Perhaps you should try some spelling variations:
"differential wheeler robot" » "differential wheeled robot", "differential wavelet robot", "differential spiele robot", "differential wheeled robots", "differential wheel robot"
"differential regler robot" » "differential role robot", "differential regler robuste", "differential pepper robot", "differential killer robot"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"differential wheeler robot\") OR (\"differential regler robot\"))".
• Removing quotes may allow a broader search: (( differential wheeler robot ) OR ( differential regler robot )).
• Adding a wildcard symbol may retrieve word variants: (("differential wheeler robot") OR ("differential regler robot"))*.