Continuous Contact Research Articles

Multibody dynamics in robotics with focus on contact events

Abstract Multibody dynamics methodologies have been fundamental tools utilized to model and simulate robotic systems that experience contact conditions with the surrounding environment, such as in the case of feet and ground interactions. In addressing such problems, it is of paramount importance to accurately and efficiently handle the large body displacement associated with locomotion of robots, as well as the dynamic response related to contact-impact events. Thus, a generic computational approach, based on the Newton–Euler formulation, to represent the gross motion of robotic systems, is revisited in this work. The main kinematic and dynamic features, necessary to obtain the equations of motion, are discussed. A numerical procedure suitable to solve the equations of motion is also presented. The problem of modeling contacts in dynamical systems involves two main tasks, namely, the contact detection and the contact resolution, which take into account for the kinematics and dynamics of the contacting bodies, constituting the general framework for the process of modeling and simulating complex contact scenarios. In order to properly model the contact interactions, the contact kinematic properties are established based on the geometry of contacting bodies, which allow to perform the contact detection task. The contact dynamics is represented by continuous contact force models, both in terms of normal and tangential contact directions. Finally, the presented formulations are demonstrated by the application to several robotics systems that involve contact and impact events with surrounding environment. Special emphasis is put on the systems’ dynamic behavior, in terms of performance and stability.

Enhancing energy‐efficient sleep scheduling for Narrowband Internet of Things devices in coordinated 5G networks within smart environments

SummaryThis research project takes on a crucial role in the quickly changing field of integrated 5G networks inside smart environments by concentrating on the creation of an extremely effective sleep scheduling system designed especially for Narrowband Internet of Things (NB‐IoT) devices. This work introduces a unique method for precisely controlling the nodes' sleep schedules through the use of convolutional neural network (CNN) architecture, which optimizes both energy usage and operating patterns. The principal goal still stands to guarantee the extended lifetime of operation and dependability of NB‐IoT devices in the larger framework of intelligent ecosystems driven by synchronized 5G networks. To achieve its objectives, the research explores a number of complex domains and employs cutting‐edge technologies and techniques, such as CNN‐based pattern recognition. This method's real‐time component is essential since it allows for prompt modifications to sleep schedules in order to optimize energy savings. Further boosting the devices' effectiveness and flexibility is continuous contact with a central server, which guarantees that the devices are updated with the most recent data and instructions. Essentially, the main objective of this study is to greatly increase the energy economy and operational lifetime of NB‐IoT devices, which will allow for stable and long‐lasting IoT deployments in the context of 5G networks in intelligent settings. This advancement is not only a boon for businesses and industries leveraging IoT technology but also a substantial step toward building smarter, more energy‐efficient, and resilient smart ecosystems that benefit society as a whole.

"So at least now I know how to deal with things myself, what I can do if it gets really bad again"-experiences with a long-term cross-sectoral advocacy care and case management for severe multiple sclerosis: a qualitative study.

Persons with severe Multiple Sclerosis (PwsMS) face complex needs and daily limitations that make it challenging to receive optimal care. The implementation and coordination of health care, social services, and support in financial affairs can be particularly time consuming and burdensome for both PwsMS and caregivers. Care and case management (CCM) helps ensure optimal individual care as well as care at a higher-level. The goal of the current qualitative study was to determine the experiences of PwsMS, caregivers and health care specialists (HCSs) with the CCM. In the current qualitative sub study, as part of a larger trial, in-depth semi-structured interviews with PwsMS, caregivers and HCSs who had been in contact with the CCM were conducted between 02/2022 and 01/2023. Data was transcribed, pseudonymized, tested for saturation and analyzed using structuring content analysis according to Kuckartz. Sociodemographic and interview characteristics were analyzed descriptively. Thirteen PwsMS, 12 caregivers and 10 HCSs completed interviews. Main categories of CCM functions were derived deductively: (1) gatekeeper function, (2) broker function, (3) advocacy function, (4) outlook on CCM in standard care. Subcategories were then derived inductively from the interview material. 852 segments were coded. Participants appreciated the CCM as a continuous and objective contact person, a person of trust (92 codes), a competent source of information and advice (on MS) (68 codes) and comprehensive cross-insurance support (128 codes), relieving and supporting PwsMS, their caregivers and HCSs (67 codes). Through the cross-sectoral continuous support in health-related, social, financial and everyday bureaucratic matters, the CCM provides comprehensive and overriding support and relief for PwsMS, caregivers and HCSs. This intervention bears the potential to be fine-tuned and applied to similar complex patient groups. The study was approved by the Ethics Committee of the University of Cologne (#20-1436), registered at the German Register for Clinical Studies (DRKS00022771) and in accordance with the Declaration of Helsinki.

