# Questions tagged [root-locus]

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11 questions
0answers
22 views

### How to treat poles with imaginary part when using root locus angle criteria - what is the angle to use?

Context: In the process of designing a phase-lead compensator for a system, I have used the design requirements to find the ideal locations for my closed-loop (CL) poles, have picked a place for a new ...
3answers
118 views

### Root Locus, Gain in Feedback Loop. Need help

So this is the system for which I have to draw a root locus if 'K' changes from 0 to infinity. The problem for me is that root locus is drawn for open loop transfer function but 'K' is in the feedback ...
1answer
259 views

### Pole Zero Cancellation on a Root Locus

Question: ...design a controller in the feedforward path to minimise the effects of the two pairs of dominant poles. Use a pole-zero cancellation technique on a root locus diagram.... I have a 5th ...
2answers
94 views

### Root Locus and Imaginary Axis

I’m having some serious issues finding the point at which the root loci cross the imaginary axis for the following Open Loop Transfer Function (OLTF) ; We have been taught to substitute s = jw and ...
1answer
110 views

### How to calculate roots using root locus method? [closed]

Find the roots of the following polynomial by use of the root locus method. 3s⁴ + 10s³ + 21s² + 24s + 30 = 0 (The root locus plot has not been given.) Can you please help me with this? This ...
2answers
80 views

### Root locus, where do they leave the line parallel to imaginary axis

I know how to sketch by hand root locus of simpler systems. Consider the root locus which Matlab gives for: $$G(s) = \frac{1}{(s+4)(s+6)(s^2 + 10s + 100)}$$ I've marked the points of interest P1 and ...
1answer
235 views

### Root locus for an open loop transfer function?

The function, rlocus(), in MATLAB is used for closed loop system roots for variation in gain K. However, I am curious if there is a similar function for variation ...
0answers
398 views

### Designing PID controller for 2 servo motor synchronization

I am trying to use a PID controller to synchronize wheel speeds in an arduino-bot so that I can get it to drive straight. I am unsure how to approach this problem without knowing the physical ...
2answers
1k views

### How to find the intersection point in rootlocus diagram?

Question: Sketch the root locus for the open loop transfer function of a unity feedback control sytem given below and determine the value of K for $\xi=0.5$ $G(s)=\frac{K}{s(s+1)(s+3)}$ --...
0answers
97 views

### Question about the transfer function found from state space model

I'll make up a problem to explain what I'm having trouble with. \dot x=\begin{bmatrix}0&1\\-5&-6\end{bmatrix}x+\begin{bmatrix}0\\1\end{bmatrix}u=Ax+Bu\\\\y=\begin{bmatrix}0&1\end{bmatrix}...
3answers
5k views

### Determining imaginary axis crossing of a root locus

I have an equation \begin{equation}{\text{L}\left(s\right)=\frac{K}{s(s+4)(s^2+6s+64)}} \end{equation} and I am trying to determine it's root locus by hand.When I try plotting it with matlab, the ...