the output of the motor will feed the sensor, and the sensor will measure either the position or the speed of the motor depending on its configuration, if it is a position or a speed control.
Try and read (ME2142-2.doc) and (Barrios_Chapter5.pdf) first, please. If you need any help , you can ask Mr. Hassan Abbas Hussien (He teaches control subject in your College).
If this is an embedded system, sensor output data (such as IR sensors, ultrasonic sensors) can be collected by MCU (such as HCS12) via A/D for IR sensors as they need A/D. The MCU can work with H-bridge and PWM to control the speed and position of motors. Hope it helps.