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: -1, Troll) by Anonymous Coward on Thursday May 12 2022, @12:14AM
when you slam on the brakes.
FUN!
(Score: 3, Insightful) by Snotnose on Thursday May 12 2022, @12:16AM (16 children)
When the asshole in front of the asshole in front of me is guaranteed to not do something stupid, requiring the asshole in front of me slam on their brakes, then I'll buy it. Until then, just watch a YouTube "dumbass drivers" video to realize why, no matter how good a driver you are, you need good brakes that are capable of burning rubber at a moment's notice.
Of course I'm against DEI. Donald, Eric, and Ivanka.
(Score: 4, Insightful) by stretch611 on Thursday May 12 2022, @02:55AM
When people slow down and allow enough distance between cars for the electric motors to bring everyone to a proper stop I see this being a reasonable approach.
That being said, I do not expect it to happen in my lifetime. Honestly, I do not see it happening while humans are allowed to actually drive at all.
Now with 5 covid vaccine shots/boosters altering my DNA :P
(Score: 2, Interesting) by Anonymous Coward on Thursday May 12 2022, @03:20AM
Based on the context of where this technology is being developed, good brakes will be a necessity. Formula E races on road and street courses. Passing on road and street circuits tends to occur in hard braking zones. Current Formula E cars can reach speeds of up to 200 mph. This is going to occur on long straights, which are often followed by a hard braking zone. An example is the start/finish straight on many circuits, which tends to be one of the places where cars reach high speeds. At the end of the straight, there's usually a fairly sharp turn that requires hard braking, and is a place where overtaking frequently occurs. If you look at Miami's street circuit [wikipedia.org] where F1 just raced, you'll see this at turn 1, which is a hard right hand turn at the end of the start/finish straight. Turns 11 and 17 are also going to be hard braking zones, where cars will carry a lot of speed and will need to decelerate quickly.
If this is being developed for racing, you can bet the braking system will need to be as powerful as the disc braking system that's currently used. If disc brakes can be replaced with purely regenerative braking, it will probably come with the benefit of making the brakes more reliable. One of the most common causes of brake failure is overheating brake rotors. You see this sometimes in NASCAR where overheating brake rotors can actually explode. The heat is generated because a caliper clamps the brake pads against the rotor, using friction to convert the kinetic energy to heat. If the kinetic energy is mostly being harvested through regenerative braking, it's not being converted to heat, and that greatly reduces one of the primary reasons for brake failure. Kinetic energy recovery systems will certainly have their own points of failure, but eliminating overheating might well make the brakes considerably more reliable.
You can bet if they're designing this to work in motorsports, it'll absolutely get the job done on your car.
(Score: 5, Insightful) by Immerman on Thursday May 12 2022, @04:55AM (12 children)
I agree with the sentiment, but burning rubber means you're significantly below your maximum acceleration. It means your tires are skidding, and thus exerting considerably less force than they would if they still had traction. Hence the existence of anti-lock brakes.
Beyond that, so long as your regenerative braking is powerful enough to lock up the wheels if you wanted to, it's as good as it gets. And since it (presumably) uses the same motor as accelerating, that means that you'd also able to burn rubber when mashing the accelerator. At cruising speed. (barring software limiters)
The actual risk is in system failures - mechanical brakes are a completely independent system that will work even if almost everything else has failed. Regenerative braking fails if there's a failure anywhere in the drive train: the transmission, the motor, the battery, the power controller, the computer, the brake pedal sensor, or the wiring for any of those.
Now, such failures may be rare, but for something as critical as stopping I'd prefer to have a simple mechanical backup system. Even if it's just a pair of cheap drum brakes on one axle that only kicks in when you completely floor the brake pedal, and aren't strong enough to lock up except in the most contrived circumstances - you're still *far* better off than trying to coast to a stop.
That said, I'm all in favor of rarely/never *using* that backup system. Brake pads end up in the air we breathe, and even the ones that don't contain asbestos still aren't exactly lung-friendly.
(Score: 3, Touché) by ewk on Thursday May 12 2022, @07:18AM (1 child)
While acceleration technically can be correct (since it can be negative after all :-) ), I believe the common term is 'deceleration' when we refer to braking :-)
I don't always react, but when I do, I do it on SoylentNews
(Score: 2) by Immerman on Thursday May 12 2022, @01:17PM
Ack, it seems I accidentally outed my physics background.
