Modular Control Research Articles

Benzylic C−H Radical Sulfation by Persulfates

AbstractSulfation is a highly valuable pathological and physiological process, yet it is often underappreciated considering the rather difficult accessibility of organosulfates. O‐sulfonation (O−SO3), a conventional and still common way to make organosulfates, restricts its applicability to hydroxyl compounds and therein lies a major challenge of library construction. Here, we describe a benzylic C−H radical sulfation with persulfates via C−O bond formation. This strategy leverages modular control over the reactivity of persulfates and the stability of sulfate radicals by coutercations. K+/NH4+ stabilized sulfate radicals act as the oxidant to generate carbon‐centered radicals from substrates, and activation of persulfates by n‐NBu4+ provides O−O resource pool to facilitate C−OSO3− bond formation via a bimolecular homolytic substitution (SH2) process.

Construction Method of a Digital-Twin Simulation System for SCARA Robots Based on Modular Communication

Due to the high cost of robots, the algorithm testing cost for physical robots is high, and the construction of motion control programs is complex, with low operation fault tolerance. To address this issue, this paper proposes a low-cost, cross-platform SCARA robot digital-twin simulation system based on the concept of digital twins. This method establishes a 5D architecture based on the characteristics of different platforms, classifies data and integrates functions, and designs a data-processing layer for motion trajectory calculation and data storage for a virtual-reality robot. To address the complexity of data interaction under different cross-platform communication forms, an editable, modular, cross-platform communication system is constructed, and various control commands are encapsulated into simple programming statements for easy invocation. Experimental results showed that, based on modular communication control, users can accurately control data communication and synchronous motion between virtual and physical models using simple command statements, reducing the development cost of control algorithms. Meanwhile, the virtual-robot simulation system, as a data mapping of the real experimental platform, accurately simulated the physical robot’s operating state and spatial environment. The robot algorithms tested using the virtual simulation system can be successfully applied to real robot platforms, accurately reproducing the operating results of the virtual system.

Autonomous ecologies of construction: Collaborative modular robotic material eco-systems with deep multi-agent reinforcement learning

To address the unprecedented challenges of construction pressurized by the global climate crisis, housing shortage, and growing shortage of skilled labor, this research presents a radical shift in the construction lifecycle of buildings, from linear processes that produce static continuous buildings to interrelational processes linking adaptative eco-systems of collaborative robots and reconfigurable building parts. Inspired by natural builders, the interdisciplinary field of collective robotic construction (CRC) offers the potential for scalable, adaptive, and resilient construction with simple robots. We establish a design framework for autonomous collaborative robotic construction (ACRC) through modular robotic material eco-systems (MRMES) trained with deep multi-agent reinforcement learning (DMARL). This involves the integration of three core aspects: (1) modular robotic material eco-systems (2) cyber-physical simulation and control with bidirectional feedback (3) adaptive intelligence through deep multi-agent reinforcement learning. The framework is implemented through three comparable case studies for collaborative modular robotic assembly of reconfigurable building parts.

Nature's All-in-One: Multitasking Robots Inspired by Dung Beetles.

Dung beetles impressively coordinate their 6 legs to effectively roll large dung balls. They can also roll dung balls varying in the weight on different terrains. The mechanisms underlying how their motor commands are adapted to walk and simultaneously roll balls (multitasking behavior) under different conditions remain unknown. This study unravels the mechanisms of how dung beetles roll dung balls and adapt their leg movements to stably roll balls over different terrains for multitasking robots. A modular neural-based loco-manipulation control inspired by and based on ethological observations of the ball-rolling behavior of dung beetles is synthesized. The proposed neural-based control contains a central pattern generator (CPG) module, a pattern formation network (PFN) module, and a robot orientation control (ROC) module. The integrated control mechanisms can control a dung beetle-like robot (ALPHA) with biomechanical feet to perform adaptive (multitasking) loco-manipulation (walking and ball-rolling) on various terrains (flat and uneven). It can deal with different ball weights (2.0 and 4.6kg) and ball types (soft and rigid). The control mechanisms can serve as guiding principles for solving sensory-motor coordination for multitasking robots. Furthermore, this study contributes to biological research by enhancing the understanding of sensory-motor coordination for adaptive (multitasking) loco-manipulation behavior in animals.

Benzylic C-H Radical Sulfation by Persulfates.

