Autonomous Control of RPM of Engine Using Feedback System From a IR Based Tachometer

There is always a need for automating a process,be it a simple/monstrous one.I got the idea to do this project from a simple challenge that i faced while finding methods to water/irrigate our small piece of land.The problem of no current supply lines and costly generators (to operate our pump) added to the difficulty.
So what we decided to do is device a method which would be cheap and easy to use,even by a worker.We decided to mount the pump on our old scooter(running condition) and run it using the shaft of the scooter wheel.All fine and good,we made the mechanical assembly and the belt drive and tested it,and it was a success.
But another problem was that,when the motor was running,a person always had to be near the scooter to monitor the RPM,and manually adjust it using throttle.So this project was made by us so that the worker can set the desired RPM he wants to make the engine run,and attend to other work in the farm.
The setup consists of :
A IR based tachometer(to measure RPM). A keypad to enter the RPM. A LCD display to show the monitored RPM and current RPM. A Stepper motor to increase/decrease the throttle. Finally,a micro-controller to manage all these processes.”