van_coupled_rt.py

import time
import numpy as np
import matplotlib.pyplot as plt
from scipy.integrate import odeint
# The van der pol oscillator has been adapted from http://dropbearcode.blogspot.com/2012/05/python-simulation-of-van-der-pol.html

# l - coupling coefficient
l = 0.1

# Coupling matricies
# Coupling weights, represented by 4x4 matrix.
weight_walk = [ [0, -l, l, -l],
              [-l, 0, -l, l],
              [-l, l, 0, -l],
              [l, -l, -l, 0]]

weight_trot = [ [0, -l, -l, l],
              [-l, 0, l, -l],
              [-l, l, 0, -l],
              [l, -l, -l, 0]]

weight_bound = [ [0, l, -l, -l],
               [l, 0, -l, -l],
               [-l, -l, 0, l],
               [-l, -l, l, 0]]

weight_control = [[0,0,0,0],
                  [0,0,0,0],
                  [0,0,0,0],
                  [0,0,0,0]]

weight = weight_walk

current_i = 0
def van_der_pol_coupled(x, t):
    x0 = x[1]
    x_ai =x[0]
    for j in range(4):
        x_ai += x[0]-(weight[current_i][j]*start_x[j])
    # x_ai *= time_step
    # osc = odeint(van_der_pol_oscillator_deriv, [x[0], x[1]], [t-time_step, t])
    x1 =  mu * ((p - (x_ai** 2.0))* x0) - x_ai*w
    res = np.array([x0, x1])
    return res

start_time = time.time()
prev_time = time.time()
time_step = 0.01

count = 0

start_y = [1, 1, 1, 1]
start_x = [0,0,0,0]
new_y = [1, 1, 1, 1]
new_x = [0,0,0,0]
oscillator_values = []
while (count <= 10):
    count+= time_step
    current_time = time.time()
    mu = 1
    p = 2
    w = 20
    x_list  = []
    for i in range(4):
        current_i = i
        osc= odeint(van_der_pol_coupled, [start_y[i], start_x[i]], [count-time_step, count])
        x = osc[1][1]
        y = osc[1][0]
        x_list.append(x)
        new_y[i] = y
        new_x[i] = x
        if (i == 0):
            plt.subplot(2, 1, 1)
            plt.scatter(y, x, c='red')
            plt.subplot(2, 1, 2)
            plt.scatter(count, x, c='red')
        if (i == 1):
            plt.subplot(2, 1, 1)
            plt.scatter(y, x, c='green')
            plt.subplot(2, 1, 2)
            plt.scatter(count, x, c='green')
        if (i == 2):
            plt.subplot(2, 1, 1)
            plt.scatter(y, x, c='blue')
            plt.subplot(2, 1, 2)
            plt.scatter(count, x, c='blue')
        if (i == 3):
            plt.subplot(2, 1, 1)
            plt.scatter(y, x, c='yellow')
            plt.subplot(2, 1, 2)
            plt.scatter(count, x, c='yellow')
    start_y = new_y
    start_x = new_x
    plt.pause(0.0001)
plt.show()