Abstract: A smart nozzle assembly includes a nozzle, a nozzle control mechanism, and camera rigidly attached to the nozzle for use with a mobile robot in an autonomous spray painting system. The nozzle control mechanism is configured to control flowrate, control the shape of the spray pattern, mix two or more colors, and clean dried paint at the nozzle tip. The nozzle assembly further includes a process for running software to manage or initiate the nozzle control mechanism's functionality and to provide the nozzle calibration. The calibration method for the nozzle uses a novel algorithm that measures the spray pattern, the distribution of paint within the spray pattern, and the relative position of the nozzle and camera. The distribution of paint within the spray pattern is measured in terms of physical quantity of delivered paint per unit area.