Terminal Multi-Constrained Finite Time Sliding Mode Guidance Law Based on Truncation Function for Hypersonic Vehicle

In order to solve the terminal guidance problem of the hypersonic vehicle, a multi-constrained guidance law with position, impact angle and impact velocity was studied. Firstly, a finite time sliding mode control method based on truncation function for second order nonlinear system was proposed, and then a reasonable truncation function was designed according to the dynamic equation of the terminal guidance phase of the vehicle to form the sliding mode control function of the longitudinal and transverse planes. Further, the auxiliary control was obtained and the guidance command was generated. Under the action of the control quantities, the system was kept on the sliding mode surface all the time, that is, the global sliding mode can be realized, and the constraints of position and impact angle can be realized. The guidance parameter was solved iteratively according to the redundant degrees of freedom in the transverse plane to ensure the constraint of impact velocity. The simulation verified that the guidance method can meet the requirements of terminal multiple constraints of hypersonic vehicle.