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This research addressed the problem of determining the payload’s three-dimensional position and possibly attitude based on observations obtained by several fixed cameras on the ground. Figure A shows an example of surveyed camera sites for the combined Corral/Mohave drop zone (DZ), whereas Fig.B demonstrates an example of the stabilized Kineto Tracking Mount (KTM) that is used to record the airdrop event from aircraft exit to impact. Figure B shows an operator seat (in the center) with multiple cameras (having different focal lengths). During the drop the operator manually points cameras at the test article. All KTMs have azimuth and elevation encoders, which sample Az/El data along with Coordinated Universal Time (UTC) once every video camera frame.


Figure A. Two drop zones (stars) with KTM sites around them (rhombs).


Figure B. The KTM with the operator seat and multiple cameras.

 
The reasons for having time, state and attitude information (TSPI) available for each test article are as follows:

  1. Firstly, it is needed to estimate the performance of the system (e.g., a descent rate at certain altitudes and at touchdown);
  2. Secondly, this information can be further used for model identification and control algorithms development;
  3. Thirdly, parachute- or parafoil-payload systems (including cluster systems) are the multiple-body flexible structures, so knowing the behavior of each component (payload and canopy), as opposed to the center of the whole system, allows to model/improve their interaction.

Obviously, nowadays an inertial measurement unit (IMU) and/or global positioning system (GPS) can be used to acquire accurate TSPI of any moving object. However, when applied to massive testing of different test articles there are several reasons preventing of using those modern navigation means. To start with, you cannot install IMU/GPS units on all test articles (there are to many of them). Second, the harsh condition of operating some of the articles will result in destroying IMU/GPS units each or every other test. Third, some of the test articles simply cannot accommodate IMU/GPS units either because of the size constrains (for instance, miniature air delivery systems, shells and bullets) or because of non-rigid structure of the object (canopies). Forth, for the parachute and parafoil systems the GPS signal is simply not available for the first 30 seconds of a ballistic flight after exiting an aircraft. All aforementioned makes using information, recorded by multiple KTMs for each test anyway, to determine TSPI of test articles very relevant.

This research addressed this issue in three ways. First, the position estimation problem was addressed and solved. Second, the pose (position and attitude) estimation problem was dealt with. Third, the graphical user interface helping to better understanding the pose estimation problem was developed. These three components are listed below. You are welcome to click on any of them to have them to appear on a separate page.

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