Reconfiguration Mechanism Research Articles

Special Issue on Applications of Reconfigurable Mechanisms and Robotics

Special Issue on Applications of Reconfigurable Mechanisms and Robotics

An ECA Regret Learning Game for Cross-Tier Computation Offloading Against Swarm Attacks in Sensor Edge Cloud

The distributed nature of multi-tier swarm attacks renders it more difficult for a single-tier intrusion detection system (IDS) to secure cross-tier computation offloading in multi-tier sensor edge cloud (SEC). To perceive and prevent such attacks, we model IDSs in different layers as an IDS federation network (IDFN) and present a generic framework to prevent cooperative attacks and reconfigure the defense strategy of IDFN across the three-tier SEC. The framework provides single-tier, two-tier, and three-tier dynamic awareness models based on the susceptible-infected-susceptible (SIS) dynamical equations to characterize the update process of message states to obtain the equilibrium solution between alarm messages and normal messages captured by IDSs. For swarm attack events from multi-tier SEC, we model the cross-tier cooperative interactions between IDSs and swarm attackers as an event-condition-action (ECA) regret learning game (ERLG) to achieve a distributed IDS reconfiguration to reduce the overall SEC alarm messages while ensuring the equilibrium of message states with the cooperation of IDSs. Simulation results demonstrate that our proposed scheme is superior to other reconfiguration mechanisms under swarm attacks in three-tier SEC.

Abnormal dynamics of functional brain network in Apolipoprotein E ε4 carriers with mild cognitive impairment

<abstract> <p>As is well known, the Apolipoprotein E (APOE) ε4 allele is the most pertinent genetic hazardous element for Alzheimer's disease (AD). Mild cognitive impairment (MCI) is considered a prodromal stage of AD. How the APOE ε4 allele modulates functional connectivity of brain network in MCI group is a question worth exploring. At present, some studies have evaluated the relationship between APOE ε4 allele and static functional network connectivity (sFNC) for MCI individuals, while the relationship of dynamic FNC (dFNC) with APOE ε4 allele still remained puzzled. Thus, we aim to detect aberrant dFNC for APOE ε4 carriers in the MCI group. On the basis of the resting-state functional magnetic resonance imaging (rs-fMRI) data, seven intrinsic brain functional networks were first recognized by the group independent component analysis. Then, the technique of sliding window was employed to determine the dFNC, and two dFNC states were detected by the k-means clustering algorithm. Finally, three temporal properties of fraction time, mean dwell time as well as transition numbers in the dFNC states were investigated. The results found that the dFNC and temporal properties in APOE ε4 carriers were abnormal compared with those in APOE ε4 noncarriers. In detail, in the MCI group, compared with APOE ε4 noncarriers, carriers had 9 pairs of abnormal dFNC and had significant differences in all the three temporal properties of the two dFNC states. In addition, two pairs of dFNC were found significantly correlated with clinical measure. This detected abnormal dynamics of temporal properties and dFNC in APOE ε4 carriers were similar with that reported for AD patients in previous studies. These results may suggest that in the MCI group, APOE carriers are more at risk for AD compared to noncarriers. Our findings may offer novel insights into the mechanisms of abnormal brain reconfiguration for individuals at genetic risk for AD, which could also be regarded as biomarkers for the early identification of AD.</p> </abstract>

Decoding the mechanism of self-discharge and optimal electrolyte reconfiguration for advanced vanadium-based aqueous zinc batteries

The self-discharge of aqueous zinc batteries during idle periods remains elusive, and warranting adequate voltage and sufficient capacity is not trivial, due to the components of the battery system and the reciprocal influence among them.

Event-Triggered Learning-Based Fault Accommodation for a Class of Nonlinear Interconnected Systems.