Streets in Suburbia as Spheres of Comfort

How to manage the “self” on the streets of suburbia when everybody knows each other? Due to the social and spatial manageability of suburban spaces, contact with more or less (un)known others is to be expected. Through repeated and continuous contact, residents are automatically and reciprocally assigned the role of acquaintances. This situation requires finding the right distance. The positioning of oneself and others, the perception and practice of distance, results in comfort and freedom from conflict. This coping strategy for public (street)spaces reflects a socio-spatial (con)figuration that is enacted as street management. Although street life is dominated by the notion of nothingness, everyone campaigns to stay private in public by setting up a “public self”. The research findings I refer to are based on two case studies in suburban spaces on the outskirts of Hanover (the state capital of Lower Saxony, Germany). In order to understand and explain the life-worlds of suburbanites in general and their manifestation on streets in particular, I conducted exploratory interviews, go-alongs and field observations. To create an atmosphere of comfort, convivial as well as conflictual situations are to be avoided, which is achieved by the residents positioning themselves and others at a distance. Since street life in the suburbs is uneventful and provides a sense of security and familiarity, living together in coexistence is routine. The delegation of responsibility for everything public enables suburbanites to be indifferent to others and the setting. The minimal sympathetic way of interacting with each other is symbolised by greetings, which both facilitates and hinders communication. In the end, the life-world suburbia and its streets are spheres of comfort because they are manageable, expectable and knowable.

Electronic tracking and identification of animals in agriculture for monitoring herd development and health

Agricultural business methods are no longer possible without computer technology, which helps to identify animals, record productivity and monitor their health. Therefore, the study aims to conduct a comparative analysis of the functionality of the main dairy farm management software for their objective assessment from the point of view of milk producers. For this purpose, information from the official websites of software products was analysed and scientific articles analysing this software were collected. As a result, all software products were divided into 3 categories: software for controlling dairy productivity and managing processes on a dairy farm from dairy equipment manufacturers; such software products include DairyPlan C21 (GEA), DATAFLOW II (Milkline), AfiFarm (Afimilk), DelPro (DeLaval) and FARMSOFT (Farmtec a. s.); dairy farm management software DairyComp 305 and UNIFORM-Agri, as well as farm software from post-Soviet developers – MilkCentre (CIAB Expert). Programmes from dairy equipment manufacturers were almost at the same level and had virtually all the necessary blocks for identifying, controlling and managing animals on a dairy farm. The software developed for dairy farm management is more effective in tandem with one of the milking parlour programmes. This class of software expands the possibilities for managing reproductive and veterinary work on the farm, as well as reduces the workload on staff by generating automatic reports for regulatory authorities and management. The third class of programs is the least developed compared to the above, but it compensates for this shortcoming by constant improvement due to the continuous contact of developers with the manufacturer. Thus, there is a significant number of software products on the software market that can provide dairy management for farms of various sizes

Biopolymer Binders for Low‐Temperature Operation of TiNb2O7 Anode in Li‐Ion Batteries

The widespread use of lithium‐ion batteries underlines the criticality of a more sustainable cell fabrication. Here, three biopolymers gelatin, pectin, and deoxyribonucleic acid (DNA) are investigated as binders for the TiNb2O7 anode material in Li cells in a temperature range between 0 and 60 ºC and compared to conventional binder polyvinylidene fluoride (PVDF). The use of biopolymers is motivated by their own environmental friendliness and the possibility to implement an aqueous electrode processing. A specific charge capacity of at least 200 mAh g−1 is found for all binders at 0 °C when testing the cycling performance of TiNb2O7 at 77.5 mA g−1 (1C rate). However, low‐rate cycling at 60 °C shows decreasing capacity for all biopolymers due to the swelling effect and continuous contact loss to the current collector, what also reflects in lowering the overall Li‐diffusion coefficient. This effect becomes less pronounced at 0 °C and high current densities, making biopolymers competitive with commercial PVDF. The electrodes with DNA binder demonstrate overall the most stable performance, arising from the biopolymer intactness and a thin solid–electrolyte interface layer. At 0 °C, the electrode with DNA provides 150 mAh g−1 at 775 mA g−1 for at least 500 discharge–charge cycles.

