The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,includ...The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.展开更多
This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits...This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.展开更多
基金support from the Laboratory Directed Research and Development program at the SLAC National Accelerator Laboratorythe National Science Foundation under Grant No.NSF-2011786Use of the Linac Coherent Light Source(LCLS),SLAC National Accelerator Laboratory,is supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences under Contract No.DE-AC02-76SF00515.
文摘The past decades have witnessed the development of new X-ray beam sources with brightness growing at a rate surpassing Moore’s law.Current and upcoming diffraction limited and fully coherent X-ray beam sources,including multi-bend achromat based synchrotron sources and high repetition rate X-ray free electron lasers,puts increasingly stringent requirements on stability and accuracy of X-ray optics systems.Parasitic motion errors at sub-micro radian scale in beam transport and beam conditioning optics can lead to significant loss of coherence and brightness delivered from source to experiment.To address this challenge,we incorporated optical metrology based on interferometric length and angle sensing and real-time correction as part of the X-ray optics motion control system.A prototype X-ray optics system was constructed following the optical layout of a tunable X-ray cavity.On-line interferometric metrology enabled dynamical feedback to a motion control system to track and compensate for motion errors.The system achieved sub-microradian scale performance,as multiple optical elements are synchronously and continuously adjusted.This first proof of principle measurement demonstrated both the potential and necessity of incorporating optical metrology as part of the motion control architecture for large scale X-ray optical systems such as monochromators,delay lines,and in particular,X-ray cavity systems to enable the next generation cavity-based X-ray free electron lasers.
基金supported by the National Defense Foundation of China(No.403060103)
文摘This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.
