Deviated Pursuit based Nonlinear Impact-Time Guidance with Finite-Time Convergence
Himanshu U.S. Bishwash, Abhinav Sinha, Shashi Ranjan Kumar
Abstract
This paper proposes two finite-time convergent guidance schemes to intercept a constant velocity target at a pre-specified impact-time. The guidance commands exploit the archetype of deviated pursuit scheme to facilitate the synthesis of impact-time constrained guidance strategies. Deviated pursuit guidance offers an exact expression of time-to-go, thereby circumventing the errors associated with approximate time-to-go estimates. The guidance strategy is derived using nonlinear engagement dynamics, which helps in avoiding errors due to linearization. The first guidance strategy is based on traditional sliding mode control with constant rate reaching law. The second guidance scheme utilizes super-twisting control, which is a higher-order sliding mode technique avowed for guaranteeing finite-time convergence and better control precision. Finally, simulations are presented to invigorate the theoretical claims and it is also shown through simulations that the desired impact-time can even be lower than the initial time-to-go value.