scholarly journals Modeling of a Soft-Rigid Gripper Actuated by a Linear-Extension Soft Pneumatic Actuator

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 493
Author(s):  
Peilin Cheng ◽  
Jiangming Jia ◽  
Yuze Ye ◽  
Chuanyu Wu
Keyword(s):  
Relative Error ◽  
Linear Extension ◽  
Pneumatic Actuator ◽  
Soft Robot ◽  
Soft Actuator ◽  
Soft Objects ◽  
Contact Sensing ◽  
Gripping Force ◽  
The Relationship ◽  
Extension Length

Soft robot has been one significant study in recent decades and soft gripper is one of the popular research directions of soft robot. In a static gripping system, excessive gripping force and large deformation are the main reasons for damage of the object during the gripping process. For achieving low-damage gripping to the object in static gripping system, we proposed a soft-rigid gripper actuated by a linear-extension soft pneumatic actuator in this study. The characteristic of the gripper under a no loading state was measured. When the pressure was >70 kPa, there was an approximately linear relation between the pressure and extension length of the soft actuator. To achieve gripping force and fingertip displacement control of the gripper without sensors integrated on the finger, we presented a non-contact sensing method for gripping state estimation. To analyze the gripping force and fingertip displacement, the relationship between the pressure and extension length of the soft actuator in loading state was compared with the relationship under a no-loading state. The experimental results showed that the relative error between the analytical gripping force and the measured gripping force of the gripper was ≤2.1%. The relative error between analytical fingertip displacement and theoretical fingertip displacement of the gripper was ≤7.4%. Furthermore, the low damage gripping to fragile and soft objects in static and dynamic gripping tests showed good performance of the gripper. Overall, the results indicated the potential application of the gripper in pick-and-place operations.

ANALYSIS OF THE ERROR IN DETERMINING THE EQUIVALENT SIZE OF A DEFECT BY THE STANDARDLESS METHOD DURING ULTRASONIC TESTING

2021 ◽  
pp. 50-57
Author(s):  
A. N. Kireev ◽  
M. A. Kireeva
Keyword(s):  
Relative Error ◽  
High Reliability ◽  
Ultrasonic Method ◽  
Experimental Studies ◽  
Standard Samples ◽  
Defect Identification ◽  
Identification Method ◽  
Maximum Value ◽  
Software Product ◽  
The Relationship

The article provides a review and analysis of the defect identification method for determining the size of discontinuities when diagnosing various machine parts and units by the manual ultrasonic method. This method makes it possible to determine the equivalent size of discontinuities of various types without using standard samples of an enterprise: point planar and volumetric; extended planar and volumetric. The method is based on the use of the relationship between the amplitude and time characteristics of the echo signal from the discontinuity and the backside signal in the object being diagnosed and the equivalent size of the discontinuity. The article presents the mathematical apparatus for the implementation of this method. Also presented is a software product that allows you to automate calculations when using this defect identification method. The article contains experimental studies of the method for determining the equivalent dimensions of discontinuities of various types, which have shown its high reliability. The maximum value of the relative error in determining the equivalent size of a point planar discontinuity was 2.867 %. The maximum value of the relative error in determining the equivalent size of a point volumetric discontinuity was 1.986 %. The maximum value of the relative error in determining the transverse equivalent size of an extended planar discontinuity was 0.667 %. The maximum value of the relative error in determining the transverse equivalent size of an extended volumetric discontinuity was 1.95 %.

scholarly journals Application and Analysis of an Ionic Liquid Gel in a Soft Robot

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Chenghong Zhang ◽  
Bin He ◽  
Zhipeng Wang ◽  
Yanmin Zhou ◽  
Aiguo Ming
Keyword(s):  
Ionic Liquid ◽  
Uv Light ◽  
Electroactive Polymers ◽  
Electroactive Polymer ◽  
Soft Robot ◽  
Polymer Gel ◽  
Basic Module ◽  
Soft Actuator ◽  
New Type ◽  
Soft Actuators

Due to their light weight, flexibility, and low energy consumption, ionic electroactive polymers have become a hotspot for bionic soft robotics and are ideal materials for the preparation of soft actuators. Because the traditional ionic electroactive polymers, such as ionic polymer-metal composites (IPMCs), contain water ions, a soft actuator does not work properly upon the evaporation of water ions. An ionic liquid polymer gel is a new type of ionic electroactive polymer that does not contain water ions, and ionic liquids are more thermally and electrochemically stable than water. These liquids, with a low melting point and a high ionic conductivity, can be used in ionic electroactive polymer soft actuators. An ionic liquid gel (ILG), a new type of soft actuator material, was obtained by mixing 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), hydroxyethyl methacrylate (HEMA), diethoxyacetophenone (DEAP) and ZrO2 and then polymerizing this mixture into a gel state under ultraviolet (UV) light irradiation. An ILG soft actuator was designed, the material preparation principle was expounded, and the design method of the soft robot mechanism was discussed. Based on nonlinear finite element theory, the deformation mechanism of the ILG actuator was deeply analyzed and the deformation of the soft robot when grabbing an object was also analyzed. A soft robot was designed with the soft actuator as the basic module. The experimental results show that the ILG soft robot has good driving performance, and the soft robot can grab a 105 mg object at an input voltage of 3.5 V.

scholarly journals Additive Manufacturing for Soft Robotics: Design and Fabrication of Airtight, Monolithic Bending PneuNets with Embedded Air Connectors

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 485 ◽  
Author(s):  
Gianni Stano ◽  
Luca Arleo ◽  
Gianluca Percoco
Keyword(s):  
Additive Manufacturing ◽  
Wall Thickness ◽  
Chamber Wall ◽  
Soft Robotics ◽  
Soft Robot ◽  
Soft Robots ◽  
Bending Performance ◽  
3D Print ◽  
Air Tightness ◽  
The Relationship

