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Large deployable mesh reflectors play a critical role in satellite communications, Earth observation, and deep-space exploration, offering high-gain antenna performance through precisely shaped reflective surfaces. Traditional dynamic modeling approaches—such as wave-based and finite element methods—often struggle to accurately capture the complex behavior of three-dimensional reflectors due to oversimplifications of cable members. To address these challenges, this paper proposes a novel spatial discretization framework that systematically decomposes cable member displacements into boundary-induced and internal components in a global Cartesian coordinate system. The framework derives a system of ordinary differential equations for each cable member by enforcing the Lagrange’s equations, capturing both longitudinal and transverse internal displacement of the cable member. Numerical simulations of a two-dimensional cable-network structure and a center-feed parabolic deployable mesh reflector with 101 nodes illustrate the improved accuracy of the proposed method in predicting vibration characteristics across a broad frequency range. Compared to standard finite element analysis, the proposed method more effectively identifies both low- and high-frequency modes and offers robust convergence and accurate prediction for both frequency and transient responses of the structure. This enhanced predictive capability underscores the significance of incorporating internal cable member displacements for reliable dynamic modeling of large deployable mesh reflectors, ultimately informing better design, control, and on-orbit performance of future space-based reflector systems. 

Abstract The advent of robotics in medicine has brought about a paradigm shift, enabling minimally invasive interventions for in-vivo practices. Pill-based robots, specifically designed at the millimeter scale, have emerged as a viable alternative to traditional endoscopic methods for gastrointestinal tract diagnostics and treatment. These millirobots, capable of navigating the complex and constrained environments of the human body, offer a significant advantage by enabling thorough visualization or targeted drug delivery in a single session without the need for sedation. We previously developed a novel deployable tensegrity robot, designed for gastrointestinal diagnostics and treatment, which addresses the limitations of conventional capsule endoscopes through its unique structure and locomotion mechanism. Tensegrity structures, characterized by a network of components in tension and compression, provide an innovative solution to the challenges of designing robots for in-vivo applications. Our millimeter-scale tensegrity robot leverages the inherent advantages of such structures — lightweight, high stiffness, and adaptability — to navigate through densely packed tissues and high-pressure environments within the GI tract. Inspired by the locomotion of earthworms, the movement mechanism of the robot enables efficient navigation and precise positioning, significantly reducing the risk of retention and ensuring patient safety. This paper investigates the design and fabrication process of the tensegrity robot, focusing on achieving a high folding ratio to facilitate its deployment as a pill-based robot. Through a comparison of the robot’s fabricated dimensions with the theoretical design, we evaluate the accuracy of the fabrication process, highlighting the potential of this innovative approach in transforming GI tract diagnostics and treatment. The deployment of such tensegrity-based millirobots marks a new era in medical devices, promising enhanced patient safety and comfort through non-invasive methods. 

Large deployable mesh reflectors are crucial in space applications due to their lightweight and efficient storage characteristics. However, achieving high surface accuracy and managing the significant thermal effects experienced during on-orbit operations remain challenges in deployable mesh reflector design. This paper presents an innovative dynamic thermal modeling methodology for large deployable mesh reflectors, effectively addressing these obstacles. The proposed method considers a comprehensive set of radiation factors including solar, Earth, Albedo, and reflector emissions. This allows for a detailed analysis of dynamic thermal behavior of the reflector, thereby accurately capturing the impact of thermal strains of cable members on surface accuracy. Simulations of a 101-node center-feed parabolic reflecting surface of a deployable mesh reflector indicate that the proposed method can reveal non-uniform temperature distributions, unlike traditional methods that presuppose uniformity. Additionally, the proposed method has proven effective in accurately predicting the root-mean-square error increase of the reflector, typically unobserved in traditional thermal modeling techniques. 

Micro-, and milli-scale robots have been of great R&D interest, due to their ability to accomplish difficult tasks such as minimally invasive diagnosis and treatment for human bodies, and underground or deep-sea tests for environment monitoring. A good solution to this design need is a multi-unit deployable tensegrity microrobot. The microrobot can be folded to only 15% of its deployed length, so as to easily enter a desired working area with a small entrance. When deployed, the tensegrity body of the robot displays lightweight and high stiffness to sustain loads and prevent damage when burrowing through tightly packed tissues or high-pressure environments. In this work, topology, initial configuration and locomotion of a deployable tensegrity microrobot are determined optimally. Based on the design, a centimeter-scale prototype is manufactured by using a fused deposition modelling advanced additive manufacturing or 3-D printing system for proof of concept. As shown in experimental results, the deployable tensegrity microrobot prototype designed and manufactured can achieve an extremely high folding ratio, while be lightweight and rigid. The locomotion design, that mimics a crawling motion of an earthworm, is proved to be efficient by the prototype equipped with stepper motors, actuation cables, control boards and a braking system.