Contact states of tubular strings during sinusoidal buckling transitions in a horizontal wellbore

Scholars working in the oil and gas industry have extensively researched the buckling behavior of downhole tubular strings. However, in most theoretical research, continuous contact between tubular strings and wellbores is assumed, which is not always true in experiments. To address this issue, a buckling model for a tubular string placed inside a horizontal wellbore using the beam-column model is built in this paper. Two contact states of the tubular string were considered: point contact and partial continuous contact. The model indicates that reducing the angular displacement of the wave peak position facilitates the tubular string's transition from point to partial continuous contact. Additionally, a higher gravity load or smaller radial clearance increases the likelihood of partial continuous contact. A new displacement calculation method has been proposed based on the buckling model. Using this method, the entire process of contact state changes of a tubular string is simulated under the sinusoidal buckling mode in this study. The results show that the contact state of the tubular string under sinusoidal buckling cannot be assumed to be a continuous contact state, and a theoretical foundation for various evaluations based on the buckling deformation of tubular strings is provided in this study.

Chronology of the Bronze Age in southeast Transylvania

The southeastern part of Transylvania has a specific location in the Carpathian Basin. Being situated on the western fringe of the Eastern Carpathians, influences from west (inner Transylvania and the Great Hungarian Plain) and east (Moldavia and the northern Pontic area) can be traced through human history. The mountains were never an impenetrable border, and their porosity has made it possible for external cultural influences to expand. As a result southeastern Transylvania can be seen as a “contact zone” between East and West, where the above-mentioned influences have sometimes been weaker, but have never ceased: the continuous contacts and links were always present between the two sides of the Carpathians, something that has been confirmed by the numerous archaeological discoveries. While in recent years more and more 14C data have been reported from central and western Transylvania, this number has been negligible from the study area. In the last three years we have managed to measure 33 samples from 23 key-sites belonging to the Bronze Age, covering the whole period. The results have brought us closer to answering the questions that have preoccupied specialists dealing with the Bronze Age for decades. Many of the dates are the first ones for some of the cultures present in the study area (for example, for the Jigodin and Gáva Cultures), offering new, independent dating. The new results confirm many of the earlier suppositions regarding the Bronze Age chronology of the area, but have also raised some problems, which will need to be clarified in the future.

Continuous contact transfer behavior in bypass coupling triple-wire indirect arc welding

Continuous contact transfer behavior in bypass coupling triple-wire indirect arc welding

Improving Working Conditions in Retail During the COVID-19 Pandemic

The COVID-19 pandemic has significantly changed the patterns of employees’ behaviour, especially in the retail sector, which requires continuous contact with consumers. The anti-pandemic measures based on physical distance, wearing medical and protective equipment, application of barriers, frequent disinfection of work surfaces and space, use of strict protocols, and safety standards significantly complicate working conditions. This paper aims to analyse and define incentives for upgrading work and working conditions in retail during the COVID-19 pandemic. The scientific importance of the paper is reflected in the fact that analytically and systematically, it defines incentives that will support the behaviour of employees during crises affecting the retail sector. Unlike existing research in trade and retail, which indicated the importance of individual incentives for improving working conditions in periods of crisis, the contribution of this paper is in the comprehensive analysis, systematization, and definition of the importance of all incentives for improving the working conditions of employees in the retail sector. In this context, empirical research was conducted on a sample of 255 employees and it tested the importance of incentives to improve working conditions such as: maintaining a safe and healthy working environment, how to treat infected workers and workers in contact, the existence of detailed instructions for employees and consumers, organizing transportation for workers, financial incentives for employees, reduction of the scope of business activities, shortening of working hours of facilities, security protocols and digitalization of work processes. The survey was conducted among employees in SMEs and large retail chains. The set hypotheses were tested using the Path Analysis or Structural Modeling (SEM) method. The correlation between the retailer size and the differences in the incentives’ impact was assessed by employing Multiple Regression Analysis. The research results showed significant deviations in the mentioned incentives depending on the size of the retailer. Based on the obtained results, a set of measures was proposed that social policymakers and retail facility management should implement to improve working conditions in retail and establish a social safety net that will support employees in times of crisis. Guidelines for future research are provided in the paper. Keywords: working conditions, work incentives, position of workers, retailing, COVID-19 pandemic.

