I have to make a control system that maintains a constant speed of a small car prototype using a DC Gearmotor regardless of external disturbances such as slopes (small slopes).
For the development of this project, the control system will consist of a PID controller that affects the speed of a DC motor. I am not able to use a microcontroller.
I will measure the real RPM of the motor by using an optical sensor which is going to give me pulses, and then I'll use the lm2917 that will transform pulses to a certain voltage value going back to the sum point (operational amplifier adder circuit). And this is how I will do the feedback of the system.
My question is: What is the transfer function of the feedback stage? (Optical sensor and the lm2917)