Study on improving the resolution of an H-shaped piezoelectric ultrasonic actuator by stick-slip principle

2021 ◽  
Author(s):  
Xinqi Tian ◽  
Weishan Chen ◽  
Yingxiang Liu ◽  
Jie Deng ◽  
Kai Li
Keyword(s):  
High Speed ◽  
Piezoelectric Actuators ◽  
Maximum Error ◽  
Operating Principle ◽  
Maximum Speed ◽  
Stick Slip ◽  
Output Displacement ◽  
Trade Offs ◽  
Motion Stage ◽  
Output Characteristics

Abstract Improving the performance of the motion stages driven by piezoelectric actuators is an enduring topic for expanding their applications. For the motion stage with a travel range of tens of millimeters, trade-offs are inevitable between getting high speed (hundreds of millimeters per second) and high resolution (tens of nanometers), due to the inherent limitations of the operating principles of the piezoelectric actuators. In order to improve the output resolution of an H-shaped piezoelectric ultrasonic actuator, sawtooth excitation voltages are used in this work rather than the conventional sinusoidal voltages in previous works. The configuration and operating principle of the actuator are discussed in detail. The actuator consists of two vertical and two horizontal longitudinal transducers. The ends of the vertical transducers act as the driving tips and drive the stage forward with the alternating slow extensions and rapid contraction, during which stick motions and slip motions of the stage are acquired. An analytic model is developed to estimate the horizontal and vertical output displacement of the driving tip. The maximum error between the predicted value of the analytical model and the experimental value is about 14%. A prototype of the motion stage is fabricated and experiments are carried out to evaluate its output characteristics. The experiment results confirm the operating principle and show that the resolution is upgraded to tens of nanometers. The prototype obtains a resolution of 19 nm, a maximum speed of 2.22 μm/s, and a maximum carrying load of 16.94 kg.

scholarly journals Mechanical and Electromagnetic Analysis of High Speed Motor/Generator for Electric Turbo Compounding System

2018 ◽  
Vol 12 (1) ◽  
pp. 121-131
Author(s):  
Bongseok Choi ◽  
Donghoon Jung ◽  
Jaek wang Lee ◽  
Ju Lee
Keyword(s):  
Permanent Magnet ◽  
Safety Factor ◽  
High Speed ◽  
High Efficiency ◽  
Mechanical Analysis ◽  
Maximum Speed ◽  
Electromagnetic Analysis ◽  
Current Limit ◽  
Output Characteristics ◽  
Volume Current

Background: Recently, environment friendly technologies are being introduced as global warming is rapidly progressing. One of the effective way to reduce the problem, Electric Turbo Compounding System has been researched globally. With this system, about 30% exhaust gas can be recycled as a power source. Therefore, this system is effective for engine systems with purposes such as downsizing and increasing efficiency of the system. Objective & Method: Surface mounted Permanent Magnet Motor is applied to this system due to its high efficiency, power density, small size, and low weight. However, during high speed operation, a retaining sleeve is essential in rotor such as Inconel 718 to satisfy a mechanical safety factor of the rotor. In this paper, through basic theory, the sleeve thickness is predicted according to the permanent magnet dimension and minimum sleeve thickness is determined satisfying mechanical safety factor by mechanical analysis. Furthermore, by electromagnetic analysis output characteristics according to the permanent magnet dimension having same constraints such as volume, current density, current and flux distribution are compared. Result & Conclusion: Based on the results of the electromagnetic analysis and mechanical analysis, the appropriate ratio of electric and magnetic loading is determined with equivalent constraint condition. Consequently, only model 2 satisfies the requirement at rated and maximum speed within the current limit.

scholarly journals Why Protect Ancient Woodland in the UK? Rethinking the Ecosystem Approach

2020 ◽  
pp. 1-24
Author(s):  
Jona Razzaque ◽  
Claire Lester
Keyword(s):  
High Speed ◽  
Biodiversity Loss ◽  
Ecosystem Approach ◽  
Lessons Learned ◽  
Value Systems ◽  
Ancient Woodland ◽  
Forestry Practices ◽  
Regulatory Frameworks ◽  
Trade Offs ◽  
The Uk

Abstract Sites of ancient woodland in the United Kingdom (UK) are diminishing rapidly and the multifunctional forest management system with its fragmented approach fails effectively to protect such woodland. In the face of reports on the destruction of ancient woodland, the HS2 High-Speed train project in the UK signifies the extent of trade-offs among the key stakeholders. Such large infrastructure projects typically come with high environmental and social costs, including deforestation, habitat fragmentation, biodiversity loss, and social disruption. This article examines the protection of ancient woodland in the UK and assesses the challenges in applying the ecosystem approach, an internationally recognized sustainability strategy, in the context of such protection. A better understanding of the ecosystem approach to manage ancient woodland is critical for promoting sustainable forestry practices in the UK and informs the discussion in this article of the importance of conserving ancient woodland globally. Lessons learned from UK woodland policies and certification schemes include the need to have in place strong regulatory frameworks, introduce clear indicators, and recognize pluralistic value systems alongside economic considerations. The article concludes that the protection of ancient woodland in the UK requires distinct and strong laws that reflect multiple values of this resource, acknowledge the trade-offs among stakeholders, and adopt an inclusive approach to reduce power asymmetries.

