3.8 Data Acquisition and Playback

The ability to easily observe vehicle system data real time is extremely important for safe and effective operations, and also for understanding controller performance. However, after the test is over it is also very helpful to have the ability to carefully examine critical portions of the previous test. To fill this need, a system has been developed to allow easy recording and clear informative playback of the original flight data.
In order to begin data acquisition, the pilot need only specify a file name, and press the record button. When finished recording, the stop button is pressed. The data stream recorded consists of the time tag, the estimated quaternion, the error quaternion, the angular velocity error, the estimated angular velocity, the magnetic field vector, the acceleration vector, and the magnitudes of the desired and commanded moments.
This data may be played back by loading it back into a playback buffer, where it is displayed on the same type of advanced 3D attitude display as is used in free flight. The data plays back like a computer movie with a slider may be used to shuttle forward or backward through the data set. The same strip chart displays are also available, and may be scaled in the same way that they are during normal flight operations. This commonality between displays makes it easier to switch back and forth between the operations and playback modes, and also makes the data easier to analyze.