To deal with the problem that multiple missiles cooperatively attack maneuvering targets with impact angle constraints, a novel leader-following missiles fixed-time cooperative guidance law was proposed. The leader-following missiles cooperative guidance model was established according to the relative motion between the target and missiles. Based on the fixed-time sliding mode control theory, the guidance law in the directions normal to the LOS (line-of-sight) was designed, so that the leader and followers could accurately attack the maneuvering target from the desired impact angles. Based on the consistency error function and the fixed-time sliding mode reaching law, the guidance law in the LOS direction of the followers was designed, which fully utilized the information exchange between missiles, and the time-to-go of the followers could quickly achieve consensus with that of the leaders in fixed time. Simulations and comparison verification indicate that the designed guidance law has higher control accuracy for time and angle constraints, no singularity and chattering phenomenon, faster convergence speed and the convergence time bound is independent of the initial states, which fully verifies the effectiveness and superiority of the proposed guidance law.

To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight (LOS) angles in Three-Dimensional (3D) space, this paper proposes a 3D leader-following cooperative interception guidance law. First, in the LOS direction of the leader, an impact time-controlled guidance law is derived based on the fixed-time stability theory, which enables the leader to complete the interception task at a prespecified impact time. Next, in the LOS direction of the followers, by introducing a time consensus tracking error function, a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go. Then, in the direction normal to the LOS, by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control (SMC) theory, an innovative 3D LOS-angle-constrained interception guidance law is developed, which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption. Moreover, it effectively suppresses the chattering phenomenon while avoiding the singularity issue, and compensates for unknown interference caused by target maneuvering online, making it convenient for practical engineering applications. Finally, theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness, superiority, and robustness of the investigated guidance law.