Commercial Actuator Research Articles

Low hysteresis in composites ceramics achieved by building polarization field and restoring force

Large strain hysteresis and remnant strain are one of the vital reasons for the absence of BiFeO3-BaTiO3-based ceramics in commercial actuator fields. Here, we elaborately propose a strategy, preparing 0–3 type composite ceramics, to reduce the hysteresis and remnant strain, and the target is successfully achieved by building restoring force and polarization field. Normal strain constant and electric field-induced strain in 0–3 composites have enhanced by 260% and 196% compared to those of non-composite ceramics, respectively. Also, hysteresis and remnant strain in 0–3 composites have decreased by 35.9% and 50.6% in contrast to those of non-composites. Superior electrostrain properties under the low electric field are attributed to the construction of polarization field, restoring force, and micro-capacitance, coinciding with phase field simulation, and the strategy will pave a useful way to optimize the hysteresis and remnant strain in BiFeO3-BaTiO3-based high-temperature ceramics.

Sulphonated-graphene oxide nanocomposite membranes with PVA-ZnO nanostructures and mechanized agitation-enhanced pt coating for soft robotics bending actuator

Ionic Polymer-Metal Composite (IPMC) actuators have garnered significant scientific attention in robotics and artificial muscles for their ability to operate at low voltage, high strain capacity, and lightweight construction. The lack of uniform bending in IPMC actuators undermines their control precision and restricts their range of potential applications. This study utilized the unique properties of nanoscale materials and Polyvinyl alcohol (PVA) to develop a membrane for soft robotic bending actuation. Subsequently, a platinum coating was applied to the membrane to mitigate the limitations of IPMCs in soft robotics applications. Herein, mechanized agitation was employed during the solution-casting process to enhance platinum metal (Pt-metal) coating on zinc oxide (ZnO) nanostructures within a PVA- sulphonated graphene oxide nanocomposite, achieving enhanced soft robotics bending actuation capabilities. The resultant membrane composed of sulphonated-graphene oxide and polyvinyl-zinc oxide coated with pt (PsGZ-Pt) was examined by exploring advanced analytical techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction spectroscopy (XRD). Furthermore, the ionic exchange capacity (IEC), proton conductivity (PC), water uptake and water loss characteristics were evaluated to be 2.1 meq. g−1, 1.95 × 10−3 Scm−1, 59.62% at 45 °C and water loss at 9 min immersion found 38%, respectively. Electromechanical studies of the PsGZ-Pt membrane (size 30 mm length, 10 mm width, 0.07 mm thickness) showed an actuation force of 0.3253 mN and a displacement of roughly 22.8 mm at ± 3 VDC. These findings highlighted the PsGZ-Pt membrane’s potential as a low-cost alternative to expensive commercial IPMC actuators based on polymers. These results presented a straightforward, low-cost approach for synthesizing PsGZ-Pt utilizing conventional technologies. The PsGZ-Pt membrane shows promise for generating low-cost, high-performance actuation materials with a wide range of industrial applications.

94‐3: 60 kHz Ultrasonic Actuators for Animal‐Friendly Haptic Displays

Enhanced piezoelectric coefficient (d33) and mechanical quality factor (Qm) are prerequisite for high performance of resonant piezoelectric applications (e.g., ultrasound haptic displays). We present high performance piezoelectric actuators with a resonant frequency above 60 kHz beyond audible ranges for animals. The ultrasonic actuators provide sufficient tactile feedback with a high vibration displacement, which is superior to that of many state‐of‐the‐art commercial actuators without any visible damages in plastic organic light‐emitting diode (POLED) displays. Furthermore, the actuators can be assembled into an ultrasound loudspeaker, which could facilitate the directional private sound for high‐end automotive applications.

Large strain with broad temperature insensitivity in PZT-PNN multilayer piezoactuators

Achieving high performance in piezoactuators at extremely low temperatures is challenging and restricts the operating temperature range of devices in practical applications. In this study, 0.5Pb(Ni1/3Nb2/3)O3-(0.5−x)PbTiO3-xPbZrO3+0.1 wt% MnCO3 bulk ceramics demonstrated a high piezoelectric strain coefficient of d33* = 1095 pm/V at 1 kV/mm. Using a tape casting method, multilayer piezoactuators with a thickness of 48 μm and 32 active layers were prepared, and these devices exhibited high active strain (0.122%, 2.5 kV/mm) and total strain (0.088%, 2.5 kV/mm). The temperature-insensitive strain response was acquired at x = 0.15, with a variation of approximately 10% over the range from −100 to 110 °C, which surpassed the stability of current commercial PZT actuators. These results demonstrate that PZT-PNN multilayer piezoactuators promise to meet the requirements of high-performance devices and have potential for applications in harsh environmental conditions.

