- #1

David J

Gold Member

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- 15

## Homework Statement

[/B]

The proportional control system of figure 3(a) (attachment 235263) has an input, ##\theta_{1}##, of 10 units. The uncontrolled input, ##\theta_{2}##, has a value of 50 units, prior to a step change down to 40 units. The result of this disturbance upon the output, ##\theta_{o}## is shown in figure 3(b) (attachment 235264)

(a) Calculate the change in offset in the output produced by the step change

(b) Draw a modified block diagram to show how the offset could be minimised by the inclusion of another control action. Also, show by means of a sketch how the modification might be expected to affect the output response.

(c) Show, by drawing a modified block diagram, how the magnitude of the disturbance could be minimised by the inclusion of a third type of control action

2. Homework Equations

2. Homework Equations

##\theta_{0}=\frac{\theta_{2} +G\theta_{1}}{1+G}##

## The Attempt at a Solution

(a)

[/B]

Prior to the step change

##\theta_{0}## = ##\frac{50 + (9*10)}{1+G}##

so ##\theta_{0}## = ##\frac{140}{10}##=## 14 m^{3 h-1}##

After the step change

##\theta_{0}## = ##\frac{40 + (9*10)}{1+G}##

so ##\theta_{0}## = ##\frac{130}{10}##=## 13 m^{3 h-1}##

So in the first instance would I be correct in saying that the change in offset in the output as a result of the step change will be ## 1 m^{3 h-1}## ?

I attached some notes, (pages 16 and 17) which I think are in relation to this question