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621.
《中国航空学报》2023,36(2):402-416
The use of space robots (SRs) for on-orbit services (OOSs) has been a hot research topic in recent years. However, the space unstructured environment (i.e.: confined spaces, multiple obstacles, and strong radiation interference) has greatly restricted the application of SRs. The coupled active-passive multilink cable-driven space robot (CAP-MCDSR) has the characteristics of slim body, flexible movement, and electromechanical separation, which is very suitable for extreme space environments. However, the dynamic and stiffness modeling of CAP-MCDSRs is challenging, due to the complex coupling among the active cables, passive cables, joints, and the end-effector. To deal with these problems, this paper proposes a workspace, stiffness analysis and design optimization method for such type of MCDSRs. Firstly, the multi-coupling kinematics relationships among the joint, cables and the end-effector are established. Based on hybrid series-parallel characteristics, the improved coupled active–passive (CAP) dynamic equation is derived. Then, the maximum workspace, the maximum stiffness, and the minimum cable tension are resolved, among them, the overall stiffness is the superposition of the stiffness produced by the active and the passive cable. Furthermore, the workspace, the stiffness, and the cable tension are analyzed by using the nonlinear optimization method (NOPM). Finally, an 8-DOF CAP-MCDSR experiment system is built to verify the proposed modeling and trajectory tracking methods. The proposed modeling and analysis results are very useful for practical space applications, such as designing a new CAP-MCDSR, or utilizing an existing CAP-MCDSR system. 相似文献
622.
《中国航空学报》2023,36(5):1-17
Serpentine nozzles are widely used in combat aircraft to realize strong stealth characteristics. Based on the layout characteristics within a confined space, a series of double serpentine nozzles with spanwise offsets are established. Using computational fluid dynamics and Taguchi method, the influence mechanisms of the Distribution of Area (DA), Distributions of Centerline for the first and second ‘S’ sections in the Vertical direction (DCV1 and DCV2), and Distribution of Centerline in the Spanwise direction (DCS) are analyzed. The impact of these factors on the total pressure recovery coefficient can be ranked as DA > DCV2 > DCS > DCV1, whereas their impacts on the discharge coefficient and axial thrust coefficient can be ranked as DCV2 > DCS > DA > DCV1. Considering the statistical significance of these factors, a nozzle in which DA changes rapidly at the exit and DCV1, DCV2, and DCS change rapidly at the entrance gives the best aerodynamic performance. Compared to the worst configuration, the total pressure recovery coefficient, discharge coefficient, and axial thrust coefficient are improved by 1.6%,3.5% and 3.6%, respectively. DA influences the gas flow acceleration in the entire serpentine channel, resulting in different wall shear stress and friction losses. The various centerline distributions influence the gas flow acceleration effects and form complex wave structures in the constant-area extension section, resulting in different local and friction losses. 相似文献
623.