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This paper reports on mechanical design, optimization, and experimental testing of a novel piezo-actuated elliptical vibration-assisted cutting (EVC) system constructed by flexure hinges. The stroke and natural frequency were analyzed based on the theoretical modeling. An enhanced central composite design was chosen as the design of experiments methodology to reduce the modeling error, and a nondominated sorted genetic algorithm-II (NSGA-II) was adopted for structure optimization. The optimized EVC generator was manufactured and experimentally tested to investigate practical properties of the proposed EVC system. It shows that the stroke of input end can reach to 30 μ m with a motion resolution of 10 nm, and the first natural frequency can reach to 2600 Hz without considering the manufacturing error. Besides, a relatively small cross-axis coupling ratio (within 0.21%) can be effectively obtained. The developed EVC system is advantageous not only to being equipped with machine tools with various configurations, but also to easily achieving arbitrary vibrations in three-dimensional space through two actuators, which is especially important for the generation of complex structured surfaces. With this paper, it is of great significance to promote industrial application of EVC techniques. [ABSTRACT FROM AUTHOR]

Piezo-driven precision positioning platforms with large stroke are greatly demanded in both scientific research and industrial applications. Although various principles have been proposed to design piezo-driven positioning platforms, the problem of backward motion commonly exists, greatly hindering their applications. To suppress the backward motion, in this paper, an idea by generating a forward frictional force to balance the reversed frictional force was proposed. Correspondingly, a specific arc-shape flexure hinge was designed to generate the forward frictional force via its elastic recovery. To verify the feasibility of the proposed idea, a positioning platform with alterable initial gap between contact surfaces is designed by the parasitic motion principle (PMP). By measuring the output displacement under various initial gaps, a critical initial gap was identified, at which the positioning platform could output stepping displacement without backward motion. Under this critical initial gap, effects of driving voltage and frequency on the backward motion are further investigated. In addition, the natural frequency and loading capacity of the positioning platform are tested. This paper confirms that using PMP, it is feasible to design piezo-driven positioning platforms with completely suppressed backward motion, which would enhance the applications of the PMP and PMP positioning platforms. [ABSTRACT FROM AUTHOR]

In this paper, innovative ocean wave power takeoff (PTO) system is presented to enhance the electrical energy generation from oscillating wave motions. This PTO system, mainly consisting of dual-ball screws, a gearbox with mechanical motion rectification and a permanent magnet synchronous generator (PMSG), can convert bidirectional irregular motions from a floating wave buoy into unidirectional steady generator rotations. Systematical operating principles, design, and prototyping details of the PTO system are presented and analyzed. A hydrodynamic–mechanical–electrical model of the system is established by reasonably representing power switches attached to the PMSG as an equivalent external resistance. The overall dynamics of the system are then analyzed in the frequency domain. Three power control strategies are proposed to maximize the wave power absorption by changing the equivalent external resistance. The effectiveness and relatively high-energy conversion efficiency of the PTO system have been demonstrated based on lab bench test results. The levelized cost of energy of a full-scale wave energy converter system is also calculated based on the proposed PTO system. [ABSTRACT FROM AUTHOR]

Piezoelectric-actuator-driven nanopositioning stages, with large stroke and low crosstalk, are quite appealing for fulfilling the through-silicon via lithography etching task. The motivation of this paper is to combine the ability to enable the nanopositioning stage running in a manner of millimeter scale workspace and nanometer scale positioning accuracy. Two pairs of flexure-guided kinematic modules with high displacement amplification ratio are adopted to construct a 4-PP (P is prismatic) XY nanopositioning stage. A new decoupling design is implemented to realize the decoupling behavior between the input actuators and output compliant limbs, respectively. Kinematics modeling including output compliance, input stiffness, displacement amplification ratio modeling, and workspace determination are carried out. After a series of mechanism dimension optimizations via particle swarm optimization algorithm, the performance of the optimized mechanism is analyzed and assessed by using the ANSYS workbench. Then, a repetitive-compensated PID controller and a single-input and single-output closed-loop control strategy are designed. Finally, a series of experimental tests in terms of crosstalk test, frequency characteristic analysis, damping property analysis, dynamic hysteresis nonlinearity characterization, signal trajectory tracking, workspace determination, and Bode diagram plotting are carried out in details. It indicates that the workspace of fabricated prototype has reached to 1.035 mm $\times$ 1.035 mm, the crosstalk ratio is kept within 0.5%, and the closed-loop positioning accuracy is determined as 400 nm. [ABSTRACT FROM PUBLISHER]

