Aiaa-99-4227 Rapid Energy Dissipation in a Yo-yo-type Wire Boom Deployment System

A wire boom deployment system has been developed that uses a mechanism which is similar to the classic yo-yo despin mechanism. The goal has been to develop a way to rapidly deploy wire booms from a spinning sounding-rocket experiment. The main challenge in using a yo-yo-type mechanism is to dissipate the excess kinetic energy so that the wire booms do not re-wrap themselves about the spacecraft after deploying. A ring has been added to the basic yoyo mechanism. It rotates with respect to the main spacecraft about the nominal spin axis, and the wire booms deploy from it. The ring/spacecraft joint is damped, and relative motion between the ring and the spacecraft dissipates the excess energy. This system is analyzed and simulated in 2 and 3 dimensions. Techniques are developed for tuning the damping law to rapidly deploy the wire booms without the occurrence of re-wrapping, and a criterion is presented that ensures 3-dimensional stability of the final equilibrium in the global minimum-energy sense. Simulation results show that the system can deploy 2.5 m wire booms in under 20 sec and that the deployment can tolerate the expected levels of asymmetry in the system configuration and the initial state. Introduction Most spacecraft need to deploy devices after launch in order to overcome the size constraints that are imposed by a booster's fairing. Wire booms are one type of deployable structure. Wire booms are long wires whose bases are attached to a spinstabilized spacecraft. Normally a wire boom also has a tip mass at its end. Centrifugal force acts to keep the wire booms taut, Fig. 1. Wire booms are attractive because they can be built using very little mass per unit length. They have been used on a number of spacecraft missions, e.g., see Refs. 1 and 2. ∗ Associate Professor, Sibley School of Mechanical and Aerospace Engineering. Associate Fellow, AIAA. # Professor, School of Electrical Engineering. ** Research Support Specialist, School of Electrical Engineering. Copyright  1999 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Fig. 1. Two views of a spacecraft with 4 wire booms and a yo-yo-type deployment mechanism. (shown during an asymmetric deployment at the time of maximum out-of-plane pendulum angle) The current study of wire boom deployment is motivated by a desire to use wire booms on small "daughter" spacecraft in a sounding-rocket study of the ionosphere. This study is called "Sounding of the Ion Energization Region: Resolving Ambiguities" (SIERRA). The sounding rocket will deploy several small spin-stabilized free-flying daughter modules. Each of these will deploy 4 wire booms with electric probes at the end of each boom. The electric probes will be used to measure the electric field. The use of several daughter spacecraft will allow the system to resolve spatial/temporal ambiguities in observed variations of the electric field. Current sounding rocket technology uses telescoping booms and other types of rigid booms. These booms are too heavy for use on small daughter modules, which is why wire booms are planned for use on this experiment. Tip Masses Wire Booms Direction of Spin