ros中自定义全局规划器python

在 ROS 中用 Python 编写自定义全局路径规划器
要在 ROS 中使用 Python 开发一个自定义的全局路径规划器，可以按照以下方法进行设计和实现。以下是详细的说明以及示例代码。
1. 创建 ROS 节点
首先需要创建一个新的 ROS 节点来承载全局路径规划的功能。可以通过 rospy 库完成这一操作[^1]。
import rospy
from nav_msgs.msg import Path, OccupancyGrid
from geometry_msgs.msg import PoseStamped
from std_srvs.srv import Empty

def global_path_planner():
rospy.init_node('global_path_planner', anonymous=True)

# 订阅地图消息
map_subscriber = rospy.Subscriber('/map', OccupancyGrid, map_callback)

# 发布路径消息
path_publisher = rospy.Publisher('/planned_path', Path, queue_size=10)

# 提供服务接口用于触发路径重新规划
recompute_service = rospy.Service('~recompute_path', Empty, handle_recompute_request)

rate = rospy.Rate(10) # 设置循环频率为每秒10次
while not rospy.is_shutdown():
rate.sleep()

if __name__ == '__main__':
try:
global_path_planner()
except rospy.ROSInterruptException:
pass
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2. 实现路径规划逻辑
在上述代码中提到的地图回调函数 (map_callback) 和服务处理函数 (handle_recompute_request) 需要进一步完善以支持实际的路径规划算法[^3]。
地图回调函数
此函数接收来自 /map 主题的消息并存储地图数据以便后续路径规划使用：
current_map = None

def map_callback(data):
global current_map
current_map = data
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处理路径重新计算请求的服务函数
当接收到重新计算路径的请求时，调用具体的路径规划算法生成新的路径，并通过主题发布出去：
def handle_recompute_request(req):
if current_map is None:
rospy.logwarn("Map has not been received yet!")
return []

start_pose = get_start_pose() # 获取起始位置
goal_pose = get_goal_pose() # 获取目标位置

planned_path = compute_global_path(start_pose, goal_pose, current_map)
publish_path(planned_path)
return []
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3. 定义路径规划的具体算法
这里可以选择任何适合的路径规划算法（如 A* 或 Dijkstra），下面是一个基于 A* 的简单实现例子[^5]:
def compute_global_path(start, goal, grid_map):
open_set = set([start])
closed_set = set()
g_score = {start: 0}
f_score = {start: heuristic_cost_estimate(start, goal)}
came_from = {}

while open_set:
current = min(open_set, key=lambda node: f_score[node])

if current == goal:
return reconstruct_path(came_from, current)

open_set.remove(current)
closed_set.add(current)

for neighbor in neighbors(grid_map, current):
if neighbor in closed_set:
continue

tentative_g_score = g_score[current] + dist_between(current, neighbor)

if neighbor not in open_set or tentative_g_score < g_score.get(neighbor, float('inf')):
came_from[neighbor] = current
g_score[neighbor] = tentative_g_score
f_score[neighbor] = g_score[neighbor] + heuristic_cost_estimate(neighbor, goal)

if neighbor not in open_set:
open_set.add(neighbor)

return [] # 如果无法找到路径，则返回空列表表示失败
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辅助函数如下所示：
def heuristic_cost_estimate(a, b):
(xa, ya), (xb, yb) = a, b
return abs(xa - xb) + abs(ya - yb)

def dist_between(a, b):
(xa, ya), (xb, yb) = a, b
return ((xa - xb)**2 + (ya - yb)**2)**0.5

def neighbors(map_data, pos):
directions = [(0, 1), (1, 0), (-1, 0), (0, -1)]
result = []
width = map_data.info.width
height = map_data.info.height
origin_x = map_data.info.origin.position.x
origin_y = map_data.info.origin.position.y
resolution = map_data.info.resolution

x, y = pos
for dx, dy in directions:
nx, ny = x + dx, y + dy
index = int((ny * resolution + origin_y) / resolution * width + (nx * resolution + origin_x) / resolution)

if 0 <= nx < width and 0 <= ny < height and map_data.data[index] != 100:
result.append(((nx, ny)))
return result

def reconstruct_path(came_from, current):
total_path = [current]
while current in came_from.keys():
current = came_from[current]
total_path.insert(0, current)
return total_path
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4. 发布路径消息
最后一步是将计算得到的路径转换成标准的 ROS 消息格式并通过指定的主题发布出来：
def publish_path(path_points):
msg = Path()
msg.header.frame_id = 'map'
msg.header.stamp = rospy.Time.now()

for point in path_points:
pose_msg = PoseStamped()
pose_msg.pose.position.x = point[0] * current_map.info.resolution + current_map.info.origin.position.x
pose_msg.pose.position.y = point[1] * current_map.info.resolution + current_map.info.origin.position.y
pose_msg.pose.orientation.w = 1.0
msg.poses.append(pose_msg)

path_publisher.publish(msg)
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