As regular inspection for the bolt connection in inaccessible areas is difficult and costly, computer vision technology provides a suitable noncontact approach for real-time bolt looseness detection as an alternative to inspection approaches. However, computer vision still suffers from various impracticalities. In this paper, a new vision-based bolt looseness detection method is designed and implemented with the bolt images acquired by a camera at arbitrary positions around the bolts. The new method includes the perspective transformation of original images acquired, identification of bolt positioning with the convolutional neural network digit recognition, detection of bolt rotation angles using Hough transform line detection, and density-based spatial clustering of applications with noise. To demonstrate the effectiveness of the new method, an experiment with bolted connections is setup. The experimental results demonstrate that the new method can accurately detect the looseness of the bolts in the bolted connection. [ABSTRACT FROM AUTHOR]

Fastener assembly is a tedious and time-consuming work because operators have to check assembly manuals and find right fastener for each hole. Hence, this paper aims to develop a three-dimensional (3-D) projection system that projects assembly instruction onto the work piece surface directly to guide operators to assemble. However, in order to project the instruction accurately, the corresponding part of the computer-aided design model of the physical scanned area needs to be attained through the rapid and accurate registration. In order to achieve this goal, first, a high-accuracy and rapid 3-D measurement system is developed; second, a fast registration method based on local multiscale geometric feature vector is proposed to accelerate the registration speed and improve the registration reliability. Experimental results demonstrate the measurement accuracy of the developed system, and verify the feasibility of the proposed registration method. Hence, the proposed method can lead to improved assembly efficiency and decreased error probability, making great contributions to large-scale structure assembly. [ABSTRACT FROM PUBLISHER]

Energy costs are typically the largest cost element in the life-cycle of a compressed-air system (CAS). Real-time usage information as well as historical data can help identify whether the CAS is functioning properly. To this end, modern variable-speed drives are able to provide this information as well as produce soft-sensor estimates of volume flow rate production and specific energy consumption of a CAS. In this paper, an identification (ID) run sequence for a twin rotary screw compressor-operated system is proposed to identify the total system volume, to improve the estimation accuracy of a volume flow rate soft sensor, and to create a specific energy consumption map for the CAS performance monitoring. Laboratory measurements are carried out to evaluate the feasibility of the proposed ID run and related estimations. Moreover, possible usage applications of the proposed methods are discussed. [ABSTRACT FROM PUBLISHER]

This paper proposes an acceleration-based robust controller for the motion control problem, i.e., position and force control problems, of a novel series elastic actuator (SEA). A variable stiffness SEA is designed by using soft and hard springs in series so as to relax the fundamental performance limitation of conventional SEAs. Although the proposed SEA intrinsically has several superiorities in force control, its motion control problem, especially position control problem, is harder than conventional stiff and SEAs due to its special mechanical structure. It is shown that the performance of the novel SEA is limited when conventional motion control methods are used. The performance of the steady-state response is significantly improved by using disturbance observer (DOb), i.e., improving the robustness; however, it degrades the transient response by increasing the vibration at tip point. The vibration of the novel SEA and external disturbances are suppressed by using resonance ratio control (RRC) and arm DOb, respectively. The proposed method can be used in the motion control problem of conventional SEAs as well. The intrinsically safe mechanical structure and high-performance motion control system provide several benefits in industrial applications, e.g., robots can perform dexterous and versatile industrial tasks alongside people in a factory setting. The experimental results show viability of the proposals. [ABSTRACT FROM PUBLISHER]