Sulfation is a highly valuable pathological and physiological process, yet it is often underappreciated considering the rather difficult accessibility of organosulfates. O-sulfonation (O-SO3), a conventional and still common way to make organosulfates, restricts its applicability to hydroxyl compounds and therein lies a major challenge of library construction. Here, we describe a benzylic C-H radical sulfation with persulfates via C-O bond formation. This strategy leverages modular control over the reactivity of persulfates and the stability of sulfate radicals by coutercations. K+/NH4+ stabilized sulfate radicals act as the oxidant to generate carbon-centered radicals from substrates, and activation of persulfates by NBu4+ provides O-O resource pool to facilitate C-OSO3- bond formation via a bimolecular homolytic substitution (SH2) process.

Kinematic-Muscular Synergies Describe Human Locomotion with a Set of Functional Synergies.

Kinematics, kinetics and biomechanics of human gait are widely investigated fields of research. The biomechanics of locomotion have been described as characterizing muscle activations and synergistic control, i.e., spatial and temporal patterns of coordinated muscle groups and joints. Both kinematic synergies and muscle synergies have been extracted from locomotion data, showing that in healthy people four-five synergies underlie human locomotion; such synergies are, in general, robust across subjects and might be altered by pathological gait, depending on the severity of the impairment. In this work, for the first time, we apply the mixed matrix factorization algorithm to the locomotion data of 15 healthy participants to extract hybrid kinematic-muscle synergies and show that they allow us to directly link task space variables (i.e., kinematics) to the neural structure of muscle synergies. We show that kinematic-muscle synergies can describe the biomechanics of motion to a better extent than muscle synergies or kinematic synergies alone. Moreover, this study shows that at a functional level, modular control of the lower limb during locomotion is based on an increased number of functional synergies with respect to standard muscle synergies and accounts for different biomechanical roles that each synergy may have within the movement. Kinematic-muscular synergies may have impact in future work for a deeper understanding of modular control and neuro-motor recovery in the medical and rehabilitation fields, as they associate neural and task space variables in the same factorization. Applications include the evaluation of post-stroke, Parkinson's disease and cerebral palsy patients, and for the design and development of robotic devices and exoskeletons during walking.

Design and Control of Modular Compliant XY Positioning stage

The modular design and controller implementation of compliant XY stage having large motion range are presented.The design involves symmetric parallel kinematic configuration using compound parallelogram flexure module (CPM) with input-output decoupling properties. The architectural parameters are determined based on the performance metrics such as stiffness, resonance frequency and motion range etc. The FEA simulation predicts the range of motion of 12 mm along each working axes.A prototype is developed to assess the performances of the stage. The results exhibit the small deviation between the two working axes which reflects the better decoupled motions.The PID controller is implemented to achieve the accuracy of positioning with submicron resolution.

Mechanically activated and deactivated ion transport across nanopores with heterogeneous surface charge distributions

To mimic the intricate and adaptive functionalities of biological ion channels, electrohydrodynamic ion transport has been studied extensively, albeit mostly, across uniformly charged nanochannels. Here, we analyze the ion transport under coupled electric field and pressure across heterogeneously charged nanopores with oppositely charged sections on their lateral surface. We only consider such pores with symmetric hourglass-like and cylindrical shapes to focus on the effects of the non-uniform surface charge distribution. Finite-element simulations of a continuum model demonstrate that a pressure applied in either direction of the pore-axis equally suppresses or amplifies the ionic conductance, depending on the electric field polarity, by distorting the quasi-static distribution of ions in the pore. The resulting anomalous mechanical deactivation and activation of ionic current under opposite voltage biases exhibit the functional modularity of our setup, while their intensities are highly tunable, substantially greater than those of analogous behaviors in other nanochannels, and fundamentally correlated to ionic current rectification (ICR) in our pores. A detailed study of ICR subsequently reveals its counterintuitive non-monotonous variations, in the pores, with the magnitude of applied voltage and the pore length, that can help optimize their diode-like behavior. We further illustrate that while the hourglass-shaped nanopores yield the more efficient mechanical suppressors of ion transport, their cylindrical analogs are the superior rectifiers and mechanical amplifiers of ion conduction. Therefore, this article provides a blueprint for the strategic design of nanofluidic circuits to attain a robust, modular, and tunable control of ion transport under external electrical and mechanical stimuli.

Adaptive Modular Neural Control for Online Gait Synchronization and Adaptation of an Assistive Lower-Limb Exoskeleton.

Gait synchronization has attracted significant attention in research on assistive lower-limb exoskeletons because it can circumvent conflicting movements and improve the assistance performance. This study proposes an adaptive modular neural control (AMNC) for online gait synchronization and the adaptation of a lower-limb exoskeleton. The AMNC comprises several distributed and interpretable neural modules that interact with each other to effectively exploit neural dynamics and adopt feedback signals to quickly reduce the tracking error, thereby smoothly synchronizing the exoskeleton movement with the user's movement on the fly. Taking state-of-the-art control as the benchmark, the proposed AMNC provides further improvements in the locomotion phase, frequency, and shape adaptation. Accordingly, under the physical interaction between the user and the exoskeleton, the control can reduce the optimized tracking error and unseen interaction torque by up to 80% and 30%, respectively. Accordingly, this study contributes to the advancement of exoskeleton and wearable robotics research in gait assistance for the next generation of personalized healthcare.

