How can I detect object and predict its motion in 2d environment?

I have some frames of an environment that include one goal , one object as obstacle, and one robot which need to reach the goal, but I need to know about the obstacle and its location by time, I assume my obstacle is moving in a line, and have a simple path. with constant velocity. optical.flow to detect speed? and kalmanfilter to predict? are suitable? or a simpler method if you know? thanks in advance