[WIP] John Deere SESAM 2 + Rolland Rollspeed 7136

[MP LEGO Technic creations]

I know that I shouldn't start another build before finishing all those previous ones but you know, when you get an idea, you sometimes just can't resist...

Well, this time it's an electric tractor - John Deere SESAM 2 (Sustainable Energy Supply for Agricultural Machinery) because I've realized that it would be useful to have something to pull a trailer full of harvested "beets" from my ROPA harvester.

I've decided to build this specific one because I wanted something that no one has built before (presumably) and I find this concept quite interesting as well.

The problem I've faced from the very beginning is lack of any documentation - I can only build according to the video below (and photos that are mostly from this video).

All I know is that it is based on a 6R tractor and its cabin comes from some kind of a harvester.

The idea si that it can work as an autonomous tractor as well as a classic tractor (well, you can attach a cabin )

I also wanted to try designing a model in digital form before ordering all those expensive green parts 

This is where I got:

• Powered by 2 Mindstorms RI Hubs
• 7 motors (already placed), a distance sensor at the front and 4 pairs of lights (front, rear and indicators)
• 4WD with central differential and automatic rear diff lock (@JoKo will know ) by 2 Large Angular motors
• Steering via 1 C+ L motor
• Rear PTO (1 Medium angular motor)
• Front hydraulics (1 Medium angular motor)
• Rear hydraulic (1 C+ L motor)
• Sariel's pneumatic pump with switch for power output
• Pendular front axle

 

 

 

First prototype of the front grille:

Cabin:

The internals:

 

 

I know, it's already quite crammed inside but as I've already built it IRL, I'm really satisfied with the result! Everything seems to work well, the drivetrain is efficient (thanks to batteries at the front it can easily pull heavy objects)

The only thing that isn't that fantastic is the diff lock (as many of you definitely spotted even in the beginning) - it works well, however it's only useful when one of the rear wheels is lifted off the ground. I can only pray that the front pendular axle will always copy terrain and have enough traction at anytimes 

 

I hope I'll manage to make a few photos of the real thing this week.

 

Thank you for reading & comments with any suggestions are welcome as always!

Edited February 28, 2023 by MP LEGO Technic creations

[Maaboo the Witch]

Nice choice. TLG should dip into the autonomous sector more, especially after 42081.

[msk6003]

Very interesting gearing. What is purpose of subtractor?

[Jundis]

Very cool!

Will follow this with great interest as I am working on a JD 8R tractor right now :-)

I think the diff lock has to be on the center diff or one free spinning front wheel means complete loss of grip...?

[SNIPE]

Looking forward to seeing this . I don't think I've seen a model that used two spike prime/robot inventor hubs before.

 

[gyenesvi]

As for somebody working with autonomous driving technology (for regular cars), autonomous tractors sound like an interesting area that unfortunately I don't know much about, so following the building of one in lego form will be interesting :) It's quite an ambitious project to place all those hubs and motors, but the shape of the tractor seems to be a good fit for it, great choice! I love the idea of the detachable cabin in the real thing, nice solution for transitioning towards autonomous operation while still having a possibility to drive it manually.

Can you tell what tasks such tractors can typically do themselves? Are they following preprogrammed paths or are they mapping the environment themselves and making some decisions? I guess you'll use the distance sensor for obstacle avoidance, right? Do you plan to implement moving along a programmed path?

Regarding the differentials in the drivetrain, I find this a bit overcomplicated. It seems to me that the diff lock is on the rear axle only, which seems a bit pointless given that there's a central diff as well. I'm guessing that even doing away with the central diff and just having open axle diffs would work more reliably. But going one step further, it would be possible to connect the two drive motors to the two rear wheels one by one for example, with a diff being sandwiched in between them as in the Cat dozer, and then using what would normally be the input of the diff to drive the front axle diff as well. That way the rear axle could not slip, but would still have a diff, and the front axle would be open. It would simplify the whole drivetrain and free up space for other stuff, though probably there's not enough space to put the motors directly next to the wheels, but maybe above the diff with some gearing.. Just an idea.

[JoKo]

Very nice project!

