This example shows a state-feedback speed-control structure for a DC motor. A PWM controlled four-quadrant Chopper is used to feed the DC motor. The Control subsystem includes the state-feedback control loop, and the PWM generation. The state vector includes the rotor speed which is measured, and the dc motor current, which is estimated using an observer. Both the observer and state-feedback controller are synthesized by pole placement using the state-space model of the system. The total simulation time (t) is 4 seconds. At t = 1.5 seconds, the load torque increases. At t = 2.5 seconds, the reference speed is changed from 1000 rpm to 2000 rpm.