線性跟馳模型車頭間距

線性跟馳模型中車頭間距的變化

import matplotlib.pyplot as plt
import numpy as np


class Linear():
    """
    a(n+1)=C*(v(n)-v(n+1))，a爲T時間後的加速度
    C=λ*T
    λ=1/(e*T)
    假設初始8輛車正常運行

    後車跟隨前車，分別8->7->6->5->4->3->2->1
    """

    def __init__(self, C):
        """初始化參數，捨棄0車，假定v0爲平衡狀態速度，其中1位前車，8爲尾車"""
        self.L = 5
        self.C = C
        self.T = 1
        self.a = [0] * 9
        self.v = [20] * 9
        self.x = [0] * 9
        self.s = [self.v[0] * self.T + self.L] * 8
        self.x[8] = 0
        for i in range(8, 1, -1):
            self.x[i - 1] = self.x[i] + self.L + self.v[0] * self.T
        self.acce = []
        self.acce.append(self.a[1:])
        self.speed = []
        self.speed.append(self.v[1:])
        self.disp = []
        self.disp.append(self.x[1:])
        self.gap = []
        self.gap.append(self.s[1:])

    def alter_acce(self):
        if self.a[1] == 0:
            self.a[1] = 6
        # self.a[1] = -self.a[1]

    def get_acce(self):
        for i in range(2, 9):
            self.a[i] = self.C * (self.v[i - 1] - self.v[i])
            self.a[i] = round(self.a[i], 2)

    def get_speed(self):
        for i in range(1, 9):
            self.v[i] = self.v[i] + self.a[i] * self.T
            self.v[i] = round(self.v[i], 2)

    def get_disp(self):
        for i in range(1, 9):
            self.x[i] = self.v[i] * self.T + 0.5 * self.a[i] * self.T * self.T + self.x[i]
            self.x[i] = round(self.x[i], 2)

    def get_gap(self):
        for i in range(1, 8):
            self.s[i] = self.x[i] - self.x[i + 1]
            self.s[i] = round(self.s[i], 2)

    def run(self):
        for i in range(0, 100):
            if i == 0:
                self.alter_acce()
            if i != 0:
                self.a[1] = 0
            self.get_acce()
            self.acce.append(self.a[1:])
            self.get_disp()
            self.disp.append(self.x[1:])
            self.get_speed()
            self.speed.append(self.v[1:])
            self.get_gap()
            self.gap.append(self.s[1:])
            if self.judge_end() <= 7 and self.judge_end() >= 1:
                print("第{}個單位時間的時候第{}輛車和第{}輛車發生了碰撞".format(i + 1, self.judge_end(), self.judge_end() + 1))
                # break
        # self.draw_acce()
        # self.draw_speed()
        # self.draw_disp()
        self.draw_gap()

    def output(self):
        """
        It is for test!
        :return:
        """
        pass

    def judge_end(self):
        for i in range(1, 8):
            if self.x[i] - self.x[i + 1] <= self.L:
                return i
        return 0

    def draw_acce(self):
        new_acce = np.transpose(self.acce)
        plt.title("accelerated speed-time")
        for i in new_acce:
            plt.plot(i)
        plt.ylabel("accelerated velocity m/s^2")
        plt.xlabel("time /T")
        plt.show()

    def draw_speed(self):
        new_speed = np.transpose(self.speed)
        plt.title("speed-time")
        for item in new_speed:
            plt.plot(item)
        plt.ylabel("velocity m/s")
        plt.xlabel("time /T")
        plt.show()

    def draw_disp(self):
        new_disp = np.transpose(self.disp)
        plt.title("displacement-time C={}".format(self.C))
        for item in new_disp:
            plt.plot(item)
        plt.ylabel("displacement m")
        plt.xlabel("time /T")
        plt.show()

    def draw_gap(self):
        plt.title("gap-time C={}".format(self.C))
        plt.axis([0,100,5,80])
        new_gap = np.transpose(self.gap)
        for item in new_gap:
            plt.plot(item)
        plt.ylabel("gap m")
        plt.xlabel("time /T")
        plt.show()


# C = input("請輸入C的值：")
for i in range(1,30,3):
    linear = Linear(i/10)
    linear.run()
    print("此時C的值是{}，T的值是{}s".format(linear.C, linear.T))