Polynomial guidance law for impact angle control with a seeker look angle limit

In this paper, the impact angle control problem is investigated by applying the polynomial shaping method. By shaping the light-of-sight angle with relative range, a guidance law called range polynomial guidance is proposed, and the coefficients are determined by boundary conditions. The range polynomial guidance law can be applied to maneuvering targets. By profiling the seeker look angle with the light-of-sight angle, a guidance law called line-of-sight polynomial guidance is developed for impact angle control under a limitation on the seeker look angle. The line-of-sight polynomial guidance law is also effective in intercepting a non-maneuvering moving target at the desired impact angle. Guidance laws with different gain sets are discussed in this paper. The proposed guidance laws take the form of proportional navigation with a time-varying navigation gain. Nonlinear simulations are performed to validate the efficacy of the proposed guidance laws in various engagement conditions. Comparison with other studies demonstrates the practicality and flexibility of the proposed guidance laws in the design of desired impact angles and maximum look angles.