Variable Time-Step Physics Engine with Continuous Compliance Contact Model for Optimal Robotic Grinding Trajectory Planning.

In the transition from virtual environments to real-world applications, the role of physics engines is crucial for accurately emulating and representing systems. To address the prevalent issue of inaccurate simulations, this paper introduces a novel physics engine uniquely designed with a compliant contact model designed for robotic grinding. It features continuous and variable time-step simulations, emphasizing accurate contact force calculations during object collision. Firstly, the engine derives dynamic equations considering spring stiffness, damping coefficients, coefficients of restitution, and external forces. This facilitates the effective determination of dynamic parameters such as contact force, acceleration, velocity, and position throughout penetration processes continuously. Secondly, the approach utilizes effective inertia in developing the contact model, which is designed for multi-jointed robots through pose transformation. The proposed physics engine effectively captures energy conversion in scenarios with convex contact surface shapes through the application of spring dampers during collisions. Finally, the reliability of the contact solver in the simulation was verified through bouncing ball experiments and robotic grinding experiments under different coefficients of restitution. These experiments effectively recorded the continuous variations in parameters, such as contact force, verifying the integral stability of the system. In summary, this article advances physics engine technology beyond current geometrically constrained contact solutions, enhancing the accuracy of simulations and modeling in virtual environments. This is particularly significant in scenarios wherein there are constant changes in the outside world, such as robotic grinding tasks.

Still face in pet dogs (Canis familiaris).

Dogs are able to cooperate in reciprocal exchange with humans but little is known about the extent of these abilities (Range & Virányi, 2015). In the Still Face paradigm, infants reply to a sudden nonreciprocal facial expression with gaze aversion and an increase in re-engagement and distress behaviors (E. Tronick et al., 1978). We directly adapted this method; the dog's owner talked to the dog, then abruptly switched to a still, neutral face, maintaining eye contact. In Study 1 (N = 20), we found that dogs showed a significant decrease in the amount of looking at the owner in the Still Face phase, paralleling the results found in gaze aversion in infants, and they performed fewer pawing and vocalizations toward the person in the Still Face phase. In Study 2 (N = 60), we included one condition of continuous physical contact, and one condition that was a direct replication of the initial study without physical contact. Similar to human infants, we found a significant decrease in looking from the Interaction phase to the Still Face phase. However, in contrast to human infants, re-engagement and stress behaviors were higher in the Interaction phase than the Still Face phase. Looking and re-engagement behaviors differed based on the condition, with a smaller difference between phases in the Petting condition. These results suggest that dogs are capable of perceiving these small changes in human affect. However, unlike human infants, dogs seem to have greater expectations about physical interactions than verbal interactions, as they reacted more strongly to an Interaction phase without physical contact than the Still Face. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Improvement on Corrosion and Wear Resistance of Graphene-Based Coatings: A Review

Poor corrosion and wear resistance of metallic materials lead to deterioration of their properties and may cause failures. In fundamental, corrosion is due to the reaction of metals with their surroundings, such as moisture, salts, and air pollutants. On the other hand, wear is a surface failure because of continuous dynamic contact between the metals' surfaces and other surfaces. In this regard, surface protection such as coatings is crucial to ensure the long life of the metallic materials. Among the surface protection available, graphene-based coatings have emerged as the most researched topic due to their excellent impermeability, chemical inertness, high hardness, and flexibility. It is reported that graphene-metal and graphene-polymer nanocomposite coatings offer versatile protection against corrosion and abrasive wear. Therefore, this review presents the current state-of-the-art graphene-based nanocomposite coatings in the field of corrosion and abrasive wear resistance. This review provides significant approach of graphene-metal and graphene-polymer, as well as the future perspectives of graphene-based coatings.

Nursing Roles in the Quality of Information in Informed Consent Forms of a Spanish County Hospital.

