Self-sensing Piezoelectric Actuator Research Articles

Control design for beam stabilization with self-sensing piezoelectric actuators: managing presence and absence of hysteresis

Control design for beam stabilization with self-sensing piezoelectric actuators: managing presence and absence of hysteresis

Motion Characteristics of Self-Sensing Piezoelectric Actuator for Yarn Micro-Gripper

In order to solve the problem of low response frequency and poor consistency of conventional yarn grippers in weft accumulators, in this study, a piezoelectric yarn gripper is used instead of conventional yarn grippers and the motion characteristics of its actuator are studied. This gripper uses a bimorph piezoelectric bending actuator with a low-cost, well integrated self-sensing method based on charge measurement. The modeling of the piezoelectric micromanipulator is based on the piezoelectric and Euler–Bernoulli beam equations. The static and dynamic characteristics of the piezoelectric actuator as well as the self-sensing capability were experimentally tested. The experimental results show that the maximum output displacement at the end of the piezoelectric actuator is 834 μm, and the maximum output force is 388 μN at 150 V driving voltage. The stability and consistency of its response are also very good, with a response speed of 24 ms. The self-sensing test of the output force also proved the feasibility of the self-sensing method used, with an error of 0.74%. The piezoelectric yarn gripper studied in this paper is promising for practical clamping applications.

Adaptive Feedforward Compensating Self-Sensing Method for Active Flutter Suppression.

A single piezoelectric patch can be used as both a sensor and an actuator by means of the self-sensing piezoelectric actuator, and the function of self-sensing shows several advantages in many application fields. However, some problems exist in practical application. First, a capacitance bridge circuit is set up to realize the function of self-sensing, but the precise matching of the capacitance of the bridge circuit is hard to obtain due to the standardization of electric components and variations of environmental conditions. Second, a local strain is induced by the self-sensing actuator that is not related to the global vibration of the structure, which would affect the performance of applications, especially in active vibration control. The above problems can be tackled by the feedforward compensation method that is proposed in this paper. A configured piezoelectric self-sensing circuit is improved by a feedforward compensation tunnel, and a gain of compensation voltage is adjusted by the time domain and frequency domain’s steepest descent algorithms to alleviate the capacitance mismatching and local strain problems. The effectiveness of the method is verified in the experiment of the active vibration control in a wind tunnel, and the control performance of compensated self-sensing actuation is compared to the performance with capacitance mismatching and local strain. It is found that the above problems have negative effects on the stability and performance of the vibration control and can be significantly eliminated by the proposed method.

Piezoelectric self-sensing actuator for active vibration control of motorized spindle based on adaptive signal separation

The motorized spindle is the core component of CNC machine tools, and the vibration of it reduces the machining precision and service life of the machine tools. Owing to the fast response, large output force, and displacement of the piezoelectric stack, it is often used as the actuator in the active vibration control of the spindle. A piezoelectric self-sensing actuator (SSA) can reduce the cost of the active vibration control system and simplify the structure by eliminating the use of a sensor, because a SSA can have both actuating and sensing functions at the same time. The signal separation method of a SSA based on a bridge circuit is widely applied because of its simple principle and easy implementation. However, it is difficult to maintain dynamic balance of the circuit. Prior research has used adaptive algorithm to balance of the bridge circuit on the flexible beam dynamically, but those algorithms need no correlation between sensing and control voltage, which limit the applications of SSA in the vibration control of the rotor-bearing system. Here, the electromechanical coupling model of the piezoelectric stack is established, followed by establishment of the dynamic model of the spindle system. Next, a new adaptive signal separation method based on the bridge circuit is proposed, which can separate relative small sensing voltage from related mixed voltage adaptively. The experimental results show that when the self-sensing signal obtained from the proposed method is used as a displacement signal, the vibration of the motorized spindle can be suppressed effectively through a linear quadratic Gaussian (LQG) algorithm.