Ultrahigh Piezoelectric Response Obtained by Artificially Generating a Large Internal Bias Field in BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractPiezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C.

Modelling and simulation of a commercially available dielectric elastomer actuator

To fully harness the potential of dielectric elastomer actuators (DEAs) in soft robots, advanced control methods are needed. An important groundwork for this is the development of a control-oriented model that can adequately describe the underlying dynamics of a DEA. Existing models commonly focus on custom-made DEAs, simplifying the modelling process due to well-known specifications and actuator structures. However, for commercial actuators, only information from the manufacturer is available, necessitating verification or completion during the modelling process. The aim of this paper is to explore how a commercial stacked silicone-based DEA can be modelled and how complex the model should be to properly replicate the features of the actuator. The static description has demonstrated the suitability of Hooke’s law. In the case of dynamic description, it is shown that no viscoelastic model is needed for control-oriented modelling. However, if all features of the DEA are considered, the generalised Kelvin–Maxwell model with three Maxwell elements shows good results, stability and computational efficiency.

Achieving large strain and excellent temperature stability in PT-PZ-LST piezoelectric ceramics

Lead-based piezoelectric ceramics are the preferred material for commercial piezoelectric ceramic actuators due to their high performance and irreplaceability. However, the operating temperature (<100 °C) and strain (0.1 %∼0.2 %) of lead-based piezoelectric ceramics are still limited. Achieving large strain in a wide temperature range remains challenging. In this paper, a new strategy is proposed to effectively increase the strain value of lead-based piezoelectric ceramics through domain engineering. The new xPbTiO3-(0.97-x)PbZrO3-0.03(La0.1Sr0.80.1)TiO2.95 (xPT-PZ-LST) ternary piezoelectric ceramic system reaches a strain value as high as 0.5 % and exhibits extremely high temperature stability (13 %) in the range of 25–230 °C. By fine-tuning the content of PT components, the average length and width of a typical tetragonal domain are transformed from 800 nm to 80 nm (long and thin) to 300 nm and 200 nm (short and wide), relatively. From the experimental results of PFM and Rayleigh analysis, the high strain can be attributed to the synergistic effect of the reduced coercive field (Ec), enhanced micro-region response, and regulated domain morphology, which ensures that high intrinsic and extrinsic contribution can be achieved at the same time. In this paper, a new strain regulation method is provided for lead-based piezoelectric ceramics, and a valuable large strain material is obtained via domain engineering.

Design and experimental validation of a new wheelchair seat stabilization system

Purpose Seat tilting wheelchair features can increase the comfort and safety of the user. Although many power wheelchairs have tilting mechanisms, they are often designed with a specific wheelchair model in mind. In this study, a design process for seat tilting mechanisms that can be applied to most rear-wheel drive wheelchair models is developed. Methodology Equations were developed to describe the geometrical and load constraints that were used to size the electric actuator that powers the system and define its position. Finally, the equations were used to create the seat tilting mechanism of a prototype wheelchair, which was then tested. Results The equations yielded coherent results which showed that advantageous actuator positions from a load minimization perspective usually require dimensions that cannot be found in commercial actuators. Also, there are positions in which the load increases exponentially, which should be avoided. The tests showed that the system was able to function properly on the prototype wheelchair and that the actuator position affected the time taken for the actuator to execute different parts of the tilting movement. Conclusions The design process presented here was successful and modelled by general equations that can be applied to most front-wheel drive wheelchairs. It presents a low-cost option for the design of seat tilting systems, which can increase their accessibility.