(1) Background: Because of their direct and continuous contact with the patient, nurses play a relevant role in ensuring that informed consent forms are complete and easy to read and comprehend. The objective of this study was to analyze the legibility and formal quality of informed consent forms for non-surgical procedures in a county hospital. (2) Methods: The readability of these forms was analyzed using the INFLESZ scale and the information they provided according to the formal quality criteria established for these forms. (3) Results: Readability was difficult in 78.08% of the forms analyzed. No form fulfilled all the criteria, the most non-compliant being the non-appearance of the verification of delivery of a copy to the patient (100%), the contraindications (94.59%), and the alternatives (83.78%) of the procedure. Statistically significant differences were observed between disciplines with respect to the INFLESZ readability score and the formal quality score, but no statistically significant correlation was found between the two scores. (4) Conclusions: The informed consent forms for non-surgical procedures analyzed presented mostly difficult readability and poor formal quality, making it difficult for patients to have understandable and complete information. Nursing professionals should be actively involved in their improvement to facilitate patient decision making.

Investigating wastewater treatment plant effluent and pharmaceutical exposure on innate cytokine expression of darters (Etheostoma spp.) in the Grand River watershed.

Fish live in continuous contact with various stressors and antigenic material present within their environments. The impact of stressors associated with wastewater-exposed environments on fish has become of particular interest in toxicology studies. The objectives of this study were to examine potential effects of wastewater treatment plant (WWTP) effluent-associated stressors on innate cytokine expression within the gills of darter species (Etheostoma spp.), using both field and laboratory approaches. Male and female darters (rainbow, greenside, fantail, and johnny darters) were collected upstream and downstream of the Waterloo WWTP in the Grand River, Ontario. Gill samples were collected from fish in the field and from a second subset of fish brought back to the laboratory. Laboratory fish were acutely exposed (96-h) to an environmentally relevant concentration of venlafaxine (1.0 μg/L), a commonly prescribed antidepressant. To assess the impacts of these stressors on the innate immunity of darters, the expression of key innate cytokines was examined. Minor significant effects on innate cytokine expression were observed between upstream and downstream fish. Moderate effects on cytokine expression were observed in venlafaxine-exposed fish compared to their control counterparts however, changes were not indicative of a biologically significant immune response occurring due to the exposure. Although the results of this study did not display extensive impacts of effluent and pharmaceutical exposure on innate cytokine expression within the gills, they provide a novel avenue of study, illustrating the importance of examining potential impacts that effluent-associated stressors can have on fundamental immune responses of native fish species.

A Novel Ball-Racket Rebound Model for Table Tennis Robot Based on Continuous Contact Force

A Novel Ball-Racket Rebound Model for Table Tennis Robot Based on Continuous Contact Force

Geometry and Kinematics of the Mecanum Wheel on a Plane and a Sphere

This article is devoted to a study of the geometry and kinematics of the Mecanum wheels, also known as Ilon wheels or the Swedish wheels. The Mecanum wheels are one of the types of omnidirectional wheels. This property is provided by peripheral rollers whose axes are deviated from the wheel one by 45 degrees. A unified approach to studying the geometry and kinematics of the Mecanum wheels on a plane and on the internal or external surface of a sphere is proposed. Kinematic relations for velocities at the contact point of the wheel and the supporting surface, and angular velocities of the roller relative to the supporting surface are derived. They are necessary to describe the dynamics of the Mecanum systems taking into account forces and moments of contact friction in the presence of slipping. From the continuous contact condition, relations determining the geometry of the wheel rollers on a plane and on the internal or external surface of a sphere are obtained. The geometric relations for the Mecanum wheel rollers could help to adjust the existing shape of the Mecanum wheel rollers of spherical robots and ballbots to improve the conditions of contact between the rollers and the spherical surface. An analytical study of the roller geometry was carried out, and equations of their generatrices were derived. Under the no-slipping condition, expressions for rotational velocities of the wheel and the contacting roller are obtained. They are necessary for analyzing the motion of systems within the framework of nonholonomic models, solving problems of controlling Mecanum systems and improving its accuracy. Using the example of a spherical robot with an internal three-wheeled Mecanum platform, the influence of the rollers on the robot movement was studied at the kinematic level. It has been established that the accuracy of the robot movement is influenced not only by the geometric parameters of the wheels and the number of rollers, but also by the relationship between the components of the platform center velocity and its angular velocity. Results of the numerical simulation of the motion of the spherical robot show a decrease in control accuracy in

Human Collaborative Control of Lower-Limb Prosthesis Based on Game Theory and Fuzzy Approximation.