In this article, a distributed learning-based fault accommodation scheme is proposed for a class of nonlinear interconnected systems under event-triggered communication of control and measurement signals. Process faults occurring in the local dynamics and/or propagated from interconnected neighboring subsystems are considered. An event-triggered nominal control law is used for each subsystem before detecting any fault occurrence in its dynamics. After fault detection, the corresponding event-triggered fault accommodation law is utilized to reconfigure the nominal control law with a neural-network-based adaptive learning scheme employed to estimate an ideal fault-tolerant control function online. Under the asynchronous controller reconfiguration mechanism for each subsystem, the closed-loop stability of the interconnected systems in different operating modes with the proposed event-triggered learning-based fault accommodation scheme is rigorously analyzed with the explicit stabilization condition and state upper bound derived in terms of event-triggering parameters, and the Zeno behavior is shown to be excluded. An interconnected inverted pendulum system is used to illustrate the proposed fault accommodation scheme.

MotoPrint: Reconfigurable Vibration Motor Fingerprint via Homologous Signals Learning

Device fingerprints can satisfy the high-security requirement of modern mobile applications (e.g., mobile payments) by guaranteeing the operation is performed on a trusted device. However, existing works on device fingerprints are weak to leakage, which leads to an irreversible failure of the device fingerprint authentication system after suffering from fingerprint theft attacks. The vulnerability drives us to propose a reconfigurable device fingerprint, i.e., <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> , that can recover the system after suffering from such attacks. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> stems from the motor vibration that can represent in both signals of the accelerometer and the gyroscope (i.e., they are homologous motion signals). Therefore, we designed a two-path feature extracting network and a sensor-independent training strategy to eliminate sensor noise that can decline authentication performance. In addition, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> has a complete reconfiguration mechanism to cope with fingerprint leakage, which brings the damaged authentication system back to health. The evaluation of 80 stand-alone vibration motors and 20 in-built ones shows that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> can achieve high authentication accuracy of 98.5%. Meanwhile, we also demonstrate the reconfigured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> , which can also effectively indicate the device's uniqueness with over 98% accuracy, is independent of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MotoPrint</i> s under other stimulating codes.

Research on the Type Synthesis of a Regular Hexagonal Prism Rubik’s Cube Mechanism

The Rubik’s Cube mechanism (RCM) is a kind of reconfigurable mechanism with multiple characteristics such as multiple configurations, variable topology, strong coupling, and reconfigurability. Crossover research on the RCM with mathematics, chemistry, cryptography, and other disciplines has led to important breakthroughs and progress. It is obvious that the invention and creation of a new RCM can provide important ideological inspiration and theoretical guidance for the accelerated iterative updating of Rubik’s Cube products and the expansion of their applications. This paper investigates the type synthesis method for a regular hexagonal prism (RHP) RCM (RHPRCM). Through analysis of the reconfigurable movement process of the RCM, two mechanism factors are abstracted, a type synthesis process for the RHPRCM is proposed, a symmetry layout method for the RCM’s revolute axis based on the RHP space polyhedron is proposed, and an analysis method for the intersection of the revolute pair contact surfaces (RPCSs) based on the adjacency matrix is proposed. Taking a revolute axis passing through the center of an RHP and having only one RPCS for each revolute axis as an example, an RHPRCM with different topological structures is synthesized. The relevant research in this paper can provide methodological guidance for the synthesis of other spatial RCMs.

3D Reconfigurable Vectorial Holography via a Dual‐Layer Hybrid Metasurface Device

AbstractMetasurface‐based vectorial holography manifests itself as an advanced platform for large‐capacity information storage, holographic display, and cryptography. However, a convenient and effective reconfigurable vectorial hologram generation mechanism still remains a challenge. Here, a rotation‐driven reconfigurable vectorial holography scheme is developed via a dual‐layer hybrid metasurface device, in which radiation‐type and birefringent metasurfaces are cascaded hybridly. Thus, reconfigurable and highly customizable intensity and polarization response of holograms in the 3D space is achieved. Rotatable radiation‐type metasurface (RTM) serves as an incidence‐wavefront modulator to excite the non‐rotatable birefringent metasurface (BM). The gradient descent optimization inverse design method is introduced to achieve the high‐efficiency reconstruction of the Jones vector and Jones matrix distribution on both RTM and BM. On this basis, numerical analysis and experimental verification of 3‐D reconfigurable vectorial holography are demonstrated in the microwave region. This scheme implies a new paradigm for 3‐D reconfigurable vectorial holography and can lead to advances in high‐capacity optical display, switchable meta‐devices, and cryptography.

