Previous generations of industrial robots are built to perform tasks rapidly and has to be put in cages for human safeness. Recently, there have been many work(s) on making robots that are safe to work side by side with human workers. Some robots have sensors to detect collision but these are not completely safe to work with people. In this paper, we propose to put robots in virtual safety cages will allow necessary. The virtual safety cages will allow humans to see the safety boundary of robots as doing dangerous operations. During non-dangerous operations, human and robots can freely roam around to maximize the degree of collaboration. We give the desiderate for the computation of the proper cage size and how to use wearable devices with haptic feedback to avoid human workers and as close to the robots as possible, as well as how to use wearable devices with haptic feedback to provide a worker with the direction and distance he should move during the deployment of a virtual safety cage.