ADCS.CONOPS.goals.attitude_goals.fixed_attitude_goal module

class ADCS.CONOPS.goals.attitude_goals.fixed_attitude_goal.Fixed_Attitude_Goal(q_ref)

Bases: Attitude_Goal

Fixed inertial attitude goal.

This class implements a concrete attitude goal that commands a constant reference attitude, independent of the current orbital state. The desired attitude is provided at construction time as a reference quaternion and is held fixed for all times.

Let the reference quaternion be denoted by

\[\mathbf{q}_{\mathrm{ref}} \in \mathbb{R}^4, \quad \lVert \mathbf{q}_{\mathrm{ref}} \rVert = 1\]

The goal mapping implemented by this class is

\[G_{\mathrm{fixed}}(\mathcal{O}(t)) = \left( \mathbf{q}_{\mathrm{ref}}, \mathbf{0} \right)\]

where \(\mathcal{O}(t)\) is the current orbital state and the reference angular velocity is identically zero.

This goal is suitable for inertial-pointing modes such as sun-safe attitudes, communication attitudes, or commissioning configurations where no tracking motion is required.

See also

Attitude_Goal, Goal

Parameters:

q_ref (ndarray)

to_ref(os0)

Return the fixed reference attitude and zero angular velocity.

This method ignores the orbital state and always returns the constant reference attitude specified at initialization.

\[\mathbf{q}_{\mathrm{ref}}(t) = \mathbf{q}_{\mathrm{ref}}, \quad \boldsymbol{\omega}_{\mathrm{ref}}(t) = \mathbf{0}\]

Parameters:

os0 (Orbital_State) – Current orbital state.

Returns:

Reference attitude quaternion and zero reference angular velocity.

Return type:

Tuple[numpy.ndarray, numpy.ndarray]