本文主要是介绍ROS开发笔记(7)——利用amcl、move_base 进行导航、基于Python编写巡逻机器人导航代码,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
在前期构建地图的基础上,本文将利用 amcl(自适应蒙特卡洛定位算法)来在地图中定位机器人,然后在此基础上利用move_base 在地图中对机器人导航。主要内容如下:
1、amcl(自适应蒙特卡洛定位算法)节点基本原理
2、move_base 节点基本工作原理
3、在地图中定位机器人
4、在rivz中导航
5、编写代码导航
1、amcl(自适应蒙特卡洛定位算法)节点基本原理
1.1、粒子云与pose估计值
amcl算法是一种粒子滤波算法,其维护一堆的位姿(pose)值用粒子(下图中机器人周围的绿色点状物的便是粒子云)表示,每个粒子具有一个概率值,概率越大代表机器人处于这个pose的可能性越大,按概率加权平均就得到了机器人pose的估计值。
1.2、运动预测更新
随着机器人的移动,各个粒子也跟随着机器人里程计数据一起运动更新。
1.3、量测更新
实际量测值:实际的机器人的传感器数据(如激光扫描scan数据)。
理想量测值:基于地图模型map数据可以算出如果机器人就处于某个粒子pose时,理想的传感器数据应该是什么样的。
如果某个粒子的|理想量测值-实际量测值| 比较小,那么这个粒子关联的概率值就要大,反之小,这样对粒子云的概率值进行更新,随着时间的推进,概率过小的粒子将被剔除,概率大的保留并重采样,这样粒子云的分布就发生了变化,如果定位算法收敛,其分布会逐步集中,中心收敛到真实pose附近。
amcl 节点信息如下:
wsc@wsc-pc:~$ rosnode list
/amcl
/gazebo
/gazebo_gui
/map_server
/move_base
/robot_state_publisher
/rosout
/rviz
/turtlebot3_teleop_keyboard
wsc@wsc-pc:~$ rosnode info amcl
--------------------------------------------------------------------------------
Node [/amcl]
Publications: * /amcl/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /amcl/parameter_updates [dynamic_reconfigure/Config]* /amcl_pose [geometry_msgs/PoseWithCovarianceStamped]* /particlecloud [geometry_msgs/PoseArray]* /rosout [rosgraph_msgs/Log]* /tf [tf2_msgs/TFMessage]Subscriptions: * /clock [rosgraph_msgs/Clock]* /initialpose [geometry_msgs/PoseWithCovarianceStamped]* /scan [sensor_msgs/LaserScan]* /tf [tf2_msgs/TFMessage]* /tf_static [tf2_msgs/TFMessage]Services: * /amcl/get_loggers* /amcl/set_logger_level* /amcl/set_parameters* /global_localization* /request_nomotion_update* /set_mapcontacting node http://wsc-pc:46609/ ...
Pid: 12958
Connections:* topic: /rosout* to: /rosout* direction: outbound* transport: TCPROS* topic: /tf* to: /amcl* direction: outbound* transport: INTRAPROCESS* topic: /tf* to: /move_base* direction: outbound* transport: TCPROS* topic: /tf* to: /rviz* direction: outbound* transport: TCPROS* topic: /particlecloud* to: /rviz* direction: outbound* transport: TCPROS* topic: /clock* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /tf* to: /amcl (http://wsc-pc:46609/)* direction: inbound* transport: INTRAPROCESS* topic: /tf* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /tf* to: /robot_state_publisher (http://wsc-pc:41277/)* direction: inbound* transport: TCPROS* topic: /tf_static* to: /robot_state_publisher (http://wsc-pc:41277/)* direction: inbound* transport: TCPROS* topic: /scan* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /initialpose* to: /rviz (http://wsc-pc:45675/)* direction: inbound* transport: TCPROSwsc@wsc-pc:~$
2、move_base 节点基本工作原理
参考链接:http://wiki.ros.org/move_base?distro=melodic
move_base综合了地图、定位系统、传感器及里程计数据,规划一条从当前位置到目标位置goal的路径。
1、navigation goal
通过 MoveBaseAction , MoveBaseGoal等实现,MoveBaseGoal封装了目标pose数据,客服端程序将MoveBaseGoal类型数据发送给MoveBaseAction服务端启动导航过程。
2、global planner
全局规划器 利用地图与规划算法规划一条从当前位置到目标位置的最优路径。
3、local planner
可以利用传感器数据识别不在地图中障碍物信息,如果本地规划行不通,会请求重新进行全局规划。
move_base与其他组件的相关接口描述如下:
rosnode info move_base
--------------------------------------------------------------------------------
Node [/move_base]
