The vertical position, x(t), of a grinding wheel is controlled by a closed loop system. The input to the system is the desired depth of grind, and the output is the actual depth of grind. The difference between the desired depth and the actual depth drives the motor, resulting in a force applied to the work. This force results in a feed velocity for the grinding wheel (Jenkins, 1997). Draw a closed-loop functional block diagram for the grinding process, showing the input, output, force, and grinder feed rate.