Forward path gain

Step 1 Define transfer functions in the forward path. The values of all gains and time constants are arbitrarily selected. 

The unit in the forward path has a steady-state gain Kf and a time constant Tf. The unit in the recycle path has a gain Kr and time constant tr. The load disturbance... 

Consider a simple feedback loop (Fig. 7.3a) in which the feedback path consists of elements which approximate to a steady-state gain K (Fig. 7.37). In this instance, the equivalent unity feedback loop is determined by placing 1 IK in the set point input to the main loop and compensating for this by adding an additional factor K in the forward part of the loop prior to the entry of the load disturbance, as in Fig. 7.38. It is easy to confirm that the standard closed loop transfer functions and are the same for the block diagrams in Figs 7.37 and 7.38. 

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