ORAC/ORAC_CubeSat.py at main · Kretski/ORAC · GitHub

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import numpy as np
import matplotlib.pyplot as plt
import random

class ORAC_CubeSat:

    def __init__(self):

        self.threshold = 0.25
        self.W = 1.0
        self.mode = "NORMAL"
        self.fault = "NONE"

    def cusum(self,data):

        mean = np.mean(data)
        return np.mean(np.abs(data - mean))

    def detect(self,a,b):

        scoreA = self.cusum(a)
        scoreB = self.cusum(b)

        if scoreA > self.threshold and scoreB < self.threshold:
            self.fault = "GYRO_A"

        elif scoreB > self.threshold and scoreA < self.threshold:
            self.fault = "GYRO_B"

        else:
            self.fault = "NONE"

    def vitality(self,error):

        self.W = 1/(1+abs(error)*3)

        if self.W < 0.7:
            self.mode = "SAFE"
        else:
            self.mode = "NORMAL"


def simulate_orbit():

    t = np.linspace(0,100,500)

    attitude = np.sin(t/10)

    return t,attitude


def run_simulation():

    t,true_att = simulate_orbit()

    gyroA=[]
    gyroB=[]

    faults=[]
    vitality=[]
    modes=[]

    orac = ORAC_CubeSat()

    drift=False

    for i in range(len(t)):

        val=true_att[i]

        gA=val + random.uniform(-0.02,0.02)
        gB=val + random.uniform(-0.02,0.02)

        if i==200:
            drift=True

        if drift:
            gA += random.uniform(-0.5,0.5)

        gyroA.append(gA)
        gyroB.append(gB)

        if len(gyroA)>20:
            gyroA.pop(0)
            gyroB.pop(0)

        if len(gyroA)>10:

            orac.detect(gyroA,gyroB)

            err=gA-gB

            orac.vitality(err)

        faults.append(orac.fault)
        vitality.append(orac.W)
        modes.append(orac.mode)

    return t,true_att,gyroA,gyroB,vitality,modes


def plot_results():

    t,true_att,gyroA,gyroB,W,modes = run_simulation()

    plt.figure(figsize=(10,6))

    plt.subplot(2,1,1)
    plt.title("CubeSat Attitude Sensors")
    plt.plot(true_att,label="True")
    plt.plot(gyroA,label="Gyro A")
    plt.plot(gyroB,label="Gyro B")
    plt.legend()

    plt.subplot(2,1,2)
    plt.title("ORAC Vitality Index")
    plt.plot(W,label="Vitality W")
    plt.axhline(0.7,color='r',linestyle='--')
    plt.legend()

    plt.tight_layout()

    plt.savefig("orac_cubesat_demo.png")

    plt.show()


if __name__=="__main__":

    plot_results()