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Live-fire testing of artillery projectiles is commonly conducted for design changes or lot-acceptance verification. And it is becoming increasingly common to record high-speed video of the projectiles as they exit the muzzle. Pitch and yaw of the projectile are key parameters for study.
The cameras are often stationary digital units capable of recording up to 100,000 frames per second. In some instances, when visual confirmation of the initial flight performance is desired, new state-of-the-art camera systems capable of automated rotation to follow a projectile are used to keep the munition in the frame longer.
To address quality control and to aid in the design of future projectiles, Navy scientists have developed an automated method to quantify the pitching and yawing motion of a projectile during ballistic flight using two trajectory-tracking video camera systems.
Sophisticated image processing tools are employed to segment the shape of the projectile in each frame of the launch video, which allows the location and observed pitch angle to be calculated with sub-pixel accuracy, with the output of a determined pitch and yaw of the projectile. Subsequent computer analysis uses the history of the projectile location and the pitching behavior to calculate estimates for the epicyclic motion, as well as other ballistic parameters such as aeroballistic coefficients.
Using two cameras located at different views of the line-of-fire allows the pitching and yawing motion history of the projectile to be calculated in three dimensions. In addition, data on the camera locations, cannon trunnion location, and the cannon pointing direction allow for automatic correction in the event of camera misalignment.
This US patent 9,721,352 is related to US patent 9,563,964. The ‘352 patent encompasses 18 method claims. The ‘964 patent represents the 2 apparatus claims.
- Rapidly analyze hundreds of video frames worth of data
- System also calculates velocity
- US patent 9,721,352 available for license
- Potential for collaboration with Navy researchers