b. (15%) Assuming k=0, estimate the amplitude of the steady-state error when the reference input is r(t) = cos(2t).

b. (20%) Suppose that we employ a unity feedback to control the motor anguiar velocity and set the desired angular velocity to 100 rad/s, as shown in Fig. 2. Assume the load torque is constant TL=0.1. Determine the phase margin of this feedback system. Also estimate the regulation error e(t) in steady state. y do(t)