Comprehensively enhanced strain performance in PIN-PMN-PT ferroelectric ceramics via composition and orientation engineering

Excellent overall strain performances (i.e., low hysteresis, giant strain, and wide temperature span) are highly desirable in commercial high-precision displacement actuators to satisfy different application scenarios. However, any single means, e.g., compositional design or orientation engineering can hardly achieve the overall improvement of strain properties in ceramics. In this work, an approach of integrating compositional design (Sm and Mn co-doping) and orientation engineering (<001>-textured) is proposed to enhance the strain performance of 0.27Pb(In1/2Nb1/2)O3-0.40Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PIN-PMN-PT) comprehensively. Initially, with the co-doping of Sm and Mn, the hysteresis of PIN-PMN-PT is substantially decreased to approximately 0.43 times that of the undoped material. Subsequently, 5 wt% BaTiO3 (BT) templates were added during the tape-casting process to orient the grains in 1 mol% Sm and Mn-doped PIN-PMN-PT ceramics. This resulted in a unique "4R" domain configuration with a reduced domain size of 0.13 µm. As a result, the domain wall energy was lowered, and the strain strength was increased to 0.35% at 70 kV/cm with low hysteresis to 8.94%. Moreover, the "clamping effect" in textured ceramics generates additional stress due to the lattice mismatch between the matrix grains and the BaTiO3 template, which inhibits the rhombohedral to the tetragonal phase transition. In addition, the fluctuation of strain value was only 8.5% over a wide temperature range of 30–150 °C, demonstrating excellent temperature stability. As a result of the combined effect of ion doping and orientation engineering, the overall strain performance in PIN-PMN-PT has been improved, providing a novel approach to designing superior and practical displacement actuators.

Realizing the invariant electrostrain response and low hysteresis via multicomponent coordination in Pb‐based ceramics

AbstractHigh‐performance piezoelectric materials are essential in many piezoelectric devices. However, the composition of piezoelectric materials usually has a great influence on their performance. In this work, xBi(Mg1/2Ti1/2)O3–yPbZrO3–zPbTiO3 (xBMT–yPZ–zPT; 0.2 ≤ x ≤ 0.4, 0.25 ≤ y ≤ 0.4, and 0.35 ≤ z ≤ 0.4) ternary ceramics with different compositions were synthesized and it was found that the strain response was not sensitive to the composition. The crystal structure, strain response, ferroelectric properties, and temperature stability of xBMT–yPZ–zPT ceramics were investigated in detail. X‐ray diffraction patterns show that all the as‐prepared xBMT–yPZ–zPT ceramics with x = 0.2, 0.3, 0.4, and 0.5 possess a perovskite structure. Under an external electric field of 6 kV mm−1, the strain values of xBMT–yPZ–zPT ternary ceramics with x = 0.2, 0.3, 0.4, and 0.5 were 0.30%, 0.31%, 0.30%, and 0.27%, respectively. In addition, the strain hysteresis of these ternary ceramics is also almost the same and low. These merits make xBMT–yPZ–zPT piezoelectric ceramics have broad application prospects in the field of commercial actuators.

PCB-integrated embedded planar magnetorquers for small satellites intelligent detumbling

The challenge of damping high tumbling rates after deployment of spacecraft from a rocket using PCB-integrated (printed circuit board) embedded planar coils that acts as pseudo- 2D magnetorquers is explored for higher form factor small satellites (2 U and 4 U). The magnetorquers cannot generate the torque if their axes are lined up with the local geomagnetic field and generally the reaction wheels are actuated to generate this torque component. CubeSats are small satellites that have cube units of 10 cm along each axis and they are usually detumbled using magnetorquer rods bringing norm to the point where reaction wheels take over to reduce the body rates to zero. In this paper, the task of removing the initial angular velocities is undertaken by using the embedded planar coils without relying on the secondary actuators using an intelligent projection based form of the B-Dot control. The proposed reconfigurable planar coils can effectively detumble the higher form factor small satellites using application-specific optimal coil configuration. The performance parameters for various possible combinations of the coils are thermally evaluated to sustain a stable thermal profile as the planar coils are embedded inside the multilayered PCB in the form of copper traces. Lastly, the proposed coils are compared with the performance parameters of the commercial actuators in the formal studies. It is found that the suggested embedded planar magnetorquers outperforms the competition.

Inchworm Motors and Beyond: A Review on Cooperative Electrostatic Actuator Systems

Having benefited from technological developments, such as surface micromachining, high-aspect-ratio silicon micromachining and ongoing miniaturization in complementary metal–oxide–semiconductor (CMOS) technology, some electrostatic actuators became widely used in large-volume products today. However, due to reliability-related issues and inherent limitations, such as the pull-in instability and extremely small stroke and force, commercial electrostatic actuators are limited to basic implementations and the micro range, and thus cannot be employed in more intricate systems or scaled up to the macro range (mm stroke and N force). To overcome these limitations, cooperative electrostatic actuator systems have been researched by many groups in recent years. After defining the scope and three different levels of cooperation, this review provides an overview of examples of weak, medium and advanced cooperative architectures. As a specific class, hybrid cooperative architectures are presented, in which besides electrostatic actuation, another actuation principle is used. Inchworm motors—belonging to the advanced cooperative architectures—can provide, in principle, the link from the micro to the macro range. As a result of this outstanding potential, they are reviewed and analyzed here in more detail. However, despite promising research concepts and results, commercial applications are still missing. The acceptance of piezoelectric materials in some industrial CMOS facilities might now open the gate towards hybrid cooperative microactuators realized in high volumes in CMOS technology.

