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The use of fabrics in the form of grids embedded in cementitious matrices—usually termed as textile-reinforced mortar, fiber-reinforced cementitious matrix, or textile-reinforced concrete—demonstrate a more stable performance in elevated temperature conditions compared with fiber-reinforced polymers. This study investigated the residual tensile properties of bare yarns and fabrics in the form of grids embedded in a cementitious mortar after exposure to 100 °C, 200 °C, and 300 °C. Three different coated fabric textiles were used as reinforcement: carbon, basalt, and glass. Additionally, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermos-gravimetric analysis (TGA) were conducted to evaluate potential changes in the internal structure of the fibers and the mortar. The cracking stress, the tensile strength, and the ultimate strain of the composite specimens were increased after exposure to 100 °C, while only carbon and glass fiber grids retained their effectiveness up to 200 °C. At 300 °C, the coupons reinforced with carbon and basalt fibers deteriorated rapidly. Only the glass counterparts showed an improved overall performance due to fiber contraction and the differences in the coating material. The results highlight the differences in the performance of the three fiber types and the important role of the coating material in the overall composite behavior. [ABSTRACT FROM AUTHOR]

Metamorphic robot might switch naturally between wheeled driving and foot walking according to the changes of external environments, so that the robot might both run fast on the smooth structure of the road and climb over obstacles in rugged mountains. Based on the generalized coordinate method, a kinematics model of the steering and reconstruction processes of the transformer robots was established. Considering the impacts of the swinging leg in contact with the environment during the reconstruction processes, an impedance control method was proposed to realize the landing smoothness control of the swinging legs. Based on the traditional impedance control, an adaptive impedance controller was designed based on Lyapunov asymptotic stability theorem, and the parameters of impedance control were optimized by particle swarm optimization algorithm. Through simulation analysis under different environmental stiffness, it is proved that the adaptive impedance controller after parameter optimization may follow the expected contact force well, and improve the adaptability of the variable cell robots to the unknown and changeable environments. Finally, a road experiment was carried out for the transformation robot to land on the feet in the reconfiguration processes, which further confirmed the superiority of the optimized adaptive impedance control method. [ABSTRACT FROM AUTHOR]

As a new type of ground transportation system, an unmanned metamorphic vehicle can naturally switch between wheeled driving and legged walking through vehicle reconstruction. Therefore, compared with traditional vehicles, unmanned metamorphic vehicles can move quickly on structural roads and have high trafficability on nonstructural roads. Furthermore, an unmanned metamorphic vehicle is applicable to interstellar detection and earthquake rescue. In this study, the topological structure of an unmanned metamorphic vehicle was designed and the reconstruction process was described. In addition, a kinematic analysis was conducted on the three stages (supporting, lifting, and standing-up) of reconfiguring the metamorphic vehicle. The kinematic and corresponding dynamic models were established based on the screw theory and the Lagrange equation. A Matlab/Simulink simulation was then carried out for the unmanned metamorphic vehicle. The simulation results describe the motion behavior of the system reconstruction, illustrating that the established kinematic and dynamic models are reasonable. Finally, the correctness of the abovementioned kinematic and dynamic models was further verified by Adams virtual prototype simulation. The above findings provide a solid foundation for future studies on stability control during the reconstruction of unmanned metamorphic vehicles. [ABSTRACT FROM AUTHOR]