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No more brakes for cars of the future:
Electric cars of the future could be able to ditch conventional brake technology in favour of powerful regeneration by battery-powered motors.
[...] Electric cars already use a combination of conventional friction braking and brake regeneration. The latter slows down vehicles using resistance from the same electric motor that propels the car, feeding that energy into the car's battery to extend its range.
DS, Citroen's luxury arm, said it is "exploring whether regenerative braking alone could eventually be the sole method to slow cars down, helping to better recharge the battery in the process, and doing away with conventional brake discs and pads".
[...] [Conventional brake pads and drums] produce "brake dust", fine particles of metallic material that separates from the pad and disc as part of the braking process.
[...] Dr Asma Beji, a non-exhaust particles expert, said in June 2021 that "the impact on health of brake wear particles is undeniable and cannot be neglected".
[...] Environmental researcher Dr Liza Selley, published a paper for the MRC Centre for Environment and Health at King's College London and Imperial College London in 2020 that suggested "diesel fumes and brake dust appear to be as bad as each other in terms of toxicity in macrophages".
[...] "Macrophages protect the lung from microbes and infections and regulate inflammation, but we found that when they're exposed to brake dust they can no longer take up bacteria.
"Worryingly, this means that brake dust could be contributing to what I call 'London throat' – the constant froggy feeling and string of coughs and colds that city dwellers endure – and more serious infections like pneumonia or bronchitis which we already know to be influenced by diesel exhaust exposure."
DS and other manufacturers including Jaguar and Porsche participate in Formula E electric car racing. The series will eliminate rear disc brakes from its next-generation machines in a bid to improve real-world research into the performance potential of purely regenerative braking.
(Score: 5, Interesting) by Thexalon on Thursday May 12 2022, @02:35AM (11 children)
Regenerative braking is all well and good, but:
1. Sometimes, it's not enough power. For instance, I'm heading down a road at around 45 mph on a snowy day, come round a corner, and there's a construction zone and completely stopped traffic, and the fact that I was able to basically override any computers that thought they knew better to stop quickly made a world of difference.
2. The more complicated a system is, the more likely it is to fail. Brakes are relatively simple (admittedly, they've gotten a bit more complicated since ABS became standard, but still simpler than an electric engine with computer chips), in part because they still need to work even if, for instance, the engine just got crushed by a large piece of flying debris due to a truck overturning.
There's a reason why even now, in 2022, new cars have at least one braking system that is completely mechanical, namely the parking/emergency brake, and it's specifically so there's a likely-working last-ditch tool for stopping a car when nothing else is working.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 1, Interesting) by Anonymous Coward on Thursday May 12 2022, @02:55AM (3 children)
> ... even now, in 2022, new cars have at least one braking system that is completely mechanical, namely the parking/emergency brake,
Sorry to burst your bubble, but electric parking brakes have been around for awhile now:
https://www.carwow.co.uk/guides/glossary/electronic-parking-brake-explained [carwow.co.uk]
Article describes how they are released...and also offers this tidbit,
There is a long list of cars that have these parking brakes. Note that they are not "emergency brakes", you are not supposed to use them in case of service brake failure!
But, if that's not bad enough (I have no plans to buy any car with electric parking brakes) I've actually seen papers written about replacing the steering with differential braking -- apply a little left brake and turn left. Clearly this requires specific steering geometry. The idea of not having a solid mechanical connection between the steering wheel and the front wheels seems pretty scary to me.
(Score: 2) by MostCynical on Thursday May 12 2022, @03:34AM (2 children)
manufacturers want it - it frees up space, and not having a large metal pole pointing at the driver is a good thing for safety,,
some have been experimenting already
https://www.topspeed.com/cars/car-news/the-bz4x-is-the-first-toyota-to-feature-steer-by-wire-and-a-tesla-like-yoke-ar193445.html [topspeed.com]
all modern jets are controlled 'by wire' - although there are hydraulic backups for some controls.
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 3, Insightful) by janrinok on Thursday May 12 2022, @12:57PM
The only aircraft I have ever seen 'slam on the brakes' during flight was the Harrier/AV8. I'm sure others can do something similar but I have just never seen them do it.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:43PM
Fly by wire uses hydraulic actuators. Manual controls (and backups) are normally cable pull systems.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @04:13AM (3 children)
Could normal case be regenerative, but when extreme stopping is need it uses the motors? A motor can lock it's rotation with energy but you would probably do some anti-lock algorithm anyway. It would just use energy instead of regenerate in extreme stopping conditions.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:46PM (2 children)
Reverse driving the motors would quickly overheat them. The energy must go somewhere, and if you aren't storing it then it must go to heat.
(Score: 2) by RS3 on Thursday May 12 2022, @06:51PM (1 child)
Maybe. Heat is due to inefficiency, including wire resistance. These newer car motors are unbelievably efficient, so very little heat generated. Also, are some liquid cooled?
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @08:32PM
In this case though, if you're not charging the battery, the energy has nowhere to go, so it'll go to heat and sound.
(Score: 3, Informative) by mcgrew on Thursday May 12 2022, @09:14PM (2 children)
For instance, I'm heading down a road at around 45 mph on a snowy day, come round a corner, and there's a construction zone and completely stopped traffic, and the fact that I was able to basically override any computers that thought they knew better to stop quickly made a world of difference.
I was a driver in the Air Force, and they train you for emergency braking. I was incredibly surprised by the last car I had with ABS; it could stop on ice faster than I could. On a slippery surface, it doesn't matter if you have drum brakes on a 14 inch wheel or 4 disks on a 16 inch wheel, they'll both stop in the same distance. When it's slick, the power of the brakes doesn't matter at all, preventing the wheels from locking does.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 1) by pTamok on Friday May 13 2022, @07:28AM (1 child)
One situation where ABS gives a longer stop distance than conventional lock-up-and-pray braking is where you are on loose, friable surfaces, such as snow, or pea-gravel. This is because, if the wheels are locked up, the snow (or gravel) piles up in front of the wheels, whereas ABS aims to keep the wheels turning at a rate just before locking up to provide maximum retardation.
Drivers used to be taught to 'pump' the brakes when needing to stop in a hurry, so that if you locked up and started sliding, reducing the brake pressure would allow the wheels to start rotating again, providing control (sliding locked-up wheels have no steering, they simply slide in the direction the car is going and provide no sideways force to turn), and allowing for more retardation (on average) than locked up wheels. It's a hard technique to learn and apply in 'panic' situations. ABS simply automates brake pumping, does it faster than humans can, and monitors the wheel rotation rate to ensure it doesn't drop to zero. If you see the black stripes on a road surface where someone has braked hard, you can see a locked up brake as a continuous black stripe, whereas ABS either leaves no stripe, or a non-contiguous strip - a dashed black line. ABS has far better performance than humans on ice as it actively monitors each wheel's rotation to ensure it doesn't lock up.
(Score: 2) by mcgrew on Friday May 20 2022, @12:49AM
The ABS' main advantage isn't stopping more quickly, although that is an advantage. Without ABS, if your brakes are locked up you can't steer no matter the surface. ABS allows you to steer out of the circumstances that require ABS.
mcgrewbooks.com mcgrew.info nooze.org