feat(docs): Add documentation for database handler and imu approximator

doc/architecture/nodes/DatabaseHandlerNode.md

@@ -0,0 +1,41 @@
+# DatabaseHandlerNode (`assignments::three::g2_2025_database_node`)
+
+The `DatabaseHandlerNode` subscribes to position and velocity topics and stores the data in a
+PostgreSQL database via the `DatabaseManager`.
+
+## Implementation Details
+
+**Parameters**
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `save_position_data` | bool | true | Enable storage of position |
+| `save_velocity_data` | bool | true | Enable storage of velocity |
+
+**Constructor**
+```cpp
+DatabaseHandlerNode()
+```
+- Initializes ROS2 node with name `database_handler_node`
+- Creates subscriptions to `estimated_position` and/or `estimated_velocity` based on parameter configuration
+
+## Functions
+
+**`void position_callback(const geometry_msgs::msg::Pose2D::SharedPtr msg)`**
+- Primary callback invoked whenever a position message is received
+- Forwards: x, y, and theta to `DatabaseManager::store_position_data`
+- Throttled warning (5 second interval) on storage failures
+
+**`void velocity_callback(const geometry_msgs::msg::Twist::SharedPtr msg)`**
+- Primary callback invoked whenever a velocity message is received
+- Forwards: linear velocity (x, y, z) and angular velocity (z) to `DatabaseManager::store_velocity_data`
+- Throttled warning (5 second interval) on storage failures
+
+## ROS2 Interface
+
+**Subscriptions**
+- `estimated_position` (geometry_msgs/msg/Pose2D)
+  - Receives calculated position estimates (only subscribed if `save_position_data=true`)
+
+- `estimated_velocity` (geometry_msgs/msg/Twist)
+  - Receives calculated velocity estimates (only subscribed if `save_velocity_data=true`)

doc/architecture/nodes/IMUPositionApproximator.md

@@ -0,0 +1,58 @@
+# IMUPositionApproximator (`assignments::three::g2_2025_imu_position_approximator_node`)
+
+The `IMUPositionApproximator` node calculates position and velocity estimates by integrating
+acceleration data from an IMU sensor. It transforms sensor data from the robot frame to the
+map frame, accounting for rotations and centripetal effects, and provides a position reset
+topic.
+
+## Implementation Details
+
+**Parameters**
+
+| Parameter | Type | Default | Description |
+|-----------|------|---------|-------------|
+| `initial_x` | double | 0.0 | Initial x position in map frame |
+| `initial_y` | double | 0.0 | Initial y position in map frame |
+| `initial_z` | double | 0.0 | Initial z position in map frame |
+| `initial_theta` | double | 0.0 | Initial orientation angle (radians) |
+| `imu_topic` | string | "imu_data" | Topic name for IMU sensor data |
+
+**Constructor**
+```cpp
+IMUPositionApproximator()
+```
+- Initializes ROS2 node with name `imu_position_approximator`
+- Creates subscription to IMU topic (configurable) and `position_reset` topic
+- Creates publishers for `estimated_position` and `estimated_velocity`
+
+## Functions
+
+**`void imu_callback(const sensor_msgs::msg::Imu::SharedPtr msg)`**
+- Primary callback invoked whenever an IMU message is received
+- Calculates time delta `dt` between measurements; skips invalid deltas (≤0 or >1 second)
+- Updates orientation: `theta += omega_z * dt` and normalizes to [-pi, pi]
+- Applies gravity compensation: subtracts 9.81 m/s^2 from z-axis acceleration
+- Transforms acceleration from robot frame to map frame using rotation matrix
+- Corrects for centripetal acceleration due to rotation
+- Integrates acceleration to update velocity, then integrates velocity to update position
+- Publishes `estimated_position` (Pose2D) and `estimated_velocity` (Twist)
+
+**`void position_reset_callback(const geometry_msgs::msg::Pose2D::SharedPtr msg)`**
+- Updates position (x, y) and orientation (theta) to provided values
+- Resets all velocities (vx, vy, vz) to zero
+
+## ROS2 Interface
+
+**Subscribers**
+- `imu_data` (sensor_msgs/msg/Imu) [configurable via `imu_topic` parameter]
+  - Receives raw IMU sensor data with linear acceleration and angular velocity
+
+- `position_reset` (geometry_msgs/msg/Pose2D)
+  - Receives position reset commands from external position determinator
+
+**Publishers**
+- `estimated_position` (geometry_msgs/msg/Pose2D)
+  - Publishes calculated position (x, y, theta) in map frame
+
+- `estimated_velocity` (geometry_msgs/msg/Twist)
+  - Publishes calculated linear velocities (x, y, z) and angular velocity (z)

src/g2_2025_odometry_pkg/CMakeLists.txt

@@ -60,7 +60,6 @@ ament_target_dependencies(database_handler_node
   geometry_msgs
 )
 
-# Install the executable
 install(TARGETS
   position_speed_approximator_node
   database_handler_node