This paper reports on the development of a piezo-actuated nanometric ultra-fast tool servo (NU-FTS) for nanocutting. For motion guidance, a flexure mechanism is especially designed using a novel kind of generalized flexure hinges with the notch profiles described by a rational Bezier curve. Both kinematics and dynamics properties of the mechanism are comprehensively modeled through a novel finite beam modeling method. With this model, the hinge is divided into a set of serially connected beams with constant cross sections. The equivalent stiffness and lumped moving mass of the mechanism are derived based on the Euler-Bernoulli beam theory. Taking advantage of the structure and performance model, the notch shape as well as the dimensions are optimized to achieve the specified criteria for the NU-FTS. Performance of the designed mechanism is verified through both finite-element analysis and practical testing on a prototype. Overall, the NU-FTS is demonstrated to have a stroke of 6 and 1.2 $ \mu $ m for the quasi-static and 10 kHz driving condition, respectively. Through dynamics inversion-based trajectory preshaping, a maximum following error around 25 and 50 nm is obtained for tracking a simple harmonic and a complicated trajectory, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a novel actuator-internal two degree-of-freedom (2-DOF) micro/nano positioning stage actuated by piezoelectric (PZT) actuators, which can be used as a fine actuation part in dual-stage system. To compensate the positioning error of coarse stage and achieve a large motion stroke, a symmetrical structure with an arch-shape bridge-type amplifier based on single notch circular flexure hinges is proposed and utilized in the positioning stage. Due to the compound bridge arm configuration and compact flexure hinge structure, the amplification mechanism can realize high lateral stiffness and compact structure simultaneously, which is of great importance to protect PZT actuators. The amplification mechanism is integrated into the decoupling mechanism to improve compactness, and to produce decoupled motion in X- and Y-axes. An analytical model is established to explore the static and dynamic characteristics, and the geometric parameters are optimized. The performance of the positioning stage is evaluated through finite element analysis and experimental test. The results indicate that the stage can implement 2-DOF decoupled motion with a travel range of 55.4 × 53.2 μm2, and the motion resolution is 8 nm. The stage can be used in probe tip-based micro/nano scratching. [ABSTRACT FROM AUTHOR]

This paper presents the methodology for the design and control of a high-stiffness fast tool servo (FTS) system for practical application in diamond machining of freeform surfaces. The electromechanical model of the FTS system is established by combining the piezoelectric actuator and the flexure hinge mechanism for the formulation of the control methodology. In order to accommodate the system nonlinearity, cutting force disturbances as well as to realize fast and accurate tracking of designated tool path required for diamond machining of freeform surfaces, a novel adaptive terminal sliding mode (NATS) control strategy capable of online self-tuning of the system gain and reach time related parameters are developed. Stability analysis of the proposed NATS controller is performed. The convergence behavior of tracking error in the presence of model parameter variations and cutting force disturbance is analyzed. Experimental verification was conducted to validate the effectiveness and robustness of the NATS control. By comparing with other related control methods, it shows significantly improved performance. The percentage of tracking error was only 0.1% for the varying trajectories on machining water-drop surface. Taking advantage of the excellent tracking performances of the FTS prototype on a diamond turning machine, various freeform surfaces were successfully produced with high quality. [ABSTRACT FROM AUTHOR]

A novel two-dimensional (2-D) linear piezoelectric stepping platform using two parallel longitudinal-bending hybrid piezoelectric actuators is proposed in this paper. The proposed platform is moved in theX-direction by combing the vertical and horizontal bending motions of the parallel actuators, whereas the movement in theY-direction is realized by the vertical bending and longitudinal hybrid motions. The platform is designed and its operating principles in two orthogonal directions are described. The finite-element method simulations are performed to verify the operating principles of the 2-D platform. Two piezoelectric actuators are fabricated and a prototype of the platform is assembled. The measured results of mechanical output performance indicate that the velocities of the platform are 101.7 and 124.2 μm/s inX- andY-directions when the voltage and frequency are ${\text{400}\,\text{V}}_{{\text{p-p}}}$ and 5 Hz, respectively, which verifies the feasibility of the proposed mechanism for the 2-D stepping platform. [ABSTRACT FROM AUTHOR]

