global_planner
Failed to get a plan from potential when a legal potential was found.
当我尝试运行global_planner时，它不能在所有情况下都起作用，起初它对于A *和use_grid_path都可以正常工作：
use_dijkstra: false
use_grid_path: true它适用于：
use_dijkstra: true
use_grid_path: false当我尝试设置（use_dijkstra：true use_grid_path：true）或（use_dijkstra：false use_grid_path：false）时，出现以下错误：
[ERROR] [1428007403.359484659]: NO PATH!
[ERROR] [1428007403.360301729]: Failed to get a plan from potential when a legal potential was found. This shouldn't happen.
navigation/global_planner/src/gradient_path.cpp
84行 if (fabs(nx - start_x) < .5 && fabs(ny - start_y) < .5)
0.5改为1
cost=CONST_NEUTRAL+COST_FACTOR*const_cost_value.
输入的地图代价地图的cost的值是0~252.当COST_NEUTRAL 是50 这个COST_FACTOR大约在0.8来确认这个输入的值，所以就是50~253.如果 这个COST_FACTOR高的话，那么cost，将会很高，在遇到障碍物的时候，总之就是不好。通过实验观测，我们发现：当cost_factor=0.55 neutral_cost=66. lethal_cost=253,这个时候的全局的路径规划效果是最好的。
相关的网址:
https://answers.ros.org/question/350510/some-errors-when-using-globalplanner/
https://www.cnblogs.com/shhu1993/p/6337004.html
teb_local_planner has problems when reaching the goal and has to correct several times
NO PATH ! error and questions to gradient_path.cpp in global_planner
ROS用A*算法，出现错误 NO PATH! [ERROR] [1554983592.481612548]: Failed to get a plan from potential when a
global_planner Failed to get a plan from potential when a legal potential was found.
查询move_base状态: https://blog.csdn.net/abcwoabcwo/article/details/103536376