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

Attention: Patch coverage is 25.00000% with 159 lines in your changes missing coverage. Please review.

Project coverage is 78.73%. Comparing base (4a41f7a) to head (0673076).
Report is 12 commits behind head on develop.

Files with missing lines	Patch %	Lines
rocketpy/simulation/flight.py	10.00%	108 Missing ⚠️
rocketpy/rocket/rocket.py	24.32%	28 Missing ⚠️
rocketpy/motors/PointMassMotor.py	56.60%	23 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #745      +/-   ##
===========================================
- Coverage    79.09%   78.73%   -0.37%     
===========================================
  Files           96       98       +2     
  Lines        11583    12118     +535     
===========================================
+ Hits          9162     9541     +379     
- Misses        2421     2577     +156

☔ View full report in Codecov by Sentry.
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DEV: Master to v1.9.0

…tPy-Team#794) * DEP: Add deprecation warnings for outdated methods and functions * DEP: Remove deprecated methods for NOAA RUC soundings and power drag plots * DEV: changelog * MNT: ruff * DEP: Update deprecation warning for post_process method to specify removal in v1.10 * MNT: Remove unused imports

…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

phmbressan · 2025-05-16T19:38:19Z

rocketpy/motors/PointMassMotor.py

+        self,
+        thrust_source,
+        dry_mass,
+        thrust_curve=None,


What is this parameter, thrust_curve? It seems not to be used in any of the attributes of the class (besides the validation schema). Have I misunderstood anything?

phmbressan · 2025-05-16T19:43:30Z

rocketpy/motors/PointMassMotor.py

+        """
+        if isinstance(thrust_source, (Function, np.ndarray, str)):
+            if thrust_curve is None or propellant_initial_mass is None:
+                raise ValueError("thrust_curve and propellant_initial_mass are required for csv, Function, or np.array inputs.")


Of course this is just aesthetics and is not a priority since the PR only came out of draft state, but this string is too long. In order to comply to the 80 chars limit, I would break it into more lines, I believe the linter does not handle it automatically.

The same is valid for the other raises.

phmbressan · 2025-05-16T19:48:09Z

rocketpy/simulation/flight.py

+        mach = free_stream_speed / speed_of_sound
+
+        # Drag computation
+        if t < self.rocket.motor.burn_out_time:


Shouldn't the time be in the interval of burn start and burn out? Do you know @MateusStano ?

It should do whatever the normal udot does. I think we changed this recently and this branch is not updated though

@aZira371 I would say you should merge develop into this branch and check if this u_dot is updated with the newer standard one

phmbressan · 2025-05-16T19:51:40Z

rocketpy/motors/PointMassMotor.py

+        """Returns the thrust of the motor as a function of time."""
+        return self.thrust_source
+
+    @funcify_method("Time (s)", "Acceleration (m/s^2)")


The output annotation and units are not correct.

phmbressan · 2025-05-16T19:54:36Z

rocketpy/motors/PointMassMotor.py

+        return self._propellant_initial_mass
+
+    @property
+    def is_point_mass(self):


This property does not make too much sense to me if it is not shared among all motors (e.g. using solid_motor.is_point_mass -> False). My recommendation would be using isinstance, unless it is used in a performance critical scenario (e.g. a long loop).

phmbressan · 2025-05-16T19:57:12Z

rocketpy/rocket/rocket.py

+        motor_mass_func = (
+            self.motor.total_mass if hasattr(self.motor.total_mass, "get_value_opt")
+            else Function(lambda t: self.motor.total_mass)
+        )


This check seems to be in place in order to convert to a Function the self.motor.total_mass if it is not one. However, the attribute from the motor class is annotated with funcify, so it will always be a Function.

phmbressan · 2025-05-16T20:00:35Z

rocketpy/motors/PointMassMotor.py

+    @funcify_method("Time (s)", "Acceleration (m/s^2)")
+    def total_mass(self):
+        """Returns the constant total mass of the point mass motor."""
+        return self.dry_mass


To me it makes sense to evaluate the mass_flow_rate of a point mass motor if the user inputs a thrust curve. The schema would be quite similar to what is already done in the Motor parent class (e.g. Motor.total_mass_flow_rate). Let me know what you think about it.

