Analysis of 3D PPN guidance laws for nonmaneuvering target
Unlike the traditional ways adopted by most of the researchers, the rotating angle of relative velocity is adopted in this work as the independent variable to analyze the analytical solution of impact angle, capture region (with or without finite line of sight (LOS) turn rate constraint), range to go, time to go, and a defined fuel cost of a traditional pure proportional navigation (PPN) guidance law for both nonmaneuvering moving, and stationary targets.
Performance analysis of differential geometric guidance law against high-speed target with arbitrarily maneuvering acceleration
The interception of high-speed target with an arbitrary maneuvering acceleration causes serious troubles to the guidance and control system design of airborne missile. A novel guidance law based on the classical differential geometry curve theory was proposed not long ago. Although it is believed and numerically demonstrated that this differential geometric guidance law (DGGL) is superior to the classical pure proportional navigation (PPN) in intercepting high-speed targets, its performance has not been thoroughly analyzed. In this paper, using the Lyapunov-like approach, the performance of DGGL against the high-speed target with an arbitrary but upper-bounded maneuvering acceleration is well studied. The upper bounds of the LOS rate and commanded acceleration of DGGL are obtained, and conditions that guarantee the capture of this type of maneuvering target are also presented. The nonlinear relative dynamics between the missile and target is taken into full account. Finally, the proposed theoretical findings are demonstrated by numerical simulation examples.
Centrifuge modelling of effects of shield tunnels on existing tunnels in soft clay
With the rapid development of the subway network,the phenomena of shield tunnels going across the adjacent tunnels are becoming more and more common.The interaction between shield tunneling and nearby tunnels is more complicated than the ordinary shield tunneling in intact soil strata.Based on the project of Shanghai Bund Passage crossing Metro Line 2,the method of centrifuge modeling together with the field measurement is employed to study the effects shield tunneling on nearby strata and existing tunnels.In centrifugal model tests,the effects simulation techniques considering the unloading of excavation,ground loss and grouting are developed to analyze the longitudinal settlement of the shield tunnel and the existing tunnel induced by the shield tunneling.Besides,the deformation distribution and settlement curves of the existing tunnels during shield construction are studied by using the monitoring data.