test_ThrusterStateEffectorUnit

test_ThrusterStateEffectorUnit.test_unitThrusters(testFixture, show_plots, thrustNumber, initialConditions, duration, long_angle, lat_angle, location, swirlTorque, rate, attachBody)[source]

Validation Test Description

This unit test script tests the stateEffector implementation of thrusters. It sets up the thruster module and runs a combination of 6 different scenarios. Each scenario uses either one or two thrusters, while also changing the thruster’s locations and whether thruster 1 is firing or not.

For information on how the thruster module works and what the closed-form solution for the thrustFactor variable is, see Module: thrusterStateEffector. Given the thrustFactor \(\kappa\), the thrust is computed as follows:

\[\textbf{F} = \kappa \cdot F_{\mathrm{max}} \cdot \hat{n}\]

where \(\hat{n}\) is the thruster’s direction vector. The torque is computed by:

\[\textbf{T} = \textbf{r}\times\textbf{F} + \kappa \cdot T_{\mathrm{maxSwirl}} \cdot \hat{n}\]

where \(\textbf{r}\) corresponds to the thruster’s position relative to the spacecraft’s center of mass and the second term represents the swirl torque. The mass flow rate is given by:

\[\dot{m} = \dfrac{F}{g\cdot I_{sp}}\]

where \(g\) is Earth’s gravitational acceleration and \(I_{sp}\) is the thruster’s specific impulse.

Test Parameters

Parameters:

  • thrustNumber (int) – number of thrusters used in the simulation

  • initialConditions (float) – initial value of the thrustFactor variable for thruster 1. Thruster always starts

  • off.

  • duration (float) – duration of the thrust in seconds.

  • long_angle (float) – longitude angle in degrees for thruster 1. Thruster 2 is also impacted by this value.

  • lat_angle (float) – latitude angle in degrees for thruster 1. Thruster 2 is also impacted by this value.

  • location (float) – location of thruster 1.

  • swirlTorque (float) – maximum value of the swirl torque on the thruster.

  • rate (int) – simulation rate in nanoseconds.

  • attachBody (flag) – whether the thruster is attached to the hub or to a different body.

Description of Variables Being Tested

In this file we are checking the values of the variables

  • thrForce

  • thrTorque

  • mDot

All these variables are compared to the true values from the closed-form expressions given in Module: thrusterStateEffector.