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path follower with multiple waypoints #8
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Hi Mert, How far apart are your waypoints? Is the delay caused by the path planner? Assuming that it is not a planning delay, please try the following:
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Hi Betwo, Thanks for your response. They are a meter away from each others. I am not sure what is causing that.
Thanks |
Hi @betwo I also checked to planning time and it is usually in between 20-100 ms. Do you think that could be the reason for the delay? Is that possible to to not the stop robot while it is planning the path? Thanks |
Hey @mertmzk, sorry for the delay, didn't find time sooner. I suppose the problem is that you are using the action client in a synchronous way:
Then the next way point is sent, which takes around 100ms as you said, before the robot starts moving again. (Bear in mind that the path following controller will slow down the robot shortly before the goal, which further amplifies the experienced delay.) To solve the issue I currently see a few possible solutions, depending on your use case
We used those solutions the past. Here is a demo with asynchronous execution and local planning: https://www.youtube.com/watch?v=4O7twdWFm4s Hope this helps, please do not hesitate to ask further questions! Cheers |
Hi @betwo Thanks for your reply. I have solved it using first solution. But currently I am having different problems. I appreciate if you could help me to solve this. I was testing all in simulation and it was working fine in my laptop. But when I deploy the code in my robot--running on Odroid XU4-- I am facing with long delay from path planner when I use map which was created by gmapping. It is sometime giving an error and not activating path_follower but sometime working with very long delays around 30K-50K ms. If I deactivate map then it works fine but I want to get it working with a map. I have played with couple of parameters on planner (2d planner) but they did not solve the problem. Any suggestion to solve this problem? Thanks |
Strange, I would expect such a behaviour from the kinematic planner in a large map that does not allow for a kinematic path to the goal. Then the search will run into the timeout. But the 2d planner does not respect kinematic constraints, so it much faster and should take nowhere close to 30-50 seconds (even if there exists no feasible path.) Do you use GMapping in simulation as well? And does the map have a similiar size and makeup? You could try to set the debug flag I hope that I can help you more if you describe (or post a few screenshots of) the search frontier over the long time that the search takes. |
Hi @betwo Thanks for your rapid response. Here some more information: Output messages from terminal including 2 errors:
Planner launch file:
Rviz output with render_open_cells: The goals that I am sending from rviz quite close to the robot and on obstacle free path as seen in the figure. Thanks |
The screen shot actually looks alright. Seems like the search has reached the goal. How long did it take until the RViz visualization looked like this? Please try the following parameter settings and check if they have an effect:
Also, please add screen shots of:
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Hi @betwo It was taking 85 seconds until Rviz looked as it was in previous example. I have tried with your suggested parameters, it is much better, between 2-3 seconds, but still not perfect. Whenever it replans the route in long paths it is stopping that 2-3 seconds to replan the route. Here I attached screenshots with 'planner/map' and visual markers. Thanks |
Sorry, again, for the delay. Does the robot stop for planning before it reaches the end of the old path? I simulated that on my machine by enabling When planning is started early enough, no stop command is sent. |
I am closing this issue for now due to the long inactivity. |
Hi
I have been testing your implementation and it works well with a single navigation goal given to navigate_to_goal actionlib. If I call the actionlib for each waypoints that I have in my path it creates delay between the waypoints.
Can we feed all the waypoints into your pathfollower node so that it smoothly (without delay) run through them? If possible that would be nice to have an example of it.
Thanks
Mert
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