In this study, a high-order sliding mode controller (HOSMC) is designed for the control of a one degree-of-freedom (DOF) flexible link space robotic arm with payload. The highorder sliding mode based controller is developed, which exploit the robustness properties of sliding-mode controllers (SMCs), while also increasing accuracy by reducing chattering effects.Ever increasing demand for high-speed performance and low energy consumption of space robotic systems require low-mass designs. This restriction puts a limitation on the degree of rigidity of space robot manipulators. These manipulators may posses' significant flexibility that needs to be taken consideration in the design of the control systems [1]. Space robot manipulators have highly nonlinear and coupled dynamics. Flexible space robot arms have structural flexibilities and resulting high number of passive degrees-of-freedom. Therefore, the control of such flexible systems has significant challenges due to the highly nonlinear structure. The high performance control of a flexiblelink space robotic arm requires the full system dynamic structural flexibilities become of increased importance particularly when high speed, high accuracy operation of lightweight structures is aimed.In this study, a high-order sliding mode controller (HOSMC) is designed for the control of a one degree-of-freedom (DOF) flexible link space robotic arm with payload. The high-order sliding mode based controller is developed, which exploit the robustness properties of sliding-mode controllers (SMCs), while also increasing accuracy by reducing chattering effects.In most related literature, the full system dynamic structural flexibilities effects are neglected to avoid increased computational complexity at the expense of compromising the tracking accuracy of the system in the transient and steady-state. As a solution to the problem, in this study, the 2 nd order HOSM (2-HOSM) control law is derived by including the structural flexibilities into the control design process. 2-HOSM controller is designed to achieve set-point positioning control. The performance of the designed control method is tested for the precise positioning of a space robotic arm under heavy uncertainties and external disturbances has been evaluated in real-time on an experimental setup. The proposed control method is applied for the set-point control and trajectory control of the system and has resulted in an improved precision and overall performance as demonstrated by experimental results. The improved accuracy obtained 2-HOSMC motivates the implementation of the schemes for demanding control applications under heavy uncertainties.
This research is about manufacturing brake pads from a polymeric composite material composed of domestic materials, which are cheaper and available in the market. An unsaturated polyester is used as the basic material. Styrene–butadiene rubber and montmorillonite clay materials available in the market are used as the fillers. The Kevlar fibers, the nylon, and the steel fibers are used as reinforcing materials to improve the mechanical properties. The Shore hardness, compressibility, thermal conductivity, impact, and wear resistance tests have been implemented. The results show that the hardness, compressive, and impact resistance of the samples increase with the increase of the reinforcement ratio by Kevlar fibers, nylon fibers, and steel fibers. The rate of wear decreases with the increase of reinforcement ratio. The thermal conductivity decreases with an increase in the reinforcement ratio by Kevlar fibers and nylon fibers while the thermal conductivity increases with an increase in the reinforcement ratio by Kevlar fibers and steel fibers. Compared to the commercial brake pads, high strength, high wear resistance, high impact resistance, high hardness, high compressive strength, low thermal conductivity, and low-cost brake pads have been proposed.
In this study, the nonlinear dynamic response of a hybrid laminated composite plate composed of basalt, Kevlar/epoxy and Eglass/epoxy under the blast load with damping effects has been investigated. The von Kármán type of geometric nonlinearities are taken into account and the rectangular composite plate is assumed to be simply supported on all edges. The Galerkin Method is used to obtain the nonlinear differential equations in the time domain, and those equations are solved by Finite Difference Method. Parametric studies are conducted. The influences of some parameters such as damping ratios, aspect ratios and different peak pressure values have been investigated.
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