Development and evaluation of a light-weight flexure-based lockable joint for morphing wings

Single degree of freedom (single-DOF) morphing wings have the advantages of light-weight and multiple morphing shapes, which can enable aircraft to adapt to uncertain flight environments and various mission types. A single-DOF morphing wing with four morphing shapes designed based on the reconfigurable mechanism is introduced firstly in this paper. Then, a light-weight compliant locking mechanism (CLM) based on flexure hinges is proposed for lockable joints in the reconfigurable mechanism. The CLM has two types depending on the locking method, namely the “plug-in” compliant locking mechanism (PCLM) and the “friction” compliant locking mechanism (FCLM). The working principles of the two CLMs are described. The mathematical models are established to assess the static and dynamic characteristics of the proposed CLM, which are also verified by the finite element simulation. The influence of the flexure hinge dimensions on the working performance of the CLM is analyzed, and its dimensions are optimized considering both the locking performance and the maximum stress. Finally, a PCLM and a FCLM actuated by SMA wires are fabricated based on the optimized dimensions. The experiment is conducted to assess the locking torque of the CLM and the feasibility of the proposed CLM used for morphing wings is confirmed.

Design and kinematical performance analysis of a novel reconfigurable parallel mechanism with three remote center-of-motion modes

In view of the demands for variability and safety in surgical procedures, this paper presents a novel reconfigurable parallel mechanism (RPM) capable of performing three remote center-of-motion (RCM) modes: 1R1T, 2R1T, and 3R1T. One of the RCM modes can transform into two distinct configurations from the switch configuration, in which one configuration offers a rotational degree-of-freedom (DOF) and a translational DOF in the YOZ plane, and the other configuration provides identical DOFs in the XOZ plane. A novel device is introduced for switching between the active and passive modes of the revolute joint, which serves as the basis for the RPM reconfiguration process. Utilizing screw theory, the mobility and actuation scheme of the RPM in each configuration are analyzed. Inverse kinematic analysis and Jacobian matrices are then carried out. Subsequently, kinematical performances, such as singularity, workspace, and dexterity, are studied. All results indicate that the proposed RPM has the ability to switch motion modes without requiring reassembly and can effectively meet the diverse demands of surgical procedures based on specific minimally invasive surgery (MIS) requirements.

Containment control of multiple unmanned surface vessels with NN control via reconfigurable hierarchical topology.

This paper investigates the containment control of multiple unmanned surface vessels with nonlinear dynamics. To solve the leader-follower synchronization problem in a containment control system, a hierarchical control framework with a topology reconfiguration mechanism is proposed, and the process of containment control is converted into the tracking of a reference signal for each vessel on its respective target heading by means of the light-of-sight (LOS) guidance. In a control system, the neural networks (NNs) are adopted to consider the uncertainty. In the follower layer, a connectivity controller with a topology reconfiguration mechanism is embedded, to change the converging positions of followers so as to avoid collision within the system, and to maintain the system connectivity when the communication equality is poor. The effectiveness of the hierarchical control framework proposed in this paper is valid by simulation.

Origami-Inspired Design of a Single-Degree-of-Freedom Reconfigurable Wing With Lockable Mechanisms

Abstract The morphing wing can enable the aircraft to maintain good flight performance in different missions or flight stages, which has enjoyed much attention in recent research. However, it is difficult to design the wing with multiple configurations and lightweight. Inspired by the origami art, a reconfigurable mechanism with a single-degree-of-freedom (single-DOF) is introduced to the morphing wing design in this paper. The bending configuration, the deployable configuration, and the configuration transformation of the reconfigurable mechanism are respectively analyzed. The lengths of some links are also optimized according to the motion requirements. Specific kinematic pairs of the reconfigurable mechanism are required to have the locking function. Therefore, a reliable “plug-in” type lockable mechanism is designed and its working performance is verified by comparing the analytical model and the finite element method model. Finally, by assembling the reconfigurable mechanism with the ribs, the reconfigurable wing which can realize the arbitrary transformation of four configurations under a single drive mode can be obtained.

