scenarioAttitudePointingNumba

Overview

This script showcases how to create a Numba Basilisk module.

Demonstrates how to stabilize the attitude tumble without translational motion. This script sets up a 6-DOF spacecraft, but without specifying any orbital motion. Thus, this scenario simulates the spacecraft translating in deep space. The scenario is a version of scenarioAttitudePointingPy where the Python MRP PD control module is replaced with an equivalent Making Numba Modules-based implementation.

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

python3 scenarioAttitudePointingNumba.py

As with scenarioAttitudePointingPy, when the simulation completes 3 plots are shown for the MRP attitude history, the rate tracking errors, as well as the control torque vector.

The MRP PD control module in this script is a class called NumbaMRPPD. It subclasses NumbaModel and implements the entire control law inside UpdateStateImpl, which is JIT-compiled by Numba to native code. Gains K and P are stored in the persistent memory namespace and can be configured before InitializeSimulation is called:

numMRPPD = NumbaMRPPD()
numMRPPD.ModelTag = "numMRP_PD"
numMRPPD.memory.K = 3.5     # [N m]
numMRPPD.memory.P = 30.0    # [N m s/rad]
numMRPPD.guidInMsg.subscribeTo(attError.attGuidOutMsg)
scSim.AddModelToTask(simTaskName, numMRPPD)

Illustration of Simulation Results

show_plots = True

Here a small initial tumble is simulated. The resulting attitude and control torque histories are shown below. The spacecraft quickly regains a stable orientation without tumbling past 180 degrees.

class scenarioAttitudePointingNumba.NumbaMRPPD(*args, **kwargs)

Bases: NumbaModel

MRP PD attitude controller implemented as a NumbaModel.

The control law is:

L_r = -(K * sigma_BR + P * omega_BR_B)

Gains K and P are stored in the persistent memory namespace so they are accessible inside the JIT-compiled UpdateStateImpl.

static UpdateStateImpl(guidInMsgPayload, cmdTorqueOutMsgPayload, memory)

Compute the commanded control torque from attitude and rate error.

scenarioAttitudePointingNumba.run(show_plots)

The scenarios can be run with the followings setups parameters:

Parameters:

show_plots (bool) – Determines if the script should display plots