(Score: 4, Interesting) by inertnet on Thursday May 12 2022, @08:23AM (2 children)
I completely agree, but would add that a backup system might fail if it is used only once in a blue moon. And that would be right when you need it most. So I would advise to build the backup system in a way that it automatically gets applied once in a while instead of the regenerative brake, without using emergency level braking of course.
(Score: 3, Insightful) by maxwell demon on Thursday May 12 2022, @04:19PM
Isn't that what inspections are for?
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @07:06PM
Tell that to my air bags
(Score: 2) by mcgrew on Thursday May 12 2022, @08:57PM (3 children)
Regenerative braking fails if there's a failure anywhere in the drive train: the transmission...
Electric motors have the greatest torque at zero RPM and need no transmissions. That's one main reason I want an EV; no oil, tranny fluid, coolant, or gasoline you have to stand there in below freezing weather to fill.
An internal combustion engine and transmission is a primitive Rube Goldberg machine with gears, pumps, pulleys, belts, etc, while an electric motor is sophisticated, having only one moving part. That said, I imagine they'll have some sort of emergency brake, probably friction.
Impeach Donald Palpatine and his sidekick Elon Vader
(Score: 2) by Immerman on Thursday May 12 2022, @10:03PM
That's true of an idealized electric motor - it's a little more complex than that for real ones.
Most electric vehicles (such as the Teslas) have single-speed transmissions - presumably to map the optimal motor speed to a typical car speed. Electric motors tend to like spinning *fast* - far faster than you'd want your wheels to spin. I believe I recall that the Tesla Roadster actually had a two-speed transmission originally, which was eventually abandoned as it kept being destroyed by the incredible torque from the motor.
(Score: 2) by ChrisMaple on Friday May 13 2022, @03:06AM (1 child)
Calling the rotor of an electric motor a "single part" is an exaggeration. In addition to a shaft, it may have permanent magnets, windings, a commutator or slip rings, and magnetic laminations, depending upon the design.
(Score: 2) by mcgrew on Friday May 20 2022, @12:45AM
True, but they're all connected together and move as one thing. That's far different than all the valves and pistons moving differently from each other in a gas engine, not to mention... well, I'm pretty sure I made my point. I've only had one motor fail that I remember, in my 70 years. I was in the Air Force, and it was the motor in my cassette deck quit. The plastic that had held the rotor's shaft had broken. A little super glue and it was as good as new.
Impeach Donald Palpatine and his sidekick Elon Vader
(Score: 2) by bussdriver on Friday May 13 2022, @01:03AM (2 children)
I have parking brakes on my rear Nissan Leaf's wheels. It has it's own special pedal which is a bit high up but thankfully exists. It is not quite enough to replace normal brakes but it really should be made to do so.
Make the parking brakes a bit stronger and easier to trigger and that would be enough of a backup. It doesn't make dust unless there is an emergency and parking with it shouldn't make any. Even now, brakes last incredibly long with regen doing most the work.
(Score: 2) by Immerman on Friday May 13 2022, @02:06AM (1 child)
Yeah, a simple mechanical parking brake would get the job done. Even if it's not as powerful as your normal brakes, it's a huge improvement over nothing. Add in a kill switch that physically cuts power to the motor when the parking brake is engaged (in case of any sort of stuck-on malfunction) and you're golden.
(Score: 2) by bussdriver on Monday May 30 2022, @05:56PM
Yes, a good point-- my electric motor can pretty easily grind past the parking brakes given it's high torque. I'm on my 2nd set of drum brakes because of that; previous owner somehow didn't notice... and after they wear down there is nothing to notice.
that said, nissan has some funky stuff going on with braking to try to make the regen and disc brakes blend so it's not jarring when it transitions to physical brakes. I've once had the computer mess up and lost brakes and the regen is not strong enough on it's own -- not even close! I figure these newer e-brakes must be sizable and add cost somewhere to replace physical brakes. You've at least got to bulk up the electronics to use the motor to brake because that has to be some huge power spikes you go past generation and start to spend energy to brake. Not just a high power generation positive spike but reversing to a huge negative spike to actively brake.
(Score: 3, Informative) by mcgrew on Thursday May 12 2022, @08:48PM
I see you're not very good a physics. Regenerative braking doesn't transfer kinetic energy into heat, as old fashioned brakes do, they should be able to stop a vehicle far faster than friction. You'll still need ABS with these brakes, or you could lock them up even faster than friction brakes.