Polymer extrusion is the most fundamental technique for processing polymeric materials, and its importance is increasing due to the rapid growth of worldwide demand for polymeric materials. However, the process thermal monitoring is experiencing several problems resulting in poor process diagnostics and control. Most of the existing process thermal monitoring methods in industry only provide point/bulk measurements, which are less detailed and low in accuracy. Physical thermal profile measurements across the melt flow may not be industrially compatible due to their complexity, access requirements, invasiveness, etc. Therefore, inferential thermal profile monitoring techniques are invaluable for obtaining detailed, accurate, and industrially compatible measurements and, hence, to achieve improved process control. In this paper, a novel soft sensor strategy is proposed to predict the real-time temperature profile across the die melt flow in polymer extrusion for the first time in industry or research. It is capable of determining the melt temperature at a number of die radial positions only based on six readily measurable process parameters. A comparison between the simulation results of the novel melt temperature profile prediction soft sensor and the experimental measurements showed that the soft sensor can predict the real-time melt temperature profile of the die melt flow with good accuracy. Therefore, this will offer a promising solution for making real-time melt temperature profile measurements noninvasively in polymer extrusion, and also, it should be applicable to other polymer processes only with a few modifications. Moreover, this technique should facilitate in developing an advanced process thermal control strategy. [ABSTRACT FROM PUBLISHER]

Most existing transtibial prostheses are energetically passive. Their ankle joints are either rigid or rotatable in a limited range, and their feet are single-segment structures without toe joints. Amputees using these passive prostheses exhibit nonsymmetrical gait patterns, consume more metabolic energy, and walk at lower speeds compared with able-bodied individuals. In this paper, we design and construct a powered transtibial prosthesis with stiffness adaptable ankle and toe joints, which are driven by adapted series-elastic actuators, to improve the walking performance of the amputees. Mechanical models of both joints are built to help analyze joints' capabilities of adjusting stiffness. In actual control of the prosthesis, we utilize a linearized trajectory control method to adjust the stiffness of both joints. To evaluate the performance of the proposed prosthesis, experiments are carried out on an amputee with a unilateral transtibial amputation. Experimental results indicate that both ankle and toe angles of the proposed prosthesis are close to those of the sound limb, and the vertical ground reaction force of the prosthetic side is similar to that of the sound side. Compared with a commercial passive prosthesis, the proposed prosthesis can help the amputee obtain more natural and symmetrical walking gaits. [ABSTRACT FROM PUBLISHER]

This paper presents the design and manufacturing processes of a new piezoactuated XY stage with integrated parallel, decoupled, and stacked kinematics structure for micro-/nanopositioning application. The flexure-based XY stage is composed of two decoupled prismatic-prismatic limbs which are constructed by compound parallelogram flexures and compound bridge-type displacement amplifiers. The two limbs are assembled in a parallel and stacked manner to achieve a compact stage with the merits of parallel kinematics. Analytical models for the mechanical performance assessment of the stage in terms of kinematics, statics, stiffness, load capacity, and dynamics are derived and verified with finite element analysis. A prototype of the XY stage is then fabricated, and its decoupling property is tested. Moreover, the Bouc-Wen hysteresis model of the system is identified by resorting to particle swarm optimization, and a control scheme combining the inverse hysteresis model-based feedforward with feedback control is employed to compensate for the plant nonlinearity and uncertainty. Experimental results reveal that a submicrometer accuracy single-axis motion tracking and biaxial contouring can be achieved by the micropositioning system, which validate the effectiveness of the proposed mechanism and controller designs as well. [ABSTRACT FROM PUBLISHER]

In this paper, a nonsmooth Kalman filtering method is proposed for noise suppression of micropositioning stages with piezoelectric actuators described by the so-called sandwich model with hysteresis. According to the characteristics of the system, a nonsmooth stochastic state-space equation is constructed. In this model, an autoswitcher is introduced to adapt the nonsmooth operation conditions. Then, the convergence of the novel Kalman filter is discussed. Subsequently, the comparison in simulation between the proposed filtering scheme with the unscented Kalman filter and particle filter is presented. Finally, the experimental results on a micropositioning stage with piezoelectric actuator are illustrated. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel disturbance-rejection tracking controller for ball screw feed drives. First, active-disturbance-rejection control (ADRC) and proportional-integral (PI) control are employed to ensure the performance of the closed-loop system. In this control framework, the extended state observer estimates and compensates for unmodeled dynamics, parameter perturbations, variable cutting load, and other uncertainties, which improves the disturbance-rejection performance and robustness of the system. Then, based on ADRC feedback linearization, a novel equivalent-error-model-based feedforward controller is designed to further improve the tracking performance of the system. This equivalent error model is independent of the mechanical model, simple to design and easy to tune. Simulations and experimental results demonstrate that the proposed control method has better tracking performance and robustness against the internal and external disturbances compared with the conventional P-PI controller. [ABSTRACT FROM AUTHOR]

