Most existing calibration techniques for multi-projector display system require that the display configuration remain fixed during the display process. We in this paper present a new approach to continuously re-calibrate the projection system to automatically adapt to the display configuration changes, while the multi-projector system is being used without interruption. By rigidly attaching a camera to each projector, we argument the projector with sensing capability and use the camera to provide online close-loop control. In contrast to previous auto or continuous projector calibration solutions, our approach can be used on surfaces of arbitrary geometr and can handle both projector and display surface movement, yielding more flexible system configuration and better scalability. Experimental results show that our approach is both accurate and robust.