Publications: * /cmd_vel [geometry_msgs/Twist]* /move_base/DWAPlannerROS/cost_cloud [sensor_msgs/PointCloud2]* /move_base/DWAPlannerROS/global_plan [nav_msgs/Path]* /move_base/DWAPlannerROS/local_plan [nav_msgs/Path]* /move_base/DWAPlannerROS/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/DWAPlannerROS/parameter_updates [dynamic_reconfigure/Config]* /move_base/DWAPlannerROS/trajectory_cloud [sensor_msgs/PointCloud2]* /move_base/NavfnROS/plan [nav_msgs/Path]* /move_base/current_goal [geometry_msgs/PoseStamped]* /move_base/feedback [move_base_msgs/MoveBaseActionFeedback]* /move_base/global_costmap/costmap [nav_msgs/OccupancyGrid]* /move_base/global_costmap/costmap_updates [map_msgs/OccupancyGridUpdate]* /move_base/global_costmap/footprint [geometry_msgs/PolygonStamped]* /move_base/global_costmap/inflation_layer/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/global_costmap/inflation_layer/parameter_updates [dynamic_reconfigure/Config]* /move_base/global_costmap/obstacle_layer/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/global_costmap/obstacle_layer/parameter_updates [dynamic_reconfigure/Config]* /move_base/global_costmap/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/global_costmap/parameter_updates [dynamic_reconfigure/Config]* /move_base/global_costmap/static_layer/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/global_costmap/static_layer/parameter_updates [dynamic_reconfigure/Config]* /move_base/goal [move_base_msgs/MoveBaseActionGoal]* /move_base/local_costmap/costmap [nav_msgs/OccupancyGrid]* /move_base/local_costmap/costmap_updates [map_msgs/OccupancyGridUpdate]* /move_base/local_costmap/footprint [geometry_msgs/PolygonStamped]* /move_base/local_costmap/inflation_layer/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/local_costmap/inflation_layer/parameter_updates [dynamic_reconfigure/Config]* /move_base/local_costmap/obstacle_layer/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/local_costmap/obstacle_layer/parameter_updates [dynamic_reconfigure/Config]* /move_base/local_costmap/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/local_costmap/parameter_updates [dynamic_reconfigure/Config]* /move_base/parameter_descriptions [dynamic_reconfigure/ConfigDescription]* /move_base/parameter_updates [dynamic_reconfigure/Config]* /move_base/result [move_base_msgs/MoveBaseActionResult]* /move_base/status [actionlib_msgs/GoalStatusArray]* /rosout [rosgraph_msgs/Log]Subscriptions: * /clock [rosgraph_msgs/Clock]* /map [nav_msgs/OccupancyGrid]* /move_base/cancel [unknown type]* /move_base/global_costmap/footprint [geometry_msgs/PolygonStamped]* /move_base/goal [move_base_msgs/MoveBaseActionGoal]* /move_base/local_costmap/footprint [geometry_msgs/PolygonStamped]* /move_base_simple/goal [geometry_msgs/PoseStamped]* /odom [nav_msgs/Odometry]* /scan [sensor_msgs/LaserScan]* /tf [tf2_msgs/TFMessage]* /tf_static [tf2_msgs/TFMessage]Services: * /move_base/DWAPlannerROS/set_parameters* /move_base/NavfnROS/make_plan* /move_base/clear_costmaps* /move_base/get_loggers* /move_base/global_costmap/inflation_layer/set_parameters* /move_base/global_costmap/obstacle_layer/set_parameters* /move_base/global_costmap/set_parameters* /move_base/global_costmap/static_layer/set_parameters* /move_base/local_costmap/inflation_layer/set_parameters* /move_base/local_costmap/obstacle_layer/set_parameters* /move_base/local_costmap/set_parameters* /move_base/make_plan* /move_base/set_logger_level* /move_base/set_parameterscontacting node http://wsc-pc:41569/ ...
