Three-dimensional nonlinear pseudo optimal guidance law for hypersonic vehicle based on twist technology

A new three-dimensional (3D) nonlinear pseudo optimal guidance law based on twist technology was proposed to resolve the coupling problem between different channels for the guidance of hypersonic vehicle. The basic concepts of angle vector, line-of-sight (LOS) twist and its rate were introduced, and through equivalence certification, the guidance problem was converted into control problem of LOS twist and twist rate, with the conclusion that the LOS twist and its rate control equals to the LOS orientation and LOS angle rate control. A 3D nonlinear guidance model was constructed on the basis of LOS twist and the rate models through twist technology. In addition, the 3D nonlinear model was decoupled into the linear one by introducing pseudo control variable to reduce the complicate resolution of differential Riccati equation. The 3D nonlinear pseudo optimal guidance laws were derived using linear quadratic regulator (LQR) corresponding to no ending constraint and ending constraints respectively. With these novel guidance laws, the decoupling process can be well avoided and the optimal characteristics of guidance parameters were ensured as well. The validity of these guidance laws was also validated through simulation experiments. © 2015, National University of Defense Technology. All right reserved.