http://rpg.ifi.uzh.ch/docs/teaching/2016/13_visual_inertial_fusion.pdf

IMU(Inertial Measurement Unit)

• Angular Velocity
• Linear Accelerations

Why IMU?

• Monocular Vision is scale ambiguous
• Pur vision is not robust enough
  • Low texture(feature)
  • High dynamic range
  • High speed motion
• Robustness is a critial issue : Tesla Accident “the autopilot sensors on the model S failed to distinguish a white tractor-trailer crossing the highway against a bright sky”

Pure IMU integration will lead to large drift (especially cheap IMUs)

• Intuition
  • Integration of angular velocity to get orientation: error proportional to t
  • Double integration of acceleration to get position: if there is a bias in acceleration, the error of position is proportional to t2
  • Worse, the actually position error also depends on the error of orientation.

In navigation, dead reckoning is the process of calculating current position of some moving object by using a previously determined position, or fix, and then incorporating estimations of speed, heading direction, and course over elapsed time.

Pre Integration IMU는 즉 IMU를 Odometery로, 카메라 포즈로 쓰고, 카메라는 Map constructing 혹은 keyframe추출 loop closure 같은 것으로 쓰는 것이다. 이렇게 되면, PnP알고리즘을 통해 camera pose를 구하는 CPU Computation을 줄일 수 있다.

NOTATION

IMU Preintegration : this is used for obtaining frame pose using imu.

many imu preintegration way using mid point integration(interpoliation)

output

pvq:pose, velocity, quaternion.

mid integration study that i need.