HELIOGYRO SOLAR SAIL BLADE TWIST CONTROL

摘要

The heliogyro is an ultra-lightweight, high performance, spinning solar sail architecture. The sail is divided into long blades supported by the centripetal acceleration of the spacecraft's spin alone. The heliogyro's attitude and thrust vector are controlled by changing the cyclic and collective blade pitch similar to a helicopter. The heliogyro's reflective sail membranes are packaged and unspooled from rolls, greatly simplifying deployment operations compared with square-rigger solar sail designs. The heliogyro also easily scales to the huge dimensions required for many applications enabled by solar sail propulsion. One principal concern for the feasibility of heliogyro's is the ability to adequately control the dynamic response of their long, unsupported blades, and in particular, to damp disturbances caused by maneuvering transients. First, the finite element equations of motion for a thin membrane are developed and validated for a single blade in twist. A Proportional/Derivative/Feed-Forward controller is implemented at the root. The control gains are optimized both through the stiffness analysis and parametrically. It is found that the blade vibrations from all maneuvers of interest can be damped in less than eight minutes using root actuation alone. This is a significant improvement over previous work in the area and is sufficiently rapid for even the most demanding heliogyro missions.