Disturbance Rejection and Set Point Tracking

The operation of a process may deviate from its desired operating conditions for two different reasons  

Disturbances. These are changes in flow rates, compositions, temperatures, levels or pressures in the process which we can not control because they are either given by the feed conditions (assumed controlled by an upstream unit), ambient conditions, such as the weather, or utilities, such as steam or cooling water. 

Set point changes. These are deliberate changes in the operating conditions, such as a change in polymer grade for a polymerisation reactor, change in distillate composition for a distillation column, etc. 

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V.17 Design the steady-state and dynamic feedforward controllers (for disturbance rejection and set point tracking) for the systems with the following transfer functions (transfer function between manipulation and controlled output Gd is the transfer function between disturbance and controlled output). Assume that Gm - Gf = 1. 

The following specifications are also given (1) use a PI controller for the feedback loop, and (2) the feedforward system should have both disturbance rejection and set point tracking capabilities... 

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