How to use the IMU raw data, rostopic echo imu

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Hello

I have one question regarding using the raw IMU data. Im using a sensor package with laser range finder, IMU and camera. My bag file consists of scans, imu data and images. I would like to know how to use the imu data to calculate the position and angular velocity of the robot. This is the output of the rostopic echo /imu/data

For example

header: 
  seq: 24237
  stamp: 
    secs: 1301628270
    nsecs: 972690349
  frame_id: /base_imu
orientation: 
  x: -0.628151834011
  y: 0.0210457909852
  z: -0.0200814530253
  w: -0.777546823025
orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
angular_velocity: 
  x: -0.00680741108954
  y: -0.00184269389138
  z: -0.00491618132219
angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
linear_acceleration: 
  x: -0.43050968647
  y: 0.00864356849343
  z: 9.79496383667
line.........

Any help??