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Negative-pressure soft pneumatic actuators enabled by asymmetrically distributed bending units

Extreme Mechanics Letters 2025年 77卷

作者： Fu, Zeyu Chen, Tianyu Zou, Haoran Zhu, Zhiwei Deng, Zichen Wang, Yifan School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical University Xi'an710072 China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore 639798 Singapore State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China

Soft pneumatic actuators are highly flexible and can adapt to complex environments, attracting significant attention for their ability to operate in settings where rigid actuators cannot. Most existing soft pneumatic actuators are powered by positive pressure, which has the disadvantage of volume increase during operation and risk of exploding under large pressures. In this study, we designed a new type of soft actuator by inducing asymmetric bending deformation throughout a holey structure under negative pressure. Using finite element analysis and a theoretical model, we studied the effects of various geometric parameters on the structure's bending behavior. We found that the displacement of the circle's center from the central axis is a parameter with the most significant impact on the bending behavior of the structure. By designing circular holes with offset from the central axis, the structure can bend toward the offset direction during subsequent bending deformation. Based on this deformation mechanism, we designed a soft gripper that bends upon actuation and effectively picks up objects. We further designed a bi-directional gripper that bends towards both sides and a circular gripper that contracts towards the center upon evacuation to hold objects. These soft grippers’ grasping capabilities are validated by experimental tests. Finally, by arranging the holes in a wavy pattern within the structure, we created a crawling robot that moves forward through cyclic negative pressure actuation. These findings highlight the potential of leveraging bending behaviors in asymmetrically distributed holey structures for the development of negative-pressure driven soft actuators and robots. © 2025 Elsevier Ltd

关键词： Pneumatic actuators

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IDEAL STATE RECONSTRUCTOR FOR DETERMINISTIC DIGITAL-control systems

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INTERNATIONAL JOURNAL OF control 1989年第6期49卷 2001-2011页

作者： POLITES, ME Control Systems Division Structures and Dynamics Laboratory Marshall Space Flight Center National Aeronautics and Space Administration AL 35812 U.S.A

A new state reconstructor for deterministic digital control systems is presented which is ideal in the following sense: if the plant parameters are known exactly, the output of the new state reconstructor will exactly equal the true state of the plant, not just approximate it. Furthermore, this ideal state reconstructor adds no additional states or eigenvalues to the system, nor does it affect the plant equation for the system in any way; it affects only the measurement equation. While there are countless ways of choosing the ideal state reconstructor parameters, two distinct methods are described here. An example is presented which illustrates the procedures for completely designing the ideal state reconstructor using both methods.

关键词： control systems, Digital

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STATE VARIABLE REPRESENTATIONS IN DIGITAL-control systems WITH MA-PREFILTERED MEASUREMENTS

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INTERNATIONAL JOURNAL OF control 1988年第6期47卷 1683-1695页

作者： POLITES, ME ED12 Control Systems Division Structures and Dynamics Laboratory Marshall Space Flight Center National Aeronautics and Space Administration AL 35812 United States

This paper derives three discrete state variable representations for a continuous-time plant driven by a zero-order hold with a combination of instantaneous measurements and measurements prefiltered by a multi-input/multi-output moving average (MA) process. These representations allow the control system engineer to model plants of this type accurately in a form which permits him to use standard techniques to design digital feedback controllers for them. An example is presented which illustrates how to obtain the coefficient matrices in each representation. Guidelines are presented for choosing the best representation to use for any given plant of this type.

关键词： control systems, DIGITAL

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Automated diagnostic approaches for defective rolling element bearings using minimal training pattern classification methods

Automated diagnostic approaches for defective rolling elemen...

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4th World Congress on Engineering Asset Management: Engineering Asset Lifecycle Management, WCEAM 2009

作者： Gryllias, K.C. Yiakopoulos, C. Antoniadis, I. School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781849960021

