<div>In dynamic environment, the suddenly appeared </div><div>human or other moving obstacles can affect the safety of the </div><div>bridge crane. For such dangerous situation, the bridge crane </div><div>must predict potential collisions between the payload and the </div><div>obstacle, keep safe distance while the swing of the payload must </div><div>be considered in the mean time. Therefore, the safe distance is </div><div>not a constant value, which must be adaptive to the relative </div><div>speed of the bridge crane. However, as far as we know, the </div><div>mathematical model between the safe distance and the relative </div><div>speed of the bridge crane has never been fully discussed. In </div><div>this paper, we propose a safe distance prediction method using </div><div>model prediction control (MPC), which can make sure that the </div><div>crane can stop before the obstacle, and avoid possible collisions, </div><div>while the relative speed and anti-swing are both considered. The </div><div>experimental results prove the effectiveness of our idea.</div>