Pid: 12968
Connections:* topic: /rosout* to: /rosout* direction: outbound* transport: TCPROS* topic: /cmd_vel* to: /gazebo* direction: outbound* transport: TCPROS* topic: /move_base/goal* to: /move_base* direction: outbound* transport: INTRAPROCESS* topic: /move_base/NavfnROS/plan* to: /rviz* direction: outbound* transport: TCPROS* topic: /move_base/local_costmap/footprint* to: /rviz* direction: outbound* transport: TCPROS* topic: /move_base/DWAPlannerROS/global_plan* to: /rviz* direction: outbound* transport: TCPROS* topic: /move_base/DWAPlannerROS/local_plan* to: /rviz* direction: outbound* transport: TCPROS* topic: /clock* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /tf* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /tf* to: /robot_state_publisher (http://wsc-pc:41277/)* direction: inbound* transport: TCPROS* topic: /tf* to: /amcl (http://wsc-pc:46609/)* direction: inbound* transport: TCPROS* topic: /tf_static* to: /robot_state_publisher (http://wsc-pc:41277/)* direction: inbound* transport: TCPROS* topic: /move_base_simple/goal* to: /rviz (http://wsc-pc:45675/)* direction: inbound* transport: TCPROS* topic: /map* to: /map_server (http://wsc-pc:33113/)* direction: inbound* transport: TCPROS* topic: /scan* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /odom* to: /gazebo (http://wsc-pc:33887/)* direction: inbound* transport: TCPROS* topic: /move_base/goal* to: /move_base (http://wsc-pc:41569/)* direction: inbound* transport: INTRAPROCESS
3、在地图中定位机器人
这一步需要启动以下文件:
需要启动的文件
roslaunch turtlebot3_gazebo turtlebot3_world.launch
roslaunch turtlebot3_navigation turtlebot3_navigation.launch
roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch
其中 turtlebot3_navigation turtlebot3_navigation.launch 启动文件中启动了map_server 、amcl 、move_base等节点,注意根据自己情况配置好map_file参数(map文件位置),否则会报找不到地图文件。另外,启动move_base节点时一开始报了一个错误“costmap params Invalid argument "/map" passed to canTransform”,根据错误提示,解决方法是,参数配置文件 global_costmap_params.yaml 与 global_costmap_params.yaml 中类似于 “global_frame: /map ” 改为 “global_frame: map ”,两个文件中各需要修改两处地方。
<launch><!-- Arguments --><arg name="model" default="$(env TURTLEBOT3_MODEL)" doc="model type [burger, waffle, waffle_pi]"/><arg name="map_file" default="$(find turtlebot3_navigation)/maps/map.yaml"/><arg name="open_rviz" default="true"/><!-- Turtlebot3 --><include file="$(find turtlebot3_bringup)/launch/turtlebot3_remote.launch"><arg name="model" value="$(arg model)" /></include><!-- Map server --><node pkg="map_server" name="map_server" type="map_server" args="$(arg map_file)"/><!-- AMCL --><include file="$(find turtlebot3_navigation)/launch/amcl.launch"/><!-- move_base --><include file="$(find turtlebot3_navigation)/launch/move_base.launch"><arg name="model" value="$(arg model)" /></include><!-- rviz --><group if="$(arg open_rviz)"> <node pkg="rviz" type="rviz" name="rviz" required="true"args="-d $(find turtlebot3_navigation)/rviz/turtlebot3_navigation.rviz"/></group>
</launch>
为了使算法收敛,初始位置误差不要太大,初始误差大小可以看激光传感器数据与地图障碍物信息的位置误差,启动roslaunch turtlebot3_teleop turtlebot3_teleop_key.launch手动驱动机器人行走,可以使得观察数据多样化加速amcl的收敛。具体操作过程看下面的动图。
4、在rivz中导航
以下是在rivz中导航操作过程的动图:
整个系统节点交连图如下:
5、编写代码导航
通过编程实现两个目标点间来回巡逻的机器人导航代码及注释如下:
#!/usr/bin/env python
#-*- coding:utf-8 -*-import rospy
import actionlib
from move_base_msgs.msg import MoveBaseAction, MoveBaseGoal
import tf# 巡逻点
waypoints=[[(1.6,0.5,0.0),(0.0,0.0,100.0)],[(-1.8,-0.6,0.0),(0.0,0.0,180.0)]
]
def goal_pose(pose):goal_pose=MoveBaseGoal()goal_pose.target_pose.header.frame_id="map"goal_pose.target_pose.pose.position.x=pose[0][0]goal_pose.target_pose.pose.position.y=pose[0][1]goal_pose.target_pose.pose.position.z=pose[0][2]# r, p, y 欧拉角转四元数x,y,z,w=tf.transformations.quaternion_from_euler(pose[1][0],pose[1][1],pose[1][2])goal_pose.target_pose.pose.orientation.x=xgoal_pose.target_pose.pose.orientation.y=ygoal_pose.target_pose.pose.orientation.z=zgoal_pose.target_pose.pose.orientation.w=wreturn goal_poseif __name__ == "__main__": #节点初始化rospy.init_node('patrol')#创建MoveBaseAction clientclient=actionlib.SimpleActionClient('move_base',MoveBaseAction)#等待MoveBaseAction server启动client.wait_for_server()while not rospy.is_shutdown():for pose in waypoints:goal=goal_pose(pose)client.send_goal(goal)client.wait_for_result()
下面是巡逻时的动图:
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