双愚

要更自由地开发就需要会自己查API文档 http://docs.ros.org/en/latest/api/rostime/html/time_8h_source.html 第153行toSec(）函数 xibeisiber 18:24:49 ``` 1 double secs =ros::Time::now().toSec(); 2 3 ros::Duration d(0.5); 4 secs = d.toSec(); ``` xibeisiber 18:25:16 **加个toSec()试试**

http://blog.sina.com.cn/s/blog_b953bc190102xe3j.html https://blog.csdn.net/bigboygo/article/details/77119334

https://blog.csdn.net/npy_lp/article/details/42080553

在执行系统更新命令时遇到俩错误： ``` E: Malformed entry 1 in list file /etc/apt/sources.list.d/ros-latest.list (Component) E: The list of sources could not be read. ``` 此时执行： `sudo rm /etc/apt/sources.list.d/ros-latest.list` 即可解决。

https://blog.csdn.net/u010733679/article/details/52021647 https://www.arduino.cn/thread-14098-1-1.html https://my.oschina.net/lvzht/blog/645873 https://blog.csdn.net/woshidahuaidan2011/article/details/52033369

修改路径： catkin_wp/build/Makefile 

**"make install -j8 -l8" failed**  解决方法： **删除 rm -rf build devel** 还是报错  **一般这种问题，都是具体问题，具体分析了，我这是少写了一个分号**

source /catkin_wp/devel/setup.zsh

**pip3 install -U rospkg** 失效 https://www.codenong.com/cs105461099/ https://blog.csdn.net/Kingknot/article/details/104271964

sudo apt-get install python3-rospkg // 会卸载melodic？ https://answers.ros.org/question/245967/importerror-no-module-named-rospkg-python3-solved/