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OSGAR

Open Source Garden Autonomous Robot

OSGAR is a long term project which will probably incorporate more than one robotic platform in the future. The project started in 2014 when we decided to modify school garden tractor John Deere X300R into autonomous robot. The project is carried on in cooperation with the Czech University of Life Science Prague. Blog update: 6/12 — Spider3 finally autonomously moved!

John Deere X300R

Team

  • Milan Kroulík — project leader (CZU/TF)
  • Stanislav Petrásek — mechanics (CZU/TF)
  • Tomáš Roubíček — electronics (RobSys)
  • Jakub Lev — software/testing (CZU/TF)
  • Martin Dlouhý — software (robotika.cz)

2014

The idea is relatively old — our garden desires mowing every second week and I would not mind some „helper”. Yes, in meantime autonomous lawn mowers made serious advance, but it is not only our garden and there are much larger grass areas which require regular maintenance (castle gardens for example ).
In 2014 we also started school project, where self-driving tractor should cut grass and regularly monitor trees in a orchard. You could probably use GPS for basic navigation, but there are many obstacles (trees), which have to be avoided. You would need sensors for this task and if you have them then you can use them also for navigation.
This „orchard task” is similar to navigation in the row of maize field in Field Robot Event contest. We already got some experience there (and prices) with our robot Eduro. The very first experiment was to take Eduro, mount it on the top of the tractor and manually drive it through orchard to collect some data .

14th May, 2016 — Contest „Robot, go straight!”

The Czech season of outdoor competitions for autonomous robots begins in May in Písek. It is called Robot, go straight! (in Czech „Robotem rovně”) and autonomous robots should only navigate straight on paved road in central park. The track is 314m long and only small electrical vehicles are allowed.
In 2015 we asked organizers if it would be possible to make an exception so that we could participate with our modified garden tractor John Deere X300R. The permission was granted but we did not use it — the tractor was not ready yet.
In 2016 it looked much more promising because the school tractor was supposed to be at exhibition in Brno, one month before the contest. But there were problems with hydraulics components and this exhibition program had to be canceled.
But we wanted to push the project forward! We joked with Standa and Tomáš, that we can short safety switch under the seat and use it as emergency stop and then just put brick on the gas pedal and version 0 is ready. Well, what I did not know was that this „joke” will turn true and in reality we will need it for homologation and the first run:
The contest is great. It runs all day (there are four runs), so we had enough time to continue to work on the robot. In the second run the robot was already driven by Python code and pedal was controlled via CAN bus. We even collected several points and „good bye” joke was in the 4th run, when the tractor run out of gas [we are so used to regularly check the battery status, but not the gas — new experience].
For more detailed story see Robotem rovně 2016 article.

4th June, 2016 — Contest „RoboOrienteering”

The contest „Robotem rovně” was great, because it got us started. Finally! But how to proceed? We were quite exhausted from the contest so we took a break next Tuesday (our group meets up once a week). And then I realized that contests are the only way how to push out project further, i.e. complete steering mechanism. The only related contest (as far as I know) was RoboOrienteering, but the dead-line was deadly. We had to finish the robot in two weeks (mainly Tomáš and Standa). The deal was set that if I can write navigation software in two weeks they will have the hardware ready. And so we fight again!
The task for RoboOrienteering 2016 was to navigate to differently evaluated orange cones (their positions are known few minutes before the start — the teams receives USB disk with configuration text file), and drop there golf balls. There are two radii: 2.5m for double and 5m for single score.
Version 0 — the simplest thing which can possibly work — was here much harder. If nothing else to score a single point it was necessary to have integrated GPS, functional ball dispenser, and also robot had to be able to avoid collision with obstacle (part of homologation).
My part was relatively easy — if you do not have any feedback data (encoders or position of steering wheel) then your program has to be very simple. My primary goal was to integrate new sensor Velodyne VLP-16, so the first tests were simple collision detection and STOP, something we wanted to have already in Písek.
You can have a look at video from the first outdoor test. It was not perfect. You can see „gaps” which corresponds to dropped UDP packets, and at one point you can see tractor jumping back when obstacle was detected. There was a non-trivial lag between reality and processed data.
Yes, there was a bug in (my) software. After the program start it was waiting for start button. The Velodyne socket was already opened but I started to read it after button was in on position … well, fixed, no so many things damaged, ready for competition.
The tractor first autonomously steered just few hours before the contest (we arrived in Rychnov at 1am and started testing at 5am in the parking lot. So far so good. Unfortunately none of us is expert in hydraulics and we did not know that there is too much pressure in the system. It broke during homologation (it was bit uphill so I had to increase the gas) — but over the day Standa with colleagues somehow magically managed to fix it even without proper tools. [now it is revised and working fine]

Video from RoboOrienteering 2016

For more info see the article from RO16.

