Origami provides a flexible platform for constructing three-dimensional multi-stable mechanical metamaterials and structures. While possessing many interesting features originating from folding, the ...development of multi-stable origami structures is faced with tremendous demands for acquiring tunability and adaptability. Through an integration of origami folding with magnets, this research proposes a novel approach to synthesize and harness multi-stable magneto-origami structures. Based on the stacked Miura-ori and the Kresling-ori structures, we reveal that the embedded magnets could effectively tune the structure's potential energy landscapes, which includes not only altering the position and the depth of the potential wells but essentially eliminating the intrinsic potential wells or generating new potential wells. Such magnet-induced evolutions of potential energy landscapes would accordingly change the origami structure's stability profiles and the constitutive force-displacement relations. Based on proof-of-concept prototypes with permeant magnets, the theoretically predicted effects of magnets are verified. The exploration is also extended to the dynamics realm. Numerical studies suggest that the incorporated magnets not only could translate the critical frequencies for achieving certain dynamical behaviors but also fundamentally adjust the frequency-amplitude relationship. Overall, this study shows that the proposed approach would provide a novel means to control the stability profile as well as the mechanics and dynamic characteristics of origami structures, and thus, inspire new innovations in designing adaptive mechanical metamaterials and structures.
Origami structures with reconfigurable mechanical properties are increasingly in demand in engineering applications. The Square-Twist (S-T) origami, featured with excellent reconfigurability and ...torsional bistability, has a broad application prospect. However, there are relatively few reports on the abundant mechanical properties of S-T origami, especially for those uncommon configurations. In this paper, to analyze the kinematics and mechanics of the unfolding motion, an equivalent theoretical model of the S-T origami is established, which could effectively solve the challenging issues of facet bending, self-contact, and diverse loading directions. With systematic finite element analyses and experimental tests of the S-T origami structures, the effectiveness of the theoretical model along with the optimization-based numerical approach is verified. During the unfolding process, significant distinctions in the potential energy profile and the force–displacement relations among the four different configurations of the S-T origami structure are uncovered. The effects of the design geometry and the material property on the constitutive relations of the S-T origami structure are comprehensively elucidated. Finally, we demonstrate that through folding reconfiguration, an S-T origami structure could exhibit five types of force–displacement relation that are qualitatively different, including bi-stable and mono-stable profiles.
Locomotion of earthworm-like metameric robots results from shape changes of deformable segments. Morphologically, the segments could stretch, contract or bend by changing their states. Periodic shape ...changes are recognized as gaits of the robots. Robots could employ different gaits for different locomotion tasks. However, earthworm-like robots generally possess a number of independent segments and their hyper-redundant morphology (Chirikjian G S and Burdick J W 1995 IEEE Trans. Robot. Autom. 11 781-93) poses a challenge to gait planning for their locomotion. Hence, the goal of this paper is to establish a framework of in-plane gait planning for earthworm-like robots. To this end, a generic model of earthworm-like robots modelled in our prior work (Zhan X et al 2019 Int. J. Robot. Res. 38 1751-1774) is firstly reviewed and in-plane gaits of the robot are parameterized by adopting the principle of retrograde peristaltic wave (Quillin K J 1999 J. Exp. Biol. 202 661-674). Following this, gaits of earthworm-like robots could be uniquely determined by gait parameters, and gait planning of the robots is then reduced to optimizing the gait parameters. The framework mainly consists of a locomotion simulation module and a genetic algorithm module. In the locomotion simulation, the performance of each gait would be evaluated, and then gait parameters get evolved based on the fitness in the genetic algorithm module. To evaluate the fitness of each gait, two objective functions, i.e., the distance to goals and the number of locomotion steps the earthworm-like robot taken before reaching the goals, are to be minimized in the optimization. Besides, two stopping criteria are proposed to improve the efficiency of evaluation. The framework proposed in the paper could plan in-plane gaits of earthworm-like robots, in contrast, only rectilinear locomotion is considered in similar works. This greatly advances the state of art of earthworm-like robots.
In recent years, multi-stable origami structures have garnered increasing attention for their applications in dynamic scenarios such as robotic arm motions, impact energy absorption, and spectrum gap ...regulation. Understanding the intricate working mechanisms and exploring the rich dynamics of these structures necessitate the development of dynamic models. However, existing dynamic modeling methods for origami structures are often cumbersome, and the resulting dynamic models often lack interpretability. To overcome these limitations, we propose a novel data-driven dynamic modeling approach based on B-spline Galerkin method and subset selection strategy. This approach directly captures the dynamics of multi-stable origami structures using measured data, eliminating the need for reliance on empirical or prior knowledge. To validate the effectiveness of the proposed approach, we first evaluate it on the Duffing system, which has explicit expressions, successfully reconstructing the governing equation. Subsequently, we apply this method to the dynamic modeling of the origami ball structure with tri-stability and the multi-cell stacked Miura-origami (SMO) structure with high dimensionality through simulation, showing favorable results. Finally, using experimental data collected from a bi-stable SMO structure prototype, we employ the proposed method to obtain a global model that can accurately predict different dynamic behaviors over a broad range of excitation frequencies, including intra-well periodic vibrations, inter-well periodic vibrations, and inter-well chaotic vibrations. Overall, our method showcases outstanding efficacy in formulating interpretable, manageable, and comprehensive dynamic models. It plays a pivotal role in delving into the intricate dynamics of multi-stable origami structures.
