[)] i've a project ,in which i have to actuate a Dc motor According to the engine rpm:

Aim: We want to actuate a DC Motor in both direction according to Engine RPM.

CAse:1 a lever (locked position) will remain in this position upto 4500 engine rpm

CAse:2 lever should unlocked by motor after 4500 rpm(say motor rotated in clockWS)

CAse:3 when engine rpm goes down below the 4500 rpm from higher rpm lever should locked again(say motor rotated in anticlockWS)

so finally we need a
microcontroller ?
algorithm ?
circuit diagram ?
and sensor ? refer image given below



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