Proportional plus derivative controller

In summary, the conversation is about finding information on proportional-plus-derivative control and the OP seeking advice on their graph. They have found a solution with PB=20% and dAT=0.1min, resulting in a peak of 10 units at 30 seconds and then reducing at the same derivative. They are looking for additional resources and the OP has provided some helpful links. The conversation also mentions a member, Jim, who is no longer active and another member, @rude man, who is still active and may be able to provide insight.
  • #1
Jason-Li
119
14
Homework Statement
FIGURE 6 shows a proportional plus derivative controller that has a proportional band of 20% and a derivative action time of 0.1 minutes. Construct the shape of the output waveform for the triangular input waveform shown, if the input rises and falls at the rate of 4 units per minute.
Relevant Equations
None required
Hello,

There is a thread related to this question however it was marked correct but doesn't look correct to me?

https://www.physicsforums.com/threads/step-change-in-a-proportional-plus-integral-controller.961180/

I think I have it but it is quite different to other answers I have seen?
I have found
PB=20% hence gain=5
dAT = 0.1min = 6s
Would rise and peak at 2units at 30s however due to gain this will be 10units, hence change due to derivative would be:
10/30 * 6s = 2units, then once peaked at 30s it would reduce by the same derivative and create the following graph:
1610371239922.png
 
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  • #2
spoto2 said:
Find out information about proportional-plus-derivative control. Control in which the control signal is a linear combination of the error signal and its derivative.
Can you post some links to such information that would be helpful for the Original Poster (OP)? Thanks.
 
  • #3
@spoto2 @berkeman

Sorry I've looked at a few different sources but my graph still looks correct to me, any advice?
 
  • #4
Not one of my areas of expertise, unfortunately. Jim is no longer with us (RIP), but @rude man still is at PF... :smile:
 
  • #5
Hi Jason, Just wondered what your maths is behind this?
 
  • #6
Tromso80 said:
Hi Jason, Just wondered what your maths is behind this?

The maths is in the first post, which part are you unsure of?
 

1. What is a proportional plus derivative controller?

A proportional plus derivative controller is a type of feedback control system used in engineering and science applications. It combines the proportional and derivative control actions to improve the performance of a system by reducing the steady-state error and increasing the system's stability.

2. How does a proportional plus derivative controller work?

A proportional plus derivative controller works by continuously measuring the error between the desired and actual output of a system and then applying a control action based on both the proportional and derivative terms. The proportional term provides a control action proportional to the error, while the derivative term provides a control action proportional to the rate of change of the error.

3. What are the advantages of using a proportional plus derivative controller?

Some advantages of using a proportional plus derivative controller include improved system response, reduced steady-state error, and increased stability. It also allows for faster and more accurate control of a system compared to using a proportional controller alone.

4. What are the limitations of a proportional plus derivative controller?

One limitation of a proportional plus derivative controller is that it can be sensitive to noise and disturbances in the system. It also requires knowledge of the system's dynamics and parameters to design an effective controller. Additionally, it may not be suitable for highly nonlinear systems.

5. How is a proportional plus derivative controller different from a proportional-integral-derivative (PID) controller?

A proportional plus derivative controller is a simplified version of a PID controller, which also includes an integral term. The integral term helps to reduce the steady-state error in a system, while the derivative term provides faster response and improved stability. However, a PID controller is more complex and requires tuning of three parameters, while a proportional plus derivative controller only requires tuning of two parameters.

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