HeartMate 3 driveline damage by gradual corrosion due to liquid infiltration: a case report.

A 31-year-old man with a HeartMate 3 was admitted with a "Driveline Communication Fault" alarm due to liquid infiltration. Eleven months earlier, the connector between the modular and pump cables had gotten wet when he was taking a shower. The cable connector was dried immediately, and no alarm had been observed during follow-up. Subsequently, the modular cable and system controller were replaced, with corrosion found on the modular cable connector. The "Communication Fault" alarm recurred, and complete damage to the communication cables was discovered. The pump was replaced, and the removed pump cable connector showed corrosion as well. If the driveline connector gets wet, the multidisciplinary team should discuss if it should be immediately disconnected and dried, averting the need for future pump replacements due to corrosion.

Modular control architecture for safe marine navigation: Reinforcement learning with predictive safety filters

Many autonomous systems are safety-critical, making it essential to have a closed-loop control system that satisfies constraints arising from underlying physical limitations and safety aspects in a robust manner. However, this is often challenging to achieve for real-world systems. For example, autonomous ships at sea have nonlinear and uncertain dynamics and are subject to numerous time-varying environmental disturbances such as waves, currents, and wind. There is increasing interest in using machine learning-based approaches to adapt these systems to more complex scenarios, but there are few standard frameworks that guarantee the safety and stability of such systems. Recently, predictive safety filters (PSF) have emerged as a promising method to ensure constraint satisfaction in learning-based control, bypassing the need for explicit constraint handling in the learning algorithms themselves. The safety filter approach leads to a modular separation of the problem, allowing the use of arbitrary control policies in a task-agnostic way. The filter takes in a potentially unsafe control action from the main controller and solves an optimization problem to compute a minimal perturbation of the proposed action that adheres to both physical and safety constraints. In this work, we combine reinforcement learning (RL) with predictive safety filtering in the context of marine navigation and control. The RL agent is trained on path-following and safety adherence across a wide range of randomly generated environments, while the predictive safety filter continuously monitors the agents' proposed control actions and modifies them if necessary. The combined PSF/RL scheme is implemented on a simulated model of Cybership II, a miniature replica of a typical supply ship. Safety performance and learning rate are evaluated and compared with those of a standard, non-PSF, RL agent. It is demonstrated that the predictive safety filter is able to keep the vessel safe, while not prohibiting the learning rate and performance of the RL agent.

Crop health assessment through hierarchical fuzzy rule-based status maps

Precision agriculture is evolving toward a contemporary approach that involves multiple sensing techniques to monitor and enhance crop quality while minimizing losses and waste of no longer considered inexhaustible resources, such as soil and water supplies. To understand crop status, it is necessary to integrate data from heterogeneous sensors and employ advanced sensing devices that can assess crop and water status. This study presents a smart monitoring approach in agriculture, involving sensors that can be both stationary (such as soil moisture sensors) and mobile (such as sensor-equipped unmanned aerial vehicles). These sensors collect information from visual maps of crop production and water conditions, to comprehensively understand the crop area and spot any potential vegetation problems. A modular fuzzy control scheme has been designed to interpret spectral indices and vegetative parameters and, by applying fuzzy rules, return status maps about vegetation status. The rules are applied incrementally per a hierarchical design to correlate lower-level data (e.g., temperature, vegetation indices) with higher-level data (e.g., vapor pressure deficit) to robustly determine the vegetation status and the main parameters that have led to it. A case study was conducted, involving the collection of satellite images from artichoke crops in Salerno, Italy, to demonstrate the potential of incremental design and information integration in crop health monitoring. Subsequently, tests were conducted on vineyard regions of interest in Teano, Italy, to assess the efficacy of the framework in the assessment of plant status and water stress. Indeed, comparing the outcomes of our maps with those of cutting-edge machine learning (ML) semantic segmentation has indeed revealed a promising level of accuracy. Specifically, classification performance was compared to the output of conventional ML methods, demonstrating that our approach is consistent and achieves an accuracy of over 90% throughout various seasons of the year.

Muscle Synergy Analysis as a Tool for Assessing the Effectiveness of Gait Rehabilitation Therapies: A Methodological Review and Perspective.

