Stick-slip Piezoelectric Actuator Research Articles

An umbrella-shaped flexible mechanism piezoelectric actuator with driving foot trajectory control

Traditional stick-slip piezoelectric actuators generally have problems such as large backward motion and small load capacity, which affect the driving effect. In this study, the effect of no backward motion and large load capacity is realized by controlling two sawtooth wave-driven piezoelectric stacks on the basis of umbrella-shaped flexible mechanism. The trajectory of the driving foot is simulated by transient simulation and verified by experiment. A prototype of actuator is made, and the effects of voltage, symmetry of sawtooth wave, and the phase difference of the two waves on the driving effect are investigated through experiments, and the optimal driving waveform is found. Experiments have shown that no displacement regression and stable driving is achieved when driving with two sets of sawtooth waves with 100 V, 100% symmetry and 20 V, 70% symmetry. With this drive waveform at 1 Hz, the maximum horizontal and vertical loads are 150 g and 1400 g, respectively. And the maximum driving speed is 13 935 μm s−1 when the driving frequency is 7000 Hz. Experimentally, it is proved that the actuator is able to realize smooth driving and large load capacity without backward motion, and has the same forward and reverse working performance, which has greater research value and market application scenarios.

A three-degree-of-freedom piezoelectric actuator with sandwich structure: Design, modeling, and experiment

With the increased motion requirements of precision drive devices, multi-degree-of-freedom piezoelectric actuators have become key technologies for realizing multi-axis motion control. To expand upon the three-degree-of-freedom piezoelectric stick-slip driving method, a sandwich-type three-degree-of-freedom rotating inertial stick-slip piezoelectric actuator is proposed in this paper. Firstly, the structure and control strategy of the actuator were introduced. Statics analysis of the core component of the piezoelectric vibrator was carried out, and the relationship between the structural parameters and the deformation of the driving foot was obtained. Then the free and forced vibrations of the piezoelectric vibrator are analyzed to determine the dynamic response of the driving foot in the time domain. Finally, a prototype was fabricated and an experimental system was built to test its output characteristics. The test results show that when the driving voltage was 150 V and the frequency was 320 Hz, the proposed actuator achieves maximum speeds and load torques around the x-axis and y-axis of 306 mrad/s and 2 mN m, respectively. When the driving voltage was 150 V and the frequency was 450 Hz, the proposed actuator achieves a maximum speed and load torque around the z-axis of 140 mrad/s and 1.55 mN m, respectively.

A dual-mode stick-slip piezoelectric actuator imitating mantis forefoot

Most existing stick-slip piezoelectric actuators fail to achieve smooth motion and linear speed, and the backward motion cannot be actively inhibited during motion. This paper develops a novel piezoelectric actuator with stiffness-variable flexible mechanism imitating mantis forefoot, which utilizes the elastic potential energy to suppress backward motion. Furthermore, the contact condition between the driving foot and the rotor can be adjusted through a joint-like flexible structure. On this basis, contact precisely adjusted driving (CPAD) mode and triangular wave cooperative driving (TWCD) mode are proposed to achieve complete suppression of backward motion, as well as high-speed and high-resolution output. The transfer matrix method (TMM) in the cross-section of multiple state nodes has been improved and applied to accurately establish the theoretical model for the complex flexible hinge structure, with the combination of FEM for structural optimization design and mechanical properties analysis. The error between the calculated results and the experimental results is within 4%. Finally, a prototype with dimensions of Ø36 × 10 mm is manufactured and tested. The results show that both driving modes are able to achieve smooth motion output by actively suppressing backward motion, and a linear speed curve can be achieved under 800 Hz. The prototype achieves a maximum speed of 4491.38 mrad/s and a rotational resolution of 0.332 μrad, which is significantly better than existing actuators with similar size. This study shows great value for applications in the field of fast and precise positioning with size constraints.

Design and experimental investigation of a novel stick-slip piezoelectric actuator based on V-shaped driving mechanism

Design and experimental investigation of a novel stick-slip piezoelectric actuator based on V-shaped driving mechanism

Model-Free Adaptive Positioning Control of the Bidirectional Stick-Slip Piezoelectric Actuator with Coupled Asymmetric Flexure-Hinge Mechanisms.

