The variable winglet QBiT is a project I worked on throughout my undergraduate and graduate time at the University of Maryland. The purpose was to investigate the aerodynamic efficiency improvements gained by transitioning from a box wing to an open winglet configuration.
The first paper I wrote details the mechanical and aerodynamic findings: https://www.researchgate.net/publication/330913281_Aerodynamic_and_Mechanical_Design_of_a_Morphing_Winglet_for_a_Quadrotor_Biplane_Tail-sitter?_tp=eyJjb250ZXh0Ijp7ImZpcnN0UGFnZSI6Il9kaXJlY3QiLCJwYWdlIjoiX2RpcmVjdCJ9fQ
The second paper investigated its use in a path planning algorithm, and how the variable wing geometry could be used to improve the mission capabilities in simulated scenarios such as pursuit-evasion: