The shoulder joint of a robotic arm uses a DC motor with armature control and a set of gears on the output shaft. The model of the system is shown in Figure AP4.2 with a disturbance torque Td(s) which represents the effect of the load. Determine the steady-slate error when the desired angle input is a step so that θd(s) = A/s, Gc(s) = K, and the disturbance input is zero. When θd(s) = 0 and the load effect is Td(s) = M/s, determine the steady-state error when (a) Gc(s) = K and (b) Gc(s) = K/S.
Figure AP4.2
Robot joint control.

Load disturbance TAis) Controllcr K Ts) LuS (Ks) Actual angle G,(s) s(Js + b) Desired angle ol rotation