Impeach Donald Palpatine and his sidekick Elon Vader
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @12:25AM
You geezers may remember bikes with tiny generators attached to the rear wheel to power the front light bulb.
Seems the same basic principle - the momentum converted to generate electric current/charge batteries.
But it's disturbing that they are conflating the problem of conventional brake dust with that of efficacy of generator brake. Seems they know generator brake will be inadequate so they pull in enviro concerns - not exactly confidence-inspiring.
(Score: 3, Interesting) by Zinho on Thursday May 12 2022, @12:30AM (12 children)
I was under the impression that shorting the ends of a motor worked best as a brake when it was a dead short: i.e. no resistance across the motor's poles. I thought that was why the physical brakes were there - that the effect of regenerative braking was reduced the lower the car's speed - and so the brake pads took up the slack at low speeds.
Does charging the battery give better braking performance than a dead short? If so, why aren't they used exclusively? Are the car designers wanting a manual backup in case of software bugs?
Inquiring minds want to know.
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @12:55AM (4 children)
Well, majored in EE in college anyway.
Motor and generator are the two sides of a same coin. Motor converts electric energy into mechanical energy by rotating the rotor. Generator converts mechanical energy (usually from rotating rotor) into electrical energy.
Have no idea what you mean by "shorting the motor,"
Over to you better EEs and the ones familiar with regenerative brakes.
(Score: 5, Informative) by RS3 on Thursday May 12 2022, @02:00AM (3 children)
In a simplification motor and generator might be the same, but in reality optimizations make a motor much better at being a motor, same for generator.
Some motors, mainly "induction motors", won't behave as a generator to any useful extent. And, in fact, electric car motors are, from what I see and read, "induction motors".
Torque: rotational (turning) force
As most people know, a motor generally involves magnetic attraction. We generally have a stator (part that does not turn) and a rotor- part that turns. Some motors have permanent magnets in the rotor, and "field coils" around the perimeter (my washing machine for example, and most new ones). Generally the coils are arranged and wired in 3 "phases". So you energize one coil, and as the rotor moves and the magnets start to align, you now energize the next coil, de-energizing the first coil, and the rotor moves toward the 2nd coil. And so on for the 3rd coil. (Actually it's more complicated than that; ask if you want to know...)
There's a type of motor called "stepper motor" and they're generally like I described above, but usually with 4 phases. They're used in many positioning systems, like the X-Y-Z drives of 3D printer, driving the print head belt in inkjet printers, and many other positioning systems.
Anyway, there are motors without permanent magnets in the rotor, especially older ones made before the super magnets (neodymium, cobalt, etc. alloys) and they had electromagnets (coils) in the rotor (aka armature). Electrical contacts called brushes rubbed on a rotating contact assembly called a "commutator" to get the electricity into the armature coils. Many many motors are made this way and have been since 1800s. Edison made tons of motors that way. They're easy to reverse, easy to control speed, lots of torque and power, can spin very fast and are often very noisey. Most vacuum cleaners have this type of motor, many power tools. And they can run on AC or DC equally well.
Older car generators usually worked this way. The outer field coils were energized by the battery, and the rotating armature caused electric current to flow in the armature coils, through the commutator and brushes, and powered the car and charged the battery. You easily regulate the output by varying the current in the field coils. The output from the armature is DC. in these.
I have a garden tractor that has a motor/generator- one of these ^. It's not very efficient at either, though.
Another type of motor is the "induction motor". It uses AC in stator (field) coils, and due to various designs (inductive and/or capacitive) a rotating magnetic field is created. (Ask if you want to know more about this...) The rotor needs to be magnetically attracted (force) to create torque, right? Just plain steel won't give much pull, so output torque and power would be very low. Nikola Tesla came up with a clever design where the AC in the field coils "induces" an electric current in copper wires embedded in the rotor. In fact, the more you resist the motor's turning (heavier load), the more the induced rotor current, so the stronger the rotor magnetic field, and the harder the motor works. Very very clever. Induction motors are everywhere. Used to be used in washing machines, dishwashers, dryers, pumps, refrigerator compressors, etc. They come in a huge variety of sizes, up to and above 10,000 HP (horsepower, 0.746 KW.)
