Study On Variable Structure Terminal Guidance Law And Stability Of Space Interception

With the development of the new technology in aerospace and the application of the new technology in military areas the requirements for terminal guidance laws used in missile are getting more and more complex. It is necessary to search a new precise guidance law to change this situation since the classical guidance laws and modern guidance laws cannot satisfy the more and more complicated interceptions and wreck. Especially for the high maneuverable target and terminal angular constraint classical guidance laws and modern guidance laws always are noneffective. The paper makes some research of sliding mode control theory especially the design methods of controller as well as the cause and the damage of chattering. I summarize that how to design the controller. I also analyze that how to weak the chattering. On the base of the mentioned theories above a terminal guidance law based on the zeroing line of sight anglar velocity and a terminal guidance law with terminal angular constraint are presented in this paper. The stability of this terminal guidance system is also analyzed.First of all two kinds of relative motion model of missile-target are established here.The relative motion of missile-target in the three dimensional coordinates is decoupled into in the two-dimensional vertical plane and horizontal plane.And the two-dimensional relative motion model is established. Secondly in the two dimensional line-of-sight coordinates a terminal guidance laws based on the zeroing line of sight anglar velocity and with terminal angular constraint respectively are designed in this paper. The improvement of reaching law make suer of the system's rapidity and robustness and weakened the chattering leaded by variable structure control-essentially discontinuous control. Then it verifies the sliding mode existence conditions and arrival conditions and proved the system's stability under the control of the two guidance laws based on the Lyapunov direct method of nonlinear stability analysis theory. This indicates that the terminal guidance system under the control of these guidance laws can stable operation. Finally the results of simulation show that these methods are efficacious and gives the curves of sight angle sight anglar velocity missile and target distance and missile acceleration. The papers analyzes the weakened chattering under the guidance laws.