The ornamental design for a handle for a robotcart, as shown and described.
FIG. 1 is a front perspective view of a handle for a robot cart according to our new design;
FIG. 2 is a first side view of the handle shown in FIG. 1;
FIG. 3 is a second side view of the handle shown in FIG. 1;
FIG. 4 is a front view of the handle shown in FIG. 1;
FIG. 5 is a back view of the handle shown in FIG. 1;
FIG. 6 is a top view of the handle shown in FIG. 1; and,
FIG. 7 is a bottom view of the handle shown in FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. Any broken lines in the drawings are for illustrative purposes only and form no part of the claimed design.