Perhaps you should try some spelling variations:
"coder pid controllers and problem" » "coder pid controller and problem" (Expand search), "coder pid controlled and problem" (Expand search), "coder pid controllers in problem" (Expand search), "order pid controllers and problem" (Expand search), "encoders pid controllers and problem" (Expand search)
"api python python python programming" » "api pythons python python programming" (Expand search), "api piton python python programming" (Expand search), "api pitons python python programming" (Expand search), "rpa python python python programming" (Expand search), "manim python python python programming" (Expand search)

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: "((\"coder pid controllers and problem\") OR (\"api python python python programming\"))~".
• Removing quotes may allow a broader search: (( coder pid controllers and problem ) OR ( api python python python programming ))~.
• Adding a wildcard symbol may retrieve word variants: (("coder pid controllers and problem") OR ("api python python python programming"))*.