scenarioPrescribedMotionWithTranslationBranching
Overview
This scenario demonstrates the branching capability of the prescribed motion module using the linearTranslationOneDOFStateEffector module. The prescribed motion module can be configured to have state effectors attached to it rather than the spacecraft hub. To do so, the state effectors are set up normally, except their parameters are set with respect to the prescribed motion effector rather than the hub. The parameters that were previously required to be provided relative to the hub frame must instead be provided relative to the prescribed motion frame.
This example configures a spacecraft lander concept, where the spacecraft system is comprised of a small cylindrical hub, a prescribed motion platform attached underneath the hub, and three symmetrically canted telescoping landing struts that are used as shock absorbers to assist the spacecraft in safely landing. The landing struts are each canted by 60 degrees relative to the platform base (30 degrees relative to the platform normal), and are evenly spaced by 120 degrees surrounding the center of the platform base. The stowed and deployed lander configurations are shown below.
The spacecraft is at rest at the start of the simulation. The platform is actuated first, where it is commanded to simultaneously translate and rotate downwards and away from primary hub structure to model the initial phase of the lander deployment. Its reference translational and rotational displacements are chosen arbitrarily as 10 degrees and 0.5 meters, respectively. Two smoothed bang-coast-bang acceleration profiles are used to kinematically prescribe the required two-degree-of-freedom platform motion. After the platform finishes actuating, the three landing struts are each commanded to deploy away from the platform along their translational axes. Similarly, the struts are given arbitrary reference displacements of 0.2, 0.1, and 0.15 meters relative to the platform.
The script is found in the folder basilisk/examples and executed by using:
python3 scenarioPrescribedMotionWithTranslationBranching.py
The prescribed platform motion, landing strut displacements and their rates, and the hub response to the lander deployment is plotted in this scenario.
Illustration of Simulation Results
