Three-dimensional prescribed performance cooperative guidance law with spatial constraint for intercepting manoeuvring targets

This paper proposes three-dimensional cooperative guidance laws with prescribed performance. To avoid degradation in performance due to error in the estimation of the time-to-go, the relative distance between the missiles and the target is chosen as a coordination variable, and a fixed-time cooperative guidance law along the direction of the line-of-sight (LOS) is proposed. The guidance laws with prescribed performance for the elevation and direction of the azimuth of the LOS are then developed by combining the LOS angle tracking error with a performance constraint function to formulate a transformed error function. The problem of prescribed performance control is transformed into that of the boundedness of the transformed error function. A fixed-time convergence disturbance observer is designed to discuss the problem whereby information on aggregate uncertainty, including on the target, is unavailable. The results of simulations show that the proposed guidance laws are effective.