[MOC] Giant LEGO F1 Car

[TheMindGarage]

Yes, this is a giant F1 car. It's around 1.2 metres long and large enough to sit in. The main features:

• Pedal-driven rear wheels
• 8-speed sequential transmission shifted via paddles on steering wheel
• Rear disk brakes activated by button on steering wheel
• Electronically-controlled limited-slip differential
• Rack and pinion steering connected to steering wheel
• Display showing pedal RPM, gear and wheel speed

The car uses MINDSTORMS EV3 to operate the functions. It uses one standard EV3 set's worth of electronics plus an additional Large motor.

The gearbox is a 4-speed design expanded with a close-ratio 2-speed (ratios 1:1 and 1:1.2) giving 8 speeds in total. A single motor controls it - each gear requires 180 degrees of rotation. Rotating by 90 degrees puts the gearbox in neutral. A Geneva mechanism is used to control the 4-speed - when the 2-speed goes from the high gear to the low gear, the 4-speed is advanced one gear. This is how it shifts from gear 2 to gear 3. In order to reduce the amount of torque handled by the gearbox, it is geared up very highly. This increases friction and reduces efficiency, but there is no shortage of power (I calculated a human’s power output at over 100 EV3 Large motors!). The limiting factor here is how much torque the parts can handle.

The disk brakes use a 49mm tyre as the disk and red rubber pads from the EV3 Expansion set. There are two sets of callipers on each wheel (4 pads per wheel in total) giving huge stopping power. A rather complex linkage allows a single input to control both sets of callipers at the same time. An EV3 Large motor pulls on the beam which activates the brakes via a bell-crank linkage. There are two brake motors so the EV3 can operate them independently - this is important for the next step.

The differential is very ruggedly-built to prevent gear slippage or parts breaking. An extra small differential measures the speed difference between the two outputs - this goes to a Medium motor used as a rotation sensor. This allows the percentage differential slip to be calculated - if it exceeds a certain limit, the faster wheel is braked slightly (via the disk brakes) to give more torque to the slower one. The clutch ring is manually operated by a switch under the steering wheel- when engaged, it locks the output to zero, making the differential operate as a solid axle. This is a very similar system to the one used on the million-dollar McLaren P1 hypercar.

The wheels are made from tank tread links bent backwards into a tight loop. Not sure if this is considered a "legal" solution, but it works very well. The front wheels have 42 links and the rears have 48. The rear wheels have very tight spokes in order to allow them to take the massive weight of the driver. The wheels started gaining camber (tilting) and falling off under load, so I added extra support on the other side of the wheel. The beams are set up to be under tension to push the wheel towards the axle and prevent it from falling off.

The rear section uses many layers of beams and frames to make it strong enough to withstand the weight of the driver. Extra diagonal beams (the white ones) are added - they are positioned in a perfect 3:4:5 Pythagorean triple to avoid having them under compression or tension. I used a Warren truss for the central structure - that bit is virtually indestructible. The front section doesn’t look very strong, but the extra vertical beams allow it to withstand plenty of load. The chassis is very sturdy, but with a driver on board, it tends to bend quite a bit and suffers from some serious body roll issues.

The steering uses a rack-and-pinion system with just over half a turn from lock-to-lock. This is similar to the steering ratio used on F1 cars. Two large custom-built universal joints are used for the steering shaft. The shaft is reinforced to prevent torsion - even a little twisting would result in inaccurate, floppy steering.

The steering wheel is made to look like an F1 wheel. The two rear paddles are for the gears - right for shifting up, left for down. The front left paddle activates neutral gear when held - as soon as it is released, the transmission returns to the last gear selected. The front right paddle activates both brakes simultaneously. Each paddle presses a button on the EV3 infrared remote which is in the middle of the steering wheel. Its signal shines through the turntable and is captured by the IR receiver on the other side. This allows signals from the steering wheel to reach the EV3 brick wirelessly. The paddles have a very short throw and a crisp feel - they’re one of my favourite parts of the car.

The car has a full display with features like an RPM bar and wheel speed shown (since the wheels have very little grip and are liable to doing burnouts, actual speed will be quite different). The gear number is also shown. The RPM is measured by a touch sensor and a cam connected to the pedals. The cam bumps the touch sensor every 1/7th turn of the pedals. I initially tried to use a Colour sensor to detect the black chain links against the greys but the difference in reflected light was insufficient for it to be reliable.

Strength-wise, the chassis can easily deal with 20kg on the seat. Perhaps it would be ideal for a 6-year-old gearhead. Unfortunately, I'm a lot more than 20kg, so I kind of broke it. Here's the aftermath:

Here's a video of me explaining and demonstrating the features of the car. You can also skip to 10:56 to see me try out the car...

[All music is composed by me. My F1 V10 impression is not edited in any way!]

In the end, I think it was a successful experiment. I intended this MOC to be a testbed for various ideas I had, and you might possibly see a scaled-down version of some of the mechanisms (such as the differential) in a normal-sized car of mine in the future. After all, that's why real-life car manufacturers build concepts and sell low-volume cars at a loss. If it wasn't for that, we wouldn't have the Bugatti Veyron, Pagani Zonda R, Lexus LFA and other amazing machines.

Edited August 5, 2017 by TheMindGarage

[Rudivdk]

Only had a quick look, will check all details later when I have some more time.

But the size of this thing... wtf... And I like your guts of actually taking a seat yourself. 

[DugaldIC]

This is quite the ambitious build. It would be cool to see if a child could actually use it, especially to shift through the gears with all that weight. 

[1gor]

Unusual and huge project 

[Aleh]

Such complex! Well done!

[MattL600]

Would love to see more projects like this