Chapter 15    Feedforward Control

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Check Your Reading             Study Questions             Thought Questions

The questions will be categorized according to the key concepts in the chapter.

FEEDFORWARD DESIGN CRITERIA IMPLEMENTATION
FEEDBACK PRINCIPLE RATIO CONTROL

 

 

 

 

 

 

 

 

 

Check Your Reading

Solidify the Concepts
15.1   
Feedforward can be applied to compensate for any measured disturbance.		 DESIGN CRITERIA

TRUE         FALSE

 

 

 

 

 

 

 

15.2   
Which of the following appear in the feedforward design criteria?		 DESIGN CRITERIA

We need the criteria to design feedforward correctly.

 

The process must be linear.

There must not be a causal relationship between the manipulated variable and the feedforward disturbance variable.

 


  

The disturbance dynamics must not be significantly faster than the manipulated variable dynamics.

 

 

The measured feedforward variable must measure a significant disturbance.

 

 

 

 

 

 

 

 

 

 

15.3   
Only ONE measured variable can be used for feedforward control.		 DESIGN CRITERIA

TRUE         FALSE

 

 

 

 

 

 

 

 

 

15.4   
Flow ratio control can be achieved by feedforward principles, but not feedback only.		 RATIO CONTROL

TRUE         FALSE

 

 

 

 

 

 

 

 

15.5   
All measured disturbances should be used for feedforward control		 DESIGN CRITERIA

TRUE         FALSE

 

 

 

 

 

 

 

 

15.6   
The general feedforward design equation using linearized models is given in which of the following expressions?		 DESIGN CRITERIA

We derive all feedforward controllers from this equation.

 

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wpe3B.gif (1463 bytes)
 

 wpe1.gif (1502 bytes)

 

 

 

 

 

 

 

 

 

15.7
A major deficiency of feedforward control is		 FEEDBACK PRINCIPLE

How do we overcome the deficiency?

 

the lack of a tuning parameter

the occurrence of steady-state offset

 

 the propagation of measurement noise

 

 

 

 

 

 

 

 

 

 

15.8
The design goal for feedforward control is		 DESIGN CRITERIA

 

zero steady-state offset

stable, moderate adjustments to the manipulated variable

 

 perfect compensation [CV'(t)=0] during the entire dynamic response.