While using ROS with Turtlebot, there was a issue with imu sensor data. I could put odometry data and imu sensor data into robotposeekf as a input of EKF. I turned odom and imu value to 'true' in configuration. (http://wiki.ros.org/robot_pose_ekf)

However, what I could get from the EKF is something IMU data is not considered. I could see that x value of position plot is increasing but y value is 0 when I let the robot move straight following x-axis. What I expect is that output of ekf is changing according to the deviation of IMU data. When I gave angular.z > 0.3 to Turtlebot, there exist some reflection to the output of EKF. I know that I can do the experiment with circular trajectory but what I want to do measure is the error when robot move straight through the line.

Can anybody give some advices for this?