update IMU factor docs to clarify that the measurements are in sensor frame

gtsam/navigation/AHRSFactor.h

@@ -90,7 +90,11 @@ class GTSAM_EXPORT PreintegratedAhrsMeasurements : public PreintegratedRotation
 
   /**
    * Add a single Gyroscope measurement to the preintegration.
-   * @param measureOmedga Measured angular velocity (in body frame)
+   * Measurements are taken to be in the sensor
+   * frame and conversion to the body frame is handled by `body_P_sensor` in
+   * `PreintegratedRotationParams` (if provided).
+   *
+   * @param measuredOmega Measured angular velocity (as given by the sensor)
    * @param deltaT Time step
    */
   void integrateMeasurement(const Vector3& measuredOmega, double deltaT);

gtsam/navigation/CombinedImuFactor.h

@@ -208,8 +208,11 @@ public:
 
   /**
    * Add a single IMU measurement to the preintegration.
-   * @param measuredAcc Measured acceleration (in body frame, as given by the
-   * sensor)
+   * Both accelerometer and gyroscope measurements are taken to be in the sensor
+   * frame and conversion to the body frame is handled by `body_P_sensor` in
+   * `PreintegrationParams`.
+   *
+   * @param measuredAcc Measured acceleration (as given by the sensor)
    * @param measuredOmega Measured angular velocity (as given by the sensor)
    * @param dt Time interval between two consecutive IMU measurements
    */

gtsam/navigation/ImuFactor.h

@@ -121,7 +121,11 @@ public:
 
   /**
    * Add a single IMU measurement to the preintegration.
-   * @param measuredAcc Measured acceleration (in body frame, as given by the sensor)
+   * Both accelerometer and gyroscope measurements are taken to be in the sensor
+   * frame and conversion to the body frame is handled by `body_P_sensor` in
+   * `PreintegrationParams`.
+   *
+   * @param measuredAcc Measured acceleration (as given by the sensor)
    * @param measuredOmega Measured angular velocity (as given by the sensor)
    * @param dt Time interval between this and the last IMU measurement
    */