Attitude Estimation Using Modified Rodrigues Parameters

An estimator using Modified Rodrigues Parameters (MRP) for gyro-less attitude and attitude rate estimation from vector observations is given. The singularity problem associated with MRP is addressed by MRP switching. The MRP error is defined as the MRP corresponding to the rotation from the estimated attitude to the true attitude. Based on the attitude error dynamics the attitude and attitude rate estimator is designed using the extended Kalman filtering approach. A numerical example is used to demonstrate the estimator's viability.