JAUS to EtherCAT Bridge: Toward Real-Time and Deterministic Joint Architecture for Unmanned Systems

The Joint Architecture for Unmanned Systems (JAUS) is a communication standard that allows for interoperability between Unmanned Vehicles (UVs). Current research indicates that JAUS-compliant systems do not meet real-time performance guidelines necessary for internal systems in UVs. However, there is a lack of quantitative data illustrating the performance shortcomings of JAUS or clear explanations on what causes these performance issues or comparisons with existing internal communication systems. In this research, we first develop a basic C++ implementation of JAUS and evaluate its performance with quantitative data and compare the results with published performance data of Controller Area Network (CAN) to determine the feasibility of the JAUS standard. Our results indicate that the main reason of JAUS’s poor performance lies in the latency inherent in the hierarchical structure of JAUS and the overhead of User Datagram Protocol (UDP) messages, which has been used with JAUS and is slower than the high-speed CAN. Additionally, UDP has no scheduling mechanism, which makes it virtually impossible to guarantee messages meeting their deadlines. Considering the slow and nondeterministic JAUS communication from subsystems to components, which is JAUS Level 3 compliance, we then propose a solution by bringing Ethernet for Control Automation Technology (EtherCAT) to add speed, deterministic feature, and security. The JAUS-EtherCAT mapping, which we called a JEBridge, is implemented into nodes and components. Both quantitative and qualitative results are provided to show that JEBridge and JAUS Level 3 compliance can bring not only interoperability but also reasonable performance to UVs

Integrated Navigation System Design for Micro Planetary Rovers: Comparison of Absolute Heading Estimation Algorithms and Nonlinear Filtering

This paper provides algorithms to fuse relative and absolute microelectromechanical systems (MEMS) navigation sensors, suitable for micro planetary rovers, to provide a more accurate estimation of navigation information, specifically, attitude and position. Planetary rovers have extremely slow speed (~1 cm/s) and lack conventional navigation sensors/systems, hence the general methods of terrestrial navigation may not be applicable to these applications. While relative attitude and position can be tracked in a way similar to those for ground robots, absolute navigation information is hard to achieve on a remote celestial body, like Moon or Mars, in contrast to terrestrial applications. In this study, two absolute attitude estimation algorithms were developed and compared for accuracy and robustness. The estimated absolute attitude was fused with the relative attitude sensors in a framework of nonlinear filters. The nonlinear Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) were compared in pursuit of better accuracy and reliability in this nonlinear estimation problem, using only on-board low cost MEMS sensors. Experimental results confirmed the viability of the proposed algorithms and the sensor suite, for low cost and low weight micro planetary rovers. It is demonstrated that integrating the relative and absolute navigation MEMS sensors reduces the navigation errors to the desired level

New Condensation Polymer Precursors Containing Consecutive Silicon Atoms—Decaisopropoxycyclopentasilane and Dodecaethoxyneopentasilane—And Their Sol–Gel Polymerization

The sol−gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon−organic composites. The development of new sol−gel precursors is very important for obtaining new types of sol−gel products. New condensation polymer precursors containing consecutive silicon atoms—decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)—were synthesized for the preparation of polysilane−polysiloxane material. The CPS and NPS xerogels were prepared by the sol−gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N2 physisorption measurements (Brunauer−Emmett−Teller; BET and Brunauer-Joyner-Halenda; BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol−gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane−polysiloxane

Drought Tolerance Evaluation and Growth Response of Chinese Cabbage Seedlings to Water Deficit Treatment

Drought is a significant climatic factor that significantly affects the production of Chinese cabbage, a crop that is highly susceptible to drought stress. The development and cultivation of drought-tolerant varieties could be a viable strategy to minimize the damage caused by climate change and ensure stable production of Chinese cabbage. This requires the implementation of technologies for early evaluation and selection of a plethora of resources. In this study, we screened 100 varieties and breeding resources for drought tolerance under a water deficit treatment at the seedling stage. We also evaluated the growth response of Chinese cabbage varieties and breeding resources under water deficit treatment and selected drought-tolerant Chinese cabbage genotypes. We confirmed that the visual score for wilting, which evaluates the wilting response during the recovery process of Chinese cabbage seedlings through water deficit treatment and re-watering, can be used as an indicator for evaluating tolerance to drought stress. The visual score for wilting showed a high correlation with major traits representing drought tolerance. Our findings highlight the need for an integrated approach that considers various environmental conditions, varieties, and lines to select and develop drought-tolerant varieties. We selected ‘18-FH112-1’ and ‘18-FH112-1-2’ among others, and these germplasms will be useful resources for drought tolerance breeding. This study provides a foundation for future efforts to develop drought-tolerant Chinese cabbage varieties, thereby contributing to the stable production of this crucial crop

