In Takagi-Sugeno (T-S) fuzzy systems, the design of Dynamic Output Feedback Controller (DOFC) plays a crucial role in ensuring system performance. However, traditional DOFC designs often rely on instantaneous samples, which may lead to suboptimal stability and fail to leverage historical system information effectively. To address the above limitation, we propose a novel Weighted Sum-based Dynamic Event-Triggered Mechanism (WSDETM) for T-S fuzzy system that incorporates weighted historical measurement samples and internal dynamic variables to enhance the triggering condition. By considering the relative importance of past samples, the design of controller can achieve faster convergence to the equilibrium point, resulting in ensuring finite-time stability. In contrast to traditional DOFC designs focusing on asymptotic Lyapunov stability, our approach prioritizes finite-time performance, which is crucial for practical applications. Additionally, deception attacks are modelled in the system as a Markov random process, providing a more general and robust framework compared to the traditional Bernoulli process. The design of DOFC and WSDETM parameters is achieved using the cone complementarity linearization algorithm, and extensive experimental results demonstrate the superior performance of WSDETM in terms of stability, finite-time convergence, and communication efficiency. Eventually, the main results demonstrate the superiority of WSDETM in two cases.
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Open Access
Research Article
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Bioinspired adhesives mimicking octopuses, tree frogs, and geckos enable robots to grip and manipulate diverse surfaces. However, most existing systems use a single adhesion mechanism, limiting adaptability and hindering strong, reversible attachment across diverse surface conditions and environmental media. Here, inspired by the oral sucker of the lamprey (Lethenteron reissneri), we present a hybrid suction disc that integrates a thermally switchable shape-memory polymer (SMP) panel for surface conformity and a soft silicone lip for vacuum suction. When heated, the SMP softens to conform to surface irregularities; subsequent cooling restiffens it, enabling mechanical interlocking with surface asperities under vacuum. This synergistic design achieves robust, reversible, and cross-medium adhesion on challenging surfaces, both in air and underwater. The disc generated peak pull-off forces of 562 N in air and 590 N underwater on smooth substrates, over 850 times its own weight, and maintained strong adhesion even on rough surfaces (>707 μm) where conventional suction fails. Incorporating the SMP improved adhesion by 377% in air and 270% underwater compared to vacuum alone. Shear friction tests showed similar enhancements, and attachments remained secure for 26.8 h under load. The hybrid disc also enabled robotic demonstrations of gripping and cross-medium manipulation when mounted on a mechanical arm, highlighting its potential for real-world robotic applications. This work paves the way for developing multimodal adhesion systems and amphibious robots capable of adaptive gripping and reliable operation across diverse environments.
Open Access
Research Article
Just Accepted
The underwater environment contains a wealth of biological and mineral resources, making the deployment of autonomous underwater vehicles (AUVs) essential for exploration and development. Despite years of research in data-driven machine vision techniques, the offline collection of underwater data remains quite difficult compared to terres-trial samples. This paper focuses on online object exploration in underwater environments without manual intervention, including sub-tasks of close- and open-set detection, fine-grained novel-class subdivision, and few-shot incremental learning. To address this challenge, we start with a few-shot detector for detecting known classes and propose an open-set detector for exploring novel categories. The open-set detector can model unseen objects with fused semantics-localization cues and discrepancy-enhanced representation. Furthermore, we design detector-driven clustering to subdi-vide novel objects into an arbitrary number of novel classes as pseudo-labels. Finally, incremental learning is performed to model novel-category representation while maintaining base-class knowledge, where gradient rescaling and knowl-edge distillation strategies are designed to avoid catastrophic forgetting. Overall, our proposed framework, called O2Exp, can autonomously explore objects in unstructured underwater environments. Extensive experiments with public datasets and real-world tests verify the accuracy, robustness, and practicality of the proposed O2Exp framework.
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Redundant manipulators utilize their redundant solutions to achieve the position and orientation control of the end-effector in a given variety of complex tasks, which is an essential issue in the field of industrial robots. Moreover, for manipulators with unknown models, traditional control methods generate large control errors during the execution of the task or even lead to the failure of the task. To address this problem, this paper proposes a Discrete Data-Driven Position and Orientation Control (D3POC) scheme. The scheme consists of a Discrete Jacobian Matrix Learning (DJML) algorithm, a Discrete Gradient Neural Dynamics (DGND) solver, and a Kalman filter. Then, theoretical analyses are provided to demonstrate the convergence of the D3POC scheme. Subsequently, simulations, comparisons, and experiments based on this scheme are carried out on redundant manipulators. The obtained results indicate the validity, superiority, and practicability of the proposed control scheme.
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Grasp detection plays a critical role for robot manipulation. Mainstream pixel-wise grasp detection networks with encoder-decoder structure receive much attention due to good accuracy and efficiency. However, they usually transmit the high-level feature in the encoder to the decoder, and low-level features are neglected. It is noted that low-level features contain abundant detail information, and how to fully exploit low-level features remains unsolved. Meanwhile, the channel information in high-level feature is also not well mined. Inevitably, the performance of grasp detection is degraded. To solve these problems, we propose a grasp detection network with hierarchical multi-scale feature fusion and inverted shuffle residual. Both low-level and high-level features in the encoder are firstly fused by the designed skip connections with attention module, and the fused information is then propagated to corresponding layers of the decoder for in-depth feature fusion. Such a hierarchical fusion guarantees the quality of grasp prediction. Furthermore, an inverted shuffle residual module is created, where the high-level feature from encoder is split in channel and the resultant split features are processed in their respective branches. By such differentiation processing, more high-dimensional channel information is kept, which enhances the representation ability of the network. Besides, an information enhancement module is added before the encoder to reinforce input information. The proposed method attains 98.9% and 97.8% in image-wise and object-wise accuracy on the Cornell grasping dataset, respectively, and the experimental results verify the effectiveness of the method.
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Minimally invasive surgery (MIS) robots, such as single-arm stapling robots, are key to oral and maxillofacial surgery because they overcome space constraints in the oral cavity and deep throat. However, biodegradable suture staples should be developed for the single-arm stapling robots to avoid a secondary operation. For this aim, a new type of Mg-3Zn-0.2Ca-2Ag biodegradable alloy wire was developed in this study applied as suture staples. Its tensile strength, yield strength, and elongation are 326.1 MPa, 314.5 MPa, and 19.6%, respectively. Especially, the alloy wire attains the highest yield strength value reported among all the biodegradable Mg wires, which is mainly attributed to fine grain strengthening and second phase strengthening such as Mg2Zn11 nano phase strengthening. Moreover, the corrosion rate of this alloy wire in simulated body fluid (SBF) reaches 26.8 mm/y, the highest value among all the biodegradable Mg alloy wires reported so far, which is mainly from the intensified galvanic corrosion between the Ag17Mg54 phase and the Mg matrix. In vitro studies demonstrate that the alloy wire exhibits good blood compatibility and low cytotoxicity. The cone beam computed tomography (CBCT) data shows that the suture staple made of the Mg alloy wire provides better mechanical support in the early postoperative period. From the single arm robot tests, it confirms that suture staples can close the wound tightly and remain stable over time. This research provides a good material selection for the automated suturing in oral and throat surgery robots.
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