Harmonic active vibration control using piezoelectric self-sensing actuation with complete digital compensation

In this article, the implementation of a self-sensing piezoelectric actuator with complete digital compensation is presented. The proposed compensation not only minimizes the signal due to the electrical behavior of the self-sensing actuator but also takes into account the fact that piezoelectric actuator causes a local strain—not related to the global vibration of the plate—in a vibrating plate to which it is coupled. Therefore, the corrected measured current is related to the global vibration of the plate and may be used in an active control scheme. The electro-mechanical model on which is based this self-sensing actuator is first explained. Then, the electronic and digital processing implementation is presented, as well as the active time-harmonic control scheme used. Finally, results of experimental validation are presented, and the attenuation performance of the self-sensing actuator is compared to the performances of a co-localized accelerometer/lead zirconate titanate pair. It is shown that the corrected self-sensing actuator current gives results better than what is obtained with a co-localized sensor/actuator pair and that this technique may be used to control more than one frequency simultaneously.

Unbalance detection in rotor systems with active bearings using self-sensing piezoelectric actuators

Abstract Machines which are developed today are highly automated due to increased use of mechatronic systems. To ensure their reliable operation, fault detection and isolation (FDI) is an important feature along with a better control. This research work aims to achieve and integrate both these functions with minimum number of components in a mechatronic system. This article investigates a rotating machine with active bearings equipped with piezoelectric actuators. There is an inherent coupling between their electrical and mechanical properties because of which they can also be used as sensors. Mechanical deflection can be reconstructed from these self-sensing actuators from measured voltage and current signals. These virtual sensor signals are utilised to detect unbalance in a rotor system. Parameters of unbalance such as its magnitude and phase are detected by parametric estimation method in frequency domain. Unbalance location has been identified using hypothesis of localization of faults. Robustness of the estimates against outliers in measurements is improved using weighted least squares method. Unbalances are detected in a real test bench apart from simulation using its model. Experiments are performed in stationary as well as in transient case. As a further step unbalances are estimated during simultaneous actuation of actuators in closed loop with an adaptive algorithm for vibration minimisation. This strategy could be used in systems which aim for both fault detection and control action.

Design of a resonance-based mass sensor using a self-sensing piezoelectric actuator

Simple self-sensing electronics for a piezoelectric actuator which uses a potential dividing concept is proposed for a resonance-based mass sensor. The analytical model of the self-sensing electronics with a cantilever beam as a resonant structure is derived. The electronics is evaluated analytically and through experimentation, and the experimental and calculated frequency responses are found to be close to each other. A resonant-based mass measurement system is developed and tested using the proposed electronics for the range of 0–10 g. The input–output characteristic of the mass sensor with self-sensing is found to be closer to the response obtained with a collocated sensor.

Performance evaluation of piezoelectric sensor/actuator on active vibration control of a smart beam

In this paper the performance of a piezoelectric sensor/actuator pair and self-sensing piezoelectric actuator on the investigation of vibration characteristics and active vibration control of a smart beam are presented. The performance of piezoelectric patches on actuation and sensing is evaluated by investigating the vibration characteristics of the smart beam via various excitation mechanisms and transduction systems. For active vibration suppression of the smart beam, robust controllers are designed and experimentally implemented by using a piezoelectric sensor/actuator pair and self-sensing piezoelectric actuator. Finally, experimental results for active control of free and the first-resonance forced vibration of the smart beam are presented.

High-precision positioning using a self-sensing piezoelectric actuator control with a differential detection method

We present a self-sensing control method for piezoelectric actuators, which enables high-resolution positioning without an external positioning sensor. One of the present authors previously proposed a self-sensing piezoelectric actuator control system (Kawamata et al. (2008) [1] and Ishikiriyama and Morita (2010) [2]). In the previous studies, a linear relationship between piezoelectric displacement and permittivity change was discovered, and this linear relationship was applied for positioning control. To detect permittivity changes, a high frequency voltage signal (permittivity detection voltage), in addition to the driving voltage signal, was applied to the actuator. The permittivity change was monitored as the amplitude of the current at the same frequency as the permittivity detection voltage. From this current amplitude, the permittivity change was easily calculated in real time. However, the positioning resolution was insufficient compared to that of traditional external positioning sensors, such as a strain gage sensor. In this study, we improved the positioning resolution by introducing a differential current measurement using two piezoelectric elements, one on each side of a bimorph actuator. The phase of the detected current signal was taken into consideration using a lock-in amplifier. In other words, the conductivity-related current and the permittivity-related current were measured separately. With these improvements, the permittivity change related to the piezoelectric displacement could be measured precisely, and self-sensing feedback control with a positioning error of less than 0.4 μm over a movement range of 80 μm was demonstrated.

