Improvements in the Automotive Industry 1/3: Active Cockpit® — A New Crash Safety Mechanism
Collision safety in the automotive industry has not seen major improvements in over 3 decades. Nevertheless, we should all be thankful for all the minor improvements, such as the new generations of seat-belts, airbags, various electronic crash prevention systems (blind-spot monitoring, lane-keep assist/warning, automatic braking, etc.) and new alloys and composites that allow for a light yet rigid frame construction.
Unfortunately, no amount of tech or material science will ever be able to prevent the inevitable impact of a collision. This is why, humans still need to rely heavily on the mechanical safety features that surround the occupants.
In modern cars 3 things play a role in protecting the driver in case of the collision, all of them — mechanical:
- Crumple zone
- Seatbelt
- Airbag
An average collision could last between 0.05–0.1 seconds, during which a human body has to decelerate (accelerate in opposite direction) from 40–60mph to 0 in a very short distance. That is an acceleration of 20-30Gs, or more (200-300m/s²). If the driver and passengers had more time to slow down, the impact of those forces would decrease. For that, they need more distance. For instance, if the crumple zones were longer, or the car would continue to move after the crash, the energy of the impact would disperse during that time and distance. But you can’t count that, nor that we will have cars with longer crumple zones because even if you increase its length 3x, there will not be a significant decrease in the deceleration. Are there no other options left?
Turns out, There is a Potential Solution!
I have designed and tested an Active Cockpit® system, which consists of a horizontal cylindrical compartment that will house the occupants, their seats, steering wheel (connected electronically*) and all the main controls (pedals, gear shifter, etc.). The compartment will remain fixed in place motionless during normal driving, and will only be released to move when a crash is sensed, much like the airbag sensors in modern cars. In case of the impact, the new cockpit will rotate under it’s own weight and inertia around its horizontal axis, converting the translational kinetic energy into rotational, even after the vehicle has come to a complete stop. This gives us both the distance and time to further break down the energy of the impact.
*Although most cars now have electronically “connected” steering wheels, they still have an emergency mechanical clutch, that will connect the steering column to the actual wheel if the system fails. The same design is possible here as well.
Watch the simulation video below to see it in action in slow-motion:
I’ve also experimented with forward and backward rotations (from driver’s point of view, for us it would be clock- and counter-clockwise). The tests have shown advantages in both directions, but when I locked the cockpit and tested the collision the forces on the driver were much more aggressive, and resulted in breaking of some joints (see below).
And here are some older tests:
Proof of Concept — Examples You Already Know!
This concept is similar to a parkour performer landing and rolling to ease-in to the impact with the ground. A skateboarder does the same thing when dropping down a flight of stairs and continuing to move, thus converting the potential energy into kinetic.
In Our Case
We will now dive into some simple physics — namely kinematics, and try to prove our concept with basic 2D mathematics. I say “simple” and “basic” as we will not use calculus (integration & differentiation) to find our values. I had also written down some equations for rotational inertia and conservation of energies, but I did not include them in this article as they are not needed. I ran my findings by two physics and engineering professionals, and they confirmed the results! You will find their info in the Credits section.
Analogous Concepts
The Math
Now, that we’re on the same page (more or less) let’s jump into some numbers!
Below are some basic calculations to show how much force reduction there is in the new Active Cockpit® design. However to show the comparision, we will start with a conventional car.
Suppose a regular car (without this new mechanism) weighing 1000kg is traveling at a velocity of 20m/s (45mph), hits a concrete wall and stops in 0.1s and compresses by 1m.
We can determine the deceleration and force it took for the car to stop during that time and within that distance.
The Work done by the stopping force from the wall on the car is equal to the change in total energy (kinetic + potential + any heat loss/gain). Since potential energy is 0 at all times, and the work done by the force is equal to the difference between the initial and final kinetic energies (the heat generated on the wall and inside of the crumple zone can be ignored). The final velocity is 0, so the final kinetic energy is also 0, thus the magnitude of work is the same as the kinetic energy of the car, which is 1/2mV². Also, Work is Force times Distance (Displacement), and the distance was 1m, so from the two equations we find the force:
F = Ek/d = (1/2 x 1000kg x (20m/s)²)/1m = 200,000N.
Which, if divided by 10m/s² (G=9.8m/s²) gives us 20,000kg, so the average force acted on the car is equivalent of a weight of 20tonnes (44,000lb)!
