Distance-Scalar Disturbance Observer-Based Parallel Approaching Guidance Using Finite-Time Prescribed Performance

In this paper, to make an interceptor intercept a maneuvering target, a parallel approaching guidance law is developed. In order to estimate the target maneuver more accurately and reduce its influence on the guidance accuracy, a distance-scalar disturbance observer is employed. Specifically, the estimation accuracy of the designed observer is not affected by the relative distance. Finite-time prescribed performance is employed to ensure that the line-of-sight angular rate is capable of converging to a predetermined small region within the specified finite time. All signals of the interception system can guarantee an ultimately uniformly boundedness, as proven by Lyapunov stability theory. Finally, the function of the parallel approaching guidance law is demonstrated using numerical simulation.