A model-free adaptive positioning control strategy for piezoelectric stick-slip actuators (PSSAs) with uncertain disturbance is proposed. The designed controller consists of a data-driven self-learning feedforward controller and a model-free adaptive feedback controller with a radial basis function neural network (RBFNN)-based observer. Unlike the traditional model-based control methods, the model-free adaptive control (MFAC) strategy avoids the complicated modeling process. First, the nonlinear system of the PSSA is dynamically linearized into a data model. Then, the model-free adaptive feedback controller based on a data model is designed to avoid the complicated modeling process and enhance the robustness of the control system. Simultaneously, the data-driven self-learning feedforward controller is improved to realize the high-precision control performance. Additionally, the convergence of the tracking error and the boundedness of the control output signal are proved. Finally, the experimentally obtained results illustrate the advantages and effectiveness of the developed control methodology on the bidirectional stick-slip piezoelectric actuator with coupled asymmetric flexure-hinge mechanisms. The positioning error through the proposed controller reaches 30 nm under the low-frequency condition and 200 nm under the high-frequency condition when the target position is set to 100 μm. In addition, the target position can be accurately tracked in less than 0.5 s in the presence of a 100 Hz frequency.

Achieving Significant Burst Motion Based on Epicycloid Induction Principle for Stick–Slip Piezoelectric Actuator

The burst motion as a potential motion is discovered in recent years and has important effects on the output performance of the piezoelectric actuator. How to induce the burst motion has become a research hotspot and a current challenge in the field of piezoelectric actuator. To eliminate the backward motion and induce significant burst motion, an epicycloid induction principle (EIP) was proposed in this paper. Correspondingly, a stick-slip piezoelectric actuator with a special dual feet compliant mechanism (DFCM) was designed, and the corresponding prototype was fabricated to verify the EIP. Under the excitation of square wave signals, the driving and clamping feet alternately pushed the bearing, and the epicycloid motion of the bearing induced the burst motion of the slider. The threshold voltage about the clamping foot of the prototype with no backward motion was set through the pre-experiment. At this voltage, the displacement-time curves in one period showed three consecutive steps, which confirmed the feasibility of the EIP. In addition, the prototype has the resolution of 160 nm and the vertical loading capacity greater than 5 N. The proposed EIP is effective for inducing significant burst motion and offers a novel idea for the structure design of the stick-slip actuators.

A bipedal cooperative drive method for the stick-slip piezoelectric actuator to achieve smooth motion.

Existing kinds of stepping piezoelectric actuators have difficulty in maintaining smooth stepping characteristics in motion, especially with applied loads, because they are limited by their driving principle and structural design. However, non-smooth stepping characteristics not only reduce the output performance of piezoelectric actuators but also greatly limit the applications of piezoelectric actuators. In this paper, a bipedal cooperative drive method for the stick-slip actuator is proposed to improve stepping characteristics and achieve smooth motion under different conditions. Two flexible driving feetalternately push the rotor to rotate clockwise. Experimental results show that the stepping characteristics vary with the driving voltage, and the displacement curve transitions from non-smooth to smooth to sudden jump as the driving voltage rises. Furthermore, the displacement curves can maintain good smoothness within a horizontal load range of 20-30g. The maximum angular speed of the designed actuator is 1452 mrad/s when the driving voltage and driving frequency are 100V and 1400Hz, respectively. These features help broaden the practical application of actuators.

Design and evaluation of a stick-slip piezoelectric actuator with flexure hinge mechanism inspired by the earthworm.

In this work, a new bionic piezoelectric actuator inspired by the earthworm is proposed, fabricated, and tested. The operating principle of the actuator imitates the crawling motion of the earthworm. The piezoelectric stack is embedded in the stator with a flexure hinge mechanism. One side of the stator is inspired by the earthworm body. Then the elongation of the piezoelectric stack is transmitted to the driving tip to produce oblique displacement under such a stator. The vertical and horizontal components are used to press and drive the slider, respectively. The principle of the proposed actuator is described in detail. The static deformation is investigated by the FEM method. A dynamic model of the actuator is developed to further reveal the motion characteristics of the slider via theoretical analysis. Finally, the output characteristics of the proposed BPA are tested. The experimental results show that the actuator achieves a maximum output speed of 12.72 mm/s at a voltage of 100V and a frequency of 710Hz. The maximum output force is 3 N under a locking force of 2 N. Besides, the displacement resolution is tested at 87nm at a frequency of 710Hz, which indicates that the developed actuator can be applied in the field of precision actuation.