So again, electric car motors are generally 3-phase induction motors. To get them to generate electricity, for regenerative braking, you have to do some very clever electronic controls to keep rotor current going, but still extract power from the whole thing.
* Most gasoline engines have an "alternator" to generate electricity. It's pretty simple: rather than the more complicated commutator with many copper segments and many armature coils, they just have 1 armature coil, and 2 simple "slip rings" to get current into the rotating electromagnet that is the armature. The field coils are where you get the generated power, and it's AC. In most cars there are 3 stator phases (popular, huh?) and 6 diodes to "rectify" the 3-phase AC into DC for the car. Again, it's very easy to vary the armature current to regulate the output.
(Score: 3, Insightful) by Beryllium Sphere (r) on Thursday May 12 2022, @02:09AM (2 children)
Both the electric motors in my Prius are motor/generators and regenerative braking is mature technology. The problem is that there's a limit to how fast a battery can absorb power and a contingency stop can far exceed that limit. Another problem is that it's a safety-critical system and it is not necessarily easy to match the reliability of pads scraping on a disk.
(Score: 5, Insightful) by RS3 on Thursday May 12 2022, @02:28AM (1 child)
Actually your Prius has separate motor and generator: induction motor, PM rotor generator: https://www.researchgate.net/figure/Motor-generator-and-engine-of-Toyota-Prius-hybrid-THS-II-System-6_fig4_265995537 [researchgate.net]
I will always endorse regenerative braking, but yes, I 100% agree it would be beyond ludicrous stupid to eliminate friction brakes from any vehicle.
Interesting thing: a good friend has a Chevy Bolt he's had for 3+ years. AFAIK, he's had very little trouble with it, but I'll check with him.
Anyway, it does NOT do regenerative braking by default! I though that was stupid! He can put it in a mode where when he lets off the accelerator it regeneratively brakes, and there are several levels. At the highest level, it jerks you forward (sorry, it "derivative's of acceleration"s you forward! :)
IMHO, regenerative braking should happen with the brake pedal! Like as soon as you move the pedal a little. The harder you press the brake pedal, the more it should "pull" power from car's inertia, then at some point (pedal pressure) it should begin to apply friction brakes if needed.
(Score: 3, Funny) by coolgopher on Thursday May 12 2022, @06:19AM
I appreciate that jounce of word play!
(Score: 5, Informative) by lentilla on Thursday May 12 2022, @01:46AM (4 children)
Torque is proportional to the ampere-turns in a direct current (DC) motor. Or: in simple terms, the greater the current, the greater the acceleration.
Assume you have a motor connected to a set of wheels and you are rolling along at speed on a flat surface:
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:00AM (3 children)
i.e, turn the motor into a generator - suck the momentum out.
(Score: 2) by kazzie on Thursday May 12 2022, @05:05AM (1 child)
A downside of reversing the terminals (or "plugging" ) is that all the kinetic energy is dissipated as heat within the motor's windings. It's great for a fast emergency stop, but not for regular usage.
(Score: 2) by maxwell demon on Thursday May 12 2022, @07:53AM
I'd say if you feel the need for it in regular usage, you really should rethink your driving style.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @06:04AM
Doesn't the Segway control system do something like this?
If you can develop enough enough torque to "burn rubber" (forward), the physics should work to "burn rubber" (reverse).
What I am getting at is that under normal driving circumstances, regenerative braking should be sufficient most of the time, but if necessary, you have the power to forcibly brake, using energy to do so, but it will stop the vehicle every bit as fast as the most advanced mechanical antilock braking possible. It won't be efficient, but it will stop the car as quickly as possible, like ramming a car into reverse direction, which would likely flat take out a transmission. Kinda hard to take out a magnetic field though.
However, everything breaks, and for something as critical as braking, should the braking circuit fail, I would advise a single use mechanical brake be released to lock up the wheels, kinda like we use an air bag - not to be deployed until electronic braking malfunction detected. Once released, one would have to park the car and manually reset all four wheels. If the electronic braking is still detected to be malfunctioning upon attempted drive off, it will simply trip the mechanical brake again.
This might be useful for anti theft as well. It would force someone to use inordinate amounts of time trying to move the vehicle.
Time for the tow truck.
Of course, once the vehicle is parked, everything is powered down, and a mechanical pawl could be used in each wheel to lock all four wheels very similar to how an automatic transmission is locked up with a pawl in Park mode.
I am thinking minimal mechanical moving parts/bearings by using a hub motor in each wheel, including ability to still move the car even if only one motor still works, but severely speed limited as that single motor will also have to stop the car as well, and a panic stop will engage the emergency brake, that most likely you would have to visit each wheel to reset it. ( Gotta make emergency brake reset a PITA so people won't ignore it and glibly use their last braking system to failure).
I would not want to design something dangerous, neither would I want to design anything that leaves their owner stranded if it could have limped home.
Here's the rub though... Just how many of us would have an innate ability to comprehend the problem and be able to compensate? Stuff like this seems to come naturally to people with engineering interests, but would others comprehend the situation? I ask because about a year ago, one of my friend's wife almost made it home, with the oil light on. Only about 10 more miles and she would have made it.
(Score: 2) by kazzie on Thursday May 12 2022, @05:15AM
The advantange of using an external resistor or battery charger is that the excess energy is dissipated there, rather than in the motor.
The disadvantage of using them is that they limit the current flow, and thus the rate at which energy is dissipated. But if you're dissipating it in the motor, it could end up seeing 3 or 5 times (I forget which) it's rated power sent through its windings. You'd need to seriously overengineer your motor if you were going to short/plug it on a regular basis.
(Score: 2) by Immerman on Thursday May 12 2022, @10:19PM
I believe the maximum deceleration torque possible from a motor is generally achieved by applying maximum power to the motor in reverse.
My motor-physics knowledge has faded greatly, but my gut says that shorting the terminals of a DC permanent magnet motor would provide braking force, since you're inducing current in the windings that will resist the changing magnetic field (akin to the way a magnet dropping through a copper pipe in slow motion. But not nearly as much as actively powering that resistance. (akin to firing a railgun upwards, to overextend )
However, if I recall correctly many (most?) modern car motors are actually computer-controlled multi-phase AC motors that contain no permanent magnets, which can be considerably more efficient (as well as being considerably cheaper since they don't require any expensive rare earths for high-strength permanent magnets.)
The efficiency gains are in part because without permanent magnets there are none of those induced "braking" currents when coasting.
(Score: 5, Interesting) by anubi on Thursday May 12 2022, @12:51AM (17 children)
I was involved in the design an ultrasonic wire bonder.
One of the things I had to contend with was the big spool ( well, related to the rest of the design ) of gold welding wire, thinner than a human hair. And it had to be dispensed at whatever speed the weld transducer needed.
We chose a DC servomotor to drive the wire dispenser - a motor driven spool..
Much to my delight, I discovered that using a H bridge to drive the motor, using two BJTs in the upper part as emitter-follower voltage sources and MOSFETS in the lower part to switch between forward and reverse mode, if I simply drove neither the forward or reverse BJT, but turned both direction MOSFETs on, It would brake absolutely perfectly. The motor became a DC generator - shorted by the simultaneously on MOSFETs. Actually, it worked so good I had to put a 5 ohm resistors in series with the motor to drop the jerk.
The braking was proportional to speed, with the terminal braking dropping to zero, which killed off the jerk which was causing mayhem on the spool.
If this magnetic braking works as good on a car as it did on my wire bonder, you just ain't gonna get any better.
Oh, incidentally, "jerk" is the derivative of acceleration.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @01:05AM (4 children)
I didn't like him either, but sabotaging his brakes is taking things too far!
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @01:09AM (3 children)
That dude from New Jersey, right?
They should rename the state "New Jerkey."
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:04AM (2 children)
I call it "New Junky". Ever been there?
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:26AM (1 child)
New Wark resident, I see.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @02:30AM
Never resided in NJ! Yikes. Actually some areas are well-kept secrets. Much of the central and northwest are beautiful mountainous (as much as Appalachians are) woods.
(Score: 3, Funny) by dx3bydt3 on Thursday May 12 2022, @01:33AM
I have been summoned?
(Score: 4, Insightful) by sjames on Thursday May 12 2022, @02:23AM (7 children)
My concern is that the 'brakes' will have practically no holding power on a hill. Creeping back until you tap the car behind you is a problem.
(Score: 2) by RS3 on Thursday May 12 2022, @02:34AM (1 child)
(sarcasm:) Naaa, they'll apply battery power to hold you on the hill. What could possibly go wrong?
