move_base.cpp中用到的多线程:

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boost::condition_variable_any  planner_cond_;

boost::thread*  planner_thread_;

boost::recursive_mutex  planner_mutex_;

代价地图里有个锁mutex_t，其实就是boost::recursive_mutex，膨胀层里还用到了读写锁boost::shared_mutex* access_

递归锁

move_base里用的锁主要是boost::recursive_mutex planner_mutex_，而且是和boost::unique_lock, boost::recursive_mutex::scoped_lock 搭配使用。

使用到planner_mutex_的函数有planThread, executeCb, executeCycle(6次), resetState。其他3个函数，每个都只使用了一次planner_mutex_

只有一次是在生成路径后，交互变量。其他全是和planThread有关的，基本是对runPlanner赋值，比如

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boost::unique_lock<boost::recursive_mutex> lock(planner_mutex_);
planner_goal_ = goal;
runPlanner_ = true;
planner_cond_.notify_one();
lock.unlock();

经过我大量修改，move_base在有导航任务时，如果ctrl+C退出，终端必定会出现下面的错误，虽然毫无影响，但是毕竟不优雅

这个错误是在有锁的情况下，仍然加锁。 也就是多调用了lock()函数。

搜索move_base，发现只有7个lock()。逐个查看，由于是退出时的报错，所以不可能是makePlan的那个，很容易发现是planThread函数最后的那个。加上判断即可解决

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if( !lock.owns_lock() )
     lock.lock();

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[ WARN] [1709619594.875225471]: Control loop missed its desired rate of 300.00 Hz... the loop actually took 0.0087 seconds

// joint_state 报错，不是重点
[ WARN] [1709619595.976339929]: Moved backwards in time (probably because ROS clock was reset), re-publishing joint transforms!
[ WARN] [1709619595.982125868]: Detected jump back in time of 1.05772s. Clearing TF buffer.
[ WARN] [1709619595.983936734]: Detected jump back in time of 1.05592s. Clearing TF buffer.
[ERROR] [1709619595.987547945]: Exception in PurePursuitPlanner::transformPose : Lookup would require extrapolation at time 1709619597.011688232, but only time 1709619596.080649853 is in the buffe, when looking up transform from frame [map] to frame [cutter_head]
[ERROR] [1709619595.987830086]: transform GlobalPoseToLocal failed
[ERROR] [1709619595.988800520]: Exception in PurePursuitPlanner::transformPose : Lookup would require extrapolation at time 1709619597.011688232, but only time 1709619596.080649853 is in the buffe, when looking up transform from frame [map] to frame [cutter_head]
[ERROR] [1709619596.028980155]: transform GlobalPoseToLocal failed
[ERROR] [1709619596.032062451]: Connectivity Error looking up robot pose: Could not find a connection between 'map' and 'base_link' because they are not part of the same tree.Tf has two or more unconnected trees.


[ERROR] [1709619596.032538970]: in_pose frame is empty!
[ERROR] [1709619596.032780641]: Exception in PurePursuitPlanner::transform global plan: Unable to transform robot pose into global plan's frame
[ WARN] [1709619596.033289244]: Unable to get starting pose of robot, so unable to create global plan
[ WARN] [1709619596.034867606]: Unable to get starting pose of robot, so unable to create global plan
[ WARN] [1709619596.034939482]: move_base didn't receive global plan, mower's recoverying and will try again ......

[ WARN] [1709619596.036663888]: Clearing costmap to unstuck robot (3.000000m).
[ERROR] [1709619596.036978217]: Cannot clear map because pose cannot be retrieved
[ WARN] [1709619596.040011241]: Unable to get starting pose of robot, so unable to create global plan
[ WARN] [1709619596.040297600]: move_base didn't receive global plan, mower's recoverying and will try again ......

[ WARN] [1709619596.045662906]: Clearing costmap to unstuck robot (0.000000m).
[ERROR] [1709619596.046150987]: Cannot clear map because pose cannot be retrieved
[ WARN] [1709619596.052540739]: Unable to get starting pose of robot, so unable to create global plan
[ WARN] [1709619596.052682668]: move_base didn't receive global plan, mower's recoverying and will try again ......

[ WARN] [1709619596.068955672]: All recovery behaviors have failed, locking the planner and disabling it.

[ WARN] [1709619596.069181666]: Your executeCallback did not set the goal to a terminal status.
This is a bug in your ActionServer implementation. Fix your code!
For now, the ActionServer will set this goal to aborted

这个问题与时间同步和TF有关，在本地打开Rviz和SSH运行远程程序时，有很小概率出现此错误。

先写一个脚本file.sh放在/etc/rc.d/init.d，chmod -f 777 file， 再ln -s file /etc/rc.d/rc0.d/K01file 与 /etc/rc.d/rc6.d/K01file, 同时也要 ln -s file /etc/rc.d/rc3.d/S99file 与 ln -s file /etc/rc.d/rc5.d/S99file

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sudo ln -s shell_name /etc/rc0.d/K07shell_name
sudo ln -s shell_name /etc/rc3.d/S99shell_name
sudo ln -s shell_name /etc/rc5.d/S99shell_name
sudo ln -s shell_name /etc/rc6.d/K07shell_name
sudo touch /var/lock/subsys/shell_name

• /etc/rc0.d 包含关机脚本K*
• /etc/rc6.d 包含重启脚本K*

Linux关机过程:

在系统关机时，shutdown命令会告诉init程序转换到0运行级别，如果是重新启动则转换到第6运行级别。当进入0或者6运行级别后，系统将会依照下面的顺序运行:

1. init关闭所有它能关闭的进程(转换到其他运行级别也一样)