In large power transformers, the presence of stray currents in the structural elements near the high current bushings can be considerable, and this leads to hot spots. This work presents a practical analysis of overheating in the bolts that join the tank and the cover, which are near the high current bushings of the transformer. Overheating results are analyzed and discussed for the case of a 420-MVA transformer. The hot spots in the flange–bolt regions are discovered by thermal maps that are obtained during power transformer operation as a part of a preventive maintenance program. In this paper, we use copper links to ensure the connection of both the cover and tank body, significantly reducing the overheating of the flange–bolt region. The copper link solution has been validated by measurements. We have used calibrated measurement instruments in all the experiments. Moreover, a 3-D finite-element analysis of the geometry of interest has been used to verify the copper link solution. [ABSTRACT FROM PUBLISHER]

The large amount of energy consumed in machining by feed-drive systems has become an important issue in recent years because machine tools are extensively used worldwide. This paper presents a novel sliding-mode controller with a nonlinear sliding surface (NLSS) to improve the machining accuracy of ball-screw feed-drive systems. Unlike the conventional sliding-mode control design, the proposed NLSS varies according to the output (controlled variable) so that the damping ratio of the system changes from its initial low value to its final high value as the output changes from its initial value to the reference point. Hence, the proposed algorithm allows a closed-loop system to simultaneously achieve low overshoot and a small settling time, resulting in a smaller error. Experiments to verify the effectiveness of the proposed approach are carried out for a ball-screw feed-drive system for two perspectives. The first perspective is to show the effectiveness of the proposed NLSS in reducing the tracking error, while the second one is to verify the ability of the proposed approach to reduce the consumed energy and control input variation. For the first case, sliding-mode controllers with and without the nonlinear term are compared under the same parameters. The mean of the tracking error magnitude was reduced by 35% without additional electrical energy or control input variation in the controller with NLSS. In the second case, the linear gain is increased for the controller with the linear surface to obtain similar tracking performance. By using the controller with an NLSS, the consumed energy and control input variation were reduced by about 12.9% and 19.1%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the optimal design, fabrication, and control of a novel compliant flexure-based totally decoupled XY micropositioning stage driven by electromagnetic actuators. The stage is constructed with a simple structure by employing double four-bar parallelogram flexures and four noncontact types of electromagnetic actuators to realize the kinematic decoupling and force decoupling, respectively. The kinematics and dynamics modeling of the stage are conducted by resorting to compliance and stiffness analysis based on matrix method, and the parameters are obtained by multiobjective genetic algorithm (GA) optimization method. The analytical models for electromagnetic forces are also established, and both mechanical structure and electromagnetic models are validated by finite-element analysis via ANSYS software. It is found that the system is with hysteresis and nonlinear characteristics when a preliminary open-loop test is conducted; thereafter, a simple PID controller is applied. Therefore, an inverse Preisach model-based feedforward sliding-mode controller is exploited to control the micromanipulator system. Experiments show that the moving range can achieve 1 mm \times 1 mm and the resolution can reach \pm 0.4\ \mu\m. Moreover, the designed micromanipulator can bear a heavy load because of its optimal mechanical structure. [ABSTRACT FROM PUBLISHER]

Most machine tools rely on precision ball screw drives to accurately position the workpiece relative to the tool. The quality of the machining outcome depends significantly on the tracking performance of the workpiece position over a desired trajectory. This paper addresses the minimization of the tracking error in a ball screw drive system in the presence of dynamic variations. Three sources of dynamic variations are considered: mechanical flexibility, runout of the ball screw shaft, and workpiece mass change during operations. Dynamic variations due to flexibility and runout are related to the workpiece position which is continuously measurable, while the variation caused by the workpiece mass change is uncertain. The ball screw drive system affected by dynamic variations is expressed as an uncertain linear model with time-varying parameters. Based on this model, servo controllers are designed such that their parameters are adjusted in real time by the measurable workpiece position to improve the tracking performance and that their performance is maintained robustly over uncertain mass variation. The importance of taking into account flexibility and runout of the shaft, as well as mass variation, explicitly in controller design is demonstrated through a ball screw drive experimental setup. [ABSTRACT FROM PUBLISHER]