23rd November, 2016 — Hydromotor video

Standa sent me link to very nice descriptive video how transmission works in our John Deere tractor:

16th May, 2017 — „Robotem rovně” (again) and the first garden test

Last weekend we participated in contest Robot go straight! in Písek. It was primarily show how far we moved since the last year (brick on pedal to pass homologation). The sensor set was: odometry (encoders on front wheels with position angle of the left wheel), GPS used for reference, laser scanner SICK LMS100 and dual IP camera with wide angle lenses. For the first two runs we basically tuned the steering and collected real data of the environment. In the afternoon we added simple correction from camera data to avoid green areas (yes, this is a bit strange for lawn mower ).
The second day we tested our newly developed „cones algorithm” in the garden. For version 0 it is sufficient to prove that we can repeat given pattern 10 times (or better infinite times, but we do not want to wait so long). You can see it on the video bellow. We tried also to turn the cutting mechanism on, but surprise surprise John Deere turns it off whenever the mower is in backward motion. So we switched to a bit boring oval and did some experiments in higher grass.
Please forgive me the quality of the video — it is taken by digital camera 12 years old (which is still good for pictures but not for videos).

11th October, 2017 — Spider 3Rider (first tests)

There was no update on this blog, but it does not mean that there was no progress in last 6 months. You can check github, that there was some activity over the summer and also traces, but only some of them were uploaded. Nevertheless, what I wanted to write about today (at least a paragraph) was about Spider 3Rider, which is another machine we are preparing for autonomous navigation.
You can have a look at introduction video (in Czech). It is very nice machine where each wheel is steered independently, and it supports car like" and spider"" modes. Spider3 is already 3rd generation of successful radio controlled slope mowers.
The original machine was modified to support also control over CAN bus, and thus allow autonomy mode. While we are still struggling with the full control (note, that Spider3 weights over 1 ton, and you do not want to make stupid mistakes), we are already able to collect data from manual drive.
On the following picture you can see angles of all 4 wheels. Their position was printed only on change, so it is „compact graph”.
You can see that the resolution is 9 bits (0 to 511). In the middle of the graph you can see an experiment when we tried to twice turn the wheels for 360 degrees in spider mode.

18th October, 2017 — Mapping cones (ver0)

Yesterday we collected some data with autonomous John Deere for creation of a map with positions of traffic cones. The traffic cones are used both for definition of the area where the robot should perform mowing and also for robot localization. Currently the laser scanner LMS-100 is still used as primary measurement sensor and camera as backup.
The navigation algorithm for version 0 was quite simple:
  • select cone which is in front of you
  • steer wheels towards the cone
  • while the distance is more than 2 meters go
  • otherwise turn 90 degrees left and repeat
Sure enough we expected that this version will not be perfect, but the basic idea worked quite fine. We managed to run only 3 tests before the nightfall: one in front of the CZU machinery hall on the street and two in the test field area parking lot. In the first test there were the cones placed too close to each other and JD did not manage to turn and align to the next cone in time. We faked it with „moving cone” to return semi-autonomously back to base.
The other tests on the small parking are were more interesting. In particular the choice in front of you defined as the closest angle to straight line was not very good. A small tree trunk as well as strong steel cable supporting some construction were, from laser point of view, classified also as cones. So the robot moved towards them instead of the original cone. Next version will have to take into account also distance to the detected "cones" and ideally verify them with camera.
The traces as well as the code are publicly available:
You can replay logs with viewer with command line
python.exe navpat.py replay –view osgar_171017_155343.zip

8th November, 2017 — Robotour Marathon (attempt 0)

You probably noticed that there is a new contest for outdoor autonomous robots: Robotour Marathon 2017/18. In order to participate, your robot has to be able to autonomously navigate on paved road mapped in OpenStreetMap. Jakub and Standa recorded last week following video:
Note, that the video was cut, due to human intervention (you can download the whole log file here). For navigation was used demo_wall.py from the last year.
In general, autonomous navigation from point A to point B is useful also for small garden robots, so hopefully you will see some updates there next year …

6th November, 2017 — Spider3 finally autonomously moved!

Yesterday was the D-day for our Spider3 Rider, which finally (after 2 months?) autonomously moved. It was a small step for a robot but a leap for robotkind!
Yes, sure enough it was hacked to get it moving, so what you can see in the following video from Martin S. (our new team member) is: for 5s set value to 50, for 2s stop (set value to 0), for 5s set value to 0x100 - 30, for 2s stop (set value to 0). There was manual emergency STOP (remote) at the end … you may notice that the robot was still moving although the value was set to 0 (TODO configure properly the center position).
Now should come the fun with omnidirectional motion, test of Spider vs. Car mode, integration of encoders etc. There is new GPS RTK sensor and SICK TiM 571 (yes, we already recived Christmas presents ) to be integrated. Also Velodyne should be hopefully soon recalibrated in the factory (I wonder how many Puck 16 in the world have this problem):

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