Compensation of harmonic disturbances in piezoelastic structures

The use of self-sensing piezoelectric actuators in smart structures means collocation of actuator and sensor. The measured electric current carries contributions from an electrical and mechanical subsystem. The latter contribution is due to the direct piezoelectric effect that is used for the purpose of vibration control. This procedure requires the robust separation of the electric current due to the direct piezoelectric effect from the measured electric current. Due to the unfavourable ratio of these two signals, the design of an observer for the electric current due to the direct piezoelectric effect is proposed. The control design for the purpose of harmonic disturbance suppression is based on an internal model approach and is facilitated by the special structure of the underlying mathematical model. Stability issues with respect to the distributed parameter system are resolved by applying the concepts of passivity and stability in conjunction with the small gain theorem. The control concept is evaluated by exciting the piezoelastic structure under investigation at a dominant eigenfrequency.

Wing box transonic-flutter suppression using piezoelectric self-sensing actuators attached toskin

The main objective of this research is to study the capability of piezoelectric (PZT)self-sensing actuators to suppress the transonic wing box flutter, which is a flow–structureinteraction phenomenon. The unsteady general frequency modified transonic smalldisturbance (TSD) equation is used to model the transonic flow about the wing. The wingbox structure and piezoelectric actuators are modeled using the equivalent plate method,which is based on the first order shear deformation plate theory (FSDPT). Thepiezoelectric actuators are bonded to the skin. The optimal electromechanical couplingconditions between the piezoelectric actuators and the wing are collected from previouswork. Three main different control strategies, a linear quadratic Gaussian (LQG) whichcombines the linear quadratic regulator (LQR) with the Kalman filter estimator (KFE), anoptimal static output feedback (SOF), and a classic feedback controller (CFC), are studiedand compared. The optimum actuator and sensor locations are determined using thenorm of feedback control gains (NFCG) and norm of Kalman filter estimatorgains (NKFEG) respectively. A genetic algorithm (GA) optimization technique isused to calculate the controller and estimator parameters to achieve a targetresponse.

Wing box transonic-flutter suppression using piezoelectric self-sensing diagonal-link actuators

The main objective of this research is to study the capability of Piezoelectric (PE) self-sensing actuators to suppress the transonic wing-box flutter, which is a flow-structure interaction phenomenon. The unsteady general frequency modified Transonic Small Disturbance (TSD) equation is used to model the transonic flow about the wing. The wing-box structure and the piezoelectric actuators are modeled using the equivalent plate method, which is based on the first-order shear deformation plate theory (FSDPT). The piezoelectric actuators are used as diagonal-links. The optimal electromechanical-coupling conditions between the piezoelectric actuators and the wing are collected from previous work. Three main different control strategies; Linear Quadratic Gaussian (LQG) which combines the Linear Quadratic Regulator (LQR) with the Kalman Filter Estimator (KFE), Optimal Static Output Feedback (SOF), and Classic Feedback Controller (CFC); are studied and compared. The optimum actuators and sensors locations are determined using the Norm of Feedback Control Gains (NFCG) and Norm of Kalman Filter Estimator Gains (NKFEG), respectively. A genetic algorithm (GA) optimization technique is used to calculate the controller and estimator parameters to achieve a target response.

Control of PKM machine tools using piezoelectric self-sensing actuators on basis of the functional principle of a scale with a vibrating string

An adaptronic strut for machine tools with parallel kinematics for compensation of the influence of geometric errors is introduced. Implemented within the strut is a piezoelectric sensor-actuator unit separated in function. In the first part of this contribution, the functional principle of the strut is presented. For use of one piezoelectric transducer as both, sensor and actuator as so-called self-sensing actuator, the acquisition of the sensing signal while actuating simultaneously using electrical bridge circuits as well as filter properties are examined. In the second part the control concept developed for the adaptronic strut is presented. A co-simulation model of the strut for simulating the controlled multi-body behavior of the strut is set-up. The control design for the strut as a stand-alone system is tested under various external loads. Finally, the strut is implemented into a model of the complete machine tool and the influence of the controlled strut onto the behavior of the machine tool is examined.

