A Globally Exponentially Stable Hybrid Attitude and Gyro-bias Observer
  This paper presents a hybrid attitude and gyro-bias observer designed directly on the Special Orthogonal group SO(3). The proposed hybrid observer, relying on a hysteresis-based switching between two configurations, guarantees global exponential stability using biased angular velocity and inertial vector measurements. Simulation results are given to illustrate the effectiveness of the proposed observer. 
Soulaimane Berkane, Abdelkader Abdessameud, and Abdelhamid Tayebi
math.OC