mirror of
https://github.com/AtsushiSakai/PythonRobotics.git
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220 lines
6.2 KiB
Python
220 lines
6.2 KiB
Python
"""
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Path planning Sample Code with Randomized Rapidly-Exploring Random Trees (RRT)
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author: AtsushiSakai(@Atsushi_twi)
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"""
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import math
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import random
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import matplotlib.pyplot as plt
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show_animation = True
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class RRT:
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"""
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Class for RRT planning
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"""
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class Node:
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"""
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RRT Node
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"""
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def __init__(self, x, y):
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self.x = x
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self.y = y
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self.path_x = []
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self.path_y = []
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self.parent = None
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def __init__(self, start, goal, obstacle_list, rand_area,
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expand_dis=3.0, path_resolution=1.0, goal_sample_rate=5, max_iter=500):
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"""
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Setting Parameter
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start:Start Position [x,y]
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goal:Goal Position [x,y]
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obstacleList:obstacle Positions [[x,y,size],...]
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randArea:Random Sampling Area [min,max]
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"""
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self.start = self.Node(start[0], start[1])
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self.end = self.Node(goal[0], goal[1])
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self.min_rand = rand_area[0]
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self.max_rand = rand_area[1]
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self.expand_dis = expand_dis
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self.path_resolution = path_resolution
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self.goal_sample_rate = goal_sample_rate
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self.max_iter = max_iter
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self.obstacle_list = obstacle_list
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self.node_list = []
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def planning(self, animation=True):
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"""
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rrt path planning
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animation: flag for animation on or off
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"""
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self.node_list = [self.start]
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for i in range(self.max_iter):
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rnd_node = self.get_random_node()
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nearest_ind = self.get_nearest_node_index(self.node_list, rnd_node)
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nearest_node = self.node_list[nearest_ind]
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new_node = self.steer(nearest_node, rnd_node, self.expand_dis)
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if self.check_collision(new_node, self.obstacle_list):
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self.node_list.append(new_node)
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if animation and i % 5 == 0:
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self.draw_graph(rnd_node)
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if self.calc_dist_to_goal(new_node.x, new_node.y) <= self.expand_dis:
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print("Goal!!")
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return self.generate_final_course(len(self.node_list) - 1)
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if animation and i % 5:
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self.draw_graph(rnd_node)
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return None # cannot find path
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def steer(self, from_node, to_node, extend_length=float("inf")):
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new_node = self.Node(from_node.x, from_node.y)
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d, theta = self.calc_distance_and_angle(new_node, to_node)
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new_node.path_x = [new_node.x]
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new_node.path_y = [new_node.y]
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if extend_length > d:
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extend_length = d
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n_expand = math.floor(extend_length / self.path_resolution)
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for _ in range(n_expand):
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new_node.x += self.path_resolution * math.cos(theta)
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new_node.y += self.path_resolution * math.sin(theta)
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new_node.path_x.append(new_node.x)
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new_node.path_y.append(new_node.y)
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d, _ = self.calc_distance_and_angle(new_node, to_node)
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if d <= self.path_resolution:
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new_node.x = to_node.x
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new_node.y = to_node.y
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new_node.path_x[-1] = to_node.x
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new_node.path_y[-1] = to_node.y
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new_node.parent = from_node
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return new_node
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def generate_final_course(self, goal_ind):
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path = [[self.end.x, self.end.y]]
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node = self.node_list[goal_ind]
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while node.parent is not None:
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path.append([node.x, node.y])
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node = node.parent
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path.append([node.x, node.y])
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return path
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def calc_dist_to_goal(self, x, y):
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dx = x - self.end.x
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dy = y - self.end.y
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return math.sqrt(dx ** 2 + dy ** 2)
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def get_random_node(self):
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if random.randint(0, 100) > self.goal_sample_rate:
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rnd = self.Node(random.uniform(self.min_rand, self.max_rand),
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random.uniform(self.min_rand, self.max_rand))
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else: # goal point sampling
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rnd = self.Node(self.end.x, self.end.y)
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return rnd
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def draw_graph(self, rnd=None):
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plt.clf()
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if rnd is not None:
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plt.plot(rnd.x, rnd.y, "^k")
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for node in self.node_list:
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if node.parent:
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plt.plot(node.path_x, node.path_y, "-g")
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for (ox, oy, size) in self.obstacle_list:
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plt.plot(ox, oy, "ok", ms=30 * size)
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plt.plot(self.start.x, self.start.y, "xr")
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plt.plot(self.end.x, self.end.y, "xr")
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plt.axis([-2, 15, -2, 15])
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plt.grid(True)
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plt.pause(0.01)
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@staticmethod
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def get_nearest_node_index(node_list, rnd_node):
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dlist = [(node.x - rnd_node.x) ** 2 + (node.y - rnd_node.y)
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** 2 for node in node_list]
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minind = dlist.index(min(dlist))
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return minind
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@staticmethod
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def check_collision(node, obstacleList):
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for (ox, oy, size) in obstacleList:
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dx_list = [ox - x for x in node.path_x]
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dy_list = [oy - y for y in node.path_y]
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d_list = [dx * dx + dy * dy for (dx, dy) in zip(dx_list, dy_list)]
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if min(d_list) <= size ** 2:
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return False # collision
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return True # safe
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@staticmethod
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def calc_distance_and_angle(from_node, to_node):
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dx = to_node.x - from_node.x
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dy = to_node.y - from_node.y
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d = math.sqrt(dx ** 2 + dy ** 2)
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theta = math.atan2(dy, dx)
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return d, theta
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def main(gx=5.0, gy=10.0):
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print("start " + __file__)
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# ====Search Path with RRT====
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obstacleList = [
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(5, 5, 1),
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(3, 6, 2),
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(3, 8, 2),
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(3, 10, 2),
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(7, 5, 2),
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(9, 5, 2)
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] # [x,y,size]
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# Set Initial parameters
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rrt = RRT(start=[0, 0],
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goal=[gx, gy],
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rand_area=[-2, 15],
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obstacle_list=obstacleList)
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path = rrt.planning(animation=show_animation)
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if path is None:
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print("Cannot find path")
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else:
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print("found path!!")
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# Draw final path
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if show_animation:
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rrt.draw_graph()
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plt.plot([x for (x, y) in path], [y for (x, y) in path], '-r')
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plt.grid(True)
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plt.pause(0.01) # Need for Mac
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plt.show()
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if __name__ == '__main__':
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main()
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