Rolling Element Bearings consist one of the most widely used industrial machine elements, being the interface between the stationary and the rotating part of the machine. Due to their importance a plethora of monitoring methods and fault diagnosis procedures have been developed, in order to reduce maintenance costs, improve productivity, and prevent malfunctions and failures during operation which could lead to the downtime of the machine. Towards this direction, among different automatic diagnostic methods, the Support Vector Machine (SVM) method has been shown to present a number of advantages. Support Vector Machine is a relatively new computational learning method based on Statistical Learning Theory and combines fundamental concepts and principles related to learning, well-defined formulation and self-consistent mathematical theory. The key aspects about the use of SVMs as a rolling element bearing health monitoring tool are the lack of actual experimental data, the optimal selection of the type and the number of input features, and the correct selection of the kernel function and its corresponding parameters. A large number of input features have been proposed, being divided in two big categories: A) Traditional signal statistical features in the time domain, such as mean value, rms value, variance, skewness, kurtosis etc, B) Frequency domain based indices, such as energy values obtained at characteristic frequency bands of the measured and the demodulated signals. In this paper, the structure and the performance of a Support Vector Machine based approach for rolling element bearing fault diagnosis is presented. The main advantage of this method is that the training of the SVM is based on a model describing the dynamic behavior of a defective rolling element bearing, enabling thus the direct application of the SVM to experimental measurements of defective bearings, without the need of training the SVM with experimental data of a defective bearing.

关键词： Support vector machines

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Crack detection in structures, using proper orthogonal decomposition and morphological processing

Crack detection in structures, using proper orthogonal decom...

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13th International Congress on Sound and Vibration 2006, ICSV 2006

作者： Gryllias, K.C. Koukoulis, I.N. Yiakopoulos, C.T. Antoniadis, I.A. Provatidis, C.G. Dynamics and Structures Laboratory Machine Design and Control Systems Section National Technical University of Athens Athens 15773 Greece

ISBN: (纸本)9781627481502

Vibration analysis based damage identification in structures has been a subject of intensive research. As a result, a plethora of analytical, numerical and experimental techniques have been developed, involving frequency or mode-shape based methods, wavelet analysis, or higher order statistical signal processing. Parallel, a number of pattern recognition and classification approaches have been used, such as neural networks, either as standalone procedures, or in combination to the above techniques. In this paper, a method for crack dctcction in structures is presented. As a first step, using the Proper Orthogonal Decomposition (POD) method, a number of Proper Orthogonal Modes (POMs) of a crack cantilever beam are estimated. Proper Orthogonal Decomposition, closely related to Principal Component Analysis, is a powerful and elegant method of data analysis aimed at obtaining low-dimensional approximate descriptions of high-dimensional processes and eliminating noise effects. Then, the POMs are further processed, using basic morphological operators (dilation, erosion, opening, closing). The basic concept of morphological processing is to modify the shape of an object, equivalcntly considered as a set, by transforming it through its interaction with another object, called the structuring element. Using appropriate morphological processing, the position of the crack can be estimated by isolating the local sudden change effect of the crack on the space variation of each POM. Cantilever beams, containing a transverse surface opening-closing crack at different lengths and of different depths are considered and the influence of the type of the structuring element and of the noise level to the accuracy of the results is examined.© (2006) by the International Institute of Acoustics & Vibration.

关键词： Vibration analysis

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Doppler effect minimization in the spectra emitted by moving vehicles by the application of a Harmonic Signal Detection (HARD) Method

Doppler effect minimization in the spectra emitted by moving...

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6th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2009

作者： Yiakopoulos, C.T. Gryllias, K.C. Antoniadis, I.A. National Technical University of Athens School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781618390097

On-line fault diagnosis of moving vehicles is of increasing importance, especially if the diagnosis can be performed from a stationary byside station near the way of the moving vehicle. The diagnostically interesting information of a moving vehicle is available in the acoustic signal which is emitted by the source. However, the Doppler effect introduces a spectrum smear depending on the speed of the moving source, which shifts the interesting frequencies to different bands. A method is presented that allows the acquired information to be connected to the proper running of the moving vehicle, indicating the useful carrier frequencies of the source signals. The basic idea is based on the Harmonic Signal Detection Method. Since this method is a special parametric method performing directly in the time domain, it can track on-line the instantaneous speed of the moving object. The estimated speed variation of the moving object can be used to fix the problem of the frequency distortion introduced by the Doppler effect. The paper includes results of the proposed technique to simulated data and to an experimental measurement which was taken by a moving rail vehicle.

关键词： Doppler effect

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Demodulation of defective rolling element bearings vibration response with Complex Shifted Wavelets (CSMW) using a Peak Energy Criterion (PEC)

Demodulation of defective rolling element bearings vibration...

