The ornamental design for a smart curtaincontroller, as shown and described.
FIG. 1 is a first perspective view of a smart curtain controller showing my new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a back view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof; and,
FIG. 9 is an enlarged view of the selected portion in FIG. 1.
The broken lines shown in the drawings depict portions of the smart curtain controller in which the design is embodied that form no part of the claimed design.