Assembly of reconfigurable Bricard-like mechanisms to form a multimode deployable arch

Abstract. This paper deals with the construction of a novel family of multimode deployable mechanisms based on reconfigurable Bricard-like mechanisms. By connecting a number of identical threefold-symmetric (TFS) Bricard-like mechanisms, a multimode deployable arch is proposed for the first time, which can switch between the scissor-like deployable mode and the arch deformable mode through the transition configuration. Then new multimode center-driven deployable mechanisms can be obtained by connecting three and six multimode deployable arches. The obtained mechanism can switch between the scissor-like deployable mode and spherical deformable mode, and it can be reassembled by adjusting the number of TFS Bricard-like mechanisms to change its size. Finally, physical prototypes of the multimode deployable arch and multimode center-driven deployable mechanisms are fabricated and tested to validate the feasibility of the proposed approach and analysis.

Reconfigurable Antennas and Their Practical Applications—A Review

AbstractThis paper presents the review on the design of various reconfigurable antennas and their applications in the current scenario. There are more challenges involved in the design of these antennas. This paper also describes the various methods used for reconfiguring the frequency bands. The single parameter reconfiguration and hybrid reconfiguration examples are analyzed with their performances. The parameters such as gain, efficiency, and size of the existing antenna is compared. The various switches deployed in the antenna for achieving the reconfiguration are presented in this paper. The switches such as pin diodes, varactor diodes, MEMS, and mechanical switching are also elaborated with their corresponding merits and demerits. The diodes are switched on and off to activate and deactivate the structure of the antenna. Similarly, mechanical actuators are used for mechanical switching mechanism. The polarization reconfiguration mechanism between linear and circular; pattern reconfiguration mechanism between directional and omnidirectional are reviewed with various examples. In addition to that, several designs of reconfigurable filtering antennas, MIMO antennas are also reviewed in detail.

(Invited) 3D Morphable Electronic Systems Via Deterministic Microfolding

DNA and proteins fold in three dimensions (3D) to enable functions that sustain life. Emulation of such reversible folding schemes for functional materials can create promising opportunities for advancing a wide range of technologies. In particular, morphing 3D mesostructures via multiple dimensions for high-performance materials including monocrystalline silicon can enable unconventional designs in sensory robotics, biomedical devices, microelectronics, and microelectromechanical systems. Existing approaches to morphing functional materials mostly rely on planar processes, which often complicates needed mechanisms for structural reconfiguration and limits the choice of materials composition and dimension. This presentation will introduce a bioinspired microfolding strategy to realize 3D reconfigurable microelectronic systems in freestanding forms with various advanced materials and complex architectures. The microfolding mechanism allows access to any transitional states of the folded 3D structures in a reversible fashion, to modulate functionalities on demand. Demonstrations on microantennas for telecommunication, wearable accelerometers for tremor monitoring, and epicardial bioelectronic probes for cardiac mapping, all of which are achieved via the microfolding strategy, further highlight the high potential for a broad range of applications in healthcare and communications industry.

Hydrogel muscles powering reconfigurable micro-metastructures with wide-spectrum programmability

Stimuli-responsive geometric transformations endow metamaterials with dynamic properties and functionalities. However, using existing transformation mechanisms to program a single geometry to transform into diverse final configurations remains challenging, imposing crucial design restrictions on achieving versatile functionalities. Here, we present a programmable strategy for wide-spectrum reconfigurable micro-metastructures using linearly responsive transparent hydrogels as artificial muscles. Actuated by the hydrogel, the transformation of micro-metastructures arises from the collaborative buckling of their building blocks. Rationally designing the three-dimensional printing parameters and geometry features of the metastructures enables their locally isotropic or anisotropic deformation, allowing controllable wide-spectrum pattern transformation with programmable chirality and optical anisotropy. This reconfiguration mechanism can be applied to various materials with a wide range of mechanical properties. Our strategy enables a thermally reconfigurable printed metalattice with pixel-by-pixel mapping of different printing powers and angles for displaying or hiding complex information, providing opportunities for encryption, miniature robotics, photonics and phononics applications.

