Open-Loop Spinup and Deployment Control of a Tether Sling

Atether slingholds tremendous promise as an energy-storage device, permitting space transportation systems that are capable of injecting a large number of payloadswith low incremental costs. This paper developsmotor and tether deployment controls to go from rest to a desired final tether length and end velocity. Oscillations in the tether deployment angle are minimized to avoid additional tension in the tether. Open-loop control laws are developed for both power-unlimited and power-constrained cases. For unlimited power, the time-optimal mission profile dictates deployment at large angular velocities. The opposite is true when power is constrained: spinup and deployment time are reduced by deploying at very small angular velocities.