ENH: Implementing 3-dof-simulation #745

aZira371 · 2024-12-03T23:26:18Z

Pull request type

Code changes (bugfix, features)

Checklist

Tests for the changes have been added (if needed)
Docs have been reviewed and added / updated
Lint (black rocketpy/ tests/) has passed locally
All tests (pytest tests -m slow --runslow) have passed locally
CHANGELOG.md has been updated (if relevant)

Current behavior

for issue #655

New behavior

(DRAFT)
ENH: adds 3 DOF simulation capability to rocketpy.Flight.

*ENH: added "u_dot_3dof" for "solid_propulsion"
mode

*ENH: adding "u_dot_generalized_3dof" for "standard" mode (still incomplete)

*ENH: new parameter "simulation_mode" for swtiching between 3 dof and 6 dof

*ENH: updated conditions for "__init_equations_of_motion"

*ENH: 2 new example files have been created to test 3 dof model "test_bella_lui_flight_sim" and "test_camoes_flight_sim"

Breaking change

No

Additional information

This is a draft pull request!
Equations of motion have been modified in such a way that values related to various rotational dofs is set to zero.

ENH: adds 3 DOF simulation capability to rocketpy.Flight. *ENH: added "u_dot_3dof" for "solid_propulsion" mode *ENH: adding "u_dot_generalized_3dof" for "standard" mode (still incomplete) *ENH: new parameter "simulation_mode" for swtiching between 3 dof and 6 dof *ENH: updated conditions for "__init_equations_of_motion" *ENH: 2 new example files have been created to test 3 dof model "test_bella_lui_flight_sim" and "test_camoes_flight_sim"

Lucas-Prates · 2024-12-04T12:56:48Z

Thank you for your interest in implementing 3-DOF in RocketPy, @aZira371 . I will try to take a better look into it, but I notice one thing already: use 6 DOF as the default input for simulation_mode for two reasons:

most people will use 6 DOF;
changing it to 3 DOF introduces breaking changes, and we really want to avoid that. You can see that a breaking change occurred because the tests failed.

ENH: adds 3 DOF simulation capability to rocketpy.Flight. *ENH: added "u_dot_3dof" for "solid_propulsion" mode *ENH: added "u_dot_generalized_3dof" for "standard" mode *ENH: new parameter "simulation_mode" for swtiching between 3 dof and 6 dof *ENH: updated conditions for "__init_equations_of_motion"

ENH: fixed standard 3 dof *MNT: Cleaned up the "u_dot_3dof" and "u_dot_generalized_3_dof" *MNT: Corrected Typos in "simulation_mode" description *ENH: "u_dot_generalized_3_dof" fixed and tested on examples.

Gui-FernandesBR · 2025-02-08T16:12:53Z

Git rebase develop
Revert changes in the jupyter notebook
Create PointMassMotor
Create BaseRocket
Create PointMassRocket
Modify Rocket class where it's needed (here other people can help you, including Gui)
Modify the Flight class again, if needed (delete u_dot_3dof)
Include integration tests (here you can ask for help)
Format and lint the code (see the Makefile)

…into enh/3-dof-simulation

…otor ENH: added "BaseRocket" and "PointMassRocket" to rocket class ENH: added "PointMassMotor" to motor class with various input cases of thrust values

codecov · 2025-02-25T20:06:34Z

Codecov Report

❌ Patch coverage is 82.23684% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.26%. Comparing base (9cf3dd4) to head (567b9e0).
⚠️ Report is 6 commits behind head on develop.

Files with missing lines	Patch %	Lines
rocketpy/simulation/flight.py	68.11%	22 Missing ⚠️
rocketpy/motors/point_mass_motor.py	90.38%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #745      +/-   ##
===========================================
- Coverage    80.27%   80.26%   -0.02%     
===========================================
  Files          104      106       +2     
  Lines        12769    12979     +210     
===========================================
+ Hits         10250    10417     +167     
- Misses        2519     2562      +43

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

…e tests ENH: Added a new jupyter notebook for a simplified 3 DOF example MNT: PointMassMotor intialization error fixed MNT: PointMassRocket properties enhanced based on the example runs

MNT: Cleaned up the flight class u_dot_generalized_3dof TODO: Add info for 3 dof cases and fix some new issues when parachute is added.

