A model of a physical environment may be determined based at least in part on sensor data collected by one or more sensors at a robot. The model may include a plurality of constraints and a plurality of data values. A trajectory through the physical environment may be determined for an ultraviolet end effector coupled with the robot to clean one or more surfaces in the physical environment. The ultraviolet end effector may include one or more ultraviolet light sources. The ultraviolet end effector may be moved along the trajectory.