Terminal guidance law with impact angle constraint for BTT vehicle

Aiming at the requirements of bank-to-turn (BTT) vehicle attacking target with desired angle, a sliding-mode variable-structure guidance law with impact angle constraint was proposed in view of the dynamic characteristics of the control loop. Choosing bank angle command and normal overload command as control variables, a model with control loop dynamic characteristics for designing guidance law was established. Based on the model, a sliding mode variable-structure guidance law with terminal angular constraint was designed. An adaptive reaching law was designed to alleviate chattering. Through theoretical analysis, this guidance law needs lower normal overload than optimal guidance law in the initial stage. In addition, when system reaches sliding mode surface, the vehicle can impact on the target with the same effect as optimal guidance law does. Simulation results show that the proposed guidance law not only ensures the vehicle impact the target accurately with desired angle, but also distributes normal overload requirement reasonably and requires less velocity loss.