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6th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2009

作者： Gryllias, Konstantinos C. Antoniadis, Ioannis A. National Technical University of Athens School of Mechanical Engineering Machine Design and Control Systems Section Dynamics and Structures Laboratory Athens 15773 Greece

ISBN: (纸本)9781618390097

Complex Shifted Morlet Wavelets (CSMW) can be used for the demodulation of the vibration response of defective rolling element bearings, as they present a number of advantages. The most important is that according to this method, the maximal timefrequency resolution is obtained, while the magnitudes of the complex wavelet coefficients in the time domain lead directly to the required envelope. However, the key element for the successful application of the method is the optimal selection and location of the corresponding necessary time-frequency window both in the time and in the frequency domains. For this reason, a Peak Energy Criterion (PEC) is proposed in order to tune the relevant wavelet window by choosing simultaneously in an optimal way and automatically both the center frequency and the bandwidth. A number of application cases are presented and the criterion demonstrates excellent behavior as it combines the benefits of energy based criteria, with criteria characterizing the spikiness of the response.

关键词： Demodulation

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Modeling and experimental analysis of a 6-high industrial rolling mill vibration response

Modeling and experimental analysis of a 6-high industrial ro...

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7th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2010, CM 2010/MFPT 2010

ISBN: (纸本)9781618390134

During cold rolling of thin sheet, the operation is often accompanied by a variety of undesirable mechanical vibrations, generally referred to as chatter. Chatter is often associated with high rolling speeds and high thickness reductions, conditions that are generally desirable in order to increase mill productivity. Chatter can lead to unacceptable gauge fluctuations, sheet corrugations, surface imperfections, damage to mills and undesirable noise in the work environment. Four and six degree of freedom (DOF) systems describing chatter in sheet rolling in a 6-High rolling mill are proposed. The natural frequencies and the modes of the systems are extracted. The investigation includes the additional plastic deformation of the sheet in the roll-bite that is present during chatter as well as the force displacement relation between the cylindrical rolls being pressed together which is inherently nonlinear due to the changing contact area. It appears that the models are capable of predicting third octave chatter, in addition to fifth octave chatter. A number of mill operational parameters are considered. The models are validated using measurements performed at an industrial 6-high aluminium rolling mill.

关键词： Cold rolling

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Magnitude calibration of a fixed head star tracker using Astro-1 flight data

Magnitude calibration of a fixed head star tracker using Ast...

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AIAA Space Programs and Technologies Conference, 1992

作者： Rakoczy, John M. West, Mark E. Control Systems Division Structures and Dynamics Laboratory National Aeronautics and Space Administration Marshall Space Flight Center AL35812 United States

The Astro-1 ultraviolet astronomy mission was hampered by the failures of the automatic star acquisition procedure. The acquisition procedure depended on the Instrument Pointing Subsystem’s (IPS) Fixed Head Star Trackers (FHST) to acquire, track, and identify quidestars of known visual magnitude. During the Astro-1 mission it was suspected that the star magnitudes measured by the FHST were much lower than predicted. A post-flight investigation of the Astro-1 flight data confirmed and quantified this suspicion, Star magnitude calibration curves computed from the flight data depict the variance from the pre-flight calibration curves, These results are helping engineers to plan improvements to the acquisition procedure for the upcoming Astro-2 mission. © 1992 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Star trackers

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A novel electron-phonon coupling thermoelasticity with Burgers electronic heat transfer

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Applied Mathematics and Mechanics(English Edition) 2023年第11期44卷 1927-1940页

作者： Hua WU Xinyi LI Yajun YU Zichen DENG School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China MIIT Key Laboratory of Dynamics and Control of Complex Systems Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong UniversityXi'an 710049China

The electron-phonon interaction can reveal the microscopic mechanism of heat transfer in *** two-step heat conduction considering electron-phonon interaction has become an effective theoretical model for extreme environments,such as micro-scale and ultrafast *** this work,the two-step heat transfer model is further extended by considering the Burgers heat conduction model with the secondorder heat flux rate for ***,a novel generalized electron-phonon coupling thermoelasticity is proposed with the Burgers electronic heat ***,the problem of one-dimensional semi-infinite copper strip subject to a thermal shock at one side is studied by the Burgers two-step(BTS)*** thermoelastic analytical solutions are systematically derived in the Laplace domain,and the numerical Laplace inversion method is adopted to obtain the transient *** new model is compared with the parabolic two-step(PTS)model and the hyperbolic two-step(HTS)*** results show that in ultrafast heating,the BTS model has the same wave front jump as the HTS *** present model has the faster wave speed,and predicts the bigger disturbed regions than the HTS *** deeply,all two-step models also have the faster wave speeds than one-step *** work may benefit the theoretical modeling of ultrafast heating of metals.

关键词： Burgers heat transfer electron-phonon coupling two-step generalized thermoelasticity

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