For leg prosthesis user, the soft tissue and skin under the stump of are not accustomed to weight bearing, excessive continuous contact pressure can lead to the risk of degenerative tissue ulceration. This article presents a novel human-robot collaborative control scheme that achieves control weight self-adjustment for robotic prostheses to minimize interaction torque. To establish the human-robot interaction relationship, we regard the contact pressure between human residual limb and the prosthetic receiving cavity as the interaction force. We aim at reducing the interaction force under the premise of minimally changing the original motion trajectory of the robotic prosthesis. The control scheme mainly includes trajectory optimization based on a dual-agent game control scheme under a cooperative relationship, and a fuzzy logic system for improving the control accuracy of trajectory tracking of robotic prostheses with unknown dynamic parameters. Experiments were carried out on two amputee participants to verify the proposed human-robot interactive control scheme in a robotic prosthesis. The results show that the interaction torque could be reduced while maintaining minimal trajectory tracking error. The proposed control scheme could potentially facilitate the dexterous manipulation of leg prostheses, thus benefiting amputees.

Feasibility of friction stir welding using a hemispherical tool tilted towards the retreating side

The use of a hemispherical tool tilted towards the retreating side for friction stir welding 6061-T6 aluminum alloy is investigated. Joints with smooth surfaces and without internal voids are obtained. Under the same welding and rotational speeds, adapting the tilt angle makes it possible to weld various thicknesses up to 3.5 mm. Plunge depth and tilt angle are demonstrated to be key geometrical parameters driving material flow when using the hemispherical tool. Microstructural features in the weld are equiaxed and refined grains below 5 µm in the stirred zone and narrow thermo-mechanical affected zones. The through-thickness thermomechanical gradient developing beneath the hemispherical tool leads to different extents of dynamic recrystallization and recovery in the stirred zone. The tool orientation towards the retreating side and the division of the tool-workpiece interaction in continuous and intermittent contact leads to an asymmetrical thermal field around the stirred zone. Hence, the new derivative friction stir welding solution allows the welding of multiple aluminum alloy blank thicknesses using the same tool.

Trajectory Planning for Hopping Rover on Small Bodies Under Pre-Collision Attitude Adjustment Modulation

A novel pre-collision attitude adjustment (PCAA) modulation based on angular velocity and quaternions control is developed to more controllable and reliably adjust the non-spherical hopping rover's trajectory on small bodies. This corresponds to a hopping trajectory planning (HTP) framework that addresses inherent technical challenges, including attitude-trajectory coupled features, hard-to-depicting near-truth gravity and continues dynamical contact models, difficult-to-predetermine collision times with the small bodies’ surface, and complex judgments regarding whether the period of attitude adjustment is sufficient in current hops. Two main contributions are proposed, focusing on modeling and planning. To achieve a more realistic modeling of the rover's motion, its attitude-trajectory coupling dynamic model is researched, including a ground-truth irregular gravity model and continuous dynamical contact model. Additionally, a collision detection method based on the local surface smoothing technique is proposed for rapid and exact switching between the ballistic and contact motions for the subsequent planning purpose. On the other hand, redundancy planning and binary event-trigger techniques are combined for handling unpredictable available dimensions of optimization variables of PCAA-based HTP, which arise from the indeterminate scale of collision times and potential deficiency in ballistic flight time required for completing attitude maneuvers. Specifically, the solution space is preset to guarantee the unchanging dimensions of the design variables, which are activated or deactivated by coupling binary event variables for each dimension. These newly introduced events are triggered by comparing the realistic rebound time of the current hop with the necessary time for attitude maneuver, which is accurately computed by designing a first-order sliding mode controller. This approach enables an equivalent and easily implementable version of the problem to be obtained. Logically and numerically, the application of PCAA modulation is found to significantly enlarge or contract the area of the reachable region of the hopping rover and contribute to improving the convergence and reducing the relative final position error of the hopping trajectory planning problem.