运行roscore后电脑重启_重启roscore-优快云博客

本文链接：https://blog.youkuaiyun.com/Will_Ye/article/details/120870414

Problem&Analysis:

机器人的工控机在安装了一些python package后, 发现一运行roscore 电脑就重启. 奇怪得很. 也不弹报错,直接重启. 因为机器人上的工控机很多人在使用, 每个人安装的东西都一样, 需要的环境要求也不一样, 特别是安装python的package,基本都是使用python3, 跟ROS系统所使用的python2.7有冲突, 这也是导致roscore启动失败的原因.

一开始也找不到方向, 各种搜索也找不到对应的解决方法, 后来实在没办法了, 只能重装ROS, 然后就发现问题所在了. 当运行安装ROS最后两句命令:
sudo rosdep init
rosdep update

会报错,如下:

user@user-desktop:~$ sudo rosdep init
Traceback (most recent call last):
  File "/usr/bin/rosdep", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3238, in <module>
    @_call_aside
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3222, in _call_aside
    f(*args, **kwargs)
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3251, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 567, in _build_master
    ws.require(__requires__)
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 884, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/home/user/.local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 770, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'rosdep==0.21.0' distribution was not found and is required by the application

意思就是找不到对应的版本,但是rosdep是已经下载成功了的, 还是说找不到, 问题就出在这里, 我们已经安装的是Python2的rosdep, 但现在系统默认的python版本是python3, 所以我们没有安装python3的rosdep, 当然,有人说到这里可以装python3的rosdep, 但是后果是会把ros很多package删掉, 我没试过,但是根据现在的ROS版本, 目前基于python3的ROS肯定有很多package没有的.
所以改回python2才是正途.

Solution:

我试了直接在.bashrc里设置默认的python版本为2.7,
alias python='/usr/bin/python2.7'
,虽然用python -V显示当前python版本是2.7, 但是在init rosdep的时候还是失败, 说明编译的默认python版本没有换过来

用另一种方法设置默认python版本:

检查当前的python版本:
ls /usr/bin/python*
设置当前的python版本
sudo update-alternatives --config python
会显示如下信息:

user@user-desktop:~$ sudo update-alternatives --config python
There are 3 choices for the alternative python (providing /usr/bin/python).

  Selection    Path                Priority   Status
------------------------------------------------------------
* 0            /usr/bin/python3.6   2         auto mode
  1            /usr/bin/python2.7   1         manual mode
  2            /usr/bin/python3     1         manual mode
  3            /usr/bin/python3.6   2         manual mode

Press <enter> to keep the current choice[*], or type selection number: 1
update-alternatives: using /usr/bin/python2.7 to provide /usr/bin/python (python) in manual mode

可以看到星号所在的是第一个选项,python3.6, 所以只要输入1, 它对应的是python2.7就能解决所有问题了.

若没有选项出现，就需要添加python版本选项，如下：

sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.6 2

输入完,再次检查当前版本
sudo update-alternatives --config python

user@user-desktop:~$ sudo update-alternatives --config python
There are 3 choices for the alternative python (providing /usr/bin/python).

  Selection    Path                Priority   Status
------------------------------------------------------------
  0            /usr/bin/python3.6   2         auto mode
* 1            /usr/bin/python2.7   1         manual mode
  2            /usr/bin/python3     1         manual mode
  3            /usr/bin/python3.6   2         manual mode

Press <enter> to keep the current choice[*], or type selection number:

现在的python版本是2.7, 问题解决!

这时再run sudo rosdep ini
出现如下error, 没问题,只是提示我们已经设置了初始化的文件,这一步只是想测试rosdep init能不能运行.

ERROR: default sources list file already exists:
	/etc/ros/rosdep/sources.list.d/20-default.list
Please delete if you wish to re-initialize

这也是因为我之前已经装好了ROS才会出这个error, 如果第一次安装是不会出现这个的.

运行 rosdep update
到这里就结束了,此时再run roscore就不会电脑重启了

Reference

wiki.ros.org
https://blog.youkuaiyun.com/moX980/article/details/110316752