[MOC] John Deere SESAM 2 tractor

[MP LEGO Technic creations]

It might seem that the field of agriculture is not much affected by the boom of modern technologies, but it is precisely in agriculture that a rapid development of automation and robotization is expected not only in the processing of crops, but also in their cultivation.

For this reason I have decided to build something different this time - namely an official autonomous concept of a John Deere tractor called SESAM 2.

This one differs from other visions in particular by the possibility of attaching the driver's cabin and the ability to work both in a purely autonomous mode or be remotely/directly controlled from its cabin.

In the field, the cab can be detached at the headland, allowing the operator to monitor and possibly control the tractor. The efficiency is further increased by the ability to work in a swarm, so it is possible to monitor or control several machines working in the same field from one cabin.

 

Since the real tractor has a power of 500kW, I decided not to use just one motor to drive it, but two. In terms of shape, the so-called large angular motor is suitable for the model of this particular tractor, because it enables better use of space - i.e. the possibility of placing it vertically on both sides of the chassis between the axles, thereby freeing up space in the center of the model, which can subsequently be used for other functions.

A central differential is usually used to compensate for the difference in wheel speeds of the front and rear axles due to their different diameters, however the disadvantage of this variant is that if one of the wheels of the front axle is not in contact with the ground, all the power of the drive system will go to this wheel and the model will stop. By inserting suitable gears, the speed difference will be equalized, so it is possible to replace the central differential with a fixed connection of the drive shafts of both axles.

Thanks to the drive motors located on the sides of the central frame, it is possible to add a mechanical locking rear differential working on the basis of a centrifugal regulator in conjunction with another differential used to compare the revolutions of individual wheels (note: each of the output shafts of the drive differential is connected to the output shafts of the "control differential", but one of them utilizes higher number of gear wheels, so when both shafts of the drive differential are at the same speed, the "control differential" does not move) of the rear axle - if the difference in the speed of the two wheels is too high, this differential connected to the centrifugal regulator also turns, with a higher centrifugal force with the arms of this regulator will begin to lift until they are far enough away from each other that the surrounding parts prevent them from further moving away, thereby blocking the entire regulator. This will stop the "control rear differential" from rotating and close the drive differential. CREDIT goes to @JoKo, I just loved his brilliant idea so much that I decided to build a model around it  

My original design of steering included a gear rack, but it turned out to be inaccurate in practice, and the range of the wheels was greatly limited. Therefore, it was necessary to come up with a new concept - control of the steering connecting rod using a small LA.

This solution is features in particular a higher force for controlling the wheels with a reduced engine load, greater steering angle, improved accuracy and protection of the motor in extreme positions thanks to the internal safety element of the used LA. In addition, the entire axle is pendular to achieve better offroad ability.

The only pneumatic circuit uses a classic pump+switch combo:

A Medium angular motor is used for the rear PTO. Since a variety of implements can be attached to the tractor and there is no space left to build in any speed gearbox I have decided to use not one, but two coupled PTO outputs, which differ from each other in their speeds.

The front hydraulics is driven by another Medium angular motor, and sufficient load capacity is ensured by a worm gear.

Similar to the front three-point hitch, the rear hydraulics use a worm gear, with the Angular motor replaced by a more powerful Control+ L motor, as heavier equipment is attached to the rear.

When talking about lighting - John Deere is based in the US, where red turn signals are common, so it is possible to use the same LEDs for both tail lights and turn signals. Blinking is solved by software changing the intensity, where the direction lights flash in short time intervals with 100% intensity, while the rear lights only shine at half power. A small addition are two glow-in-the-dark stripes on both sides of the machine, which do not require any electric connection.

All "autonomous" features are in fact a mere Mindstorms distance sensor.

Schematic layout of mechanical functions:

Schematic layout of the mechanical functions, including the respective motors (both HUBs are located above the front axle, due to which it is heavily loaded and, together with the powerful drive system, ensure exceptional traction capabilities):

Complete tractor chassis:

At first glance, it might seem that the shape of the selected tractor is simpler than that of classic tractors, but upon closer observation it becomes clear that even apparently flat surfaces are curved, slanted or otherwise modified.

