  The VINS-Mono is a monocular visual-inertial 6 DOF state estimator proposed
by Aerial Robotics Group of HKUST in 2017. It can be performed on MAVs,
smartphones and many other intelligent platforms. Because of the excellent
robustness, accuracy and scalability, it has gained extensive attention
worldwide. In this manuscript, the main equations including IMU
pre-integration, visual-inertial co-initialization and tightly-coupled
nonlinear optimization are derived and analyzed.
