of the stage decreases with time Ton. The aforesaid phenomenon occurs to leftward or rightward movement of the upper stage and forward or backward movement of the lower stage. Given a constant time Ton, the displacement of the stage in motion decreases with the driving voltage, and the displacement of the stage in motion increases with the driving voltage.

Structure Design of the Biaxial Piezoelectric Actuated Stage Using a Novel Disk Piezoelectric Actuator

In this paper, a novel disk piezoelectric actuator structure - 4-9-9-14 piezoelectric actuator is constructed, and it is made of piezoelectric buzzer to drive a biaxial piezoelectric actuated stage. The 4-9-9-14 piezoelectric actuator offers a better balanced capability of forward rotation and reverse rotation than the conventional edge-driving piezoelectric actuator. The biaxial piezoelectric actuated stage structure comprises a base, a V-shaped guide rail, an optical scale measurement system, a preload adjusting structure, and a load-carrying stage. The movement of a stage is read and analyzed by means of LabVIEW operating in conjunction with an optical scale. Stage movement-related signals read by the optical scale are processed. With a human-machine interface of LabVIEW, the movement of the stage is depicted by a waveform chart to thereby facilitate the observation of the waveform chart and the understanding of propulsion of the stage by the actuator.

Development of a Recurrent Fuzzy CMAC With Adjustable Input Space Quantization and Self-Tuning Learning Rate for Control of a Dual-Axis Piezoelectric Actuated Micromotion Stage

This paper proposes a recurrent fuzzy cerebellar model articulation controller (RFCMAC) for a dual-axis micromotion stage powered by piezoelectric actuators. The proposed RFCMAC employs an adjustable input space quantization method with a learning rate capable of self-tuning. The proposed RFCMAC is aimed at dealing with the adverse effects due to unknown hysteresis nonlinearity, modeling uncertainty, and external disturbance that are commonly found in the piezoelectric actuator systems. The proposed RFCMAC mainly focuses on overcoming the drawbacks of the conventional CMAC control scheme when used to control a piezoelectric actuator system. In particular, the adjustable input space quantization method uses a simple repartitioning decision function to determine an appropriate input space quantization. In addition, the self-tuning law for the learning rate of the proposed RFCMAC is derived based on the discrete-time Lyapunov function so that convergence and faster learning can be guaranteed. Finally, in order to validate the effectiveness of the proposed control methodology, several contour-following experiments were conducted on a dual-axis piezoelectric actuated micromotion stage. Experimental results show that the proposed control scheme is feasible, and its performance is superior to that of the conventional CMAC control scheme.

Stepping Experiment Analysis of a Biaxial Piezoelectric Actuated Stage

In this research, our research team used the self-designed piezoelectric actuator to achieve the micro/nanometer level precise positioning biaxial piezoelectric actuated stage through the redesign of stage mechanism. A novel piezoelectric actuator structure - 4-9-9-14 piezoelectric actuator is constructed, and it is made of piezoelectric buzzer to drive the stage. The movement of the piezoelectric actuated stage is read and analyzed by means of NI PCI-6115 data acquisition card and LabVIEW software operating in conjunction with a linear encoder. The new consideration of tuning time Tonis used to place of traditional method of changing the magnitude of driving voltage to control the stepping distance of the stage. Under a constant driving voltage, the displacement of the stage increases with time Ton, and the displacement of the stage decreases with time Ton. The aforesaid phenomenon occurs to leftward or rightward movement of the upper stage and forward or backward movement of the lower stage. Given a constant time Ton, the displacement of the stage in motion decreases with the driving voltage, and the displacement of the stage in motion increases with the driving voltage.

Structure Design of a Novel Biaxial Piezoelectric Actuated Stage

In this paper, a disk piezoelectric actuator structure - 4-9-9-14 piezoelectric actuator is constructed, and it is made of piezoelectric buzzer to drive a novel biaxial piezoelectric actuated stage. The 4-9-9-14 piezoelectric actuator offers a better balanced capability of forward rotation and reverse rotation than the conventional edge-driving piezoelectric actuator. The biaxial piezoelectric actuated stage structure comprises a base, a V-shaped guide rail, an optical scale measurement system, a preload adjusting structure, and a load-carrying stage. The movement of a stage is read and analyzed by means of LabVIEW operating in conjunction with an optical scale. Stage movement-related signals read by the optical scale are processed. With a human-machine interface of LabVIEW, the movement of the stage is depicted by a waveform chart to thereby facilitate the observation of the waveform chart and the understanding of propulsion of the stage by the actuator.