Even if your battery dies, or electronic problems, by then cars will have nice thick rubber bumper perimeters, much like bumper cars, but softer. So you can roll back. No more damages and wasteful insurance money spent. (/sarcasm...)
(Score: 3, Funny) by sjames on Friday May 13 2022, @12:45AM
Now I have "Red Barchetta" running through my head.
(Score: 1) by anubi on Thursday May 12 2022, @06:53AM (1 child)
That is a good concern!
If energy is not expended to hold the vehicle stationary, like a Segway, what you say is exactly what will happen once you overcome the hysteretic magnetic field and static friction of the motor bearings.
If it wasn't for friction and hysteresis, this system would approach a stop asymptotically, and never get there.
In the case of the wire bonder, friction did the job.
Agreed, there must be mechanical takeover to maintain stop once an active ( powered ) stop has been attained. Actively maintaining stop will require significant energy.
For stop and go traffic, an active stop is probably ok, but we are definitely going to need a mechanical Park mode. Without some sort of mechanical " wheel chocks ", the car will most definitely roll down the hill.
Thanks for bringing that up.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Interesting) by sjames on Friday May 13 2022, @12:28AM
Yes. That might be a fairly complex system to be both effective and reasonably fail resistant. I'm not so sure anything beyond press the brake pedal a little harder will really work. That means the friction brakes will still need to be able to handle being activated when the car is still moving (and we're still stuck with anti-lock mechanisms).
That isn't to say that I oppose augmenting existing regenerative braking to handle more, including where practical bringing the car to a complete stop. I just don't want to see bumper cars out there.
I think it's a real concern in the wake of more than one manufacturer replacing the cable actuated emergency brake (which I have needed on 2 occasions) with an electrically actuated "parking brake" that has two states: free wheeling and lock-'em-up.
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @12:55PM (2 children)
Yes, but you also have the Parking Brake thing that will have to remain and be purely mechanical for many reasons. The stopped car on a hill could as well use this too or maybe a combination of the two. The point is,
1. EM brake would reduce the need brake replacements
2. and no more thousands of tons of brake dust in the air to breath -- that's probably a good thing?
3. holding something stationary needs a lot smaller brakes than making it stop from 100km/h and also see #1
(Score: 2) by sjames on Friday May 13 2022, @12:38AM (1 child)
I'm not so sure drivers will remember or even know to apply a parking brake to stop in traffic. In all likelihood, there will still need to be a friction brake tied to the action of pressing the brake pedal. We can and should have regenerative brakes (common on hybrids and electric vehicles now) and it's great if we can make the regenerative phase of braking to a stop longer and more effective. But not having friction brakes at all as implied in TFA is out of the question.
It's worth noting that more than one manufacturer has replaced cable actuated emergenmcy brakes with electrically actuated "parking brakes" that are worthless for bringing a car to a controlled stop in an emergency.
(Score: 0) by Anonymous Coward on Friday May 13 2022, @10:00AM
"It's worth noting that more than one manufacturer has replaced cable actuated emergenmcy brakes with electrically actuated "parking brakes" that are worthless for bringing a car to a controlled stop in an emergency."
Others here seem to have a really good approach...a two stage system...where a light to medium braking is regenerative, a harder braking reverts back to existing hydraulics.
I can see a parking pawl. I have one on my automatic transmission. Like you say, useless for a controlled stop. But once stopped, it locks the drive shaft.
I'd much rather my engine fail than my brakes fail. I will still drive my machine with a flakey engine, but if it's brakes are acting up, it gets towed.
(Score: 2) by RS3 on Thursday May 12 2022, @02:43AM (2 children)
That's very cool. I like the clean simplicity. Nowadays you'd have 200KHz (well, maybe 50-100) choppers, current sensing (back EMF), digital signal processing / analysis, and if done well it might work very well, but much development, and probably not easy to troubleshoot fix someday in the future.
Did you use a "dancer" in your design? (Arm with gentle spring tension and roller at the tip to cushion the start-stop motion).
(Score: 2, Informative) by anubi on Thursday May 12 2022, @08:00AM (1 child)
Yes, we used a dancer, well we called it a tensioner. Mostly gravitic.
It was so we could have a couple of inches of despooled wire free as the despooling inertia and time constants of the despooler were over two orders of magnitude slower than the motions of the weld transducer.