Aiming to simulate the experimentally observed three kinds of one-stepping characteristics in stick-slip piezoelectric actuators, i.e., backward motion, smooth motion, and sudden jump, a new dynamic model is proposed with consideration of the deformation of overall system. Being different from the existing dynamic models that consider the overall system as a rigid body, the stiffness coefficient and damping coefficient of the overall system are introduced in the newly proposed model. By adjusting the parameters according to the experimental conditions, these three kinds of characteristics are successfully simulated for the first time in this field. By comparison with the existing dynamic models of stick-slip piezoelectric actuators, the effectiveness, advancement, and necessity of the proposed dynamic model are demonstrated. This model is expected to be helpful for the structure design and performance prediction of stick-slip piezoelectric actuators. [ABSTRACT FROM AUTHOR]

Robot calibration to provide an accurate kinematic model is widely adopted in the advanced controller development of articulated serial robot performing complicated tasks. Conventional calibration methods mainly focus on the complete, continuous, and minimal error modeling. The generation and accumulation of errors have not been explicitly explained. In addition, the error identification and compensation sometimes are not practical for controller establishment. This article presents a robot calibration method using finite and instantaneous screw theory. From the differentiation of finite screw, the errors are defined by the deviations of instantaneous screws at initial pose. The error modeling is explicit. We also propose an advanced optimization algorithm based identification method and regard the geometry of redundant errors as constraints. The identified instantaneous screw errors are then converted to the joint actuation errors. Without modifying existing motion controller, errors are compensated by modified inputs. A UR3 robot is taken as an example to illustrate the calibration method. Simulation and experiment are implemented for verification. Comparing with the accuracy before calibration, the position and orientation accuracy of UR3 robot after calibration has improved by 94.75% and 89.29%. The results also show that modified inputs can be conveniently connected to controller development. [ABSTRACT FROM AUTHOR]

This article proposes a practical design guide for a linear electromagnetic actuator based on the concept of magnetic screw transmission, in which manufacturing and assembly technologies are investigated. The surface-inserted design is first used to form a required helical-shape magnetic pole, which exhibits simple processing, high precision, and robust structure. Moreover, different topologies are developed using the 3-D finite-element analysis aided design, with the goal of optimizing thrust force. In addition, different number of permanent-magnet (PM) segments are first proposed to reduce the cogging effect. Afterward, the linear actuator integrates the rotary machine and the magnetic screw together to construct a compact design and decouples the magnetic circuits. The decoupling design focuses on the self-shielding effect of the Halbach PM array, and the special bearing supports are selected to avoid the eccentricity. Finally, a prototype is built using the developed techniques. Experiments are carried out on a linear test bench, verifying the theoretical analysis. [ABSTRACT FROM AUTHOR]

To enhance the torque and output power of the rod-shaped piezoelectric rotary motors, in this article, we employ alumina to substitute the metal parts of the transducers considering that the high Young's modulus of alumina may avoid preload-induced vibration reduction and enable the transducers to generate the high driving force. Besides, alumina exhibits a relatively low density compared to most of the materials commonly used as the vibrating bodies (except aluminum alloy); this probably enhances the power densities of the piezoelectric motors. To assess the validity of our proposal, we constructed a Langevin-type alumina/lead–zirconate–titanate (PZT) motor and investigated its load characteristics. The transducer of 35 mm in outer diameter operated in orthogonal bending (B2) modes and drove the rotor with its end surface. The alumina/PZT motor yields the maximal torque and maximal output power of 1.56 N·m and 26.0 W, respectively, both of which exceed those of the metal/PZT motors having identical structure and working in B2 modes. Additionally, its power density reaches 56.3 W/kg, relatively high among the rod-shaped rotary motors although some of which work in more powerful modes. This article validates the effectiveness of our proposal and provides a new approach to improve the performance of the rod-shaped piezoelectric rotary motors. [ABSTRACT FROM AUTHOR]

