control-system/README.md

routh_table

This repo is belong to Control System class contains with Automated Routh Table Calculator based on Python. This code 100% original made by my hand :), please leave some notes if you're going to use it. Thanks!

Libraries

Libraries that used in this program is numpy and pandas. numpy works by define and perform array while pandas is the final form after numpy.array to simplify the presentation. They imported by write

import numpy as np
import pandas as pd

RouthStability Class

This class contains lots of procedures to simplify our Routh Stability Table Generator process.

def __init__(self, den):
    self.den = np.array([float(item) for item in den.split()])
    self.deg = len(self.den)

The constructor __init__ takes string of coefficiens from polynomial, extract the number, and load into class variable. It also define self.deg variable to save array's length, reducing number of calling len() function

def set_k(self, k):
    self.den = np.append(self.den, float(k))
    self.deg += 1

This function only takes one number from user and append it to self.den which defined as gain (constant). Also self.deg will increase by one

def calc_routh(self):
    height = (self.deg+1)//2
    arr = np.zeros((height + 2,height))
    for index in range(self.deg):
        if index % 2 == 0:
        arr[0][index//2] = self.den[index]
        else:
        arr[1][(index-1)//2] = self.den[index]

    for i in range(2, height+2):
        for j in range(height-1):
        arr[i][j] = (arr[i-1][0]*arr[i-2][j+1] - arr[i-2][0]*arr[i-1][j+1])//2
        arr[i][j] += 0

    self.df = pd.DataFrame(arr)
    self.show_tab()
    if self.is_stable() == True:
        print("SYSTEM IS STABLE")
    else:
        print("SYSTEM IS UNSTABLE")

calc_routh(self) as the core process of this class contains initialization and process about Routh Stability Process. Firstly, it define an empty zero (basically it filled with zeros) and iteratively being inserted by self.den (refering to Routh Table principle). After that, each cell will be updated by calculating Routh Table formula

arr_{i,j} = \frac{arr_{i-1][0]*arr[i-2][j+1] - arr[i-2][0]*arr[i-1][j+1]}{arr_{i-1][0]}