Virtual Roll Gyro for Spin-Stabilized Projectiles

A computer-implemented method employing at least one hardware implemented computer processor for determining roll rate for a spin-stabilized projectile, the method comprising:

• operating the at least one hardware processor to execute program instructions to:
• measure a yaw signal and a pitch signal for the projectile, wherein:
• (i) for a trajectory path being travelled by the projectile over the Earth's surface, projectile stability is created by spinning of the projectile about a longitudinal spin axis oriented tangent to the projectile trajectory,
• (ii) the yaw signal represents yaw motion of the projectile about a yaw axis oriented along a line through the Earth's center and orthogonal to the spin axis,
• (iii) the pitch signal represents pitch motion of the projectile about a pitch axis orthogonal to the spin axis and the yaw axis, and
• wherein the yaw signal and the pitch signal are modulated by spin rate of the projectile spinning about the spin axis;
• extract a roll rate signal from one of the yaw signal and the pitch signal;
• and
• provide the yaw signal, the pitch signal, and the roll rate signal to an inertial measurement unit (IMU) configured to control orientation of the projectile with respect to the trajectory path.