Air tightness is a challenging task for 3D-printed components, especially for fused filament fabrication (FFF), due to inherent issues, related to the layer-by-layer fabrication method. On the other hand, the capability of 3D print airtight cavities with complex shapes is very attractive for several emerging research fields, such as soft robotics. The present paper proposes a repeatable methodology to 3D print airtight soft actuators with embedded air connectors. The FFF process has been optimized to manufacture monolithic bending PneuNets (MBPs), an emerging class of soft robots. FFF has several advantages in soft robot fabrication: (i) it is a fully automated process which does not require manual tasks as for molding, (ii) it is one of the most ubiquitous and inexpensive (FFF 3D printers costs < $200) 3D-printing technologies, and (iii) more materials can be used in the same printing cycle which allows embedding of several elements in the soft robot body. Using commercial soft filaments and a dual-extruder 3D printer, at first, a novel air connector which can be easily embedded in each soft robot, made via FFF technology with a single printing cycle, has been fabricated and tested. This new embedded air connector (EAC) prevents air leaks at the interface between pneumatic pipe and soft robot and replaces the commercial air connections, often origin of leakages in soft robots. A subsequent experimental study using four different shapes of MBPs, each equipped with EAC, showed the way in which different design configurations can affect bending performance. By focusing on the best performing shape, among the tested ones, the authors studied the relationship between bending performance and air tightness, proving how the Design for Additive Manufacturing approach is essential for advanced applications involving FFF. In particular, the relationship between chamber wall thickness and printing parameters has been analyzed, the thickness of the walls has been studied from 1.6 to 1 mm while maintaining air tightness and improving the bending angle by 76.7% under a pressure of 4 bar. It emerged that the main printing parameter affecting chamber wall air tightness is the line width that, in conjunction with the wall thickness, can ensure air tightness of the soft actuator body.

Modeling of PVA Modified Non-Woven for Submerged Membrane Bioreactor Treating Synthetic Wastewater

2011 ◽  
Vol 356-360 ◽  
pp. 1109-1117
Author(s):  
Chun Hua Zhang ◽  
Yu Ying Dong ◽  
Feng Jie Zhang
Keyword(s):  
Wastewater Treatment ◽  
Relative Error ◽  
Membrane Bioreactor ◽  
Synthetic Wastewater ◽  
Design Parameters ◽  
Stable Operation ◽  
Fouling Resistance ◽  
Submerged Membrane Bioreactor ◽  
Operation Conditions ◽  
The Relationship

In this study, a mathematical model has been developed for the submerged membrane bioreactor (SMBR). Polyvinyl alcohol (PVA) Modified Non-woven model is immerged in MBR to be used for synthetic wastewater treatment. The results show that membrane fouling resistance is mostly cake resistance occurring during filtration. Based on the concept of specific fouling resistance and Darcy law that describes the relationship between flux and resistance during filtration driven by pressure, a module is established to explain the relationship between specific fouling resistance and time during filtration controlled by cake resistance in SMBR. The decline trend of flux can be predicted by the model. The model is used to predict the decline trend of flux during pharmaceutical wastewater treatment. Compared with experimental data, the relative error is less than 10% at t>b, the relative error is less than 5% at t>2b. It shows that the model can predict the decline trend of flux during stable operation of SMBR. But the relative error is bigger during unstable operation at initial stage (t<b). The model developed in this study would provide a useful tool in optimizing operation conditions as well as design parameters for a SMBR system.

scholarly journals Soft Actuator Model for a Soft Robot With Variable Stiffness by Coupling Pneumatic Structure and Jamming Mechanism

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 26356-26371 ◽  
Author(s):  
Feng-Yu Xu ◽  
Feng-You Jiang ◽  
Quan-Sheng Jiang ◽  
Yu-Xuan Lu
Keyword(s):  
Variable Stiffness ◽  
Soft Robot ◽  
Soft Actuator

scholarly journals Design, analysis and experiment of finger soft actuator with nested structure for rehabilitation training

2020 ◽  
Vol 12 (11) ◽  
pp. 168781402097153
Author(s):  
Ning Meng ◽  
Wang Kun ◽  
Li Mingxin ◽  
Yu Ke ◽  
Wu Zhi
Keyword(s):  
Inner Core ◽  
Structural Parameters ◽  
Structure Design ◽  
Core Structure ◽  
Rehabilitation Robot ◽  
Hand Rehabilitation ◽  
Soft Actuator ◽  
Nested Structure ◽  
Simulation Results ◽  
Gripping Force

Compared with the rigid hand rehabilitation robot, the soft hand rehabilitation robot has the advantages of good flexibility, which is of great significance to its research. In order to make the soft hand rehabilitation robot have the advantages of high stiffness and simple manufacturing process, a nested structure is proposed for finger soft actuator in this paper. The nested structure consists of outer restraint structure and inner core structure. The inner core structure can realize deformation under the action of air pressure. The outer restraint structure can improve bending efficiency by restraining deformation in non-functional direction of inner core structure. On this basis, the processing technology of nested structure is designed, and the effect of structural parameters on performance is analyzed. In order to illustrate the advantages of nested structure, the performance of nested structure and fiber-constrained structure is compared by simulation, which includes bending angle, gripping force and expansion amount (by measuring the deformation of the cross section). The simulation results show the advantages of the nested structure. A prototype of the soft hand rehabilitation robot is developed with nested structure as finger soft actuator, and the experimental results prove the feasibility of design. The results of this study provide a reference for the structure design of soft hand rehabilitation robot.

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