Impact angle constraint dual-layer adaptive guidance law with actuator faults

To intercept maneuvering target considering impact angle constraint and actuator faults, a novel three-dimensional (3D) guidance law is proposed in this paper. To guarantee the interception, the multi-variable super-twisting-algorithm-like (STA-like) is adopted in the proposed guidance law, so as to drive the line-of-sight (LOS) angle to the desired value and its rate to zero in finite time in both pitch and azimuth directions. However, it is usually a difficult task for STA-like to select the proper design parameters, and the necessary disturbance gradient for STA-like is also not clearly known, owing to realistic actuator faults and the independence between missile and target. Moreover, the actuator faults in this paper are formulated as disturbances in the control scheme, and the necessary disturbance gradient for STA-like is not clearly known as well. To solve these problems, a multi-variable dual-layer adaptive scheme is employed to adjust the control gains and guarantees its precision. The theoretical analysis and numerical simulation results demonstrate the effectiveness of the proposed guidance law. The combination of STA-like and adaptive theory in the presented guidance law for the first time can guarantee the successful interception and can generate precise and robust control signal simultaneously with impact angle constraint and actuator faults consideration.