Achieving high consistency in forward and reverse motions of stick-slip piezoelectric actuator by a symmetrical structure and optimized installation method

Achieving high consistency in forward and reverse motions of stick-slip piezoelectric actuator by a symmetrical structure and optimized installation method

Design, analysis, and experiment of a piezoelectric stick–slip rotary actuator with asynchronous-driven dual stators

The piezoelectric stick–slip actuator with a compact structure shows great merits for space-critically limited applications, such as high-precision positioning and micro-nano operations. It can be used as a rotating part in micro-nano manipulators. However, piezoelectric stick–slip actuators operate under the friction-inertia principle. The backward motion is almost inevitable at low driving frequencies, hugely detrimental to manipulation accuracy, thus posing challenges to the configuration design and driving strategy of the actuator. This paper proposes a stick–slip rotary actuator with asynchronous-driven dual stators. Based on the principle of minimum motion branch chains and piezoelectric stacks, a dual-stator stick–slip rotary actuator with 2-R force-couple flexible stators is designed to enhance structure compactness. Then, an asynchronous driving method is proposed that enables the actuator to increase stickiness and reduce slippage without changing the driving waveform to minimize the backward motion. After that, the kinetic model with electromechanical-frictional coupling properties is developed, and the motion and load characteristics of the actuator are analyzed through MATLAB/Simulink simulations. The causes of the motion and load characteristics are discussed, and measures to improve the motion speed and load capacity are proposed. Finally, a prototype is fabricated, and several experiments are carried out. The results show that the backward motion of the actuator is significantly suppressed in the asynchronous driving mode, and its output displacement exhibits good stepping characteristics. The actuator has the advantages of a simple structure, little volume, small backward motion, and high resolution, demonstrating structural and performance superiorities for micro-nano manipulators in space-constrained applications.

A stick-slip piezoelectric actuator with an integrated sensing unit for the measurement and active control of the contact force

A stick-slip piezoelectric actuator with an integrated sensing unit for the measurement and active control of the contact force

Analysis and comparison of the effect of different drive feet on the output performance of stick–slip piezoelectric actuators

In recent years, researchers have conducted many investigations on load capacity and structural optimization. However, the backward motion is still not sufficiently investigated. Therefore, a new piezoelectric actuator with different drive feet is presented in this paper. Different working requirements can be met by varying drive feet. Firstly, the amplification ratio of the flexible driving mechanism is obtained by the flexibility matrix method. Secondly, the piezoelectric actuator is dynamically modeled and numerically analyzed via AMEsim, and systematic analysis of the backward motion mechanism, smooth motion, and sudden jump is provided. Finally, an experimental investigation is conducted on the piezoelectric actuator. Under the same pre-displacement, it was observed that the large stiffness of the drive foot 1 is suitable for low speed and high load. On the other hand, the lower stiffness of drive foot 2 is suitable for high speed and low loads. Lastly, the medium stiffness of the drive foot 3 is suitable for medium speed and medium load. Repeatability of experiments for three different drive feet is conducted to verify the proposed method for the alternative drive feet. Compared with previous studies, the designed actuator achieves alternative drive foot, high speed, large load, and smooth motion.

A novel two-degrees of freedom (2-DOF) piezo-driven positioning platform with the working stroke being over 20 cm.

Multi-degrees of freedom piezo-driven precision positioning platforms with large working strokes are demanded in many research fields. Although many multi-degrees of freedom piezo-driven positioning platforms have been proposed, few of them can achieve both large working stroke and high speed, which hinders their applications. In this study, a two-degrees of freedom piezo-driven positioning platform was proposed by stacking two identical stick-slip piezoelectric actuators. To simplify the practical implementation of a large working stroke, the actuator employed a special structure, in which the compliant mechanism and the slider were connected together as a mover and the guide rail was fixed as a stator. The working stroke of the actuator can be increased easily by increasing only the length of the guide rail without changing the output performances. By designing a lever-type compliant mechanism (LCM) on the side surface of the slider, a large loading space was obtained. Theoretical calculation and finite element analysis of the LCM were performed in detail. As the structures of these two stick-slip piezoelectric actuators are the same, only the output performances of the upper actuator (x direction) were tested as an example. Experimental results indicated that the upper actuator had a stable bi-direction motion with a working stroke being over 20cm. The maximum speeds along the positive x and negative x directions reached 17.864 and 18.73 mm/s, and the resolutions were 100 and 230nm, respectively. Furthermore, the vertical loading capacity was larger than 60 N.