Improvement of Self-sensing Piezoelectric Actuator Control Using Permittivity Change Detection

We present a self-sensing control method of piezoelectric actuators that compensate the hysteresis characteristics by using the linear relationship between the permittivity change and the piezoelectric displacement. In this article, improvement of this method is described. Increasing the frequency of the voltage for a permittivity detecting, the sensitivity of the permittivity detection was improved and the accuracy of the displacement sensing could be enhanced. In addition, by applying this self-sensing method, we tried to overcome the creep phenomenon that is a peculiar problem of piezoelectric actuators.

MCH-07 Improvement of self-sensing piezoelectric actuator control using permittivity change detection(Micro/Nanomechatronics III,Technical Program of Oral Presentations)

MCH-07 Improvement of self-sensing piezoelectric actuator control using permittivity change detection(Micro/Nanomechatronics III,Technical Program of Oral Presentations)

Piezoelectric Self-Sensing Actuator for Beam Vibration Control Based on Blind Source Separation

A blind source separation based vibration control method using piezoelectric self-sensing actuator is proposed. Two piezoelectric ceramic patches acting as actuators and two current amplifiers consist of the self-sensing bridge circuit. Each piezoelectric current is a mixture of strain rate current and capacitor current. As they are orthogonal and independent with each other, the blind source separation technique is introduced to obtain the pure strain rate signal. An effort is made to solve the problem of BSS uncertainty in separation order. Open loop experimental results on cantilever beam show the feasibility and validity of the proposed method.

Study on Displacement Self-Sensing of Piezoelectric Actuator

This paper aims to make piezoelectric ceramic actuator self-sense its own displacement in the absence of independent sensor. It is derived from the basic piezoelectric equation that the free charge on the wafer of piezoelectric ceramic actuator contains displacement information. So a displacement self-sensing method based on integrate circuit is presented. Voltage driving circuit for the piezoelectric ceramic actuator and integrated circuit for gathering free charge are designed. Based on the proposed compound circuits, the actuator can sense its own displacement while actuation. It is convenient to adjust the circuit and easy to acquire sensitive signal by using this method, and the impedance mismatching problem met in bridge method is overcome. The experimental results show that piezoelectric self-sensing actuator can effectively measure its displacement signal under the conditions of different wave form of driving voltage and different driving voltage frequency.

Adaptive Control of Nonlinear Free Vibrations of Composite Plates Using Piezoelectric Actuators

A coupled structural-electrical finite element modal formulation is employed for the control of nonlinear free vibrations of beams and composite plates. Multiple modes of the nonlinear free vibration are considered in closed-loop simulations. Two different controllers are designed and investigated for the suppression of nonlinear free vibrations. The first is the position output feedback controller comprising a linear quadratic regulator (LQR) and an extended Kalman filter (EKF). The EKF is used to consider the nonlinear state-space matrix and has a gain sequence evaluated online. The second controller is the output feedback adaptive LQR/EKF controller. This adaptive controller includes an adaptive modal frequency identification and state estimation algorithm. Numerical simulations show that the adaptive LQR/EKF controller with system identification is effective in suppressing nonlinear free vibrations of a beam and a composite plate with unpredictable sudden frequency changes. The placement of piezoelectric self-sensing actuators is based on three approaches: one is the norm of optimal feedback control gain matrix method, the second is the H 2 norm, and the last one is the norm of Kalman filter estimation gain method.

Dynamic Characteristics of Smart Hull Structures Featuring Piezoelectric Materials

In this paper, dynamic characteristics of an end-capped hull structure with surface bonded piezoelectric actuators are studied. Finite element technique is used to ensure application to practical geometry and boundary conditions of smart hull structure. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure. Piezoelectric self-sensing actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller.

Active control of noise transmission through a plate using embedded self-sensing piezoelectric actuators

This paper presents a study of active noise isolation using an advanced composite board with built-in piezoelectric elements, which are used as both sensors and actuators. An identification system, which estimates the radiated sound from the voltage signals of the built-in piezoelectric elements in the smart board, was constructed based on Rayleigh's integral formula so that no external microphone is needed for noise control. A FIR filter was used as the controller and its coefficients were updated adaptively using the Filtered-X LMS algorithm to minimize the estimated value of the sound pressure. The technique of self-sensing actuators was also used to reduce the number of needed piezoelectric elements in the control. Experiments were performed and the results showed that the transmitted noise level was successfully reduced at several resonant peaks.