Honored to see a diff-lock in it. I would suggest to get the best from only one diff lock to connect it to the most loaded axle. And to get rid of the central diff. Driving one axle with each motor (maybe it's hard without moving one motor). Or even driving both axles coupled with 2 motors. It doesn't induce that much wheel drag and for an off road vehicle it's OK.

If it isn't an option to move the diff-lock action to front axle let's say it's locking the axle the most likely to loose traction!

Looking forward to see more!

 

9 hours ago, msk6003 said:

Very interesting gearing. What is purpose of subtractor?

It's there to spin the yellow centrifugal mechanism which locks the diff when too much speed difference between the wheels

There you'll have more info about it

 

[MP LEGO Technic creations]

9 hours ago, msk6003 said:

Very interesting gearing. What is purpose of subtractor?

It's used to lock the rear diff. For more info you can take a look at this topic from @JoKo:

 

8 hours ago, Jundis said:

Very cool!

Will follow this with great interest as I am working on a JD 8R tractor right now :-)

I think the diff lock has to be on the center diff or one free spinning front wheel means complete loss of grip...?

Thanks! 

I'll love to see your approach to the 8R. I also started this model by looking at JD lineup but as I wanted it to be powered by Powered Up/Spike/Mindstorms, I quickly realized that there simply won't be enough space for all these functions (or even for batteries ) in these.

And yes, you're right - the downside of the current drivetrain means exactly this. I'd place it on the central diff if I found the correct gearing for 81/107 mm tractor tyres. Maybe anyone else could help?

7 hours ago, SNIPE said:

Looking forward to seeing this . I don't think I've seen a model that used two spike prime/robot inventor hubs before.

 

I'm facing an issue with steering - it takes ages before the tractor turns (I wonder why because if Powered Up / C+ is capable of this function, Mindstorms should be able to steer quick as well, shouldn't it?)

6 hours ago, gyenesvi said:

It's quite an ambitious project to place all those hubs and motors, but the shape of the tractor seems to be a good fit for it, great choice!

Yup, there are some other autonomous tractors but none of them has as good shape as this one!

However, although it seems pretty boxy, its bodywork is full of curves/slopes that most likely won't be easy to recreate even from system bricks (still looking forward to this though)

6 hours ago, gyenesvi said:

I love the idea of the detachable cabin in the real thing, nice solution for transitioning towards autonomous operation while still having a possibility to drive it manually.

Indeed. I'm not aware of any other concept with the same approach. And as a bonus - it stops the model from looking as those vacuum cleaners/garden mowers 

6 hours ago, gyenesvi said:

Regarding the differentials in the drivetrain, I find this a bit overcomplicated.

I agree. It's definitely not an ideal solution. First of all I wanted to not to include a central diff at all but tries to find a proper gearing for used combination of tyres failed. (But I suppose someone could have better ideas than me - but then the space is quite limited so I wanted it to be done by 2 pairs of gears which would have 1 stud offset of axis as well)

The next idea was to use one motor per axle with different speeds (as mentioned by @JoKo) but then, wouldn't it loose some of its power on inclines? (Probably doesn't matter as the current version can loose traction as well - I was aware of this problem, which is why the batteries are placed right above the front axle). 

At the end of the day - this function works better than if it fasn't there but I'll see whether it can't be made even better (of course I mean less useless )

 

And I'm glad @JoKo himself, the author of the original idea, likes it!

 

I'm open to any other suggestions or criticism and please let me know if I forgot to answer any questions!

[MP LEGO Technic creations]

And I forgot to add some more info obout the original tractor:

I believe that it isn't able to drive autonomously on roads, though it's capable of automatic field work as well as being remotely controlled

Some of its features

• Battery module with a capacity of 1,000 kWh of energy storage which is housed along the full length of the chassis (approx. weight of 18 tons)
• 500 kW (680 hp) of power is available for the electric powertrain
• Depending on the electric attachments or electric machines, up to a maximum of 1,000 kW is available to drive them
• The tractor was designed as part of Germany’s GridCON 2 project, with the goal of zero emissions from agricultural machinery
• The machine is basically cabless, except when its driven on the road - the cab can be hung in the front linkage and you can move the tractor to the land manually
• The cab makes it possible to drive the tractor both autonomously and manually, with or without a cab
• Communication between the cab and the tractor is wireless
• The cab can be detached in the field to be used as "an office" and to keep an eye on the robot
• In addition, the prototype can work in swarms, which allows it to work together with several robots at the same time, in such a case, it may then be desirable to be able to monitor the work from a central cabin

I haven't decided yet how to replicate its autonomous features - it's definitely going to stop when an obstacle is in front of it. 

