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https://github.com/AtsushiSakai/PythonRobotics.git
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210 lines
4.6 KiB
Python
210 lines
4.6 KiB
Python
"""
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Frenet optimal trajectory generator
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author: Atsushi Sakai (@Atsushi_twi)
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"""
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import numpy as np
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import matplotlib.pyplot as plt
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import copy
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class quinic_polynomial:
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def __init__(self, xs, vxs, axs, xe, vxe, axe, T):
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# calc coefficient of quinic polynomial
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self.xs = xs
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self.vxs = vxs
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self.axs = axs
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self.xe = xe
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self.vxe = vxe
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self.axe = axe
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self.a0 = xs
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self.a1 = vxs
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self.a2 = axs / 2.0
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A = np.array([[T**3, T**4, T**5],
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[3 * T ** 2, 4 * T ** 3, 5 * T ** 4],
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[6 * T, 12 * T ** 2, 20 * T ** 3]])
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b = np.array([xe - self.a0 - self.a1 * T - self.a2 * T**2,
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vxe - self.a1 - 2 * self.a2 * T,
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axe - 2 * self.a2])
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x = np.linalg.solve(A, b)
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self.a3 = x[0]
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self.a4 = x[1]
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self.a5 = x[2]
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def calc_point(self, t):
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xt = self.a0 + self.a1 * t + self.a2 * t**2 + \
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self.a3 * t**3 + self.a4 * t**4 + self.a5 * t**5
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return xt
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def calc_first_derivative(self, t):
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xt = self.a1 + 2 * self.a2 * t + \
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3 * self.a3 * t**2 + 4 * self.a4 * t**3 + 5 * self.a5 * t**4
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return xt
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def calc_second_derivative(self, t):
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xt = 2 * self.a2 + 6 * self.a3 * t + 12 * self.a4 * t**2 + 20 * self.a5 * t**3
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return xt
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class quartic_polynomial:
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def __init__(self, xs, vxs, axs, vxe, axe, T):
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# calc coefficient of quinic polynomial
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self.xs = xs
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self.vxs = vxs
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self.axs = axs
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self.vxe = vxe
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self.axe = axe
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self.a0 = xs
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self.a1 = vxs
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self.a2 = axs / 2.0
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A = np.array([[3 * T ** 2, 4 * T ** 3],
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[6 * T, 12 * T ** 2]])
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b = np.array([vxe - self.a1 - 2 * self.a2 * T,
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axe - 2 * self.a2])
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x = np.linalg.solve(A, b)
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self.a3 = x[0]
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self.a4 = x[1]
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def calc_point(self, t):
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xt = self.a0 + self.a1 * t + self.a2 * t**2 + \
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self.a3 * t**3 + self.a4 * t**4
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return xt
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def calc_first_derivative(self, t):
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xt = self.a1 + 2 * self.a2 * t + \
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3 * self.a3 * t**2 + 4 * self.a4 * t**3
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return xt
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def calc_second_derivative(self, t):
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xt = 2 * self.a2 + 6 * self.a3 * t + 12 * self.a4 * t**2
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return xt
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class Frenet_path:
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def __init__(self):
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self.t = []
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self.d = []
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self.d_d = []
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self.d_dd = []
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self.s = []
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self.s_d = []
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self.s_dd = []
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self.x = []
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self.y = []
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self.yaw = []
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self.c = []
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max_speed = 50.0 / 3.6
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max_accel = 2.0
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max_curvature = 1.0
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maxd = 5.0
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dd = 1.0
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dt = 1.0
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T = 10.0
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target_speed = 30.0 / 3.6
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dv = 5.0 / 3.6
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nv = 2
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def calc_frenet_paths(c_speed, c_d):
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frenet_paths = []
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for di in np.arange(-maxd, maxd, dd):
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for Ti in np.arange(dt, T, dt):
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fp = Frenet_path()
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lat_qp = quinic_polynomial(c_d, 0.0, 0.0, di, 0.0, 0.0, Ti)
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for t in np.arange(0.0, Ti, 0.1):
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fp.t.append(t)
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fp.d.append(lat_qp.calc_point(t))
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fp.d_d.append(lat_qp.calc_first_derivative(t))
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fp.d_dd.append(lat_qp.calc_second_derivative(t))
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for tv in np.arange(target_speed - dv * nv, target_speed + dv * nv, dv):
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tfp = copy.deepcopy(fp)
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lon_qp = quartic_polynomial(
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0.0, c_speed, 0.0, tv, 0.0, Ti)
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for t in fp.t:
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tfp.s.append(lon_qp.calc_point(t))
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tfp.s_d.append(lon_qp.calc_first_derivative(t))
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tfp.s_dd.append(lon_qp.calc_second_derivative(t))
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frenet_paths.append(tfp)
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return frenet_paths
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def calc_global_paths(fplist):
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for fp in fplist:
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fp.x = fp.s
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fp.y = fp.d
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return fplist
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def check_paths(fplist):
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okind = []
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for i in range(len(fplist)):
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# speed check
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if any([v > max_speed for v in fplist[i].s_d]):
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continue
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elif any([abs(a) > max_accel for a in fplist[i].s_dd]):
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continue
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okind.append(i)
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return [fplist[i] for i in okind]
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def frenet_optimal_planning():
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c_speed = 0.0
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c_d = 1.0
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fplist = calc_frenet_paths(c_speed, c_d)
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fplist = calc_global_paths(fplist)
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fplist = check_paths(fplist)
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for fp in fplist:
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plt.plot(fp.x, fp.y)
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def main():
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print(__file__ + " start!!")
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frenet_optimal_planning()
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plt.axis("equal")
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plt.grid(True)
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plt.show()
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if __name__ == '__main__':
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main()
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