According to the modular hypothesis for the control of movement, muscles are recruited in synergies, which capture muscle coordination in space, time, or both. In the last two decades, muscle synergy analysis has become a well-established framework in the motor control field and for the characterization of motor impairments in neurological patients. Altered modular control during a locomotion task has been often proposed as a potential quantitative metric for characterizing pathological conditions. Therefore, the purpose of this systematic review is to analyze the recent literature that used a muscle synergy analysis of neurological patients' locomotion as an indicator of motor rehabilitation therapy effectiveness, encompassing the key methodological elements to date. Searches for the relevant literature were made in Web of Science, PubMed, and Scopus. Most of the 15 full-text articles which were retrieved and included in this review identified an effect of the rehabilitation intervention on muscle synergies. However, the used experimental and methodological approaches varied across studies. Despite the scarcity of studies that investigated the effect of rehabilitation on muscle synergies, this review supports the utility of muscle synergies as a marker of the effectiveness of rehabilitative therapy and highlights the challenges and open issues that future works need to address to introduce the muscle synergies in the clinical practice and decisional process.

Modulating the morphology and protonation degree of chitosan coatings for enabling controlled fabric functionalization

Chitosan (CS), a versatile biopolymer known for its diverse bioactivity, is commonly used as a coating or finishing agent to enhance fabric performance and broaden their applications. However, conventional methods for introducing CS coating layer on the fabrics often relies on using composition to control their functionality, limiting the ability to tailor properties for specific needs. In this study, we introduce an innovative coating platform utilizing drying, ionic gelation, or a combination of both to control the morphology and amino-protonation degree of CS. This approach allows the development of three distinct functional CS coatings from the same material composition. The method is effectively applied to cotton and polylactic acid (PLA)-based non-woven fabrics, preserving the permeability, breathability, and mechanical properties of the substrates. By varying processing conditions, it is found that CS coatings can impart distinct functions to the fabrics upon their morphology, such as attaining high degree of hydrophobicity (with a water contact angle reaching 129°), broad-spectrum antibacterial activity (>99.99 %) for the sample prepared by combined drying and ionic gelation methods. Additionally, our CS-coated fabrics can exhibit good biocompatibility, as demonstrated by cytocompatibility and histocompatibility evaluations, while excellent anti-adhesive properties and healing performance in infected wound models in rats can be obtained with the presence of CS microsphere. Our methods are straightforward and potentially scalable, enabling modular control over the functionality of CS-coated fabrics to meet diverse requirements. This work offers a promising strategy for modifying fabric properties with CS coatings, making it suitable for various applications such as facial masks, dressings, and antibacterial textiles.

Fault Tolerance Analysis and Optimization of Centralized Control Platform Based on Artificial Intelligence and Optimization Algorithm

To enhance the reliability and self-healing of the system, the research on fault tolerance of the reconfigurable modular centralized control center is its development trend. Most of the previous research has focused on hardware redundancy. Improving fault tolerance performance is an essential topic in the research of centralized control platforms. Firstly, the problem of centralized fault tolerance in the working configuration of a reconfigurable manipulator is studied. The effect of each hinge on fault tolerance in the existing configuration is studied with the criterion of manoeuvrability and tolerable space. The fault module was first modelled to represent the system architecture information. A modular motion rule based on autonomous recombination technology is proposed. A self-organizing deformation algorithm with fault tolerance is studied. The fault tolerance of the motion pairs is compensated by adding a small number of motion pairs to ensure the configuration characteristics. With the addition of a failure compensation device, the joint’s range of motion was reduced, and the fault tolerance rate was enhanced. After the failure of the robot arm, the fault tolerant control method can still ensure that the robot arm can perform work in its tolerable working space. The test results show that the fault tolerance analysis method is practical and feasible. It lays a theoretical foundation for the application in aerospace, industry and other fields.

Triple Activation Facilitates Modular and Stoichiometric Control over Cocrystals of Phenazine

Triple Activation Facilitates Modular and Stoichiometric Control over Cocrystals of Phenazine

Exploring plant-derived phytochrome chaperone proteins for light-switchable transcriptional regulation in mammals

