A model of the boring machine control is shown in Figure 2, where Y(s) is the actual angle of direction of travel of the boring machine and R(s) is the desired angle. The effect of load on the machine is represented by the disturbance, D(s). D(s) R(s) Desired angle E(s) Y(s) Boring machine Angle K+1ls G(s) = s(s +1) Figure 2 Y(s) (a) Determine the transfer function D(s) (7 marks) (b) If we wish to reduce the effect of the disturbance, specifically, we want to maintain the steady-state response to the unit step disturbance at lim y(t) = 0.01 when the input angle r(t) = 0, what value of K should we select? (6 marks) (c) Let the disturbance d(1) = 0. The error signal is defined as E(s) = R(s) Y(s). E(s) Determine the transfer function R(s) (7 marks) (d) Let the disturbance d(1) = 0. If we choose K = 20, find the steady-state error , of the closed-loop system to a unit step input r(1). (5 marks)