Constrained path-planning for an aerial-towed cable system

This paper studies the coupled motion of an aircraft towing a cable for applications such as precision deployment or retrieval of payloads, or close surveying of land/ocean environments. There is a complex interaction between the motion of the cable tow-point, aerodynamic drag, and tension forces on the motion of the cable tip. The path-planning algorithm involves determining the motion of the aircraft, as well as the cable deployment rate, to achieve precision 'hits' of the cable tip with known ground targets in a three-dimensional space. By utilizing the motion of the towed-body as a differentially flat output, the aircraft controls and/or reel rate are computed via an inverse technique. The motion of the towed-body is approximated using Chebyshev polynomials so as to pass through the desired points while minimizing its overall acceleration. The technique is implemented in a nonlinear programming environment to constrain the aircraft dynamics to within acceptable limits.