MATLAB Simulink

hi frnds........

i want to replace pid with fuzzy in a closed loop,but for tat i need a closed loop system with pid(can be speed control) which shud give result in matlab simulation.

my problem which resist me frm dng this is,we all knw tat for any closed loop we need subtractor tool,but it doesnt suited for any of reference value(voltage,speed).

plss any one can send me the correct simulation model.