The system we will study this week and next is a position control system. We already know the relationship between voltage and angular velocity for the DC motor. Integrating the angular velocity gives the angle, and wrapping a cord around a drum attached to the motor shaft gives a linear position. More complicated than the velocity related problems we've addressed so far, but hopefully more interesting.
The television system in the final two labs will involve the synchronization of two rotating disks. This may also be viewed as a control system where the controlled variable is phase. Since phase is the difference between two angles, and control of angle is what we are actually doing in this lab, there will be some relationship between what we do here and what we do in the final labs. More on this later.
We will attack the position control system in three stages: First we will modify the motor amplifier to cope with its new duties and build an additional circuit to handle the sensor. Next we will characterize the open loop system. Finally (next week) we will connect it together and characterize the resulting closed loop system.