 

 

Designing the model is also greatly hampered by the lack of visual material. All searchable photos are just a snapshot of a certain part of a not-so-long video. This video, along with the minimal amount of information published, is the only source from which the LEGO model was designed. The chassis of the production 6R series tractor gave a slight idea of the dimensions, but the body design was purely based on my own experience.

Since the cabin will often stand on the ground, I came up with the idea of equipping it with rubber pads, which not only dampen the impact when it is placed, but also provide it with better stability even on uneven surfaces due to higher friction.

The interior is equipped with small details, such as an adjustable steering wheel collumn and armrest or a lockable storage space under the folding passenger seat.

Various devices can of course be attached to this tractor - here is, for example, Rolland Rollspeed 7136 trailer:

To the controlling app - on a mobile device (tablet) the Mindstorms application will be directly connected to one of two HUBs in the model, which will directly control the motors connected to this HUB, while on the other HUB a stored program will be run waiting for the start signals that will be forwarded to it from tablet through the first HUB and their mutual (HUB-to-HUB) communication. And for more convenient control, I also used the Sony Dualshock 4 game controller.

Program streamed to HUB 1:

1) Control of rear and direction lights

2) Front axle steering

3) Sending a signal for HUB 2 - turning on the front lights with the brightness value "light brightness" (14)

4) Setting the value of the "sensor" variable needed for its activation/deactivation

5) Forward/backward control along with obstacle detection and emergency stop (15)

6) Sending a signal for HUB 2 – starting the PTO in one way

7) Sending a signal for HUB 2 – starting the PTO in the other way

8) Sending a signal for HUB 2 – starting the pump in one way

9) Sending a signal for HUB 2 – starting the pump in the other way

10) Sending a signal for HUB 2 - lowering the front three-point hitch

11) Sending a signal for HUB 2 – raising the front three-point hitch

12) Sending a signal for HUB 2 - lowering the rear three-point hitch

13) Sending a signal for HUB 2 – raising the rear three-point hitch

14) Setting the value of the "brightness of the lights" variable needed to turn them on/off

15) Setting the value of the "stop" variable for turning on/off the emergency brake

 

Program stored in HUB 2:

1) Signal reception from HUB 1 – turning on/off the front lights

2) Signal reception from HUB 1 – lowering/raising the front three-point hitch

3) Signal reception from HUB 1 – lowering/raising the rear three-point hitch

4) Receiving a signal from HUB 1 – starting the PTO in one or the other direction

5) Receiving a signal from HUB 1 – starting the pump in one direction or the other

 

Some dimensions:

• Length (without cab/with cab): 360mm/445mm
• Width (without cabin/with cabin): 180 mm/225 mm
• Height (without antennas/with antennas): 184 mm/218 mm
• Wheelbase: 160 mm
• Wheel track (front/rear axle): 136 mm/136 mm
• Weight: 2660 g (Without cabin); 3035 g (With cabin)
• Proportional axle load: Front - 55%; rear - 45%
• Load capacity of three-point hitches: Front - 626 g; Rear - 565 g (well, that's definitely interesting )

The model consists of a total of 2950 original parts, while I managed to build in the following features:

• all-wheel drive (2x Large Angular motor)

• automatic rear differential lock

• front axle steering (1x C+ L motor)

• swinging front axle

• front three-point hitch (1x Medium Angular motor)

• rear three-point hitch (1x C+ L motor)

• auxiliary drive of implements (1x Medium Angular motor)

• pneumatic drive of external devices (1x C+ L motor)

• front and rear lighting (4 pairs of LED lights)

• obstacle detection and automatic braking systém (Distance sensor)

• remotely detachable cab with movable interior details

• robust bodywork with easy access to control units

Link to WIP topic:

I hope this post has not somehow exceeded the maximum allowed length or anything like that 

Thanks for visiting & comments are welcome!

[Jundis]

So nice to see this finally finished!

What a machine you built here

[Milan]

Beautiful machine, with a striking color, and a magnificent presentation.
Frontpaged.

[MP LEGO Technic creations]

37 minutes ago, Milan said:

Beautiful machine, with a striking color, and a magnificent presentation.
Frontpaged.

