The robotic shepherding problem has earned significant research interest over the last few decades due to its potential application in precision agriculture. In this paper, we first modeled the sheep flocking behavior using adaptive protocols and artificial potential field methods. Then we designed a coordination algorithm for the robotic dogs. An occlusion-based motion control strategy was proposed to herd the sheep to the desired location. Compared to formation based techniques, the proposed control strategy provides more flexibility and efficiency when herding a large number of sheep. Simulation and lab based experiments, using real robots and global vision-based tracking system, were carried out to validate the effectiveness of the proposed approach.