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.
Two composite guidance laws based on the backstepping control and disturbance observers with autopilot lag
A composite three-dimensional (3D) missile guidance law is proposed for manoeuvering targets with the consideration of the first-order autopilot dynamics without any linearization. This guidance law consists of a backstepping controller and a feedforward compensation based on disturbance observers. In this control scheme, the unknown target acceleration is regarded as part of the lumped disturbance, estimated by a disturbance observer, and then feedforward compensated. The backstepping controller is introduced to deal with unmatched disturbances. Moreover, both the nonlinear disturbance observer (NDOB) and the generalized proportional integral observer (GPIO) are employed in the derivation. Simulation studies demonstrate the effectiveness of the proposed guidance law, and compare the guidance performance of the two composite guidance laws with different disturbance observers.
New approach to vision-based BGA package inspection
Ball grid array (BGA) techniques have developed very fast due to the advantages of more I/O ports, small size, and so on. In this paper, a vision-based algorithm for BGA package inspection is proposed to accurately estimate center and diameters of solder-balls of BGA packages, so that defects of BGA packages, such as missing or extra balls, oversize or undersize balls, over-height or under-height balls, and pitch can be detected for ensuring the quality of BGA packages.