Converted from a sensor_msgs/Imu message.
http://docs.ros.org/api/sensor_msgs/html/msg/Imu.html

orientation.x
orientation.y
orientation.z
orientation.w
orientation_covariance - 3x3 matrix
angular_velocity.x (m/s^2)
angular_velocity.y (m/s^2)
angular_velocity.z (m/s^2)
angular_velocity_covariance - 3x3 matrix
linear_acceleration.x (m/s^2)
linear_acceleration.y (m/s^2)
linear_acceleration.z (m/s^2)
linear_acceleration_covariance - 3x3 matrix
