Jaehyung Jung

ABOUT ME 

I am a Ph.D. candidate at the Department of Aerospace Engineering, Seoul National University, Republic of Korea. My research interest includes navigation systems for autonomous robots with onboard sensors.

Most of my work is based on Bayesian filtering that fuses measurements from an inertial measurement unit, cameras, and LiDAR. My goal is to develop a practical and robust navigation algorithm from a thorough theoretical background. CV

Education

Ph.D., Aerospace Engineering, Seoul National University (2019 ~ Aug. 2023, expected)

M.S., Aerospace Engineering, Seoul National University (2019)

B.S., Aerospace Engineering, Pusan National University (2017) 

PUBLICATIONS

"Gaussian Mixture Midway-Merge for Object SLAM with Pose Ambiguity"

 IEEE Robotics and Automation Letters, 2022

We introduce a Gaussian mixture merge method in a matrix Lie group called "Midway-merge" that reduces an approximation error when merging probability density functions. We demonstrate the midway-merge method in an object-level SLAM problem with pose ambiguity to deal with multiple hypotheses. 

We open-source our work on GitHub

In this work, we design a visual-inertial navigation system with the direct intensity measurement inspired by the famous direct sparse odometry (DSO). Our contribution includes 1) the stochastic image gradient that makes our system robust to bad initialization points and 2) modeling the state-space on matrix Lie group that yields proper representation for an inertial navigation system. 

We open-source our work on GitHub

"Object-based Visual-Inertial Navigation System on Matrix Lie Group"

IEEE International Conference on Robotics and Automation 2022

We formulate the invariant extended Kalman filter in the object SLAM problem. The idea is to model the state-space in the matrix Lie group and fuse visual and inertial measurements in a fully probabilistic fashion to increase the temporal consistency of a single view pose detector. We adopt a deep neural network-based pose detector as a sensor and validate our proposed method in the KITTI dataset.

"Ensemble Kalman Filter Based LiDAR Odometry for Skewed Point Clouds Using Scan Slicing" 

IEEE International Conference on Robotics and Automation 2022

Collaborative work with Dr. Yeongkwon Choe. We focus on a solution for the motion distortion in a mechanical spinning LiDAR for a localization and mapping problem. He splits a LiDAR scan into several small pieces and builds the ensemble Kalman filter to deal with the multi-modal problem due to the narrow field of view. Nice work!

We designed a pose tracking filter using RGB images, a stream of events from a dynamic vision sensor, and IMU. Our contribution is seamless fusion of multi-modal sensors in high-dynamic scenarios that is one of the most challenging problem in vision-based navigation.

"Observability Analysis of IMU Intrinsic Parameters in Stereo Visual-Inertial Odometry

IEEE Transactions on Instrumentation and Measurement, 2020

We analytically prove that IMU intrinsic parameters (scale factors and misalignments) are actually observable in 6-DOF generic motion in a visual-inertial navigation system. We investigated the rank of the observability matrix built from Lie derivatives in a nonlinear system. Our theoretical results are confirmed by a numerical simulation and real-world experiments. 

"Monocular Visual-Inertial-Wheel Odometry using Low-Grade IMU in Urban Areas

IEEE Transactions on Intelligent Transportation Systems, 2020

Collaborative work with Hyundai MnSOFT. We developed visual-inertial-wheel odometry that replaces the noisy integration of an accelerometer with the single integration of a wheel odometer. We evaluated our system in tens of kilometers driving dataset collected in tunnels and streets in Seoul.

"Patch-based Stereo Direct Visual Odometry Robust to Illumination Changes

International Journal of Control, Automation, and Systems, 2018

My first international journal paper. To solve brightness change issue and large motion in direct visual odometry, we proposed a motion prior term and bucketed illumination model.

Collaborative work with Dr. Sejong Heo. He derived the multi-state constraint Kalman filter on matrix Lie groups to solve the inconsistency of the estimator.  He proves that the linearized system defined by the invariant error does not depend on the current estimates in unobservable subspaces. I mainly wrote scripts for processing open-source datasets, the EuRoC MAV dataset.