MateusStano · 2025-05-23T17:30:42Z

rocketpy/environment/environment.py

+        warnings.warn(
+            "This function is deprecated and will be removed in v1.10.0. "
+            "Please use the new method `tools.geodesic_to_utm` instead.",
+            DeprecationWarning,
+        )


Did you add this or is this a synchronization issue? If so please merge develop into this branch

MateusStano · 2025-05-23T17:51:35Z

rocketpy/motors/PointMassMotor.py

+class PointMassMotor(Motor):
+    """Class representing a motor modeled as a point mass.
+    Inherits from the Motor class and simplifies the model to a thrust-producing
+    object without detailed structural components."""
+
+    def __init__(
+        self,
+        thrust_source,
+        dry_mass,
+        thrust_curve=None,
+        propellant_initial_mass=None,
+        propellant_final_mass=None,
+        burn_time=None,
+        center_of_dry_mass_position=0,
+        reshape_thrust_curve=False,
+        interpolation_method="linear",
+        coordinate_system_orientation="nozzle_to_combustion_chamber",
+    ):


Seems there are a few parameters here that can be removed since it does not matter for the point mass case:

coordinate_system_orientation

center_of_dry_mass_position

thrust_source and thrust_curve are redundant. Just keep whichever has the same name used in the other Motor Classes

MateusStano · 2025-05-23T17:57:13Z

rocketpy/motors/PointMassMotor.py

Name of this file needs to be snake case

MateusStano · 2025-05-23T17:58:38Z

rocketpy/motors/PointMassMotor.py

+    def __init__(
+        self,
+        thrust_source,
+        dry_mass,
+        thrust_curve=None,
+        propellant_initial_mass=None,
+        propellant_final_mass=None,
+        burn_time=None,
+        center_of_dry_mass_position=0,
+        reshape_thrust_curve=False,
+        interpolation_method="linear",
+        coordinate_system_orientation="nozzle_to_combustion_chamber",
+    ):


All arguments of the init have to be saved to an attribute of the same name. So you have to do self.propellant_final_mass = propellant_final_mass and so on.

Just be careful that some of the parameters are already saved in the Motor class

MateusStano · 2025-05-23T18:10:05Z

rocketpy/motors/PointMassMotor.py

+    @funcify_method("Time (s)", "Propellant Mass (kg)")
+    def propellant_initial_mass(self):
+        return self._propellant_initial_mass


There is no need to make this a property in this class. Just a standard attribute is fine

MateusStano · 2025-05-23T18:29:35Z

rocketpy/rocket/rocket.py

+class BaseRocket:
+    """Base class for a rocket model with minimal attributes and methods."""
+    def __init__(self, mass):
+        self.mass = mass
+        self.motor = None
+    def add_motor(self, motor):
+        self.motor = motor
+        self.evaluate_total_mass()
+    def evaluate_total_mass(self):
+        if self.motor:
+            return self.mass + self.motor.total_mass
+        return self.mass
+
+


This class seems useless right now. You can just remove it

MateusStano · 2025-05-23T18:43:53Z

rocketpy/rocket/rocket.py

+class PointMassRocket(BaseRocket):
+    """Rocket modeled as a point mass for 3-DOF simulations."""  


