implement trajectory generator

Author: AtsushiSakai

PathPlanning/LatticePlanner/model_predictive_trajectory_generator.py

@@ -0,0 +1,96 @@
+"""
+Model trajectory generator
+
+author: Atsushi Sakai
+"""
+
+import numpy as np
+import scipy.interpolate
+import matplotlib.pyplot as plt
+import math
+#  import unicycle_model
+
+L = 1.0
+ds = 0.1
+
+
+class State:
+
+    def __init__(self, x=0.0, y=0.0, yaw=0.0, v=0.0):
+        self.x = x
+        self.y = y
+        self.yaw = yaw
+        self.v = v
+
+
+def generate_trajectory(s, km, kf, k0):
+
+    n = s / ds
+    v = 10.0 / 3.6  # [m/s]
+    time = s / v  # [s]
+    tk = np.array([0.0, time / 2.0, time])
+    kk = np.array([k0, km, kf])
+    t = np.arange(0.0, time, time / n)
+    kp = scipy.interpolate.spline(tk, kk, t, order=2)
+    dt = time / n
+
+    #  plt.plot(t, kp)
+    #  plt.show()
+
+    state = State()
+    x, y = [state.x], [state.y]
+
+    for ikp in kp:
+        state = update(state, v, ikp, dt, L)
+        x.append(state.x)
+        y.append(state.y)
+
+    return x, y
+
+
+def update(state, v, delta, dt, L):
+
+    state.v = v
+    state.x = state.x + state.v * math.cos(state.yaw) * dt
+    state.y = state.y + state.v * math.sin(state.yaw) * dt
+    state.yaw = state.yaw + state.v / L * math.tan(delta) * dt
+    state.yaw = pi_2_pi(state.yaw)
+
+    return state
+
+
+def pi_2_pi(angle):
+    while(angle > math.pi):
+        angle = angle - 2.0 * math.pi
+
+    while(angle < -math.pi):
+        angle = angle + 2.0 * math.pi
+
+    return angle
+
+
+def test_trajectory_generate():
+    s = 5.0  # [m]
+    k0 = 0.0
+    km = math.radians(30.0)
+    kf = math.radians(-30.0)
+
+    #  plt.plot(xk, yk, "xr")
+    #  plt.plot(t, kp)
+    #  plt.show()
+
+    x, y = generate_trajectory(s, km, kf, k0)
+
+    plt.plot(x, y, "-r")
+    plt.axis("equal")
+    plt.grid(True)
+    plt.show()
+
+
+def main():
+    print(__file__ + " start!!")
+    test_trajectory_generate()
+
+
+if __name__ == '__main__':
+    main()