Statically Balanced Flexural Pivot for Space Mechanisms: Modelling, Optimisation, and Prototype Validation

Abstract

Space mechanisms often require precise rotational motion while operating in vacuum, under temperature variations, and over long mission durations. Conventional mechanisms relying on tribological components can suffer from friction, backlash, wear, and lubrication-related contamination or degradation. Flexural pivots avoid these issues by using elastic deformation instead of sliding or rolling contact. However, they generate restoring torque when rotated, increasing actuator effort, and large-stroke designs can lose stiffness in constrained degrees of freedom.

This thesis, conducted with the European Space Agency, investigates a statically balanced flexural pivot designed to reduce restoring torque across a wide range of motion while maintaining stiffness in degrees of constraint. These goals are achieved with a design combining a novel positive-stiffness guidance backbone with preloaded negative-stiffness elements. Through nonlinear modelling, optimisation, prototype development, and testing, the work shows that separating guidance and balancing functions is a promising route towards low-torque flexural pivots for space mechanisms.