Again, if anyone has any ideas, I'll try my best to implement these!

Edited February 28, 2023 by MP LEGO Technic creations

[Jundis]

1 hour ago, MP LEGO Technic creations said:

I'd place it on the central diff if I found the correct gearing for 81/107 mm tractor tyres. Maybe anyone else could help?

Exactly this was my question in the "Generic Building Help Topic" :D

Gearing is as follows:

- Rear wheel (107 mm) is geared down with 12/28 (Diff) and 8/32 (portal wheel hub).

- Front Wheel (81 mm) is geared down with 12/28, 12/20 and 20/28.

Speed difference is about 2..3%, while the rear wheels are a little bit faster. With a motor rpm of 330 (Control+ L-Motor) the speed is about 0.26 m/s.

 

Edited February 28, 2023 by Jundis

[JoKo]

I have never touched Mindstorm and don't know much about autonomous tractors but plowing (or any other action) the entire surface of a field (carpet or garden) seems a good challenge for this kind of machine. Could be something like: forward 1m / 180° left turn / forward 1m / 180° right turn repeat x times

1 hour ago, MP LEGO Technic creations said:

The next idea was to use one motor per axle with different speeds (as mentioned by @JoKo) but then, wouldn't it loose some of its power on inclines?

If you can gear each axle with approximate ratio you will not have to loose much rpm and power from the slowed motor.

[1gor]

17 minutes ago, Jundis said:

Exactly this was my question in the "Generic Building Help Topic" :D

Gearing is as follows:

- Rear wheel (107 mm) is geared down with 12/28 (Diff) and 8/32 (portal wheel hub).

- Front Wheel (81 mm) is geared down with 12/28, 12/20 and 20/28.

Speed difference is about 2..3%, while the rear wheels are a little bit faster. With a motor rpm of 330 (Control+ L-Motor) the speed is about 0.26 m/s.

 

Perhaps my experience could be kind of usefull here; the simplest way is to have central differential between axles and same ratio on front and rear differential; just put portal axle hubs with 12-20 reduction on axle where 107 tires will be...

btw @MP LEGO Technic creations very interesting concept you chose for your project. During Christmas holidays i saw video of this (semi) autonomous future tractor and I wonder who will try to replicate it 

[MP LEGO Technic creations]

32 minutes ago, JoKo said:

If you can gear each axle with approximate ratio you will not have to loose much rpm and power from the slowed motor.

I've just made a quick attempt to fit the drive motors back-to-back and it seems that it's a perfect fit - no more space left for lenght reduction (currently with the old gearing, just the diff removed).

However, there's definitely not enough space for mounting the diff lock the way it was done before.

 

[gyenesvi]

43 minutes ago, MP LEGO Technic creations said:

I've just made a quick attempt to fit the drive motors back-to-back and it seems that it's a perfect fit - no more space left for lenght reduction (currently with the old gearing, just the diff removed).

It looks simple enough :) And now you are just one step away from the almost perfect gear ratio in the same amount of space: instead of 16:16 use 12:20, and then instead 16:20 downgearing use up-gearing by 20:16. The total will be 0.75, whereas 81/107=0,757.

I don't think you really need a diff lock this way. If you do, then you can still build it permanently locked at the rear withou changing anything but the diff. I'd focus on other functions on this one.

As for autonomous features, for one it would be indeed nice to program it to sweep an area by moving in lines and turning around in the end. Add the obstacle avoidance and it's already quite cool :)

By the way, with such a perfect gearing ratio, even hard coupling the motors could work..

[eric trax]

Choosing this tractor is a fantastic idea to hide technical hubs. I didn't know they could be equipped with a cabin. I will be watching the progress!

[MP LEGO Technic creations]

@gyenesvi What do you think about this version with the central diff removed and with the gearing you've mentioned? (I'm still not in that phase to leave the rear diff lock out completely )

This version requires only minor modifications of the concept - replacing the differential with 3 knob gears.

