1,721,048 research outputs found
Simulation analysis of cable-driven rolling joint for humanoid robot via Adams
No full textThis study introduces a novel anthropomorphic cable-driven rolling joint structure that can achieve bidirectional motion using a single motor. A specific cable system configuration is designed, and an experimental platform is constructed. To ensure the safety of the cable-driven rolling joint and facilitate the exploration of cable tension dynamics, Adams software is employed for modeling and simulation of the joint. The simulation results are validated against experimental data obtained from the physical platform. By comparing the motion effects of two winch drive simulation methods—the winch function and the large disk winding method—while varying the joint angle over time, consistent behavior is observed. Additionally, the tension changes in the upper and lower cable systems are analyzed as the joint angle varies. Despite minor deviations caused by cable deformation and pulley friction at extreme joint positions, the Adams simulations align well with the experimental observations. Notably, the simulation accurately captures the trend of cable tension relative to joint angle, demonstrating Adams' efficacy as a powerful tool for analyzing and optimizing cable-actuated rolling joints
Digital twin-based health service framework and its application in permanent magnet synchronous motors
No full textDesign and Dynamic Analysis of a Bio-Inspired Rolling Joint Manipulator Based on Pulley-Cable System
No full textCable-driven joints have gained widespread use in various applications, yet the inherent limitations in cable stiffness and strength pose challenges in ensuring joint stability and operational safety. Enhancing joint stiffness and predicting cable tension changes during motion are essential to mitigate the risk of cable breakage. This article presents the design of a novel bio-inspired rolling joint manipulator, featuring a single-motor-driven pulley transmission system with symmetrical tension amplification. A novel cable winding drive mechanism with integrated tension detection is proposed. The tension distribution across the pulley system is analyzed via the classic Euler equation. A comprehensive system model is established, spanning from the motor-driven winch, through the guide pulleys, to the load-bearing tension amplification pulley. By incorporating the derived tension distribution into the kinematic and dynamic equations of the joint, the model accurately predicts how cable tension evolves during joint movement. The theoretical formulations and tension distribution are validated through both software simulations and prototype experiments, demonstrating high consistency. The results confirm that the dynamic model proposed in this article is more accurate and comprehensive, considering friction and tension transmission
Dynamically updated digital twin for prognostics and health management: Application in permanent magnet synchronous motor
Get PDFCurrent research on Digital Twin (DT) based Prognostics and Health Management (PHM) focuses on establishment of DT through integration of real-time data from various sources to facilitate comprehensive product monitoring and health management. However, there still exist gaps in the seamless integration of DT and PHM, as well as in the development of DT multi-field coupling modeling and its dynamic update mechanism. When the product experiences long-period degradation under load spectrum, it is challenging to describe the dynamic evolution of the health status and degradation progression accurately. In addition, DT update algorithms are difficult to be integrated simultaneously by current methods. This paper proposes an innovative dual loop DT based PHM framework, in which the first loop establishes the basic dynamic DT with multi-filed coupling, and the second loop implements the PHM and the abnormal detection to provide the interaction between the dual loops through updating mechanism. The proposed method pays attention to the internal state changes with degradation and interactive mapping with dynamic parameter updating. Furthermore, the Independence Principle for the abnormal detection is proposed to refine the theory of DT. Events at the first loop focus on accurate modeling of multi-field coupling, while the events at the second loop focus on real-time occurrence of anomalies and the product degradation trend. The interaction and collaboration between different loop models are also discussed. Finally, the Permanent Magnet Synchronous Motor (PMSM) is used to verify the proposed method. The results show that the modeling method proposed can accurately track the lifecycle performance changes of the entity and carry out remaining life prediction and health management effectively
Design and Analysis of a Rolling Joint Based on Tension Amplification
No full textOwing to structural rigidity and inherent quality issues in traditional industrial manipulators, attaining essential safety in man-machine cooperation proves challenging. In this study, we emulate the human arm tendon drive principle, positioning the motor, reducer, and other high-quality components behind and driving them with cables. To address the stiffness issue in low-mass manipulators, we design the structure of a bilateral conjugate gear rolling joint using a pulley tension amplification mechanism. Analyzing the designed rolling joint, we unveil the kinematic relationship between cable length and joint angle. Simultaneously, we derive expressions for the stiffness and strength of the rolling joint, laying a theoretical foundation for subsequent joint optimization. We have also analyzed the overall pulley system and derived the tension transfer. Conducting kinematics simulation with the Adams simulation software, we unveil the impact of the number of turns on the joint angle. The observed motion results align with the theoretically derived outcomes
Modeling and Experimental Verification of a Cable-Driven Rolling Joint System Considering Preload and Friction Effect
Get PDFIn the realm of cable-driven robotics, the cable-driven rolling joint (CDRJ) is a transformative innovation that effectively increases stiffness based on biomimicry while maintaining the robot's slim and lightweight structure. This study presents a comprehensive model of CDRJ that meticulously considers the effects of cable friction, integrating the influences of cable pretension, elastic deformation, and the frictional interaction between the cable and the pulley on the system's performance. The research delves into the distribution law of cable tension influenced by frictional forces and the consequential motion hysteresis observed during reverse rotation. An enhanced LuGre friction model is introduced to address the complexities of line contact friction between cables and pulleys. Building upon this, a dynamic model of CDRJ is established, capturing the motion characteristics throughout the process, including the discontinuous friction phenomena inherent in reverse rotation. This article culminates with the construction of an experimental prototype of a cable rolling joint system, through which the friction coefficient is determined. Experimental results corroborate the dynamic model's proficiency in simulating the motion characteristics of CDRJ, underscoring its potential for accurate tension prediction and force assessment within intricate pulley systems. Meanwhile, the generalized model of the pulley-cable system developed in this research may be applied in the fields of biomechanics, prosthetics, and bionic design, providing new insights into various cable-driven systems
Dynamically adaptive cascading updates for hierarchical digital twins
No full textTraditional sensors encounter challenges such as high collection costs, insufficient measurement points, and low data quality in the monitoring and maintenance of modern equipment. These challenges significantly affect the effectiveness and efficiency of monitoring and maintenance processes. Digital twin (DT) technology, as a digital replica of physical entities, is regarded as the 'digital sensor' of physical entities due to its high-precision modeling and dynamic updating capabilities. Compared to traditional sensors, DT models provide substantial improvements in both data volume and quality. However, creating a DT model with high precision and robust dynamic characteristics is notably challenging, particularly when the relationships and state features of the physical entity are complex and variable. To address this issue, a cascading update strategy was introduced. This strategy coordinates complex hierarchical DT update tasks, ensuring model accuracy. Furthermore, a signal characteristic-based dynamic adaptive update algorithm is proposed. This algorithm optimizes the DT updating process and enhances the model's dynamic characteristics. The proposed method is validated using experimental data on plunger pump barrel-port plate oil leakage. The results demonstrate that the method significantly improves the accuracy and updating efficiency of the DT model. It achieves a balance between precision and update time costs, enhancing DTs accuracy and practicality as a 'digital sensor'
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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