…cketPy into enh/3-dof-simulation

rocketpy/motors/PointMassMotor.py

rocketpy/simulation/flight.py

rocketpy/motors/PointMassMotor.py

rocketpy/rocket/rocket.py

rocketpy/motors/PointMassMotor.py

rocketpy/environment/environment.py

rocketpy/motors/PointMassMotor.py

rocketpy/rocket/rocket.py

rocketpy/simulation/flight.py

Develop

-MNT: removing the parameters not needed for point mass kind of motors -MNT: removing extra parameter thrust_curve -MNT: fixing problems with motor class inheritance

-ENH: removed 'BaseRocket' class now 'PointMassRocket' inherits directly from 'Rocket' class

-MNT: fixed calculations of mass flow rate and exhaust velocity -MNT: adjusted propellant initial mass setter error by allocating the input initial mass to the property

MNT: renaming pointmassmotor.py -MNT:snake case renaming

…ization and clarity

Copilot

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 15 comments.

rocketpy/simulation/flight.py

tests/unit/simulation/test_flight_3dof.py

rocketpy/simulation/flight.py

tests/unit/motors/test_point_mass_motor.py

rocketpy/rocket/point_mass_rocket.py

docs/user/three_dof_simulation.rst

rocketpy/simulation/flight.py

Gui-FernandesBR

LGTM

rocketpy/motors/point_mass_motor.py

phmbressan

The PR looks good. Main points missing for me that could be easily appended to a following PR:

There are still no "sanity-check" tests for the results. We could probably make an "acceptance" test for it, by picking up a known battle-tested Flight and hoping for the landing coordinates being close. The tolerances for it are a point worth discussing. Maybe even comparing to a parabolic trajectory might give some insight (for sanity-checking a ballistic Flight);
Still on the validation side: results should be pretty close if one runs a bare-bones Rocket in 6-DOF, right?
Some tests lack proper docstrings;
Smaller comments I left throughout my review.

I'm fine proceeding with a merge here, but the first point for me is important before releasing the feature.

phmbressan · 2025-11-27T06:13:39Z

rocketpy/motors/point_mass_motor.py

+    @cached_property
+    def center_of_propellant_mass(self):
+        """Center of propellant mass is always zero"""
+        return Function(0.0)
+
+    # Propellant inertias: always zero, but return as Function objects
+    def _zero_inertia_func(self):
+        return Function(0.0)


Annoying, but I would discretize both based on self.thrust to ensure consistency/speed for the outputs.

could elaborate what you mean by discretize here exactly?

Check above lines from the same file, there should be a .set_discrete_based_on_model call somewhere. This is done to optimize the code for speed, keeping the data crunching based on arrays (instead of lambdas).

rocketpy/rocket/point_mass_rocket.py

rocketpy/simulation/flight.py

aZira371 · 2025-11-27T07:25:40Z

The PR looks good. Main points missing for me that could be easily appended to a following PR:

There are still no "sanity-check" tests for the results. We could probably make an "acceptance" test for it, by picking up a known battle-tested Flight and hoping for the landing coordinates being close. The tolerances for it are a point worth discussing. Maybe even comparing to a parabolic trajectory might give some insight (for sanity-checking a ballistic Flight);

Still on the validation side: results should be pretty close if one runs a bare-bones Rocket in 6-DOF, right?

Some tests lack proper docstrings;

Smaller comments I left throughout my review.

I'm fine proceeding with a merge here, but the first point for me is important before releasing the feature.

Agreed on the first and second point. I can run a 3 DOF example of one of the already existing examples and see how it works. From there we will also be able to understand tolerances.