 

Edited March 1, 2023 by MP LEGO Technic creations

[gyenesvi]

1 hour ago, MP LEGO Technic creations said:

@gyenesvi What do you think about this version with the central diff removed and with the gearing you've mentioned? (I'm still not in that phase to leave the rear diff lock out completely )

This version requires only minor modifications of the concept - replacing the differential with 3 knob gears.

This is what I actually thought when I wrote that even hard coupling could work; that you could even go back to the initial version but without the center diff and keep the motor layout and rear diff lock if you wish. I think at this point it's worth building a proof of concept chassis just with the drivetrain in place to see how it works in reality with these wheel sizes and gearing ratios. If there is no noticeable sliding of the wheels, I'd definitely go on with this version because the drive motor placement is quite space efficient here, leaving room in the middle for other stuff (and you can make a decision about the diff lock later, whether there will be space for it or you need the space for something else).

[MP LEGO Technic creations]

12 minutes ago, gyenesvi said:

I think at this point it's worth building a proof of concept chassis just with the drivetrain in place to see how it works in reality with these wheel sizes and gearing ratios.

I've already built the previous version of the tractor (with the central differential) a week ago or so and I'll just swap it for those knob gears when I'll have some time. I'll also make a few tests and photos of the real thing afterwards 

Edited March 1, 2023 by MP LEGO Technic creations

[MP LEGO Technic creations]

I've found some time today and began with rear fenders - I have to say that those look somewhat thick compared to the original, though they are able to hide a pair of working lights.

And here is how it look together with the cabin:

I've also started testing the real build - no serious issues spotted yet.

The performance has improved - now it's able to climb inclines of about 45 degrees (I used plastic board so if surface with bigger roughness was used, it could be even better)

Edited March 16, 2023 by MP LEGO Technic creations

[MP LEGO Technic creations]

Time for another update!

For this tractor I've chosen Rolland Rollspeed 7136 trailer.

I know, dark turquoise is quite similar to regular green so it's rather not in contrast...

The real pain was to find parts that exist in dark turquoise - especially brackets.

It was built first in real life to try all the functions and modeled in Stud.io afterwards.

Contains about 2090 parts; front ladder is still left-to-do.

These are current functions:

• Linked live axles suspension with torsion bars on both axles
• Rear wheels steering connected to the tractor via a rod
• Large LA for bed elevation - connected to tractor's PTO
• Pneumatically opened tailgate - 2 short thick pneumatic cylinders; connected to tractor's pneumatic outputs; opens up to 90 degrees for maximum unloading efficiency
• Manually foldable front support
• Manually opened grain chute at the back (or whatever it's called)

 

 

 

 

And now with the tractor:

 

Hopefully the next update will be in 1-2 days with real-life photos (haven't had enough time to take those yet).

Edited March 13, 2023 by MP LEGO Technic creations

[MP LEGO Technic creations]

Here's how the remotely operated cabin attaching process works:

And a few photos:

 

 

And I'm working on an incline climbing test video as well

Thank you for visiting!

[JoKo]

Nice mechanism to lift the cabin! If I understand well it's automated?  and it looks very clean.

I can't wait to see some hard terrain test to see if the diff-lock makes a difference.

Edited March 16, 2023 by JoKo

[gyenesvi]

4 hours ago, MP LEGO Technic creations said:

Here's how the remotely operated cabin attaching process works:

That's cool!

Are you planning to cover up the body and hide all the electronics? It looks pretty naked this way.

[MP LEGO Technic creations]

@JoKo and @gyenesvi Thank you!

The mechanism is not automated yet - I need to figure that out in the Mindstorms app first 

And yes, I'll definitely build some bodywork to make it look like the original, right after I'll find the right combination of parts. Even though it looks very boxy, the whole tractor is full of angles or curves, which will be difficult to recreate without too many gaps here and there. Moreover, I'm struggling with the lack of documentation (I couldn't find any photos from the side). 

I'll still try my best though 

[Jundis]

Looks very good so far!

I am impressed you already designed a suitable trailer :D

Also I cannot believe the green 20t gear could lift cab on the front hitch. For my 8R, I am currently using 2 small LAs, but the gear would solve this issue way better!