Abstract:

The strapdown image seeker has the advantages of compact structure, high overload resistance, and low cost, meeting the requirements of miniaturization, overload resistance, and low cost of precision guided projectile. However, the oscillation and precession of the projectile caused by spin during projectile’s flight increase the difficulty of decoupling the line of sight angle and the attitude angle of the projectile, which has long constrained the application of strapdown seekers in guiding projectiles. To regard this, a method for extracting the line of sight angle of a rotating strapdown image guided projectile is proposed, and a rotating strapdown image terminal guidance scheme with field of view constraints is designed. By solving the full angle of attack equation, virtual velocity vectors are extracted within the field of view of the seeker, and a closed-loop guidance loop is established. By using intermittent control, a nonlinear sliding surface with field of view constraints and a tangent-type obstacle Lyapunov function are constructed to achieve stable locking within the target field of view. An adaptive extended state observer is introduced to estimate and compensate for target motion, reducing the phenomenon of body shaking. The proposed method is validated through numerical simulation and flight experiments, and the hit accuracy meets the expected requirements to achieve precise guidance control of rotating strapdown image guided projectile.

Key words: image guidance, rotating strapdown, attitude isolation, field of view angle constraint, obstacle Lyapunov function