The block diagram of Figure Q2 shows a speed control system in which the output of the controller is subject to a torque disturbance d(s). In the diagram, n, (s), n(s) and d(s) are the Laplace transforms of the reference speed, output speed, and disturbance torque, respectively. In the absence of a disturbance torque d(s), the output speed (s) is equal to the reference speed (s). d(s) r(s) + C(s) 1 Js n(s) Figure Q2 a) Evaluate the transfer function between the disturbance torque, reference speed and the output speed. b) Evaluate the steady state output of this system to a unit-step disturbance torque. Assume that the reference input is zero. c) Suppose that we wish to choose a suitable controller whose transfer function is C(s) to cancel the effect of a disturbance torque d(s) at steady state and to ensure that the constant disturbance torque applied to the output of the controller will cause no speed change at steady state. Using the result in b), derive a condition for C(s) that can satisfy this requirement.