Real-Time and Deterministic Joint Architecture for Unmanned Systems

The Joint Architecture for Unmanned Systems (JAUS) is a communication standard that allows for interoperability between Unmanned Vehicles (UVs). Current research indicates that JAUS-compliant systems do not meet real-time performance guidelines necessary for internal systems in UVs. However, there is a lack of quantitative data illustrating the performance shortcomings of JAUS or clear explanations on what causes these performance issues or comparisons with existing internal communication systems. In this research, we first develop a basic C++ implementation of JAUS and evaluate its performance with quantitative data and compare the results with published performance data of Controller Area Network (CAN) to determine the feasibility of the JAUS standard. Our results indicate that the main reason of JAUS's poor performance lies in the latency inherent in the hierarchical structure of JAUS and the overhead of User Datagram Protocol (UDP) messages, which has been used with JAUS and is slower than the high-speed CAN. Additionally, UDP has no scheduling mechanism, which makes it virtually impossible to guarantee messages meeting their deadlines. Considering the slow and nondeterministic JAUS communication from subsystems to components, which is JAUS Level 3 compliance, we then propose a solution by bringing Ethernet for Control Automation Technology (EtherCAT) to add speed, deterministic feature, and security. The JAUS-EtherCAT mapping, which we called a JEBridge, is implemented into nodes and components. Both quantitative and qualitative results are provided to show that JEBridge and JAUS Level 3 compliance can bring not only interoperability but also reasonable performance to UVs

Complex ligand adsorption on 3D atomic surfaces of synthesized nanoparticles investigated by machine-learning accelerated ab initio calculation

Nanoparticle surfaces are passivated by surface-bound ligands, and their adsorption on synthesized nanoparticles is complicated because of the intricate and low-symmetry surface structures. Thus, it is challenging to precisely investigate ligand adsorption on synthesized nanoparticles. Here, we applied machine-learning-accelerated ab initio calculation to experimentally resolved 3D atomic structures of Pt nanoparticles to analyze the complex adsorption behavior of polyvinylpyrrolidone (PVP) ligands on synthesized nanoparticles. Different angular configurations of large-sized ligands are thoroughly investigated to understand the adsorption behavior on various surface-exposed atoms with intrinsic low-symmetry. It is revealed that the ligand binding energy (E-ads) of the large-sized ligand shows a weak positive relationship with the generalized coordination number((CN)) . This is because the strong positive relationship of short-range direct bonding (E-bind) is attenuated by the negative relationship of long-range van der Waals interaction (E-vdW). In addition, it is demonstrated that the PVP ligands prefer to adsorb where the long-range vdW interaction with the surrounding surface structure is maximized. Our results highlight the significant contribution of vdW interactions and the importance of the local geometry of surface atoms to the adsorption behavior of large-sized ligands on synthesized nanoparticle surfaces.11Nscopu

Complex ligand adsorption on 3D atomic surfaces of synthesized nanoparticles investigated by machine-learning accelerated ab initio calculation

Nanoparticle surfaces are passivated by surface-bound ligands, and their adsorption on synthesized nanoparticles is complicated because of intricate and low-symmetry surface structures. Thus, it is challenging to precisely investigate ligand adsorption on synthesized nanoparticles. Here, we applied a machine-learning-accelerated ab-initio calculation into experimentally resolved 3D atomic structures of Pt nanoparticles to analyze the complex adsorption behavior of polyvinylpyrrolidone (PVP) ligands on synthesized nanoparticles. Different angular configurations of the large-sized ligands are thoroughly investigated to understand adsorption behaviors onto the various surface-exposed atoms with intrinsic low-symmetry. It is revealed that long-range van der Waals interaction (EvdW) shows weak negative relationship against generalized coordination number (-CN-), in contrast to the positive relationship in short-range direct bonding (Ebind), which attenuates the correlation between ligand binding energy (Eads) and -CN-. In addition, the PVP ligands favor to adsorb at which the long-range vdW interaction with surrounding surface structure is maximized. Our results highlight the significant contribution of vdW interactions and importance of local geometry of surface atoms to adsorption behavior of large-sized ligands on synthesized nanoparticle surfaces