Add aircraft actuator uncertainty characterization example

CITATION.cff

@@ -14,5 +14,5 @@ authors:
     orcid: "https://orcid.org/0000-0002-1987-9268"
     affiliation: "McGill University"
 title: "decargroup/dkpy"
-version: v0.1.12
+version: v0.1.9
 url: "https://github.com/decargroup/dkpy"

README.rst

@@ -141,6 +141,6 @@ If you use this software in your research, please cite it as below or see
         url={https://github.com/decargroup/dkpy},
         publisher={Zenodo},
         author={Steven Dahdah and Timothy Everett Adams and James Richard Forbes},
-        version = {{v0.1.12}},
+        version = {{v0.1.9}},
         year={2025},
     }

doc/conf.py

@@ -7,10 +7,10 @@
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
 project = "dkpy"
-copyright = "2024, Steven Dahdah, Timothy Everett Adams and James Richard Forbes"
+copyright = "2025, Steven Dahdah, Timothy Everett Adams and James Richard Forbes"
 author = "Steven Dahdah, Timothy Everett Adams and James Richard Forbes"
-version = "0.1.12"
-release = "0.1.12"
+version = "0.1.9"
+release = "0.1.9"
 
 # -- General configuration ---------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration

doc/examples.rst

@@ -178,13 +178,14 @@ particular, the response of the system states and actuator inputs are shown.
 
 .. image:: _static/example_6/6_plot_inputs.png
 
-Multi-Model Uncertainty Characterization
-----------------------------------------
+Multi-Model Uncertainty Characterization: Academic Model
+--------------------------------------------------------
 
-In this example, an unstructured uncertainty set is characterized from a set
-of nominal and off-nominal frequency responses. The off-nominal models are
-generated from a nominal model by randomly perturbing the parameters within a
-known bound.
+In this example, an unstructured uncertainty set is characterized from a set of
+nominal and off-nominal frequency responses. This is an academic example as the
+uncertain model in this problem is arbitrarily selected for the purpose of
+demonstration. The off-nominal models are generated from a nominal model by
+randomly perturbing the parameters within a known bound.
 
 .. literalinclude:: ../examples/7_uncertainty_characterization.py
    :language: python
@@ -240,7 +241,35 @@ set. The optimal weight frequency responses and fitted weights are shown below.
 
 .. image:: _static/example_7/7_uncertainty_weight.png
 
+Multi-Model Uncertainty Characterization: Aircraft Actuator Model
+-----------------------------------------------------------------
 
+In this example, an unstructured uncertainty set is characterized from a set of
+nominal and off-nominal frequency responses. In this example, the uncertainty
+of an aircraft actuator model is characterized using an actuator model from an
+example given in Section 14.1 of [M04]_. 
+
+.. literalinclude:: ../examples/8_aircraft_actuator_uncertainty_characterization.py
+   :language: python
+
+The off-nominal frequency response data is generated by sampling valid
+perturbations from the uncertainty model provided in the problem statement.
+
+.. image:: _static/example_8/8_sval_actuator.png
+
+Three different candidate uncertainty models are evaluated: additive
+uncertainty, multiplicative input uncertainty, and inverse multiplicative
+input uncertainty. The multiplicative input uncertainty is selected as it
+yields the smallest residual singular values.
+
+.. image:: _static/example_8/8_sval_residual_max.png
+
+The left uncertainty weight is constrained to be scalar whereas the right uncertainty
+weight is constrained to the identity matrix. Given that the right uncertainty
+weight is the identity matrix, a fit does not need to be performed for this weight
+as it will be neglected in the generalized plant.
+
+.. image:: _static/example_8/8_magnitude_uncertainty_weight.png
 
 
 

examples/6_dk_iteration_non_square_perturbation.py

@@ -57,7 +57,7 @@ def example_dk_iter_list_order_aircraft():
     # DK-iteration controller synthesis
     dk_iter = dkpy.DkIterListOrder(
         controller_synthesis=dkpy.HinfSynLmi(
-            lmi_strictness=5e-7,  # Have to play with tolerances.
+            lmi_strictness=5e-7,
             solver_params=dict(
                 solver="MOSEK",
                 eps=5e-8,
@@ -74,7 +74,7 @@ def example_dk_iter_list_order_aircraft():
             ),
         ),
         d_scale_fit=dkpy.DScaleFitSlicot(),
-        fit_orders=[4, 4],
+        fit_orders=[4, 4, 4],
     )
     # Alternative MATLAB block structure description
     # block_structure = np.array([[n_u_delta, n_y_delta], [n_w, n_z]])

examples/7_uncertainty_characterization.py

@@ -8,33 +8,12 @@
 def example_uncertainty_characterization():
     """Multi-model uncertainty characterization from frequency response data."""
 
