[WIP] Tentative formalization of a tilt estimation

[affeldt-aist]

Tentative formalization of:

@article{benallegue2023ieeetac,
  author       = {Mehdi Benallegue and Abdelaziz Benallegue and Rafael Cisneros and Yacine Chitour},
  title        = {Velocity-Aided {IMU}-Based Tilt and Attitude Estimation},
  journal      = {{IEEE} Trans. Autom. Control.},
  volume       = {68},
  number       = {10},
  pages        = {5823--5836},
  year         = {2023},
  doi          = {10.1109/TAC.2022.3225758},
  note = {Available at \url{https://hal.science/hal-04271257v1/file/benallegue2019tac_October_2022.pdf}}
}