Wow, I really am honored!
Just a stupid question of mine - should't the first two photos be rearranged so a picture of an actual build would be shown on the front page?

Edited March 28 by MP LEGO Technic creations
Oops, maybe I've mislooked

[Maaboo the Witch]

Absolutely breathtaking! The scaling is simply perfect.

[LEGO Train 12 Volts]

So much green so much beauty!
Magnificent project, excellent reproduction!

[gyenesvi]

Wow, this turned out amazing! Great functional internals with incredible electronics amount and density, covered in a beautifully shaped body, you really went all in with the green, I like it a lot! In the beginning I wouldn't have believed that you can hide two such big hubs and all the motors so nicely. Great work!

[Paul B Technic]

Amazing and so well presented.

[allanp]

Very cool machine and very well presented. Nice work, thank you for sharing . Would be cool to see a sort of pull test, like how much weight can this beastie move? I bet that on a smooth hard floor, towing a skate board or something, it could haul a fair bit of weight!

[Divitis]

Impressive work, you've captured the look of the original perfectly. My favorite detail is the cabin interior, how does a minifig look in there? It seems to be perfectly in scale.

 

Do you maybe have a video of the auto-locking differential in action? I would love to see it

[JoKo]

Beautiful!

So nice to see my system in such a perfect MOC. 

1 hour ago, Divitis said:

Do you maybe have a video of the auto-locking differential in action? I would love to see it

You can see the same system in action  in this video: 

https://youtu.be/rR2us0vD4M8

 

[Divitis]

2 hours ago, JoKo said:

Beautiful!

So nice to see my system in such a perfect MOC. 

You can see the same system in action  in this video: 

https://youtu.be/rR2us0vD4M8

 

Thanks for sharing, and please make that video public and properly tagged, it deserves more that 74 views!!

I though that as soon as it engaged and the speed of the wheels evened out, the mechanism would disengage and so kept working in some sorf of on-and-off fashion.

But it is seems very reliable, congratulations!

Is it your original idea or some real life mechanism emply something similar?

Apologies if going o/t

 

[Gargoles]

We want video!!

[Maaboo the Witch]

18 minutes ago, Gargoles said:

We want video!!

I'm sure the OP will post one if you ask nicely!!!

[JoKo]

4 hours ago, Divitis said:

Thanks for sharing, and please make that video public and properly tagged, it deserves more that 74 views!!

I though that as soon as it engaged and the speed of the wheels evened out, the mechanism would disengage and so kept working in some sorf of on-and-off fashion.

But it is seems very reliable, congratulations!

Is it your original idea or some real life mechanism emply something similar?

This video was just to illustrate the mechanism in topics about my trial truck MOCs. (https://youtu.be/BRvybPfbMoo and https://youtu.be/sowGB9vvKBg) 

It is my original idea. I was inspired while playing with differentials, combining two of them like this "subtract" the two wheels speed. The James Watt centrifugal controller was the second inspiration. Very simplified and crude but the idea of "something happens when it turns too quickly" is still there. It is indeed reliable on flat ground at least but will lock when tilted, which I consider more useful than a problem in use. I don't think this can be useful in real life, sounds like a transmission crusher to me. Maybe with a centrifugal clutch instead of violently locking the main differential...

Back to the topic. I also hope that @MP LEGO Technic creations will show us his tractor at work!

 

[technicbuilder]

Great idea , and verry well build with Lego Bricks .

And some nice Technical funktions .

[Lego Tom]

This is a great build but I have to say, the real item takes the soul out of tractors.

[HorcikDesigns]

What a machine!

Would like to see this one in person someday on an exhibition. 

[Maaboo the Witch]

38 minutes ago, Lego Tom said:

This is a great build but I have to say, the real item takes the soul out of tractors.

Even autonomous machines need human overseers.

[Lego Tom]

10 minutes ago, Maaboo the Witch said:

Even autonomous machines need human overseers.

Yeah but they wear old jeans and DB Cooper T-shirts instead of overalls and baseball caps.

[everybrickasculpture]

Probably the coolest lego tractor in the world, well done!

[Axadder]

Superb model!

[Naijel]

Awesome work!!! Well done!

[tonych]

WOW! Amazing model!