High-Fidelity Optical Techniques for In Situ Position and Attitude Determination of Wind-Tunnel Models

Measurements of test article attitude and position are critical but are often difficult to make due to packaging constraints and model orientations where gravity-based sensors are not applicable. We propose a novel means of determining the position and attitude of a wind-tunnel model or other object of interest through intelligent evaluation of images of the object. While earlier measurements using analog film were limited in accuracy to approximately 50 microns, recent developments in high-speed digital camera technology have allowed significantly improved accuracy while increasing acquisition rates to at least tens of kHz. We will develop a user-friendly software package, based upon an algorithm utilizing optimized edge detection and least-squares fittings, to determine precisely the continuous position and attitude of bodies in silhouette images. The technique uses input from data acquisition mechanisms already widely available in many wind tunnel facilities (e.g., from schlieren or backlighting images), and the current state of the art has been developed by members of the proposed team. Our product will enable real-time or near real-time measurements of model attitude at 10+ kHz with the necessary accuracy for position characterization, with minimal additional experimental overhead in equipment or time.