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Advice for IMU and GPS powered outdoor path following

asked 2020-02-06 15:47:19 -0500

jdtiger gravatar image

Hello,

I am developing an autonomous lawnmower (its a large zero-turn mower.) I have a basic understanding of ROS and have programmed some smaller projects with it, but I am not sure what packages to turn to for this project. My project is very simple because the target field is empty of obstacles. I simply want to mow the field once with centimeter accurate GPS and and then have the mower repeat the same path without missing any grass. The move_base and navigation stack options I have seen seem overly complicated for my simple problem.

Although this isn't part of the question, just for reference, I control the two steering arms with actuators. I am using ROS1 Kinetic on Ubuntu 16. I have hall-effect sensors in the wheels but have struggled to get accurate data from them.

My best understanding at this point is that I could use robot_localization to publish the GPS coordinates as the actual location of the mower, but what path following node can I use? I don't want to plan any new path or look for obstacles ( I actually have a cheap LiDAR already programmed separately for safety, it checks for people or animals walking in the front of the mower)

My current plan is to write my own controller that follows a reset path, but I am beginning to think that I would be wasting my time because there are probably better solutions that I just don't know about already written.

Any advice is appreciated! Thank you!

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This sounds a lot like #q342389 (but smaller scale, obviously).

The terminology you are looking for (I believe) is "pure pursuit".

There should be a nr of packages that provide those kinds of controllers.

gvdhoorn gravatar image gvdhoorn  ( 2020-02-07 03:28:32 -0500 )edit

Thank you for the tip on "pure pursuit" and the other question, that is what I am looking for

jdtiger gravatar image jdtiger  ( 2020-02-07 07:49:44 -0500 )edit

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answered 2020-02-06 21:30:07 -0500

Ozan Mert Duran gravatar image

If there are features you can map against, I would highly advise to use the lidar to localize the robot. The GPS units in the <$100 range are not centimeter accurate to my knowledge, in my experience, a ublox gps which is what quadcopters use are good to several meters (3m radius or diameter). Once localized, the IMU sensor measurement drift should be insufficient for you to deviate much from a path, along with using the GPS to provide geo-fencing.

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Thank you for your response, I am using two Emlid Reach RS+ units with RTK to get the centimeter accuracy. My lidar has a view of 12 meters, but my target field is 2 acres and the lidar wouldn't see any features most of the time.

jdtiger gravatar image jdtiger  ( 2020-02-07 07:40:26 -0500 )edit

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Asked: 2020-02-06 15:47:19 -0500

Seen: 165 times

Last updated: Feb 06 '20