Stroboscopic in situ neutron diffraction approach to elucidate the kinetics of strain mechanisms in ferroelectric materials

The electromechanical properties of ferroelectrics are often strongly frequency-dependent, but the underlying structural kinetics are not well known or understood. Here, we use in situ stroboscopic neutron diffraction combined with a comprehensive structural refinement method to examine the frequency-dependent structural change in the commercial actuator material PIC 151 at realistic operating frequencies. A broad range of frequencies was measured and analyzed in detail. This work further underlines the crucial role of the field-induced phase transformation for explaining the kinetics in ferroelectric materials. Both the tetragonal majority phase and the rhombohedral minority phase contribute with different effects to the frequency dependence of the strain mechanisms. Even creep effects well beyond the probed frequencies can be explained with the observations.

Design and experimental validation of a piezoelectric actuator tracking control based on fuzzy logic and neural compensation

This work proposes two control feedback-feedforward algorithms, based on fuzzy logic in combination with neural networks, aimed at reducing the tracking error and improving the actuation signal of piezoelectric actuators. These are frequently used devices in a wide range of applications due to their high precision in micro- and nanopositioning combined with their mechanical stiffness. Nevertheless, the hysteresis is one the main phenomenon that degrades the performance of these actuators in tracking operations. The proposed control schemes were tested experimentally in a commercial piezoelectric actuator. They were implemented with a dSPACE 1104 device, which was used for signal generation and acquisition purposes. The performance of the proposed control schemes was compared to conventional structures based on proportional-integral-derivative and fuzzy logic in feedback configuration. Experimental results show the advantages of the proposed controllers, since they are capable of reducing the error to significant magnitude orders.

Giant electric field–induced strain in lead-free piezoceramics

Piezoelectric actuators are indispensable over a wide range of industries for their fast response and precise displacement. Most commercial piezoelectric actuators contain lead, posing environmental challenges. We show that a giant strain (1.05%) and a large-signal piezoelectric strain coefficient (2100 picometer/volt) are achieved in strontium (Sr)-doped (K,Na)NbO3 lead-free piezoceramics, being synthesized by the conventional solid-state reaction method without any post treatment. The underlying mechanism responsible for the ultrahigh electrostrain is the interaction between defect dipoles and domain switching. The fatigue resistance, thermal stability, and strain value (0.25%) at 20 kilovolt/centimeter are comparable with or better than those of commercial Pb(Zr,Ti)O3-based ceramics, showing great potential for practical applications. This material may provide a lead-free alternative with a simple composition for piezoelectric actuators and a paradigm for the design of high-performance piezoelectrics.

Data-Driven Kinematic Model of PneuNets Bending Actuators for Soft Grasping Tasks

The paper proposes a novel data-driven approximation kinematic (DAK) model to estimate the shape and opening level of a PneuNets soft gripper in relation to the applied pressure signal. The model offers suitable capabilities for implementing in real-time applications involving soft grasping planning and size recognition of fragile objects with different sizes and shapes. The proposed DAK model estimates the free bending behavior of a PneuNets actuator (soft gripper finger) based on a set of approximation functions derived from experimental data and an equivalent serial mechanism that mimics the shape of the actuator. The model was tested for a commercial PneuNets actuator with decreasing chamber height, produced by SoftGripping Co. (Hamburg, Germany). The model validation is accomplished through a set of experiments, where the shape and elementary displacements were measured using a digital image processing technique. The experimental data and the estimated data from the DAK model were compared and analyzed, respectively. The proposed approach has applicability in sensorless/self-sensing bending control algorithms of PneuNets actuators and in soft grasping applications where the robotic system must estimate the opening level of the gripper in order to be able to accomplish its task.

