[TC26] Arctic Monowheel

[Tobi Wankenobi]

Imagine the huge flat arctic snow-fields. Not every way is difficult to manage and needs a tracked vehicle. Some missions just require a transport to go fast.
The Arctic Monowheel is the vehicle of choice, when tracked vehicles are too slow and weather conditions do not allow to fly.

„Riding a Monowheel is a very unique feeling. You get the impression, that you’re half flying, and half sailing. But with an incredibly speed and always in control of the direction.“ Robert, Monowheel Pilot

 

The idea to build a mono wheel, started growing at that moment where my son saw one in a „future-book“ and told me, that this is not possible… :-)

AND YES, it is not actually a monowheel, as there are two wheels. But looking at it from the side it looks pretty much like it. The vehicle faces the same challenges for balancing in driving direction, as a real monowheel, but is of course more stable in the other direction.

 

The challenges for building the final versions are:

- Implement a decent controlling algorithm to keep the mono wheel stable while driving.
- Build it with even weight distribution
- Make it look nice and clean (my biggest challenge :-)

First Prototype. Two XL Motors driving the Monowheel (one for each side).

 

[Seasider]

Glad someone else has gone unusual in terms of method of movement too.

I think the biggest challenge will be keeping your central bit level as it drives as you’re normally reliant of the weight counteracting the drive of the wheel.

Good Luck 

[Tobi Wankenobi]

I had to change the small 12-tooth gears to larger ones, because the motor was not able to provide enough speed to compensate the wobbling movements... (I could have geared-up before, but I want the motor-wheel connection as short as possible and with as little play as possible.)

I also implemented a P-Controller with the PoweredUp App. Works fine, but I can imagine, that even smoother movement can be achieved. Has everyone implemented a PID-controller with PoweredUp App?

[Maaboo the Witch]

I reckon this thing would sink in snow. There's a reason arctic vehicles have wide tracks: weight distribution.

[1gor]

Perhaps adding tracks would make it more usable on snow and ice...

[n8walker]

In my opinion, part of the contest is to search for interesting concepts that might be useful, even if they are unconventional. Otherwise everybody would just create a tracked vehicle which - I agree - is the most useful on snow. But maybe this concept has some benefits as well. For example, it can not tip over. 

[Seasider]

Remember there are ice sheets and not just soft powder snow. And TLG themselves have done walkers and unusual vehicles for their arctic theme

[Maaboo the Witch]

1 hour ago, Seasider said:

Remember there are ice sheets and not just soft powder snow. And TLG themselves have done walkers and unusual vehicles for their arctic theme

This 🐕 has no treads on its wheels, which are entirely smooth, so I'm not sure how well it would perform on ice either. Wouldn't the wheels spin in place and turn the ice to slush?

[Tobi Wankenobi]

Deadline approches, so its time to finish up things... Video will follow soon.

Arctic Monowheel: The fastest Arctic Transport if you cannot fly. :-)

 

 

[Tobi Wankenobi]

Finished building, porgramming, video shooting.

The Arctic Monowheel features remote control with proportional steering and speed control, working stoplights as well as an electronic stabiliy control. The electronic stability control is especially important, as monowheels tend to seesaw as easily can be seen in the video.

The Arctic Monowheel is driven by two XL motors, one for the left wheel, one for the right wheel. Both motors as well as the stoplights are controlled by a PU Technic hub. As monowheels only have one axis, an electronic stability control system was programmed. It basically features a P-controller (Proportional Controller), who is programmed to get the passenger cabin of the monowheel horizontally. Therefore, the motors actively worke agains wiggling of the monowheel. This is possible, because the technic hub has a build-in gyro sensor, which can easily be read out and serves as input for the controller. When accelerating the monowheel, there is no direct speed command sent to the motors, but instead, the P-controller is given a different input value. (e.g. to controll the cabin to -10° tillted position) This then makes to monowheel to move forward. Because of this additional stability control, it was not possible to use a Buwizz, as they dont offer programming capabilities.

To control the Arctic Monowheel, I used my Universal Vehicle Controls, becuase I like to have haptic feedback, and it just feels better.

See how it moves:

 

[Tobi Wankenobi]

A model like the Arctic Monowheel is not only done by assembling bricks and pieces, but also assembling programming-blocks.

I like to share the programming of the Arctic Monowheel (explanation below):

1. Mode selector for "Electronic Stability Control" (Enabled/Disabled). The position of the hub in the controls is read out (The hub is connected to the mode select lever, and tilts, when the lever is moved)

2. Path for Operation of the Monowheel with Electronic Stabilty Control Disabled.

3. Block to enable smooth and proportional steering of the two drive motors with one joystick. Joystick Y-Position is used to make one motor turn slower (or even backwards), in relation to the other. I used this part for a tank before, and I could take it over 1:1.

4. Path for Operation of the Monowheel with Electronic Stabilty Control Enabled.

5. Proportional Controller for the stability of the cabin of the Monowheel. 1.5 is the proportional factor which I determined experimentally. Making it too big, makes the Monowheel become unstable, making it too small will not give enough stabilitzation effect

6. Steering block of this path (basically copy and paste from above)

7. Stoplights activation block. (Whenever the joystick speed controll is reduced for more than 3 units, the stoplight is turned on for a certain time)

 

For completeness, the programming showing the most right blocks:

 

[Divitis]

This is impressive work, and big thanks for sharing the code too!

[2GodBDGlory]

I keep meaning to comment on this, and keep forgetting...

It's pretty cool to see that self-balancing principle working here! I used to have one of those "hoverboards" that worked like that, and always thought it was quite a clever working principle. It's definitely nice to see in Technic, and the programming that went into it is impressive, though not as easy for the casual observer to notice!

Edited January 14 by 2GodBDGlory

[Tobi Wankenobi]

10 hours ago, Divitis said:

This is impressive work, and big thanks for sharing the code too!

Thank you!

1 hour ago, 2GodBDGlory said:

...and the programming that went into it is impressive, though not as easy for the casual observer to notice! 

The key element of the self-balancing is the programming code at 5.) The angle of the hub is multiplied with the Proportional Factor (in this case 1.5). As soon as the hub gets out of the horizontal positon, the difference is multiplied with 1.5 and the value is feeded into the motor drive block as power parameter. The more it gets off, the more power the motor gets to steer against and make it go back to horizontal position. The additional coding is used to allow the steering, as well as to have a seperate path with not electronic stability control.