Maybe having this inherit from the Rocket class will make the implementation easier. Then all_info and plots and prints will already be defined

MateusStano · 2025-05-23T18:47:24Z

rocketpy/simulation/flight.py

+        elif self.equations_of_motion == "solid_propulsion" and self.simulation_mode == '3 DOF':
+            # NOTE: The u_dot is faster, but only works for solid propulsion
+            self.u_dot_generalized = self.u_dot_3dof
+        elif self.simulation_mode == '3 DOF':
+            # NOTE: The u_dot is faster, but only works for solid propulsion
+            self.u_dot_generalized = self.u_dot_generalized_3dof


Can the PointMassRocket run with 6dof? If not then I think we should just check if the rocket is a PointMassRocket and set the equations of motion to 3dof

MateusStano · 2025-05-23T18:50:14Z

rocketpy/simulation/flight.py

-            M1 += M
-            M2 += N
-            M3 += L
-        # Off center moment
-        M3 += self.rocket.cp_eccentricity_x * R2 - self.rocket.cp_eccentricity_y * R1
-
-        # Calculate derivatives
-        # Angular acceleration
-        alpha1 = (
-            M1
-            - (
-                omega2
-                * omega3
-                * (
-                    rocket_dry_I_33
-                    + motor_I_33_at_t
-                    - rocket_dry_I_11
-                    - motor_I_11_at_t
-                    - mu * b**2
-                )
-                + omega1
-                * (
-                    (
-                        motor_I_11_derivative_at_t
-                        + mass_flow_rate_at_t
-                        * (rocket_dry_mass - 1)
-                        * (b / total_mass_at_t) ** 2
-                    )
-                    - mass_flow_rate_at_t
-                    * ((nozzle_radius / 2) ** 2 + (c - b * mu / rocket_dry_mass) ** 2)
-                )
-            )
-        ) / (rocket_dry_I_11 + motor_I_11_at_t + mu * b**2)
-        alpha2 = (
-            M2
-            - (
-                omega1
-                * omega3
-                * (
-                    rocket_dry_I_11
-                    + motor_I_11_at_t
-                    + mu * b**2
-                    - rocket_dry_I_33
-                    - motor_I_33_at_t
-                )
-                + omega2
-                * (
-                    (
-                        motor_I_11_derivative_at_t
-                        + mass_flow_rate_at_t
-                        * (rocket_dry_mass - 1)
-                        * (b / total_mass_at_t) ** 2
-                    )
-                    - mass_flow_rate_at_t
-                    * ((nozzle_radius / 2) ** 2 + (c - b * mu / rocket_dry_mass) ** 2)
-                )
-            )
-        ) / (rocket_dry_I_11 + motor_I_11_at_t + mu * b**2)
-        alpha3 = (
-            M3
-            - omega3
-            * (
-                motor_I_33_derivative_at_t
-                - mass_flow_rate_at_t * (nozzle_radius**2) / 2
-            )
-        ) / (rocket_dry_I_33 + motor_I_33_at_t)
-        # Euler parameters derivative
-        e0dot = 0.5 * (-omega1 * e1 - omega2 * e2 - omega3 * e3)
-        e1dot = 0.5 * (omega1 * e0 + omega3 * e2 - omega2 * e3)
-        e2dot = 0.5 * (omega2 * e0 - omega3 * e1 + omega1 * e3)
-        e3dot = 0.5 * (omega3 * e0 + omega2 * e1 - omega1 * e2)
-


Why are these changes made to u_dot?

MateusStano · 2025-05-23T18:52:20Z

rocketpy/simulation/flight.py

+        mach = free_stream_speed / speed_of_sound
+
+        # Drag computation
+        if t < self.rocket.motor.burn_out_time:


It should do whatever the normal udot does. I think we changed this recently and this branch is not updated though

@aZira371 I would say you should merge develop into this branch and check if this u_dot is updated with the newer standard one

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

Gui-FernandesBR and others added 9 commits March 23, 2025 19:17

Merge pull request RocketPy-Team#793 from RocketPy-Team/develop

76fb5ef

DEV: Master to v1.9.0

REL: Update version to 1.9.0 (RocketPy-Team#795)

4df0b38

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

		class PointMassRocket(BaseRocket):
		"""Rocket modeled as a point mass for 3-DOF simulations."""

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ENH: Implementing 3-dof-simulation #745

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aZira371 commented Dec 3, 2024 •

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Lucas-Prates commented Dec 4, 2024 •

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Gui-FernandesBR commented Feb 8, 2025 •

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