scholarly journals Specific Absolute Velocity Thresholds during Male Basketball Games Using Local Positional System; Differences between Age Categories

2021 ◽  
Vol 11 (10) ◽  
pp. 4390
Author(s):  
Carlos Sosa ◽  
Alberto Lorenzo ◽  
Juan Trapero ◽  
Carlos Ribas ◽  
Enrique Alonso ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Real Time ◽  
Effect Size ◽  
High Speed ◽  
Maximum Speed ◽  
Large Effect Size ◽  
Moderate Effect Size ◽  
Positional System ◽  
Moderate Effect ◽  
Distance Zone

The aim of this study was (I) to establish absolute specific velocity thresholds during basketball games using local positional system (LPS) and (II) to compare the speed profiles between various levels of competitions. The variables recorded were total distance (TD); meters per minute (m·min); real time (min); maximum speed (Km h−1), distance (m), percentage distance, and percentage duration invested in four speed zones (standing–walking; jogging; running; and high-speed running). Mean and standard deviation (±SD) were calculated, and a separate one-way analysis of variance was undertaken to identify differences between competitions. TD (3188.84 ± 808.37 m) is covered by standing–walking (43.51%), jogging (36.58%), running (14.68%), and sprinting (5.23%) activities. Overall, 75.22% of the time is invested standing–walking, jogging (18.43%), running (4.77%), and sprinting (1.89%). M·min (large effect size), % duration zone 2 (moderate effect size); distance zone 4 (large effect size), and % distance zone 4 (very large effect size) are significantly higher during junior than senior. However, % distance zone 1 (large effect size) and % duration zone 1 (large effect size) were largely higher during senior competition. The findings of this study reveal that most of the distance and play time is spent during walking and standing activities. In addition, the proportion of time spent at elevated intensities is higher during junior than in senior competition.

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

Interface Features of the DDR SDRAM Memory Test Diagnostic Device

2021 ◽  
Vol 26 (3-4) ◽  
pp. 282-290
Author(s):  
S.V. Volobuev ◽  
◽  
V.G. Ryabtsev ◽  
Keyword(s):  
Data Transmission ◽  
High Speed ◽  
Maximum Speed ◽  
Diagnostic Device ◽  
Semiconductor Memory ◽  
Storage Devices ◽  
Memory Modules ◽  
Electronic Elements ◽  
Synchronization Scheme ◽  
Test Diagnostics

The I/О synchronization scheme plays an important role in achieving maximum speed and reliability of data transmission during memory operation. This paper presents the interface architecture of the DDR SDRAM test diagnostic device. It was demonstrated that the proposed interface components provide the formation of a bidirectional synchro signal for gating written and read data when performing test diagnostics of chips and DDR SDRAM memory devices. Compared to traditional methods, the proposed interface components were made on integrated electronic elements, which reduced the size and power consumption. It has been established that the use of a multiphase synchronization system to implement the interface eliminated the use of delay lines, the disadvantages of which are large dimensions and the complexity of changing the delay time. The interface components under consideration are intended for use in test diagnostics devices that have a multiprocessor structure, which increases the speed of forming test actions and reference reactions. The performed functional modeling and debugging of strobe signal generators confirmed the feasibility of the designs. The proposed interface of the test diagnostics device allows performing test diagnostics of modern high-speed chips and semiconductor memory modules at the operating frequency, which increases the reliability of the results obtained. Interface components can be used by manufacturers of test diagnostics tools for modern high-speed storage devices.

Comparisons between Hullform and Propulsor Combinations for a High-Speed Sealift Ship

2009 ◽  
Author(s):  
Dominic S. Cusanelli ◽  
Michael B. Wilson
Keyword(s):  
High Speed ◽  
Propeller Shaft ◽  
Rotating Shaft ◽  
Mixed Flow ◽  
Scale Evaluation ◽  
Model Scale ◽  
Trade Offs

Designed ‘from the ground up’ for high speed, many trade-offs were made within the hullform parameters of this notional 298 m, 36,000 Long Ton, High Speed Sealift (HSS) ship, in an effort to optimize 39-knot performance. Resistance and powering comparisons are drawn between several hullform and propulsor combinations, considered the most applicable to HSS, which include: conventional 2-screw and 4-screw, open-propeller, shaft and strut; waterjet propulsion (axial and mixed-flow jet hulls); hybrid contra-rotating shaft-pod (twin shafts, twin pods) and dual-pods (twin sets of dual pods). This model-scale evaluation established that 39-knots was achievable by several candidate hullform and propulsor variations on this sealift ship, within the anticipated installed power levels.