2. rc0.d/rc6.d目录下的第一个命令开始运行，锁定系统文件为关机作准备

3. rc0.d/rc6.d目录下的第二个命令运行，卸载除根文件系统以外的所有文件系统(如挂载的windows分区)

4. rc0.d/rc6.d中的命令将把根文件系统重新挂载为只读属性

5. rc0.d/rc6.d中的命令调用sync程序把缓存中的数据写入文件系统

6. 最后的命令是重新启动或者关闭内核程序

即使是手动断电，也会执行脚本。但是注意：如果是耗时的脚本命令，断电时间太快，来不及执行。但如果是shutdown或reboot命令，是可以执行的

运行时节点出现报错

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user@user:~/nav$ rosrun test test_node
/opt/ros/noetic/bin/rosrun: line 150: /home/isward/isward_ii_ws/devel/lib/test/test_node: Success

roscore报错

安装完ROS后，运行roscore报错

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Traceback (most recent call last): File "/opt/ros/groovy/lib/python2.7/dist-packages/roslaunch/__init__.py", line 230, in main write_pid_file(options.pid_fn, options.core, options.port) File "/opt/ros/groovy/lib/python2.7/dist-packages/roslaunch/__init__.py", line 106, in write_pid_file with open(pid_fn, "w") as f: IOError: [Errno 13] Permission denied: '/home/user/.ros/roscore-11311.pid'

roscore报错 2

在一堆报错的最后是:

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InvalidURL: URL can't contain control characters. '192.168.1.35 ' (found at least ' ')

roscore报错 3

原因是因为ROS1支持的是Python2.7，而我之前将Ubuntu自带的Python升级到了3.8，也就是默认版本改变了，所以导致了相关的错误。 解决方法
改回来之后，有些程序可能还是需要python3.8，这时运行python3.8 file.py，可能会报错no module named rospkg 和 no module named pydot，所以需要pip install rospkg pydot

rosbash出错

source setup.bash出现的错误，发现我用的是zsh，换了之后正常

Network communication failed

执行ROS命令结果报错 Network communication failed

这可能是当前用户没有这个权限，切换到root再试试

rosdep init 报警

这是因为之前运行过了，可以无视这个问题

[rosrun] Couldn’t find executable named ……

rosrun出错

环境变量没设置好，应当是IP和端口组合

编译出错

对用到的某个文件没有给权限，找到执行chmod 755即可

rosnode list无结果

roscore和rosrun可以正常运行，但是rosnode list只有rosout，rostopic list没有任何话题。无法用命令对节点和话题操作，可能是通信问题。原因不明，重启电脑后正常。

编译rviz出错

没有安装yaml-cpp或者版本不对，因为rviz读取PersistentSettings文件时需要这个库，下载0.5.1版本的yaml，把之前安装的yaml删掉，重新编译安装。编译生成的几个文件在/usr/local/lib和/usr/local/include，如果找不全，就先用现在的版本再编译一遍就知道了

Lost sync with device, restarting

启动bringup.launch，偶尔会出现这个错误，这是下位机和ROS通讯失败造成的，报错在rosserial，很少发生

rqt报错

后来明白，原因是发布坐标系的节点在ubuntu 20.04，rqt在ubuntu 18

rqt_tf_tree运行失败

运行rqt_tf_tree，会出现 wait_for_service(/rqt_gui_py_node/tf2_frames), failed to contact ,will keep trying ， rqt_tf_tree一直打不开。

原因是IP变动的问题，重新设置IP地址，最好主机与从机都设置为静态ip。

Rviz启动失败

一次没操作好，导致Rviz报错

这个文件是存在的，和其他电脑上正常的Rviz对应的文件路径相同。一直查不到原因，在网上查来查去，反复查ogre这个库是不是装的出问题了，还以为是OpenGL版本变高了，其实这是显卡决定的。最后终于发现链接的librviz.so不是官方路径的，而是我自己工作空间的。可以先用官方的替换

执行任何ROS命令报一堆错

硬盘空间耗尽

编译报错

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The build space at '/home/user/catkin_ws/build' was previously built by ''. Please remove the build space or pick a different build space.

原因是硬盘空间耗尽

Unable to communicate with master

执行任何ROS命令都会报错 Unable to communicate with master

已经运行了ROS节点，结果发现什么ROS命令都会报这个错，后来终于发现，启动节点的环境变量是一套，后来改了，ROS命令都报这个错误。注意ROS_IP如果使用名称而不是数字，必须是/etc/hosts里定义的。

Rviz一个关于时间戳的报错，不必理会 Detected jump back in time of 0.223145s. Clearing TF buffer.

客户端的报错:

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ERROR: service [/task_dispatcher] responded with an error: b'Error opening file: '

服务端的报错:

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Exception thrown while processing service call: Error opening file

ROS时间信息的来源有两种，系统时间和仿真时间，分别被称为Wall Time和ROS Time，可以通过参数use_sim_time来进行选择，当use_sim_time为true时选择使用仿真时间，反之使用系统时间。

系统时间直接通过访问本地时钟来获得，而仿真时间则需要订阅/clock话题获得，每当接收到该话题的消息，时间才会更新，在没有接收到该话题的第一个消息时，当前时间为0，/clock是通过仿真时间服务器发布的，通常为ros_bag节点或仿真器如gazebo

由于Rviz也订阅了clock话题，所以在Rviz的状态栏里能看到这两个时间。clock由秒和纳秒两部分组成:

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clock: 
  secs: 26
  nsecs:   7000000

现如今sophus需要依赖fmt库，因此优先安装 fmt

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git clone  https://github.com/fmtlib/fmt.git
cd fmt
mkdir build
cd build
cmake ..
make
sudo make install

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find_package(FMT REQUIRED)
target_link_libraries(your_program   fmt::fmt)