Abnormal microRNA (miRNA) expressions and promoter methylation of genes detected in sputum may provide biomarkers for non-small lung cancer (NSCLC). Here, we evaluate the individual and combined ...analysis of the two classes of sputum molecular biomarkers for NSCLC detection.
We analyze expression of 3 miRNAs (miR-21, miR-31, and miR-210) and methylation of 3 genes (
,
, and
), which were previously identified as potential biomarkers for NSCLC, in sputum of a set of 117 stage I NSCLC patients and 174 cancer-free smokers. The results are validated in a different set of 144 stage I NSCLC patients and 171 controls. The panel of 3 miRNA biomarkers has 81.5 % sensitivity and 85.9 % specificity; the panel of 3 methylation biomarkers displays 82.9 % sensitivity and 76.4 % specificity for NSCLC detection. Integrated analysis of 2 miRNAs (miR-31 and miR-210) and 2 genes (
and
) yields higher sensitivity (87.3 %) and specificity (90.3 %) compared with the individual panels of the biomarkers (
< 0.05). Combined analysis of all the 3 miRNAs and 3 genes does not have performance superior to that of the panel of 2 miRNAs and 2 genes (
> 0.05). The performance of combined use of the two classes of biomarkers was confirmed in the validation set.
The integration of two different classes of biomarkers synergistically improves both the sensitivity and the specificity for the early detection of NSCLC.
Bioinspired Robots
In article number 2206336, Qinyan Zhou, Jian Xu, and Hongbin Fang pioneer a neurobiologically inspired control architecture for earthworm‐like robotic in‐pipe locomotion. The ...distributed oscillators serve as a mapping between earthworm neural oscillations and robotic segment deformations, and the collective dynamics of the oscillator network is exploited to achieve complex gait patterns and better robotic locomotion performance, thus laying a solid foundation for attaining autonomy, polymorphism and adaptivity of metameric peristaltic locomotion.
While a piezoelectric-based vibration-driven system is an excellent candidate for actuating small-size crawling-type locomotion robots, it has the major drawback of limited stroke output that would ...severely constraint the system's locomotion performance. In this paper, to advance the state of the art, we propose two novel designs of piezoelectric vibration-driven locomotion systems. The first utilizes the resonant amplification concept, and the second explores the design of a bistable device. While these two ideas have been explored for piezoelectric actuation amplification in general, they have never been exploited for crawling-type robotic locomotion. Numerical analyses on both systems reveal that resonance and bistability can substantially increase the systems’ average locomotion speed. Moreover, this research shows that with bistability, the system is able to output high average locomotion speed in a wider frequency band, possess multiple locomotion modes, and achieve fast switches among them. Through proof-of-concept prototypes, the predicted locomotion performance improvements brought by resonance and bistability are verified. Finally, the basin stability is evaluated to systematically describe the occurring probability of certain locomotion behavior of the bistable system, which would provide useful guideline to the design and control of bistable vibration-driven locomotion systems.
•Two novel designs of piezoelectric vibration-driven locomotion systems are proposed.•Bistability is utilized in locomotion systems for the first time.•Bistability induces wider working frequency band and multiple locomotion modes.•Prototype experiments verify the predicted locomotion performance enhancement.•Basin stability is evaluated to provide guidelines for system design and control.
Taking inspiration from natural organisms, the field of bio-inspired robotics is advancing rapidly. Earthworm-like robots, in particular, have undergone significant development, progressing from ...linear to planar motion. However, challenges arise due to surface-dependent slippage and imprecise actuation, complicating the creation of accurate trajectory perception models for different locomotion patterns of earthworm-like robots on varying terrains. In this study, we introduce a novel model-free method that leverages an inertial measurement unit and autonomous zero-speed interval (ZVI) detectors, which greatly enhances the autonomous and precise trajectory estimation capabilities of earthworm-like robots. Our technique features a multi-condition ZVI detection mechanism that incorporates proprioceptive sensor information generated during motion while interacting with the surface. This approach addresses oscillations in the zero-speed interval, thereby improving the precision of ZVI detection. Furthermore, by combining a Zero Velocity Update (ZUPT) method with a lightweight error state Kalman filter, our algorithm enables the robot to perceive its motion trajectory with centimeter-level accuracy across various gait patterns. Comparative evaluations with other algorithms underscore the remarkable performance of our method. Notably, our approach can even estimate the slipping behavior of the anchored robot segment, offering valuable insights for future robot control and planning.
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