>> 3. Is this node doing same as what robot_pose_ekf is doing? Can i avoid the >> use of robot_pose_ekf? The robot pose ekf can merge multiple poses with corresponding covariance into one single pose. It was designed to merge wheel odemetry, imu data and a full 6D pose. See the documentation for more details Wim -- -- Wim Meeussen Willow Garage Inc.