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import matplotlib.pyplot as plt
import numpy as np
from matplotlib.animation import FuncAnimation
from scipy.integrate import odeint

def SystDiffEq(y, t, m1, m2, a, b, l0, c, g):
    # y = [phi, psi, phi', psi'] -> dy = [phi', psi', phi'', psi'']
    dy = np.zeros_like(y)
    dy[0] = y[2]
    dy[1] = y[3]

    phi = y[0]
    psi = y[1]
    dphi = y[2]
    dpsi = y[3]

    # a11 * phi'' + a12 * psi'' = b1
    # a21 * phi'' + a22 * psi'' = b2

    l = np.sqrt(8 * a ** 2 * (1 - np.cos(phi)) + l0 * (l0 - 4 * a * np.sin(phi)))
    a11 = ((4/3) * m1 + m2) * a
    a12 = m2 * np.sin(psi - phi)
    b1 = (-(m1 + m2) * g * np.cos(phi) 
         + c * ((l0 / l) - 1) * (4 * a * np.sin(phi) - 2 * l0 * np.cos(phi))
         - m2 * b * dpsi ** 2 * np.cos(psi - phi))
    
    a21 = a * np.sin(psi - phi)
    a22 = b
    b2 = - g * np.sin(psi) + a * dphi ** 2 * np.cos(psi - phi)

    detA = a11 * a22 - a12 * a21
    detA1 = b1 * a22 - a12 * b2
    detA2 = a11 * b2 - b1 * a21

    dy[2] = detA1 / detA
    dy[3] = detA2 / detA

    return dy
    

# Дано:
a = b = l0 = 1
DE = 2 * a
g = 9.8
m1 = 50
m2 = 0.5
a = b = l0 = 1
c = 250
t0 = 0
phi0 = 0
psi0 = np.pi / 18
dphi0 = 0
dpsi0 = 0

# Задаю функции phi(t) и psi(t) 

step = 1000

t = np.linspace(0, 10, step)

y0 = np.array([phi0, psi0, dphi0, dpsi0])

Y = odeint(SystDiffEq, y0, t, (m1, m2, a, b, l0, c, g))

phi = Y[:,0]
psi = Y[:,1]
dphi = Y[:,2]
dpsi = Y[:,3]

ddphi = np.zeros_like(t)
for i in np.arange(len(t)):
    ddphi[i] = SystDiffEq(Y[i], t[i], m1, m2, a, b, l0, c, g)[2]


N = m2 * (g * np.cos(psi) 
          + b * dpsi ** 2
          + a * (ddphi * np.cos(psi - phi)
                 + dphi ** 2 * np.sin(psi - phi)))

fgrt = plt.figure()
phiplt = fgrt.add_subplot(3, 1, 1)
plt.title("phi(t)")
phiplt.plot(t, phi, color = 'r')
psiplt = fgrt.add_subplot(3, 1, 2)
plt.title("psi(t)")
psiplt.plot(t, psi)
nplt = fgrt.add_subplot(3, 1, 3)
plt.title("N(t)")
nplt.plot(t, N)
fgrt.show()


fig = plt.figure()
gr = fig.add_subplot(1, 1, 1)
gr.axis('equal')


# Балка DE
Xd = 0
Yd = 0

Xe = Xd + DE * np.cos(phi)
Ye = Yd + DE * np.sin(phi)

balkaDE = gr.plot([Xd, Xe[0]], [Yd, Ye[0]], color='black', linewidth=5)[0]
pD = gr.plot(Xd, Yd, marker='o', color='r')[0]
pE = gr.plot(Xe, Ye, marker='o', color='r')[0]

# Пружина

Xc = DE
Yc = l0

pC = gr.plot(Xc, Yc, marker='o', color='r')[0]

def get_spring(coils, width, start, end):
    start, end = np.array(start).reshape((2,)), np.array(end).reshape((2,))
    len = np.linalg.norm(np.subtract(end, start))
    u_t = np.subtract(end, start) / len
    u_n = np.array([[0, -1], [1, 0]]).dot(u_t)
    spring_coords = np.zeros((2, coils + 2))
    spring_coords[:,0], spring_coords[:,-1] = start, end
    normal_dist = np.sqrt(max(0, width ** 2 - (len ** 2 / coils ** 2))) / 2
    for i in np.arange(1, coils + 1):
        spring_coords[:,-i] = (start 
                               + ((len * (2 * i - 1) * u_t) / (2 * coils)) 
                               + (normal_dist * (-1) ** i * u_n))
    return spring_coords[0,2:], spring_coords[1,2:]



pS = gr.plot(*get_spring(70, 0.1, [Xe[0], Ye[0]], [Xc, Yc]), color='black')[0]

# Стержень AB

Xa = Xd + DE / 2 * np.cos(phi)
Ya = Yd + DE / 2 * np.sin(phi)

Xb = Xa + b * np.cos(psi - np.pi / 2)
Yb = Ya + b * np.sin(psi - np.pi / 2)

sterjenAB = gr.plot([Xa[0], Xb[0]], [Ya[0], Yb[0]], color='black', linewidth=1)[0]
pA = gr.plot(Xa, Ya, marker='o', color='r')[0]
pB = gr.plot(Xb, Yb, marker='o', color='black', markersize = 20)[0]


def run(i):
    balkaDE.set_data([Xd, Xe[i]], [Yd, Ye[i]])
    pE.set_data(Xe[i], Ye[i])
    pS.set_data(*get_spring(70,0.1, [Xe[i], Ye[i]], [Xc, Yc]))
    pA.set_data(Xa[i],Ya[i])
    pB.set_data(Xb[i], Yb[i])
    sterjenAB.set_data([Xa[i], Xb[i]], [Ya[i], Yb[i]])

anim = FuncAnimation(fig, run, frames = step, interval = 1)

plt.show()

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