A novel piezo-actuated compliant mechanism is developed to obtain triaxial translational motions with decoupled features for nanocutting. Analytical modeling of the working performance followed by Pareto-based multiobjective optimization is conducted for determining dimensions of the mechanism. Finite element analysis on the designed mechanism verifies the accuracy of the developed model, accordingly demonstrating the effectiveness of the optimal design process. Open-loop test on the prototype shows that proper strokes with low coupling and high natural frequencies are obtained as estimated. Low tracking error in closed-loop test suggests that the developed mechanism can precisely follow the desired trajectory to form complicated nanostructures. Finally, closed-loop based nanosculpturing is conducted, demonstrating the effectiveness of the developed triaxial motion system for nanocutting well. [ABSTRACT FROM PUBLISHER]

A piezoelectric-driven actuator based on coupling motion has been proposed and tested to achieve a large linear working stroke with high resolution. “Z-shaped” flexure hinges are exploited for the symmetric flexure hinge mechanism to reduce the structural stress. Coupling motion is obtained by placing this symmetric flexure hinge mechanism with an angle of \theta =20^\circ to the slider. Experimental results indicate that linear motion with a large working stroke is effectively obtained by this coupling motion; the maximum motion speed is V_{s}= 6057 μm/s and the maximum output force is F_{g}=$ 350 g. Additionally, the influences of input frequency f$ and input voltage U_{e} are investigated, and the system kinetic model is established to better analyze the performance of this designed piezoelectric-driven linear actuator. [ABSTRACT FROM PUBLISHER]

A trapezoid-type stick–slip piezoelectric linear actuator using a right circular flexure hinge mechanism was proposed, designed, fabricated, and tested with the aim of accomplishing linear driving based on stick–slip motion. The angle adjustment of the trapezoid beam was used for generating lateral motion on the driving foot of the flexure hinge mechanism. A method of tuning the lateral motion of the flexure hinge mechanism was discussed. Based on the finite-element method, a proper angle of the trapezoid beam was obtained. The analysis results proved that asymmetrical flexure hinge mechanism can increase static friction force in slow extension stage and decrease kinetic friction force in quick contraction stage by lateral motion of the driving foot. A prototype was fabricated and its experimental system was established. The mechanical output experiments showed that the prototype achieved maximum output velocity and load of 5.96 mm/s and 3 N at a voltage of 100 V$p-p$ and a frequency of 500 Hz, respectively. [ABSTRACT FROM PUBLISHER]

A novel bi-piezoelectric jet dispenser with a zoom mechanism is proposed to distribute adhesives rapidly. The work frequency of the new jet dispenser can reach 500 Hz. The volume of the minimum dot is about 25 nL, and the volume error among dots is not more than ±10%. The dot size can be controlled by adjusting the driving voltage of the piezoelectric stack, filling pressure, and the opening time of the valve. Subsystem physical models of the jet valve are presented on the basis of the bi-piezoelectric principle and the zoom mechanism, which involves an electromechanical model, dynamic model, and fluid–solid coupling model. Based on these physical models, a coupled mechanical–electrical fluid simulation model is established, which can be simulated. The simulation results of the multiphysics-coupled model are in accordance with the experiment. The coupling model will develop a reliable simulating platform for high-speed fluid jet. The effectiveness of the bi-piezoelectric method and models is confirmed, and it will provide a new technology for microelectronics packaging. [ABSTRACT FROM PUBLISHER]

Virtual prototyping of car doors enhanced with haptic feedback is a promising way to decrease the number of physical prototypes. We clarify, correct, summarize, and extend our previous work on the haptic simulation of car doors. A fundamental issue is the derivation of the performance specification of a task-optimized haptic interface, which is based on the knowledge of the typical user interaction with a car door and a comprehensive model of the dynamics of a rotatory car door. We reason that a direct drive with a high torque output ( \geq 100\ \N\cdot\m) and a high control bandwidth has to be used. Consequently, we created a backlash-free very stiff device providing a safe and high-fidelity haptic rendering. Finally, we conducted an extensive user study with 17 participants. An important result is that the haptic simulation can be reliably used to evaluate different door concepts if the difference between them is larger than 5 \N\cdot\m. Furthermore, the participants did not like a high effort for closing the door, while both a low and a medium effort are appreciated. This is in accordance with the heuristic findings of the automotive industry, which shows the effectiveness of our virtual prototyping approach. [ABSTRACT FROM PUBLISHER]