OSGAR

Autor: Martin Dlouhý, 2014-07-28

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: 16/5 — Robotem rovně and garden tests

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:

homologation

1st run

4th run: out of gas

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.

Velodyne Puck VLP-16

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]

Ball dispenser

The team

Autonomous collision avoidance

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).