Effect of stress on the phase transition and optimizing electric-induced strain behavior of Bi0.5Na0.5TiO3-SrTiO3 lead-free co-fired multilayer piezoactuators

A series of (1-x)Bi1/2Na1/2TiO3-xSrTiO3+0.05 wt% MnO2 lead-free multilayer piezoactuators was prepared using a tape casting method, and the field-induced strain performance, temperature stability, electric fatigue and load characteristics were evaluated to assess potential practical applications. In contrast to traditional PZT ceramics, the fabrication of BNT bulk ceramics into multilayer piezoactuators provides significantly decreased strain (S)-electric field (E) characteristics as a result of internal compressive residual stress. The inactive edge distance, sintering temperature and layer thickness were all found to affect the compressive residual stress of the actuator. Through reconstructing the material composition and structure of BNT-ST actuators, active strain (0.168 %, 2 kV/mm), total strain (>0.15 %, E ≤ 2.5 kV/mm) and blocking stress (42.6 MPa) were realized in BNT-based cofired multilayer actuators, displaying a better performance than commercial PZT actuators. These results indicate that environmental-friendly BNT-based lead-free multilayer piezoactuators are promising candidates with regard to practical applications.

Al2O3/WS2 Surface Layers Produced on the Basis of Aluminum Alloys for Applications in Oil-Free Kinematic Systems.

The article presents the results of an aluminum oxide layer doped with monolayer 2H tungsten disulphide (Al2O3/WS2) for applications in oil-free kinematic systems. The results concern the test carried out on the pneumatic actuator operational test stand, which is the actual pneumatic system with electromagnetic control. The cylinders of actuators are made of Ø 40 mm aluminum tube of EN-AW-6063 aluminum alloy which is used in the manufacture of commercial air cylinder actuators. The inner surfaces of the cylinder surfaces were covered with an Al2O3/WS2 oxide layer obtained by anodic oxidation in a three-component electrolyte and in the same electrolyte with the addition of tungsten disulfide 2H-WS2. The layers of Al2O3 and Al2O3/WS2 obtained on the inner surface of the pneumatic actuators were combined with a piston ring made of polytetrafluoroethylene with carbon (T5W) material and piston seals made of polyurethane (PU). The cooperation occurred in the conditions of technically dry friction. After the test was carried out, the scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) analysis of the surface of the cylinder bearing surfaces and piston seals of the pneumatic cylinders was performed. The analysis revealed the formation of a sliding film on the cylinder surface modified with tungsten disulfide, as well as on the surface of wiper seals. Based on the SEM/EDSM tests, it was also found that the modification of the Al2O3 layer with tungsten disulfide contributed to the formation of a sliding film with the presence of WS2 lubricant, which translated into smooth cylinder operation during 180 h of actuator operation. The cylinder with the unmodified layer showed irregular operation after approximately 70 h thereof.

High-Performance Tracking for Piezoelectric Actuators Using Super-Twisting Algorithm Based on Artificial Neural Networks

Piezoelectric actuators (PEA) are frequently employed in applications where nano-Micr-odisplacement is required because of their high-precision performance. However, the positioning is affected substantially by the hysteresis which resembles in an nonlinear effect. In addition, hysteresis mathematical models own deficiencies that can influence on the reference following performance. The objective of this study was to enhance the tracking accuracy of a commercial PEA stack actuator with the implementation of a novel approach which consists in the use of a Super-Twisting Algorithm (STA) combined with artificial neural networks (ANN). A Lyapunov stability proof is bestowed to explain the theoretical solution. Experimental results of the proposed method were compared with a proportional-integral-derivative (PID) controller. The outcomes in a real PEA reported that the novel structure is stable as it was proved theoretically, and the experiments provided a significant error reduction in contrast with the PID.

Health Monitoring of Aviation Hydraulic Fluids Using Opto-Chemical Sensor Technologies

Passenger safety requires that in commercial airplanes hydraulic actuators be powered by fire-resistant hydraulic fluids. As a downside, such fluids are hygroscopic which means that these tend to accumulate humidity from the environment and that the dissolved humidity tends to produce acidity which can corrode all kinds of metallic components inside a hydraulic system. As such damage in safety-critical subsystems is hard to localize and expensive to repair, sensor technologies are required which allow the state of water contamination and fluid degradation to be routinely checked and necessary maintenance actions to be scheduled in a way that causes minimum flight interruptions. The paper reviews progress that has been made in developing such sensor systems and in commissioning these into practical flight operation. Sensor technologies that proved optimally adapted to this purpose are multi-channel non-dispersive (NDIR) systems working in the mid-infrared range. Additional options concern optical absorption sensors working in the near-infrared and visible ranges as well as fluorescence sensors.