* docs: Update test docstrings to follow RocketPy style guidelines Co-authored-by: aZira371 <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: aZira371 <[email protected]>

aZira371 · 2025-11-27T09:49:23Z

@Gui-FernandesBR @phmbressan
Here is a comparison of results of 3 dof and 6 dof on bella lui rocket example. as expected the impact/landing point is drastically incorrect. This is expected as 3 dof only implements translation motion (meaning the quaternion rates are 0) , to model rotational kinematics I can introduce an evolving unit direction vector for the “effective body/flight‑path axis” with a simple kinematic or quasi‑static weathercocking model. What do you think? This can be an implementation after this PR is merged!

just a small note on how the Weathercocking Model Works:

Calculate the current body z-axis direction from quaternions (attitude vector)
Calculate the desired direction as the opposite of the freestream velocity (normalized)
Compute the rotation axis as the cross product of current and desired directions
Apply angular velocity proportional to sin(misalignment_angle) (for quasi-static alignment)
Compute quaternion derivatives from this angular velocity

aZira371 · 2025-11-27T11:05:02Z

Results with preliminary weathercocking implementation and creating quasistatic attitude variation for 3 dof :
termination at apogee :-

termination at apogee false : -

Gui-FernandesBR · 2025-11-27T12:19:36Z

@phmbressan thank you for the quick response. I will merge this PR as this is becoming quite dated now.
@aZira371 will make smaller, separate PRs to solve your remaining comments.

Lucas-Prates added Enhancement New feature or request, including adjustments in current codes Flight Flight Class related features labels Dec 4, 2024

Lucas-Prates linked an issue Dec 4, 2024 that may be closed by this pull request

ENH: 3-DOF simulation #655

Open

Lucas-Prates changed the title ~~DRAFT: for ENH/3-dof-simulation (See #655)~~ ENH: Implementing 3-dof-simulation Dec 4, 2024

aZira371 added 2 commits December 6, 2024 01:26

MNT: cleaned up new functions and

9b00c57

ENH: fixed standard 3 dof *MNT: Cleaned up the "u_dot_3dof" and "u_dot_generalized_3_dof" *MNT: Corrected Typos in "simulation_mode" description *ENH: "u_dot_generalized_3_dof" fixed and tested on examples.

Gui-FernandesBR force-pushed the develop branch from 2931c30 to 7864590 Compare February 8, 2025 19:00

aZira371 added 2 commits February 25, 2025 17:15

Rebase: Merge branch 'develop' of https://github.com/aZira371/RocketPy …

87e9180

…into enh/3-dof-simulation

ENH: Addition of point mass classes to rocketpy.rocket and rocketpy.m…

4524219

…otor ENH: added "BaseRocket" and "PointMassRocket" to rocket class ENH: added "PointMassMotor" to motor class with various input cases of thrust values

aZira371 and others added 6 commits April 11, 2025 20:31

ENH: PointMassMotor and PointMassRocket working as intended after som…

57b4732

…e tests ENH: Added a new jupyter notebook for a simplified 3 DOF example MNT: PointMassMotor intialization error fixed MNT: PointMassRocket properties enhanced based on the example runs

MNT: Removing unnecessary files added by mistake.

81ce869

Merge branch 'RocketPy-Team:master' into enh/3-dof-simulation

0673076

MNT: Cleaned up PointMassMotor and PointMassRocket class

47c9f2f

MNT: Cleaned up the flight class u_dot_generalized_3dof TODO: Add info for 3 dof cases and fix some new issues when parachute is added.

Merge branch 'enh/3-dof-simulation' of https://github.com/aZira371/Ro…

f6ad658

…cketPy into enh/3-dof-simulation

MNT: Cleaning up flight class and PointMassMotor class

33cb63a

aZira371 marked this pull request as ready for review May 10, 2025 17:51

aZira371 requested a review from a team as a code owner May 10, 2025 17:51

phmbressan reviewed May 16, 2025

View reviewed changes

MateusStano requested a review from Gui-FernandesBR May 16, 2025 20:54

MateusStano requested changes May 23, 2025

View reviewed changes

aZira371 and others added 6 commits June 11, 2025 01:18

Merge branch 'enh/3-dof-simulation' into develop

1d2d4dc

Merge pull request #1 from aZira371/develop

fe21271

Develop

MNT: point mass motor cleanup

b18b241

-MNT: removing the parameters not needed for point mass kind of motors -MNT: removing extra parameter thrust_curve -MNT: fixing problems with motor class inheritance

