Structure estimation of a moving object using a moving camera: An unknown input observer approach

A state observer is designed for estimating the structure of a moving object with time-varying velocities seen by a moving camera. A nonlinear unknown input observer strategy is used where the object's velocity is considered as an unknown input to the perspective dynamical system. The object is assumed to be moving on a ground plane. The downward-looking camera observing the moving object is also moving (e.g., attached to an air vehicle) with known velocities. The developed method provides the first causal, observer-based structure estimation algorithm for a moving camera viewing a moving object with unknown time-varying object velocities.