An observer-based approach for the projection onto a 2d-curve under movement

Standard path control laws of autonomous vehicles use the shortest distance between the vehicle’s position and the path as a control error. In order to determine this distance, the projection point onto the path needs to be determined continuously. This requires fast algorithms that feature high numerical reliability in the field of vehicle application.This paper presents two different observer-based approaches for the projection problem. The identity observer reconstructs all states of interest for path control. The second one, a reduced observer, only possesses the curve parameter as a state and calculates the other values by algebraic formulas. Both algorithms consider the continuous movement of the vehicle, the run of the curve, and work without any approximation of the curve. Furthermore, they are applicable for arbitrary parameterized smooth curves, guarantee the required numerical stability, have short calculating time, and show good statistical properties. The performance is shown in several simulations as well as under real conditions.     

Fabrication of three-dimensional copper nanodomes as anode materials for direct methanol fuel cells

In this study, we demonstrate a novel approach for fabricating copper nanodomes (Cu-NDs) by combining of soft lithography, nanosphere lithography, physical vapor deposition (PVD) and electrochemical deposition methods. The 3D nano structures were characterized using surface microscopic techniques. The methanol oxidation activity of the Cu-NDs anode was tested by electrochemical methods in 0.1 M KOH +1 M CH₃OH solution and the results were compared with that of bulk Cu as a reference point. The results showed that very well-structured, uniformly and homogeneously distributed Cu-NDs could be fabricated using these combined methods. The peak current density related to methanol oxidation reaction increased and charge transfer resistance reduced almost three times at the Cu-NDs electrode with respect to the bulk Cu. Also, the Cu-NDs electrode has good time stability and high tolerance to CO_ads poisoning. The enhanced activity of the nanostructures was related to good intrinsic activity of Cu for this reaction and their larger available electrochemical active sites.     

Inertial sensors-based torso motion mode recognition for an active postural support brace*

ABSTRACT

In order to achieve high-level control for an active postural support brace, it is important for a wearable robot to be capable of recognizing human motion intentions. An inertial sensors-based torso motion mode recognition method is proposed in this study. The experiments are conducted to define range of torso motion, capture human motion signals by using four inertial sensors on seven healthy subjects, and utilize a classification method to achieve torso motion recognition based on human intent. Up to sixteen modes for torso motion recognition are investigated, and cascaded classification methods combining a quadratic discriminant analysis (QDA) classifier and a support vector machine (SVM) classifier are deployed. With selected cascaded classification strategies, cross-validation yielded classification accuracies of 95.18% (QDA) and 96.24% (SVM). The obtained results of the study show that inertial sensors based motion recognition is viable to achieve in high recognition accuracy which is promising for future robotic applications.     

Eliminating Dendrites and Side Reactions via a Multifunctional ZnSe Protective Layer toward Advanced Aqueous Zn Metal Batteries

The development of aqueous Zn metal batteries (AZMBs) is impeded by severe corrosion, H₂ evolution, and dendrite formation issues. In addition, the inability of AZMBs to achieve a large capacity also hinders their commercialization. Here, a multifunctional ZnSe protective layer is reported to synchronously solve the above issues. The ZnSe layer can efficiently provide anticorrosion while also suppressing hydrogen evolution. Systematic analyses of the mechanism suggest that the low Zn affinity of ZnSe and the unbalanced charge distribution at the interface can promote a uniform distribution of Zn²⁺ and accelerate Zn²⁺ migration, thus realizing dendrite-free behavior. Therefore, the Zn@ZnSe symmetric cell exhibits notable rate performance and cycling stability (1500 h). Moreover, this symmetric cell can still stabilize with a low polarization (50 mV), even at 10 mA cm⁻² with 5 mAh cm⁻². The full cell paired with MnO₂ achieves a long lifespan (1800 cycles) with a Coulombic efficiency near 100%. Therefore, this strategy for eliminating dendrites and side reactions at a high rate with a large capacity provides a promising solution for the development of AZMBs.     

Adsorption behavior of methylene blue onto titanate nanotubes

Calcined titanate nanotubes were synthesized with hydrothermal treatment of the commercial TiO₂ (Degussa P25) followed by calcination. The morphology and structures of as-prepared samples were investigated by transmission electron microscopy, X-ray diffraction and N₂ adsorption/desorption. The samples exhibited a tubular structure and a high surface area of 157.9 m²/g. The adsorption of methylene blue onto calcined titanate nanotubes was studied. The adsorption kinetics was evaluated by the pseudo-first-order, pseudo-second-order and Weber's intraparticle diffusion model. The pseudo-second-order model was the best to describe the adsorption kinetics, and intraparticle diffusion was not the rate-limiting step. The equilibrium adsorption data were analyzed with three isotherm models (Langmuir model, Freundlich model and Temkin model). The best agreement was achieved by the Langmuir isotherm with correlation coefficient of 0.993, corresponding to maximum adsorption capacity of 133.33 mg/g. The adsorption mechanism was primarily attributed to chemical sorption involving the formation of methylene blue-calcined titanate nanotubes nanocomposite, associated with electrostatic attraction in the initial bulk diffusion.     

