Three-Dimensional Impact Time and Angle Guidance via Controlling Line-of-Sight Dynamics

In this paper, a three-dimensional guidance law is developed for intercepting a maneuvering target with impact angle constraint at a specified impact time. To achieve this goal, the LOS error dynamics is utilized to track a constant LOS signal and a quadratic LOS profile in the pitch and yaw planes, respectively. The designated LOS profile in the yaw plane has a simple structure, i.e., a quadratic polynomial in time. To nullify the LOS tracking errors in finite time, the non-singular terminal sliding mode technique is utilized to obtain the guidance commands. Furthermore, a set of reliable LOS profiles are systematically determined to ensure the feasibility of the guidance law. The proposed guidance law can guarantee the desired impact angles and zero miss distance as mandatory requirements. Meanwhile, a single tuning parameter provides an additional freedom to meet the desired impact time. Finally, numerical results with various engagement scenarios are provided to validate effectiveness of the proposed guidance law.