scenarioAttitudeGG

Overview

Illustrates how to add a GravityGradientEffector to a 6U cube-sat spacecraft while a Hill-frame pointing control solution is active. This script expands on scenarioAttitudeGuidance sets up a 6-DOF spacecraft which is orbiting the Earth. More illustrations on using the gravity gradient torque effector can be found in the modules UnitTestGravityGradientEffector folder.

The script is found in the folder xmera/examples and executed by using:

python3 scenarioAttitudeGG.py

The simulation layout is shown in the following illustration. The GravityGradientEffector is added to the spacecraft to create a position depended external torque. This

Illustration of Simulation Results

In this simulation the reference frame is not aligned with the Hill frame, but rather it has a fixed angular offset along the 2nd body axis. As the Body frame inertia tensor is diagonal, this reference orientation represents a non-equilibrium gravity gradient torque orientation. Thie simulation results are shown in the following figures:

Where in scenarioAttitudeGuidance the attitude error asymptotically converged to zero, with the gravity gradient torque the closed loop dynamics is now only Lagrange stable or bounded.