SolRadAndGravityDynamics.compute_covariance_dynamics¶
- SolRadAndGravityDynamics.compute_covariance_dynamics(state, et_time, radial_distance_cb, position_sc_to_bodies, radial_distance_sc_to_bodies, direction_sun_to_sc, distance_sun_to_sc)[source]¶
This method computes the dynamics for the covariance matrix.
The dynamics for the covariance matrix is the product of the Jacobian matrix of the dynamics for the state with respect to the state and the current covariance matrix, plus the process noise matrix
\[\mathbf{\partial \mathbf{P}}{\partial t} = \mathbf{J}\mathbf{P} + \mathbf{P}\mathbf{J}^T + \mathbf{Q}\]where \(\mathbf{P}\) is the covariance matrix, \(t\) is time,
\[\mathbf{J}=\frac{\partial \mathbf{f}(\mathbf{x})}{\partial\mathbf{x}}\]with \(\mathbf{J}\) being the Jacobian matrix, \(\mathbf{f}(\mathbf{x})\) is the state dynamics function, and \(\mathbf{x}\) is the state vector.
- Parameters:
state (ndarray) – The state vector at the current time
et_time (float) – The ephemeris time
radial_distance_cb (float) – The distance from the central body to the body we are estimating
position_sc_to_bodies (List[ndarray]) – The position from the spacecraft to the other bodies considered for gravity
radial_distance_sc_to_bodies (List[float]) – The distance from the spacecraft to the other bodies
direction_sun_to_sc (ndarray) – The unit direction vector from the sun to the spacecraft
distance_sun_to_sc (float) – The distance between the sun and the sc at the current time in units of AU
- Returns:
The covariance time derivative.
- Return type:
ndarray