Study on Dynamic Accuracy of CNC in Aviation Part

2011 ◽  
Vol 314-316 ◽  
pp. 1717-1720
Author(s):  
Li Du ◽  
Wei Wang ◽  
Zhi Yong Song ◽  
Jie Xiong Ding
Keyword(s):  
High Speed ◽  
Influence Factors ◽  
Maximum Error ◽  
Error Sources ◽  
Dynamic Accuracy ◽  
Cutting Test ◽  
Manufacture Process ◽  
Shape Precision ◽  
Dynamic Errors ◽  
And Control

Thin-walled parts are widely used in aerospace engineering. For their complexity under loading and the higher shape precision, it’s difficult for their manufacturing on high speed machine. In order to understand manufacture process, characteristic of aviation part in high speed machining is investigated. Error sources on parts are classified and the maximum error, dynamic errors are studied on its main influence factors, such as cutting force and vibration. Finally, useful method on cutting test part is proposed, which can observe and control dynamic accuracy of aviation part and ensure effective manufacture.

scholarly journals Numerical Study of Longitudinal Inter-Distance and Operational Characteristics for High-Speed Capsular Train Systems

Vehicles ◽  
2022 ◽  
Vol 4 (1) ◽  
pp. 30-41
Author(s):  
Bruce W. Jo
Keyword(s):  
Error Rate ◽  
High Speed ◽  
Position Control ◽  
Numerical Study ◽  
Design Parameters ◽  
Maximum Speed ◽  
Integer Number ◽  
Vehicle Speed ◽  
Start Time ◽  
Distance Control

High-speed capsular vehicles are firstly suggested as an idea by Elon Musk of Tesla Company. Unlike conventional high-speed trains, capsular vehicles are individual vessels carrying passengers and freight with the expected maximum speed of near 1200 [km/h] in a near-vacuum tunnel. More individual vehicle speed, dispatch, and position control in the operational aspect are expected over connected trains. This numerical study and investigation evaluate and analyze inter-distance control and their characteristics for high-speed capsular vehicles and their operational aspects. Among many aspects of operation, the inter-distance of multiple vehicles is critical toward passenger/freight flow rate and infrastructural investment. In this paper, the system’s equation, equation of the motion, and various characteristics of the system are introduced, and in particular control design parameters for inter-distance control and actuation are numerically shown. As a conclusion, (1) Inter-distance between vehicles is a function of error rate and second car start time, the magnitude range is determined by second car start time, (2) Inter-distance fluctuation rate is a function of error rate and second car start time, however; it can be minimized by choosing the correct second car start time, and (3) If the second car start time is chosen an integer number of push-down cycle time at specific velocity error rate, the inter-distance fluctuation can be zero.

scholarly journals High-Velocity Shear and Soft Friction at the Nanometer Scale

2021 ◽  
Vol 7 ◽  
Author(s):  
Per-Anders Thorén ◽  
Riccardo Borgani ◽  
Daniel Forchheimer ◽  
David B. Haviland
Keyword(s):  
High Speed ◽  
Surface Deformation ◽  
Soft Materials ◽  
Lateral Force ◽  
Velocity Shear ◽  
Polymer Materials ◽  
Amplitude Dependence ◽  
Dynamic Force ◽  
Stick Slip ◽  
Soft Polymer

We study high-speed friction on soft polymer materials by measuring the amplitude dependence of cyclic lateral forces on the atomic force microscope (AFM) tip as it slides on the surface with fixed contact force. The resulting dynamic force quadrature curves separate the elastic and viscous contributions to the lateral force, revealing a transition from stick-slip to free-sliding motion as the velocity increases. We explain force quadratures and describe how they are measured, and we show results for a variety of soft materials. The results differ substantially from the measurements on hard materials, showing hysteresis in the force quadrature curves that we attribute to the finite relaxation time of viscoelastic surface deformation.

scholarly journals Modal Kinematic Analysis of a Parallel Kinematic Robot with Low-Stiffness Transmissions

Robotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 132
Author(s):  
Paolo Righettini ◽  
Roberto Strada ◽  
Filippo Cortinovis
Keyword(s):  
High Speed ◽  
Parallel Robots ◽  
Maximum Speed ◽  
Kinematic Structure ◽  
End Effector ◽  
New Approach ◽  
Working Space ◽  
Modes Of Vibration ◽  
Parallel Kinematic ◽  
Actuated Joints

Several industrial robotic applications that require high speed or high stiffness-to-inertia ratios use parallel kinematic robots. In the cases where the critical point of the application is the speed, the compliance of the main mechanical transmissions placed between the actuators and the parallel kinematic structure can be significantly higher than that of the parallel kinematic structure itself. This paper deals with this kind of system, where the overall performance depends on the maximum speed and on the dynamic behavior. Our research proposes a new approach for the investigation of the modes of vibration of the end-effector placed on the robot structure for a system where the transmission’s compliance is not negligible in relation to the flexibility of the parallel kinematic structure. The approach considers the kinematic and dynamic coupling due to the parallel kinematic structure, the system’s mass distribution and the transmission’s stiffness. In the literature, several papers deal with the dynamic vibration analysis of parallel robots. Some of these also consider the transmissions between the motors and the actuated joints. However, these works mainly deal with the modal analysis of the robot’s mechanical structure or the displacement analysis of the transmission’s effects on the positioning error of the end-effector. The discussion of the proposed approach takes into consideration a linear delta robot. The results show that the system’s natural frequencies and the directions of the end-effector’s modal displacements strongly depend on its position in the working space.

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