Heterostructures of 2D Molybdenum Dichalcogenide on 2D Nitrogen-Doped Carbon: Superior Potassium-Ion Storage and Insight into Potassium Storage Mechanism

Constructing 2D heterostructure materials by stacking different 2D materials can combine the merits of the individual building blocks while eliminating their shortcomings. Dichalcogenides are attractive anodes for potassium-ion batteries (KIBs) due to their high theoretical capacity. However, the practical application of dichalcogenide is greatly hampered by the poor electrochemical performance due to sluggish kinetics of K⁺ insertion and the electrode structure collapse resulting from the large K⁺ insertion. Herein, heterostructures of 2D molybdenum dichalcogenide on 2D nitrogen-doped carbon (MoS₂, MoSe₂-on-NC) are prepared to boost their potassium storage performance. The unique 2D heterostructures possess built-in heterointerfaces, facilitating K⁺ diffusion. The robust chemical bonds (C S, C Se, C Mo bonds) enhance the mechanical strength of electrodes, thus suppressing the volume expansion. The 2D N-doped carbon nanosheets interconnected as a 3D structure offer a fast diffusion path for electrons. Benefitting from these merits, both the MoS₂-on-NC and the MoSe₂-on-NC exhibit unprecedented cycle life. Moreover, the electrochemical reaction mechanism of MoSe₂ is revealed during the process of potassiation and depotassiation.     

Theoretical study on the effect of an O vacancy on the hydrogen storage properties of the LaFeO3 (010) surface

Based on first-principles calculations, we investigated the hydrogen adsorption dissociation on the LaFeO₃ (010) surface with an O vacancy. It was confirmed that H₂ molecules have four kinds of adsorption modes on LaFeO₃ (010) surfaces with an O vacancy. First, H atoms are adsorbed on O atoms to form an OH group. Second, H atoms are adsorbed on Fe atoms to form FeH bonds. Third, two H atoms are adsorbed on the same O atom to form H₂O. Fourth, two H atoms are adsorbed on the same Fe atom and it is a new type of adsorption, which does not exist in the ideal surface. The main channel of dissociative adsorption is the fourth adsorption mode of OH and FeH, where the H atoms adsorbed on the surface of Fe can be easily diffused into O atoms. Charge population analysis showed that increasing the O vacancy enhanced the interaction between FeH. In the system containing O vacancies adsorbed H atoms in the top of Fe to diffuse to the top of O need to overcome the energy barrier decreased from 0.968 eV to 0.794 eV. So the existence of an O vacancy enhances the hydrogen absorption properties of Fe atoms in LaFeO₃.     

Distributed cooperative localization with lower communication path requirements

Free communication topology for cooperative localization cannot be guaranteed in real scenarios. A flexible distributed algorithm aiming at reducing communication path requirements is presented under EKF. In this algorithm, not all agents need to communicate with each other instantaneously for covariance update and it has no adverse effect on state update. We prove that the missed covariance update caused by communication absence can be exactly corrected when it is required. Additionally, we prove that this algorithm is adaptive to most available one-way communication topologies. The equivalent localization performance to free connection communication is achieved.     

Formal verification of behaviour networks including sensor failures

The paper deals with the problem of verifying behaviour-based control systems. Although failures in sensor hardware and software can have strong influences on the robot’s operation, they are often neglected in the verification process. Instead, perfect sensing is assumed. Therefore, this paper provides an approach for modelling the sensor chain in a formal way and connecting it to the formal model of the control system. The resulting model can be verified using model checking techniques, which is shown on the examples of the control systems of an autonomous indoor robot and an autonomous off-road robot.     

面向人机融合的智能动力下肢假肢研究现状与挑战

智能动力下肢假肢在残疾人生活中起着越来越重要的作用.解决人-智能假肢-环境融合中的关键科学问题是实现假肢穿戴者安全、流畅运动的必要条件.本文针对此问题,综述了面向人机融合的智能动力下肢假肢研究,包括智能动力下肢假肢的仿生结构和控制方法、人体运动意图识别、复杂环境下的人-智能假肢融合、以及用于下肢假肢的感知替代和反馈,深入探讨了智能动力下肢假肢人机融合研究中所面临的挑战和问题,最后,本文对该领域的未来发展方向进行了展望和总结.