One Degree of Freedom Approach for an Autonomous Descent Vehicle Using a Variable Drag Parachute

摘要

This paper describes a novel method for controlling the landing location of a descent vehicle using a variable-drag parachute. Wind data is collected prior to descent and used to predict the descent path from initial parachute deployment to landing. The landing target location takes the form of a finite line segment on the ground surface. Guidance is achieved by modifying the effective surface area of the parachute. The control algorithm uses a 1-DOF model to predict and control the landing location. Experimental results are presented to demonstrate the feasibility of the approach. First, results from wind tunnel testing quantify how throttling of a parachute through simple manipulation of parachute shroud lines changes the cross sectional area and the resulting drag force. Second, the accuracy of the descent path prediction algorithm was evaluated experimentally using a stratospheric balloon flight. These data were used to validate the ability of the proposed control algorithm to accurately predict landing location. Together, these tests demonstrate the potential for using inexpensive onboard flight hardware to autonomously sense and control a descent vehicle to reach a linear target on the ground.