-    # Generate example data
+    # Load example data
     eg = dkpy.example_multimodel_uncertainty()
     response_nom = eg["complex_response_nominal"]
     response_offnom_list = eg["complex_response_offnominal_list"]
     omega = eg["omega"]
 
-    # Plot: Magnitude response of nominal and off-nominal systems
-    fig, _ = dkpy.plot_magnitude_response_uncertain_model_set(
-        response_nom,
-        response_offnom_list,
-        omega,
-    )
-
-    # Plot: Phase response of nominal and off-nominal systems
-    fig, _ = dkpy.plot_phase_response_uncertain_model_set(
-        response_nom,
-        response_offnom_list,
-        omega,
-    )
-
-    # Plot: Singular value response of nominal and off-nominal systems
-    fig, ax = dkpy.plot_singular_value_response_uncertain_model_set(
-        response_nom,
-        response_offnom_list,
-        omega,
-    )
-
     # Uncertainty models
     uncertainty_models = {
         "additive",
@@ -44,41 +23,58 @@ def example_uncertainty_characterization():
         "inverse_multiplicative_input",
         "inverse_multiplicative_output",
     }
+
+    # Compute uncertainty residual frequency response
     response_residuals_dict = dkpy.compute_uncertainty_residual_response(
         response_nom,
         response_offnom_list,
         uncertainty_models,
     )
 
-    # Plot: Singular value response of uncerainty residuals
-    figure_dict = dkpy.plot_singular_value_response_residual(
-        response_residuals_dict, omega
-    )
-
-    # Plot: Comparison of singular value response of uncerainty residuals for each
-    # uncertainty model
-    fig, _ = dkpy.plot_singular_value_response_residual_comparison(
-        response_residuals_dict, omega
-    )
-
     # Compute uncertainty weight frequency response
     response_weight_left, response_weight_right = (
-        dkpy.compute_optimal_uncertainty_weight_response(
+        dkpy.compute_uncertainty_weight_response(
             response_residuals_dict["inverse_additive"], "diagonal", "diagonal"
         )
     )
 
     # Fit overbounding stable and minimum-phase uncertainty weight system
-    weight_left = dkpy.fit_overbounding_uncertainty_weight(
-        response_weight_left, omega, [4, 5]
+    weight_left = dkpy.fit_uncertainty_weight(response_weight_left, omega, [4, 5])
+    weight_right = dkpy.fit_uncertainty_weight(response_weight_right, omega, [3, 5])
+
+    # Plot: Magnitude response of nominal and off-nominal systems
+    dkpy.plot_magnitude_response_uncertain_model_set(
+        response_nom,
+        response_offnom_list,
+        omega,
+    )
+
+    # Plot: Phase response of nominal and off-nominal systems
+    dkpy.plot_phase_response_uncertain_model_set(
+        response_nom,
+        response_offnom_list,
+        omega,
     )
-    weight_right = dkpy.fit_overbounding_uncertainty_weight(
-        response_weight_right, omega, [3, 5]
+
+    # Plot: Singular value response of nominal and off-nominal systems
+    dkpy.plot_singular_value_response_uncertain_model_set(
+        response_nom,
+        response_offnom_list,
+        omega,
+    )
+
+    # Plot: Singular value response of uncerainty residuals
+    dkpy.plot_singular_value_response_residual(response_residuals_dict, omega)
+
+    # Plot: Comparison of singular value response of uncerainty residuals for each
+    # uncertainty model
+    dkpy.plot_singular_value_response_residual_comparison(
+        response_residuals_dict, omega
     )
 
     # Plot: Magnitude response of uncertainty weight frequency response and overbounding
     # fit
-    fig, _ = dkpy.plot_magnitude_response_uncertainty_weight(
+    dkpy.plot_magnitude_response_uncertainty_weight(
         response_weight_left,
         response_weight_right,
         omega,

examples/8_aircraft_actuator_uncertainty_characterization.py

@@ -0,0 +1,64 @@
+"""Multi-model aircraft actuator uncertainty characterization from frequency response
+data.
+
+"""
+
+from matplotlib import pyplot as plt
+
+import dkpy
+
+
+def example_aircraft_uncertainty_characterization():
+    """Multi-model aircraft actuator uncertainty characterization from frequency
+    response data.
+    """
+    # Load example data
+    eg = dkpy.example_aircraft_actuator_uncertainty()
+    response_actuator = eg["response_actuator_nominal"]
+    response_actuator_offnom_list = eg["response_actuator_offnominal"]
+    omega = eg["omega"]
+
+    # Compute the residual response for different uncertainty models
+    response_residual = dkpy.compute_uncertainty_residual_response(
+        response_actuator,
+        response_actuator_offnom_list,
+        {"additive", "multiplicative_input", "inverse_multiplicative_input"},
+    )
+
+    # Compute the optimal uncertainty weights with a given structure
+    response_weight_left, response_weight_right = (
+        dkpy.compute_uncertainty_weight_response(
+            response_residual["multiplicative_input"],
+            "scalar",
+            "identity",
+        )
+    )
+
+    # Fit an overbounding LTI system to the optimal uncertainty weight response
+    weight_left = dkpy.fit_uncertainty_weight(response_weight_left, omega, 1)
+
+    # Plot: Singular value response of nominal and off-nominal systems
+    dkpy.plot_singular_value_response_uncertain_model_set(
+        response_actuator, response_actuator_offnom_list, omega, hz=True
+    )
+
+    # Plot: Comparison of singular value response of uncerainty residuals for each
+    # uncertainty model
+    dkpy.plot_singular_value_response_residual_comparison(
+        response_residual, omega, hz=True
+    )
+
+    # Plot: Magnitude response of uncertainty weight frequency response and overbounding
+    # fit
+    dkpy.plot_magnitude_response_uncertainty_weight(
+        response_weight_left,
+        response_weight_right,
+        omega,
+        weight_left=weight_left,
+        hz=True,
+    )
+    plt.show()
+
+
+if __name__ == "__main__":
+    example_aircraft_uncertainty_characterization()

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "dkpy"
-version = "0.1.12"
+version = "0.1.9"
 dependencies = [
     "numpy>=1.21.0",
     "scipy>=1.7.0",