Mermaid diagram

gtsam/navigation/navigation.md

@@ -33,4 +33,101 @@ The `navigation` module in GTSAM provides specialized tools for inertial navigat
 - **[AcceleratingScenario](https://github.com/borglab/gtsam/blob/develop/gtsam/navigation/Scenario.h)**: Implements constantly accelerating motion.
 - **[ScenarioRunner](https://github.com/borglab/gtsam/blob/develop/gtsam/navigation/ScenarioRunner.h)**: Executes scenarios and generates IMU measurements.
 
-These components together provide a comprehensive framework for fusing inertial data with other sensor measurements in navigation and robotics applications.
+# IMU Factor and Preintegration Overview
+
+This document provides an overview of the key classes involved in IMU preintegration and factor creation within the `gtsam/navigation` module. These components are essential for performing state estimation using Inertial Measurement Unit data, often fused with other sensors like cameras or GPS.
+
+## Class Relationship Diagram (Mermaid)
+
+```mermaid
+classDiagram
+    direction TD
+
+    class PreintegratedRotationParams {
+        +Matrix3 gyroscopeCovariance
+        +Vector3 omegaCoriolis
+        +Pose3 body_P_sensor
+    }
+    class PreintegrationParams {
+        +Matrix3 accelerometerCovariance
+        +Matrix3 integrationCovariance
+        +bool use2ndOrderCoriolis
+        +Vector3 n_gravity
+    }
+    PreintegrationParams --|> PreintegratedRotationParams : inherits
+
+    class PreintegrationCombinedParams {
+        +Matrix3 biasAccCovariance
+        +Matrix3 biasOmegaCovariance
+        +Matrix6 biasAccOmegaInt
+    }
+    PreintegrationCombinedParams --|> PreintegrationParams : inherits
+
+    class PreintegratedRotation {
+        +double deltaTij_
+        +Rot3 deltaRij_
+        +Matrix3 delRdelBiasOmega_
+        +integrateGyroMeasurement()
+        +biascorrectedDeltaRij()
+    }
+    PreintegratedRotation ..> PreintegratedRotationParams : uses
+
+    class PreintegrationBase {
+        <<Abstract>>
+        +imuBias::ConstantBias biasHat_
+        +resetIntegration()*
+        +integrateMeasurement()*
+        +biasCorrectedDelta()*
+        +predict()
+        +computeError()
+    }
+    PreintegrationBase --|> PreintegratedRotation : inherits
+
+    class ManifoldPreintegration {
+        +NavState deltaXij_
+        +update()
+    }
+    ManifoldPreintegration --|> PreintegrationBase : implements
+
+    class TangentPreintegration {
+        +Vector9 preintegrated_
+        +Matrix93 preintegrated_H_biasAcc_
+        +Matrix93 preintegrated_H_biasOmega_
+        +update()
+    }
+    TangentPreintegration --|> PreintegrationBase : implements
+
+    class PreintegratedAhrsMeasurements {
+       +Matrix3 preintMeasCov_
+    }
+    PreintegratedAhrsMeasurements --|> PreintegratedRotation : inherits
+
+    %% Assuming PreintegrationType is TangentPreintegration for example %%
+    %% Change TangentPreintegration to ManifoldPreintegration if needed %%
+    PreintegratedImuMeasurements --|> TangentPreintegration : inherits
+    class PreintegratedImuMeasurements {
+        +Matrix9 preintMeasCov_
+    }
+
+    PreintegratedCombinedMeasurements --|> TangentPreintegration : inherits
+    class PreintegratedCombinedMeasurements {
+       +Matrix preintMeasCov_ (15x15)
+    }
+    PreintegratedCombinedMeasurements ..> PreintegrationCombinedParams : uses
+
+    class ImuFactor {
+    }
+    ImuFactor ..> PreintegratedImuMeasurements : uses
+
+    class ImuFactor2 {
+    }
+    ImuFactor2 ..> PreintegratedImuMeasurements : uses
+
+    class CombinedImuFactor {
+    }
+    CombinedImuFactor ..> PreintegratedCombinedMeasurements : uses
+
+    class AHRSFactor {
+    }
+    AHRSFactor ..> PreintegratedAhrsMeasurements : uses
+```