add some getters to kalmanFilter.h for future use.

modules/common/math/kalman_filter.h

@@ -134,6 +134,48 @@ class KalmanFilter {
    */
   void SetControlMatrix(const Eigen::Matrix<T, XN, UN>& B) { B_ = B; }
 
+  /**
+   * @brief Get the system transition function under zero control.
+   *
+   * @return Transition matrix.
+   */
+  const Eigen::Matrix<T, XN, XN>&  GetTransitionMatrix() { return F_; }
+
+  /**
+   * @brief Get the covariance matrix of the transition noise.
+   *
+   * @return Covariance matrix
+   */
+  const Eigen::Matrix<T, XN, XN>& GetTransitionNoise() { return Q_; }
+
+  /**
+   * @brief Get the observation matrix, which maps states to observations.
+   *
+   * @return Observation matrix
+   */
+  const Eigen::Matrix<T, ZN, XN>& GetObservationMatrix() { return H_; }
+
+  /**
+   * @brief Get the covariance matrix of the observation noise.
+   *
+   * @return Covariance matrix
+   */
+  const Eigen::Matrix<T, ZN, ZN>& GetObservationNoise() { return R_; }
+
+  /**
+   * @brief Get the covariance matrix of current state belief distribution.
+   *
+   * @return State covariance matrix
+   */
+  const Eigen::Matrix<T, XN, XN>& GetStateCovariance() { return P_; }
+
+  /**
+   * @brief Get the control matrix in the state transition rule.
+   *
+   * @return Control matrix
+   */
+  const Eigen::Matrix<T, XN, UN>& GetControlMatrix() { return B_; }
+
   /**
    * @brief Updates the state belief distribution given the control input u.
    *