Restraining the Backward Motion of a Piezoelectric Stick-Slip Actuator With a Passive Damping Foot

The backward motion is an intrinsic feature of the conventional piezoelectric stick-slip actuator (PSSA), limiting the output speed and applications. Various methods have been proposed for restraining the backward motion. Each method has its pros and cons for the practical application of driving a precision motion stage. A novel method for restraining the backward motion is proposed in this article, in which a passive damping foot is utilized to hold the runner when the active driving foot slips on the runner. An actuator is developed based on this mechanism. The structural dimensions of the actuator are determined with an analytic model and a finite element model. A prototype of the proposed actuator is fabricated and tested by experiments. The experiments validate the operating principle of the actuator for restraining the backward motion, which is eliminated (the backward ratio is less than 1%) when the passive damping foot has an appropriate clamping force. The proposed method is very valuable for designing a PSSA with no backward motion, and it can broaden the applications for precision manipulations.

Design, analysis and experiments of a stick-slip piezoelectric actuator working under the self-deformation mode

In this paper, the self-deformation mode of the stick-slip principle was proposed, and accordingly a piezoelectric actuator based on the self-deformation mode was designed, which could achieve stable bidirectional outputs with long stroke. To increase the stepping displacement of the output end and reduce the structural stress, an arc-shape flexible hinge with variable section was employed as the output part of the flexible hinge mechanism. The self-deformation motion was obtained by the deformation of the driving mechanism caused by the reaction force of the mover in the driving process. The stepping and self-locking characteristics of the actuator under various initial gaps were tested, and the evolution of stepping characteristics with the driving voltage, frequency and external load was analyzed. The experimental results showed that by the self-deformation mode, the long stroke with good linearity could be easily achieved for both the forward and reverse motions, and the maximum self-locking force reached 5 N. Furthermore, the maximum driving speed reached 2754 μm s−1 under the driving voltage of 120 V.

A stick-slip piezoelectric actuator with high assembly interchangeability

The stick-slip piezoelectric actuator with simple driving signal and structure is a very promising type for achieving the high resolution and large stroke. However, as a typical actuator working by the friction-inertia principle, the contact between the stator and mover requires precise adjustment, which brings difficulty for the assembly of the actuator. Excessive assembly errors may even cause the piezoelectric actuator to fail to work. Accordingly, to decrease the effects of assembly factors on the output performances and enhance the assembly interchangeability of stick-slip piezoelectric actuators, a method of low stiffness contact was proposed in this study, which used the flexible foot to replace the generally employed rigid foot with high stiffness. By comparing with the rigid foot actuator, the feasibility of the proposed method was theoretically analyzed first. Then, the effects of preload deformation and three potential assembly errors (deflection, overturning and pitching) on the output performances were characterized. Finally, a highly interchangeable actuator with compact structure was designed, and its abilities for quick disassembly and assembly, interchangeability of the stator and large-stroke stable motion were tested. Experimental results indicated that the proposed actuator can achieve good motion stability and high interchangeability. The strategy of low stiffness contact can significantly decrease the assembly requirement, which is beneficial to the practical production and application of stick-slip piezoelectric actuators.

Development and evaluation of a new piezoelectric stick-slip actuator using stair type flexure hinge

A new piezoelectric stick-slip actuator using stair type flexure hinge is proposed and developed in this work. It’s spirited by referencing the reported “Z-shaped” flexure hinge in the literatures and the idea of asymmetric structure. In this design, the PZT stack can generate elongation displacement under the excitation of sawtooth signal, and then the elongation can be transmitted into the vertical and horizontal displacements on the driving tip by the stair type flexure hinge. The slider is pressed by the vertical displacement and driven by the horizontal displacement, respectively. The working principle of the proposed actuator is clarified. The statics characteristics are investigated by the theoretical and simulation methods. Finally, the mechanical output characteristics of the developed prototype are tested. The maximum output velocity is 8.5 mm/s when the voltage and frequency are 100 V and 720 Hz. The maximum output force is tested as 2.6 N when the preloading force is 3 N. The experiment results validate the feasibility of the proposed piezoelectric stick-slip actuator based on stair type flexure hinge.