ENH: restructuring rocket class

8aa1016

-ENH: removed 'BaseRocket' class now 'PointMassRocket' inherits directly from 'Rocket' class

MNT: fixing certain calculations on point mass motor

87e7dce

-MNT: fixed calculations of mass flow rate and exhaust velocity -MNT: adjusted propellant initial mass setter error by allocating the input initial mass to the property

Rename PointMassMotor.py to pointmassmotor.py

0e4d8a4

MNT: renaming pointmassmotor.py -MNT:snake case renaming

Gui-FernandesBR and others added 9 commits November 26, 2025 23:13

adds docs

9540a68

Refactor PointMassRocket class into its own module for improved organ…

699236e

…ization and clarity

refactored tests

ae7d4b0

Merge branch 'develop' into enh/3-dof-simulation

22797a3

fix test

9516f43

remove example notebook

9619aab

type hint fix

fdb6f7c

Configure matplotlib to use non-interactive backend for tests

f4886e2

fix tests

015579a

Gui-FernandesBR requested a review from Copilot November 27, 2025 02:43

Copilot started reviewing on behalf of Gui-FernandesBR November 27, 2025 02:43 View session

Copilot finished reviewing on behalf of Gui-FernandesBR November 27, 2025 02:46

Copilot AI reviewed Nov 27, 2025

View reviewed changes

Gui-FernandesBR and others added 3 commits November 26, 2025 23:59

solve comments by copilot

5ec0c8d

small fix

bcf51fe

Merge branch 'develop' into enh/3-dof-simulation

ba73174

Gui-FernandesBR approved these changes Nov 27, 2025

View reviewed changes

rocketpy/motors/point_mass_motor.py Show resolved Hide resolved

Gui-FernandesBR requested a review from phmbressan November 27, 2025 03:13

phmbressan approved these changes Nov 27, 2025

View reviewed changes

This was referenced Nov 27, 2025

[WIP] Update docstrings of new tests according to RocketPy guidelines #880

Closed

docs: Update test docstrings to follow RocketPy NumPy style guidelines aZira371/RocketPy#2

Merged

aZira371 self-assigned this Nov 27, 2025

Merge branch 'develop' into enh/3-dof-simulation

567b9e0

Gui-FernandesBR merged commit 704c796 into RocketPy-Team:develop Nov 27, 2025
9 of 10 checks passed

github-project-automation bot moved this from Mid-Term to Closed in LibDev Roadmap Nov 27, 2025

Uh oh!

ENH: Implementing 3-dof-simulation #745

ENH: Implementing 3-dof-simulation #745

Uh oh!

Conversation

aZira371 commented Dec 3, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Pull request type

Checklist

Current behavior

New behavior

Breaking change

Additional information

Uh oh!

Lucas-Prates commented Dec 4, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Gui-FernandesBR commented Feb 8, 2025 • edited by MateusStano Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

codecov bot commented Feb 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Gui-FernandesBR left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

phmbressan left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

phmbressan Nov 27, 2025

Choose a reason for hiding this comment

Uh oh!

aZira371 Nov 27, 2025

Choose a reason for hiding this comment

Uh oh!

phmbressan Nov 27, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

aZira371 commented Nov 27, 2025

Uh oh!

aZira371 commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

aZira371 commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

aZira371 commented Dec 3, 2024 •

edited

Loading

Lucas-Prates commented Dec 4, 2024 •

edited

Loading

Gui-FernandesBR commented Feb 8, 2025 •

edited by MateusStano

Loading

codecov bot commented Feb 25, 2025 •

edited

Loading

phmbressan left a comment •

edited

Loading

aZira371 commented Nov 27, 2025 •

edited

Loading

aZira371 commented Nov 27, 2025 •

edited

Loading