Development of High Precision Position Stage and its Performance

This paper presents a high precision position stage which has the movement range of 0.4 micrometer and 1 nanometer precision. The piezoelectric actuator stage is composed of vertical position control part and horizontal position control part. With the three vertical piezoelectric actuators and three horizontal piezoelectric actuators, the stage can adjust the position in three directions and three angles around. The simulation and experimental results show that the first natural frequencies of the stage in three directions are bigger than 400Hz with the 600kg load, which means that the system are very strong to satisfy the stiff requirement. To evaluate the performance of the precision stage, vertical and horizontal movement and resolution are experimented with capacitance type displacement sensor whose sensitivity is 0.1V/um. The results show the stage can satisfy the design requirement.

Evolutionary Algorithm Based Feedforward Control for Contouring of a Biaxial Piezo-Actuated Stage

The main objective of this paper is to establish a precision contouring control of a biaxial piezoelectric-actuated stage. The positioning accuracy of the piezoelectric-actuated stage is limited due to the hysteretic nonlinearity of the piezo-electric actuators (PEA). To compensate this hysteresis problem, a feedforward controller based on an evolution algorithm is proposed. The dynamics of the hysteresis is formulated by the Bouc-Wen model and the evolutionary algorithms (EAs) are studied to identify the optimal parameters of the Bouc-Wen model. To verify the consistency, two micro-contouring tasks are implemented by the proposed feedforward controller with the feedback of linear optical scales in DSP based real-time control architecture.

Evolutionary algorithm based feedforward control for contouring of a biaxial piezo-actuated stage

The main objective of this paper is to establish a precision contouring control of a biaxial piezoelectric-actuated stage. The positioning accuracy of the piezoelectric-actuated stage is limited due to the hysteretic nonlinearity of the piezoelectric actuators (PEA). To compensate this hysteresis problem, a feedforward controller based on an evolution algorithm is proposed. The dynamics of the hysteresis is formulated by the Bouc–Wen model and the evolutionary algorithms (EAs) are studied to identify the optimal parameters of the Bouc–Wen model. To verify the consistency, two micro-contouring tasks are implemented by the proposed feedforward controller with the feedback of linear optical scales in DSP based real-time control architecture.

Tracking control of a piezo‐actuated stage based on a frictional model

AbstractThe tracking control accuracy of a piezoelectric actuator (PEA) is limited due to the actuator's inherent hysteretic nonlinearity. Direct drive of PEA on a positioning stage with friction force will cause control problems. An approximated dynamic model of PEA with consideration of friction force is novel synthesized for control. This model is based on a second‐order transfer function with two parameterization terms. The first time delay term consists of the hysteresis of piezo effect combined with frictional force lag with varying velocity. The second term is comprised of both presliding and sliding regimes. The H‐infinite tracking controller is designed to compensate for the structural uncertainty associated with time delay and the unstructured frictional force in the PEA stage. Iterative Learning Control is implemented to reduce the unmodeled repetitive error by a factor of 20. Numerical simulations and experimental tests consolidate the root mean square (RMS), positioning error close to the hardware reproducibility and accuracy level. Experimental results show the controlled stage can be potentially used for precise positioning. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

MEMS integrated submount alignment for optoelectronics

One of the most expensive and time-consuming production processes for single-mode fiber-optic components is the alignment of the photonic chip or waveguide to the fiber. The alignment equipment is capital intensive and usually requires trained technicians to achieve desired results. Current technology requires active alignment since tolerances are only /spl sim/0.2/spl mu/m or less for a typical laser diode. This is accomplished using piezoelectric actuated stages and active optical feedback. Joining technologies such as soldering, epoxy bonding, or laser welding may contribute significant postbond shift, and final coupling efficiencies are often less than 80%. This paper presents a method of adaptive optical alignment to freeze in place directly on an optical submount using a microelectromechanical system (MEMS) shape memory alloy (SMA) actuation technology. Postbond shift is eliminated since the phase change is the alignment actuation. This technology is not limited to optical alignment but can be applied to a variety of MEMS actuations, including nano-actuation and nano-alignment for biomedical applications. Experimental proof-of-concept results are discussed, and a simple analytical model is proposed to predict the stress strain behavior of the optical submount. Optical coupling efficiencies and alignment times are compared with traditional processes. The feasibility of this technique in high-volume production is discussed.