scispace - formally typeset
Search or ask a question
Author

Fujun Wang

Bio: Fujun Wang is an academic researcher from Tianjin University. The author has contributed to research in topics: Actuator & Ultrasonic sensor. The author has an hindex of 24, co-authored 106 publications receiving 1505 citations. Previous affiliations of Fujun Wang include University of Illinois at Urbana–Champaign & Chinese Ministry of Education.


Papers
More filters
Journal ArticleDOI
Fujun Wang1, Cunman Liang1, Yanling Tian1, Xingyu Zhao1, Dawei Zhang1 
TL;DR: In this paper, a micro gripper with a three-stage flexure-based amplification has been designed to achieve large jaw displacements, which can grasp microobjects with the maximum jaw motion stroke of 190μm corresponding to the 100-V applied voltage.
Abstract: This paper presents a novel microgripper mechanism for micromanipulation and assembly. The microgripper is driven by a piezoelectric actuator, and a three-stage flexure-based amplification has been designed to achieve large jaw displacements. The kinematic, static and dynamic models of the microgripper have been established and optimized considering the crucial parameters that determine the characteristics of the microgripper. Finite element analysis was conducted to evaluate the characteristics of the microgripper, and wire electro discharge machining technique was utilized to fabricate the monolithic structure of the microgripper mechanism. Experimental tests were carried out to investigate the performance of the microgripper and the results show that the microgripper can grasp microobjects with the maximum jaw motion stroke of 190 μm corresponding to the 100-V applied voltage. It has an amplification ratio of 22.8 and working mode frequency of 953 Hz.

136 citations

Journal ArticleDOI
TL;DR: In this article, a piezoelectric actuated compliant micro gripper was designed to get a large jaw motion stroke, and a three-stage flexure-based amplification composed of the homothetic bridge and leverage mechanisms was developed and the key structure parameters were optimized.
Abstract: The design and control of a novel piezoelectric actuated compliant microgripper is studied in this paper to achieve fast, precise, and robust micro grasping operations. First, the microgripper mechanism was designed to get a large jaw motion stroke. A three-stage flexure-based amplification composed of the homothetic bridge and leverage mechanisms was developed and the key structure parameters were optimized. The microgripper was manufactured using the wire electro discharge machining technique. Finite element analysis and experimental tests were carried out to examine the performance of the microgripper mechanism. The results show that the developed microgripper has a large amplification factor of 22.6. Dynamic modeling was conducted using experimental system identification, and the displacement and force transfer functions were obtained. The position/force switching control strategy was utilized to realize both precision position tracking and force regulation. The controller composed of an incremental proportional-integral-derivative control and a discrete sliding mode control with exponential reaching law was designed based on the dynamic models. Experiments were performed to investigate the control performance during micro grasping process, and the results show that the developed compliant microgripper exhibits good performance, and fast and robust grasping operations can be realized using the developed microgripper and controller.

126 citations

Journal ArticleDOI
TL;DR: 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 and is evaluated through finite element analysis and experimental test.
Abstract: 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.

93 citations

Journal ArticleDOI
TL;DR: In this paper, the topographic and wetting properties of Inconel 718 (IN718) surfaces were modified via nanosecond laser treatment and the effects of laser parameters, such as laser scanning speed and laser power, on surface features were also discussed.

93 citations

Journal ArticleDOI
TL;DR: The design and control of a novel asymmetrical microgripper driven by a piezoelectric (PZT) actuator is presented, designed as an asymmetrical structure with one movable jaw, so it has the advantages of no dense mode and fixed locating datum compared with the symmetrical microGripper with two movable jaws.
Abstract: Microgripper is an important tool in high precision micromanipulation task, which directly affects the quality and efficiency of micromanipulation. This paper presents the design and control of a novel asymmetrical microgripper driven by a piezoelectric (PZT) actuator. The developed microgripper is designed as an asymmetrical structure with one movable jaw, so it has the advantages of no dense mode and fixed locating datum compared with the symmetrical microgripper with two movable jaws. The main body of microgripper is a compact flexure-based mechanical structure with a three-stage amplification mechanism. Based on the three-stage amplification structure, large-range, robust and parallel grasping operation can be realized. The characteristics analyses of the developed microgripper are carried out by finite element analysis (FEA). A position-force switching control strategy is utilized to regulate the position and grasping force of movable jaw. Discrete-time sliding model (DSM) controller is designed to control the position and grasping force. Experimental studies are conducted and the experiment results show that the microgripper exhibits good performance and high precision grasping operations can be realized through the developed control strategy.

82 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, the state-of-the-art with respect to inspection methodologies compatible with additively manufactured (AM) processes is explored with the intention of identifying new avenues for research and proposing approaches to integration into future generations of AM systems.

1,024 citations

Journal ArticleDOI
TL;DR: In this paper, a comprehensive review on the classification of DED systems, process variables, process physics, modeling efforts, common defects, mechanical properties, and quality control methods is presented.
Abstract: Additive manufacturing (AM) is a new paradigm for the design and production of high-performance components for aerospace, medical, energy, and automotive applications. This review will exclusively cover directed energy deposition (DED)-AM, with a focus on the deposition of powder-feed based metal and alloy systems. This paper provides a comprehensive review on the classification of DED systems, process variables, process physics, modelling efforts, common defects, mechanical properties of DED parts, and quality control methods. To provide a practical framework to print different materials using DED, a process map using the linear heat input and powder feed rate as variables is constructed. Based on the process map, three different areas that are not optimized for DED are identified. These areas correspond to the formation of a lack of fusion, keyholing, and mixed mode porosity in the printed parts. In the final part of the paper, emerging applications of DED from repairing damaged parts to bulk combinatorial alloys design are discussed. This paper concludes with recommendations for future research in order to transform the technology from “form” to “function,” which can provide significant potential benefits to different industries.

273 citations

Journal ArticleDOI
TL;DR: Monitoring of laser processes has been researched actively since the 1980's in several institutes around the world and has been commercially applied to even the newest laser processes, e.g. additive manufacturing.

206 citations

Journal ArticleDOI
TL;DR: This review is aimed to summarize the recent developments and achievements in stepping piezoelectric actuators with large working stroke, especially, the emphasis is on three main types of stepping pieZoelectrics actuators, i.e., inchworm type, friction-inertia type, and parasitic type.
Abstract: Precision positioning systems with large working stroke (millimeter or more) and micro/nano-scale positioning resolution are widely required in both scientific research and industries. For this kind of applications, piezoelectric materials based actuators show unique advantages and have been widely employed. To overcome the demerit of the limited working stroke for single piezoelectric element, various stepping motion principles have been proposed in the past years, and accordingly, stepping piezoelectric actuators with various structures have been designed and evaluated. This review is aimed to summarize the recent developments and achievements in stepping piezoelectric actuators with large working stroke. Especially, the emphasis is on three main types of stepping piezoelectric actuators, i.e., inchworm type, friction-inertia type, and parasitic type. The motion principles of these three types of piezoelectric actuators and the corresponding developments of various actuators are discussed respectively, followed by pointing out the existing problems in these three types of piezoelectric actuators and proposing some potential research directions in this topic. It is expected that this review is helpful for relevant researchers to understand stepping motion principles as well as piezoelectric actuators, and to successfully select and design stepping piezoelectric actuators for specific applications.

168 citations