An ultrawideband antenna with two independently tunable notch bands

This paper presents a planar CPW-fed Ultrawideband (UWB) antenna with two independently tunable notch bands. The proposed design consists of a modified Rhombus-shaped monopole structure that is integrated with a dual band-stop filter based on hexagonal split ring resonators (HSRR). The antenna is capable of suppressing multiple frequency bands within ultrawideband range (3.1–11 GHz) such as WLAN and X-band downlink satellite communication frequency bands with an independent tunable mechanism to fulfill the on-demand band rejection. The frequency reconfigurability of the two notch bands is obtained by loading the hexagonal filter arms with two varactor diodes (for each band). Details of antenna design steps and reconfigurability mechanism are illustrated. The notch band element is explained using equivalent circuit model and surface current distribution at lower and higher notch frequency bands. A prototype of the proposed design is printed on the RO4003C (ϵr = 3.55) substrate printed circuit board (PCB) and tested to authenticate the performance. The proposed antenna volume is 21.5 ▪ 48 ▪ 1.524 mm3 and demonstrates an omnidirectional radiation pattern in E and H planes with an average gain of 3.7 dBi across the operational passbands, while a sharp reduction in gain of -6.8 dBi and -3.5 dBi is achieved at the lower and higher notch bands, respectively. Continuous tuning is achieved experimentally from 5.08 to 5.77 GHz and 7.75 to 8.52 GHz for the lower and higher notch bands, respectively. Excellent agreement is observed between the simulated and measured results. Application areas include radio-frequency identifications, ground-penetrating radar, and wireless communications.

Design of a class of reconfigurable hybrid mechanisms for large complex curved surface machining based on topological graph theory

A design method for hybrid mechanism configuration synthesis based on topological graph theory is proposed to address the challenge of machining large and complex curved surfaces in the aerospace domain. The method leads to the generation of a new class of reconfigurable large extension hybrid mechanisms. Firstly, the spatial mechanism topological graph (SMTG) is obtained by evolving the structure of chemical molecules, which is used to express the spatial mechanism topological relationships. Then, combining graph theory methods with the SMTG, the topological relationships between motion modules of the hybrid mechanism are expressed, and the mechanisms of each motion module are designed. Finally, mechanisms of different functional modules are topologically connected and combined using the proposed topological connection relationship for the motion modules of hybrid mechanisms, thus resulting in a class of reconfigurable hybrid mechanisms (RHMs) with large extensibility. The RHMs exhibit strong structural stability, a large working space, and a small volume of occupation. It can be installed on the ends of industrial robots or in large guideways in the future to achieve high-precision machining of large complex curved structures.

Kirigami‐Inspired Planar Deformable Metamaterials for Multiple Dynamic Electromagnetic Manipulations

AbstractThe Kirigami technique has recently inspired the design of reconfigurable electromagnetic metamaterials that can be easily realized by embedding a patterned cutting array into a supportive substrate. However, these existing designs mainly focus on the 2D‐to‐3D transformable morphology that induces the modulation of the spectral responses. This work proposes a kirigami‐based planar reconfiguration mechanism and extends advanced applications in the dynamic near‐field imaging and tunable double‐foci metalens. These extraordinary tunabilities originate from three meta‐atoms that can be mutually transformed into the morphologies with non‐chirality and opposite chirality under the tensile strain. By utilizing the transmittance characteristics of reconfigurable meta‐atoms, the metamaterial is constructed to achieve three‐foldable near‐field displays and a longitudinal double‐foci metalens empowered with tunable focusing length and intensity ratio. Two anisotropic chiral meta‐atoms in deformed states that possess overwhelming transmittance difference of circularly cross‐polarized components to magnify the focusing intensity ratio of two foci for the proposed metalens are further proposed. The exhibited observations provide typical examples of a wide spectrum of applications of the kirigami‐based reconfiguration mechanism, and it may pave the avenue to spark manifold functional devices for applicable electromagnetic manipulations such as multifunctional hologram display, dynamic beam shaping, and steering, as well as the conformal design of meta‐devices.

A new reconfigurable parallel mechanism using novel lockable joints for large scale manufacturing

A new reconfigurable parallel mechanism using novel lockable joints for large scale manufacturing