Design of Nonsingular Terminal Sliding Mode Guidance Law with Disturbance Observer

Guidance law is an algorithm used to guide a missile to attack a target. The target evasive maneuvers are difficult to measure by sensors in the missile guidance law design, and are usually treated as known bounded disturbance leading to large error in intercepting targets with high-speed and high-maneuvering. A high-order sliding mode interference observer is designed to estimate the target evasive maneuver for a nonsingular terminal sliding mode guidance law to achieve better interception performance. Simulation results show that the proposed guidance law has a flatter ballistic curve and faster response to target maneuvering.