Synthetic biology applications require finely tuned gene expression, often mediated by synthetic transcription factors (sTFs) compatible with the human genome and transcriptional regulation mechanisms. While various DNA-binding and activation domains have been developed for different applications, advanced artificially controllable sTFs with improved regulatory capabilities are required for increasingly sophisticated applications. Here, in mammalian cells and mice, we validate the transactivator function and homo-/heterodimerization activity of the plant-derived phytochrome chaperone proteins, FHY1 and FHL. Our results demonstrate that FHY1/FHL form a photosensing transcriptional regulation complex (PTRC) through interaction with the phytochrome, ΔPhyA, that can toggle between active and inactive states through exposure to red or far-red light, respectively. Exploiting this capability, we develop a light-switchable platform that allows for orthogonal, modular, and tunable control of gene transcription, and incorporate it into a PTRC-controlled CRISPRa system (PTRCdcas) to modulate endogenous gene expression. We then integrate the PTRC with small molecule- or blue light-inducible regulatory modules to construct a variety of highly tunable systems that allow rapid and reversible control of transcriptional regulation in vitro and in vivo. Validation and deployment of these plant-derived phytochrome chaperone proteins in a PTRC platform have produced a versatile, powerful tool for advanced research and biomedical engineering applications.

A modular decentralized control system of multi-connected processes in the presence of structural disturbances

The object of research is digital systems of decentralized control of quasi-stationary multi-connected processes taking into account structural disturbances. It was determined that the promising development of decentralized control of multi-connected processes is research related to considering the possibility of its application for real situations of partial disruption of interconnections between subsystems in multidimensional stochastic systems. Such studies are not sufficiently developed today, therefore the topic of the proposed work should be considered relevant from the theoretical and applied points of view. The problem of decentralized management of multi-connected stochastic objects is formalized, taking into account the internal relationships between their local subsystems of the system. A method of decentralization of a multi-connected system is proposed, the advantage of which is the use of simple computational procedures of transformation and permutation of matrix elements of the global model. The concept of c-robustness of a multi-connected dynamic system is introduced, which guarantees its asymptotic stability and suboptimality in the event of structural disturbances. Methods of robust decentralized control are proposed for cases of explicit and implicit tasks of interconnections between local subsystems. The proposed methods have a certain advantage in comparison with the method of local control coordination, which consists in increasing the efficiency of decentralized control with a guaranteed level of suboptimality. Experimental modeling of the considered method for models of multi-connected chemical-technological systems describing the relationship between the input and output parameters of the processes was carried out. During the simulation, the global system was decomposed into 4 local subsystems. Modeling of the task of decentralized management was also carried out according to the well-known method of coordination, based on finding the values of uncertain multipliers. A comparative analysis of the results obtained using this standard method and the proposed robust methods shows the superiority of the latter.

Muscle Synergy during Wrist Movements Based on Non-Negative Tucker Decomposition.

Modular control of the muscle, which is called muscle synergy, simplifies control of the movement by the central nervous system. The purpose of this study was to explore the synergy in both the frequency and movement domains based on the non-negative Tucker decomposition (NTD) method. Surface electromyography (sEMG) data of 8 upper limb muscles in 10 healthy subjects under wrist flexion (WF) and wrist extension (WE) were recorded. NTD was selected for exploring the multi-domain muscle synergy from the sEMG data. The results showed two synergistic flexor pairs, Palmaris longus-Flexor Digitorum Superficialis (PL-FDS) and Extensor Carpi Radialis-Flexor Carpi Radialis (ECR-FCR), in the WF stage. Their spectral components are mainly in the respective bands 0-20 Hz and 25-50 Hz. And the spectral components of two extensor pairs, Extensor Digitorum-Extensor Carpi Ulnar (ED-ECU) and Extensor Carpi Radialis-Brachioradialis (ECR-B), are mainly in the respective bands 0-20 Hz and 7-45 Hz in the WE stage. Additionally, further analysis showed that the Biceps Brachii (BB) muscle was a shared muscle synergy module of the WE and WF stage, while the flexor muscles FCR, PL and FDS were the specific synergy modules of the WF stage, and the extensor muscles ED, ECU, ECR and B were the specific synergy modules of the WE stage. This study showed that NTD is a meaningful method to explore the multi-domain synergistic characteristics of multi-channel sEMG signals. The results can help us to better understand the frequency features of muscle synergy and shared and specific synergies, and expand the study perspective related to motor control in the nervous system.

Fault-Tolerant Phototaxis of a Modular System Inspired by Gonium pectorale Using Phase-Based Control

In this study, we proposed a model for modular robots in which autonomous decentralized modules adaptively organize their behavior. The phototaxis of Gonium pectorale, a species of volvocine algae, was modeled as a modular system, and a fault-tolerant modular control method of phototaxis was proposed for it. The proposed method was based on the rotation phase of the colony and adaptively adjusted an internal response-related parameter to enhance the fault tolerance of the system. Compared to a constant parameter approach, the simulation results demonstrated a significant improvement in the phototaxis time for positive and negative phototaxis during module failures. This method contributes to achieving autonomous, decentralized, and purposeful mediation of the modules necessary for controlling modular robots.