Achieving smooth motion of stick–slip piezoelectric actuator by means of alternate stepping

Piezoelectric actuators are widely used in various precision instruments owing to their rapid response, high motion accuracy, and immunity to electromagnetic interference. However, achieving smooth motion with a load is difficult when using existing piezoelectric actuators because of their unique driving principle, which limits their application. To achieve smooth motion with a load, a stick–slip piezoelectric actuator using the alternating stepping method was proposed in this study. The two driving feet collaborate to push the slider through a single piezoelectric stack. After considering the structure and working principle of the actuator, a feasibility analysis was performed. Subsequently, the pseudo-rigid-body method, elastic beam method, and finite element method were applied to calculate the displacement relationship of the flexure hinge mechanism. Finally, the prototypes were processed to evaluate their output performance. The comparative experiments explain the role of driving feet-A and B and demonstrate that biped synergy can achieve smooth motion. The subsequent test results show that the designed actuator has exceptionally high adaptability, and the output performance is relatively stable when the pre-tightening deformation is between 50 µm and 200 µm. Most importantly, the designed actuator has good smoothness under no-load and horizontal load conditions, and the maximum speed and resolution are 24.42 mm/s and 0.80 µm, respectively. This is conducive to broadening the application range of piezoelectric actuators.

A flexure hinged piezoelectric stick–slip actuator with high velocity and linearity for long-stroke nano-positioning

It is difficult to simultaneously achieve high linearity, high velocity, and high resolution for long-stroke piezoelectric actuators due to their discontinuity. To improve the velocity and linearity, a linear piezoelectric stick–slip actuator is proposed inspired by the fast response characteristics of piezoelectrics, which can achieve dynamic adjustment of the normal pressure by the design of flexure hinge structure. Additionally, a new dynamic model of piezoelectric stick–slip is proposed, and the step characteristics of the backward motion to displacement surge are simulated by the proposed model. The dynamic adjustment of the normal pressure can be increased by adding the inertia block to the end of the driving arm. Compared with the performance of the actuator without an inertia block, the velocity is increased, the backward motion is suppressed, and the linearity is improved. Moreover, the linear fitting correlation coefficients R 2 of displacement curve is used to evaluate the linearity of the actuator, which can reach 0.9999 at both low (10 Hz) and high (1300 Hz) frequencies, the maximum velocity is 101.76 mm s−1, the stroke is 75 mm, and the resolution is 25 nm.

A stick-slip linear actuator with high speed and nano-resolution by resonance/non-resonance hybrid driving.

To achieve high speed, nano-resolution, and large stroke, a resonance/non-resonance hybrid piezoelectric stick-slip actuator with a lever-type flexure hinge (LTFH-PSSA) is proposed in this work. The actuator can achieve high speed and large stroke in the resonance mode by the stick-slip working principle and achieve nano-resolution in the non-resonant mode by the direct drive working principle. The excitation electrical signals used in the two working modes are the sine waveform and half-sine waveform, respectively. Compared with the traditional sawtooth waveform, the excitation signal of the sine and half-sine waveforms have no sudden change of voltage, which are more conducive to reduce the impact and vibration of the system. Moreover, a series of static analysis and modal analysis of the stator are carried out by the finite element method. The experimental system is built to test the output characteristics of the LTFH-PSSA. In the resonance state by the stick-slip working principle, the impedance analysis and frequency characteristic test of the LTFH-PSSA are carried out, which states that the tested resonance frequency agrees well with the simulated ones. When the locking force, the voltage, and the frequency are 2 N, 100 Vp-p, and 1850 Hz, the speed of the LTFH-PSSA is up to 52.71 mm/s, and the backward motion is suppressed completely as well. In the non-resonance state, the resolution can reach 2.19 nm and 2.69 nm in the forward and backward motion, respectively. So far, the proposed actuator ranks first in speed and resolution among all reported LTFH-PSSAs.