We can also calculate the acceleration, and do so in two ways:
1. a = F/m = 200,000N/1000kg = 200m/s²
2. a = (V0-V)/t = (20m/s-0m/s)/0.1s = 200m/s²
However, that is the cumulative force of all masses involved. According the F = ma (mass times acceleration) we know that the total force is acceleration times the sum of all individual masses of the body. Say, the driver weighs 80kg, then the force on his body would be F = m(driver) x a = 80 x 200 = 16,000N. Similarly, the forces acting on a 50kg torso, 5kg head and 25kg legs would be 10,000N, 1,000N and 5,000N respectively. That is the force the seatbelts and the airbag will have on the driver and his body parts. There is also the pressure that could be calculated from the surface area of the seatbelt, elasticity of the airbag and seatbelts, but we will not be going into that level of detail, because it does not matter for our purposes.
What matters, is the comparison of forces exerted on the driver between cars of equal weight and parameters, with the exception of the Active Cockpit design.
Proof
Further calculations below have shown a drastic drop (nearly 2x) in impact forces, and although the occupants will now have to experience centrifugal forces, it is better than oscillating back and forth in place, like in modern cars.
Why did I choose to rotate the driver clockwise? To counter the speed on the head. For a split second, his head will be traveling at 0m/s, because it will be going backward at the same rate as the car is going forward. Also, the only difference in our math the direction of rotation would make, is in the direction of tangential acceleration, which will contribute to the net force in some quarters.
Taking the Fun out of Cars? F#@!$ AGAIN?!
With all kinds of government regulations, emissions control, mpg standards, material shortages, trade wars and HEAVY use of hollow plastic parts, cars have already become ugly, monotonous, and non-exciting.
“This will make it worse!” you might say. Well, as a car designer, an automotive enthusiast and a Top Gear fan (BBC), I am here to tell you “No! It doesn't have to!” (or maybe not by as much :)
Here is a Design I Made Around our New, Rotating Cockpit:
It is a strange breed indeed. Currently it’s categorized as a 2-seater SUV/hot hatch. It is huge (over 5m long, 16ft, the size of an S-Class MB), but with the right proportions, we can make it work. Alternatively, we could cram the driver into a smaller cylinder for a race car feel. This design will be ideal for an electric car on a skateboard platform, like Tesla and the new Porsche Taycan.
BONUS!
Rear LED Panel for Personalized Messages, which you can update daily.
And, everybody’s favorite personalized messages (usually put by some Tesla owners). I do own a Tesla, but I did not go for the plates.
Prior Art
After months of research, I have found no other such applications in automotive, aerospace or any other industries, nor in patent searches (US and international), so I patented it myself. I believe that this has the potential to save more lives or lessen injuries in various types of craft and crashes.
My Preferences in Cars
To me a car has to be fun and look good. The motto of Pininfarina Design is “soprattutto deve essere bello” (above all, it must be beautiful). It also needs to be nimble and agile, and for that it needs to have a low center of gravity. My top 3 favorite cars are:
- Lotus Elise/Exige (2001+)
- Porsche Cayman/Boxster (2014+)
- Chevrolet Corvette (C5-C8)
None of these cars would allow for the fitment of the above system, but there could be ways. For instance, the axis of rotation could be vertical to the floor.
The car above can still maintain a low center of gravity if it had the battery pack and motors inside the floor like earlier mentioned Tesla and Porche.
Future
Spherical compartment would be better in absorbing impacts from all directions, however, most fatalities happen from frontal impacts. A vertical rotational axis was also considered but will require more width to rotate the driver and passenger independently. This would solve the current issue for side impacts (currently not optimized).
Credits
I have run my calculations by Joseph Graves, who holds two B.S. in engineering, a minor in mathematics. I will link his profile here.
I also double-checked this with a Hayk Aramyan PhD — a professor of physics from Yerevan State Engineering University.
Conclusion
This method still needs research and more detailed and accurate calculations.
I am in the process of 3D-printing and testing this concept on a small scale, and then later on a full-size scale with accelerometers and other sensors.
If you think there are some issues with this concept or my calculations, please, feel free to comment, as I am open to a discussion.
In Loving Memory of H. Petrosyan
Professor Petrosyan, from the Politechnical Engineering Institute of Yerevan, Armenia, had inspired me and thousands of his other students for decades to learn about kinematics, electromagnetism, and quantum physics. Some of his students went to work internationally in various engineering labs.
Unfortunately, his life was cut off way too short in the summer of 2009, and he passed away living a young son, a wife and thousands of students behind. Although I am not an engineer, nor a physicist, I credit his enthusiasm and professionalism in helping me not to be afraid of physics, so that I could learn and love it instead! I had the luck of learning from other GREAT professors as well in the US and Armenia, but if it wasn’t for him, I wouldn’t have followed the path that I took and would’ve never designed this system.
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All the material, drawings, renderings and calculations were created and are the registered property of Aren Khachatryan and Aren Designs LLC. Some images were borrowed from the web and include credits. Please be respectful when re-sharing, and thanks for reading!
