For those not afraid to mix LEGO with RC components, you might like this one: iWD4. 

A 100% LEGO chassis and body, driven by 4 brushless drone motors placed inside the wheel hub. In-wheel drive or independent wheel drive.  The result is spectacular. Great speed, great control, and hardly any wear-out, since there aren't many moving parts.

The rims are LEGO compatible and 3D printed, the electronics are drone based, steering is done by a LEGO compatible Geek servo. Rest is all LEGO, including suspension and removable body. 

Please have a look at this short intro video. Happy to share more details.

Edited January 12, 20232 yr by janssnet

28 minutes ago, janssnet said:

NB Can't seem to upload any images. Reached my 100kb ?!?! attachment limit    Is there a way to work around this? 

Upload it to something like bricksafe and then post a link here. It will automatically embed the image.

Amazing! The power and speed are terrifying. Overall shape reminds me of the game "rollcage"; with slightly flatter chassis it could drive upside down. 

This is pretty cool and interesting. I like the overall shape and the suspension is also nice. Is the suspension geometry asymmetric? Meaning upper arms longer than lower ones. If yes, what is the benefit of that? Is it stability in cornering?

Can you show more pictures of how the wheels are mounted to the lego wheel hub? The motors seem to be pretty slim to fit into the rim while even the mounting lego parts seem to be inside the rim already.

I have come across your Brushless buggy just a few days ago and was also fascinated by it. I immediately recognised the build style on this one being the same as that one :) I like the simple but organic shapes and the color scheme!

On 1/10/2023 at 10:47 AM, gyenesvi said:

Is the suspension geometry asymmetric? 

Can you show more pictures of how the wheels are mounted to the lego wheel hub?

Suspension is symmetric. However, the front wheels have positive castor angle of 8 degrees. To improve straight line stability. Is not an easy fix, but makes a huge difference at higher speed.

Please find some extra pictures showing the in-wheel motors. These 5010 motors fit perfectly. Are relatively low cost and available at low KV's, which gives more than enough torque to drive a car.

 

 

Thanks for the images. Looks like a simple and neat assembly. How come that the screws from the inside that go through the 3L alternating lego connector are just exactly 2 studs apart? Is that just luck and it was spaced like that on the motor (suspicious), or is that a hole you drilled yourself just to fit the 2 stud distance?

25 minutes ago, janssnet said:

Suspension is symmetric.

Oh, okay, on the latest renders I see it better, I realized why I thought that the lower arms would be mounted outer than the upper ones, but was mistaken.

Quote

How come that the screws from the inside that go through the 3L alternating lego connector are just exactly 2 studs apart?

Most drone motors (with these dimensions) have 4 M3 mounting holes. 2 with a 19mm distance, 2 with 16mm distance. The latter fits LEGO perfectly  No drilling necessary.

Edited January 11, 20232 yr by janssnet

9 minutes ago, janssnet said:

2 with 16mm distance

Wow, that's a great coincidence :)

the rims are beautiful.

my question (to everyone maybe): how complicated would it be to get torque vectoring (using self programmed ic?) with such a setup?

did i mention that the role cage looks very trustworthy?

14 hours ago, pow said:

how complicated would it be to get torque vectoring (using self programmed ic?) with such a setup?

Funny you should mention this ..... That is exactly how I started. Inspired by these guys https://mammuth.works I thought I could do my own LEGO-version of this.

Please have a look at the first demo set up. 4 Brushless motors, magnetics & hall sensors on every wheel-hub and 2(!) Arduinos. First goals: 1. Sync motors to get perfect straight line stability 2. Implement a software-differential. The result: A horrible driving experience. Feedback loop is too slow to react on bumps in the road and motors (and ESCs) take too long to compensate for sudden moves. 

That is how I ended up doing an 'independent 2 wheel drive' car with a simple Arduino based sw-differential and a gyro. Have a look at the video here. 

The gyro is doing a far better job than trying to sync 4 motors. A sudden change in yaw, is immediately compensated by steering in the oppositie direction. The sw-diff is a simple mixer, reading the steering PWM and include this into the throttle PWM. Gives (adjustable) understeer or oversteer. Works nicely.

The most important finding however, when using in-wheel brushless motors,  there is no need for differentials! The motors easily adapt in the turns, offering great torque while cornering and the gyro keeps things perfectly straight (when the right ESCs are used). As Mammoth says, this could well be the next gen in RC racing.

Nevertheless, doing a small scale torque vectoring project, to simulate the real world is still an interesting challenge. Have a look here https://hackaday.com/2014/07/12/independent-wheel-drive-rc-car/  Great project but haven't seen the car driving straight at full throttle. Let me hear your thoughts on this ....

That is so damn overengineered. I love it!

You put so much knowledge into your rc stuff. i am totally baffled with what you came up. My brain is still trying to cope with all that information. I am watching yt videos on this topic in literally every minute i can free up to really understand what you are doing. ...and why.

why not completely switching over to a Raspi (pico?) using after market gyro (they cost nearly nothing) and some voltage regulators to drive the motors? It involves some coding of course. On the other hand it could be a very light weight and heavily configurable way to drive the car.

Just finalised a video presenting the iWD4 project. What a ride it has been! 

Let me hear your views, will this become a new class of RC Car racing?

 

I really love it! I have already made a comment on your YT channel, but I wanted to appreciate your great input. Maybe in the future, when I will understand all the required components I will try something like this myself, haha!

Thanks for sharing all that knowledge. i like it!

what does low cost mean?

Hey! That's super inspiring, it's on a whole different level and far beyond. Everything is ingenious, and it seems like there are only advantages?

It's a shame that it's so complex to implement. Even though I've pretty much mastered the brushless solution, this is surpassing me again