# What is a root locus plot?

## What is a root locus plot?

– The Root Locus Plot is a plot of the roots of the characteristic equation of the closed-loop system for all values of a system parameter, usually the gain; however, any other variable of the open- loop transfer function may be used.

## What is the main objective of root locus analysis technique?

Explanation: The main objective of drawing root locus plot is to obtain a clear picture about the transient response of feedback system for various values of open loop gain K and to determine sufficient condition for the value of ‘K’ that will make the feedback system unstable.

What are the properties of root locus?

The root loci are symmetrical with respect to the real axis of the s-plane . In general, the root loci are symmetrical with respect to the axes of symmetry of the pole-zero configuration of G(s)H(s).

How can root locus be used to determine stability?

The root locus procedure should produce a graph of where the poles of the system are for all values of gain K. When any or all of the roots of D are in the unstable region, the system is unstable. When any of the roots are in the marginally stable region, the system is marginally stable (oscillatory).

### How do you do root locus?

Construction of Root Locus

1. Rule 1 − Locate the open loop poles and zeros in the ‘s’ plane.
2. Rule 2 − Find the number of root locus branches.
3. Rule 3 − Identify and draw the real axis root locus branches.
4. Rule 4 − Find the centroid and the angle of asymptotes.

### Why root locus technique is necessary?

Root locus is helping us to map graphically as graph all possible locations of the poles within the system on the s-plane. The different locations of the poles are obtained under the effect of gain changes (proportional gain).

How do you plot a root locus?

What is the difference between root locus and Bode plot?

Bode plots tells us how many resonant peaks are there if I am not wrong (magnitude response). Phase response is absolutely important. Root locus tells about response when gain changes (stability is clear from response).

## Can root locus cross each other?

Two or more branches can intersect at a point that does not belong to the real axis. with j = 0, 1. A branch can not intersect itself. This property is immediate since, by construction, the gain k increases along the root locus branches.

## How would you determine whether the root locus plot crosses the imaginary axis or not?

We can calculate the point at which the root locus branch intersects the imaginary axis and the value of K at that point by using the Routh array method and special case (ii). If all elements of any row of the Routh array are zero, then the root locus branch intersects the imaginary axis and vice-versa.

What root locus tells us?

Key concept: The Root Locus Plot The root locus plot indicates how the closed loop poles of a system vary with a system parameter (typically a gain, K). We can choose a value of ‘s’ on this locus that will give us good results.

Where does the root locus start?

open-loop poles
The root locus branches start at the open-loop poles and end at the open-loop zeros or at infinity. 3. The real axis root loci have an odd number of poles plus zeros to their right.

### Apa yang merupakan dasar teori root locus?

Program penunjang praktikum III. Dasar Teori Root Locus (tempat kedudukan akar) merupakan suatu analisis dalam keilmuan control engineering yang menggambarkan pergeseran letak pole-pole suatu sistem loop tertutup dari peerubahan besarnya penguatan loop terbuka dengan gain adjustment.

### Bagaimana cara menggambar root locus?

Dalam menggambar root locus ada dua hal yang harus dipahami, yaitu titik pencar (break away point) dan temu pole-pole (break in point). Dalam menentukannya bisa melalui dua cara, yaitu: Jika ada, kini tentukan titik potong kurva root locus melalui sumbu imajiner.

Mengapa root locus digunakan untuk menentukan stabilitas sebuah sistem?

Sehingga apabila diartikan secara harfiah, maka root locus adalah tempat kedudukan dari akar-akar persamaan karakteristik sebuah sistem yang ditentukan oleh nilai K. Nilai K itu sendiri dalam root locus MATLAB bisa 0 sampai tak hingga. Dengan adanya root locus, seseorang dapat menentukan stabilitas sebuah sistem.

Apakah potong kurva root locus dengan sumbu real?

Titik potong kurva root locus didapat dengan mendifferensiasikan fungsi ‘k’ terhadap ‘s’, sehingga didapat S1 = (-8/3) + j (11/9)1/2 dan s2 = (-8/3) – j (/9)1/2 . Jika kita perhatikan, perpotongan kurva root locus dengan sumbu real tidak mungkin pada titik akar-akar yang didapat, karena akar-akar yang didapat complex (punya bagian imajiner).