Guidance

The guidance subsystem determines the commanded trajectory required to intercept the target.

Overview

Guidance algorithms calculate the desired acceleration commands based on:

• Current missile state
• Target information
• Engagement geometry

Common guidance laws include:

• Proportional Navigation (PN)
• Augmented Proportional Navigation (APN)
• Pure Pursuit
• Command to Line of Sight (CLOS)

Proportional Navigation

Proportional Navigation (PN) is one of the most widely used guidance laws (Siouris, 2004). The lateral acceleration command is proportional to the line-of-sight (LOS) rate:

$$a_c=N^{\prime }{V}_c\dot{\lambda }\text{\hspace{1em}(1)}$$

where:

• $a_c$ is the commanded lateral acceleration
• $N^{\prime }$ is the effective navigation constant (typically 3–5)
• $V_c$ is the closing velocity
• $\dot{\lambda }$ is the line-of-sight rate

The navigation constant $N^{\prime }$ in (1) determines the aggressiveness of the guidance law. Higher values result in more aggressive maneuvering but also higher acceleration demands.

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