Otherwise, the weld transducer would snap the weld wire in a manner in much the same way we break off a strip of toilet paper by snapping it against the inertia of the roll.
Ours was functionally similar to the vacuum columns used by those old magnetic tape transports. Also, ours had gravitic aspects as gold wire, even at this microscopic size, was still influenced by gravity and we needed to minimize inertia, yet keep the gold wire in a micro-tension at all times.
The whole function of a powered despooler was to maintain that critical length of immediately available wire for the weld head. If it drew wire, and an insufficient amount of wire was available, it would break the wire, which was time consuming and wasteful to re-thread into the weld head.
You've done this. No one who hasn't could not have asked that question. I just typed this much to edify those who haven't.
I look back on this as one of the better designs. Extremely simple. A hybrid analog electromechanical computer, doing some things in the mechanical domain and other things in the analog domain, almost none in the digital domain. There are several places where the analog computation, such as speed and motor current, was done by a PN junction. Just a few CMOS gates and timers. Just turn it on, it works.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Interesting) by RS3 on Thursday May 12 2022, @06:43PM
The beauty of simplicity. We have to keep in mind that some people only know digital solutions- they just don't have much mechanical experience, and less analog. I like the blended solution.
Where I work now, food & beverage processing, we have several machines that do similar functions, on a bigger scale of course. Most of them are some kind of labeler. One has a spool of flattened plastic sleeves that get expanded, cut, and dropped onto cans and jars. They then go through a steam tunnel to shrink them onto the container. That machine has a large air box, rather than vacuum, to make a loop to allow for the tugs.
When I was a kid, my dad worked at Univac in their tape drive division and worked on vacuum loop stuff, as well as head read-write amps, etc.
Oh- another labeling machine at work is idiotic. It has dancers that are too short to deliver the entire label, so they have a very powerful servo motor that tries to start and stop, very quickly, a large 18" or so very heavy roll of labels. The idiots used set screws which not only loosen very quickly but gouge the shafts. They didn't even flatten the shafts for the set screws! I fixed it by drilling through the hubs and motor shaft and inserting a roll pin. But you can't get enough friction with the roll, so it doesn't really do what it's supposed to. Much to most people's amazement, I can get the machine to run pretty well, but I'm the only one who can. Other operators / maintenance techs are not engineers, nor have the understanding, patience, nor attention to detail that I have. Point is: I need to modify the dancers- lengthen the lever arm, which isn't too difficult, and should make the machine more friendly to less technical people.
BTW, long ago, 1970s and 80s, a friend's dad worked at GE doing wire bonding, making hybrid circuits that went into satellites, including the still working "LandSat" birds. I can do that level of precision - if I don't have any caffeine that day.
(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.
"Think of how stupid the average person is. Then realize half of 'em are stupider than that." - George Carlin
(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.
[nostyle RIP 06 May 2025]
(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.
Impeach Donald Palpatine and his sidekick Elon Vader
(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.
Impeach Donald Palpatine and his sidekick Elon Vader
(Score: 3, Insightful) by PinkyGigglebrain on Thursday May 12 2022, @03:30AM (6 children)
Suffer an electrical issue that kills the power to the wheel moters and your really going to want a set of physical brake pads to stop the car safely.
Park on a slope and you'll need something to keep the car still while the power is off.
Great concept but it seems to me the declaration of the brake pads imminent death might be just a little premature.
"Beware those who would deny you Knowledge, For in their hearts they dream themselves your Master."
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @06:34AM (5 children)
Do cars still have parking pawls? It's a little ratchet like thing that locks the drive train when you put the transmission in park. I wouldn't want that to be the only thing preventing it from rolling. You should always set the emergency brake and if it isn't a pad, drum, or disk then maybe they'll just have to have something like the pawl on all 4 wheels for maximum safety. It would only engage when you're in park, so the brake dust wouldn't be there which was the big concern expressed above.
(Score: 3, Informative) by janrinok on Thursday May 12 2022, @01:08PM (4 children)
All these drivers of automatic cars! If you have a manual gearbox it is easy to park. Nose pointing steeply downhill, select reverse gear, nose pointing steeply uphill, select 1st. Apply the handbrake. You are also expected to turn your front wheels so that the vehicle will only roll as far as the kerb. I'm not saying everyone does this but it used to be taught for the driving test - and it might still be.
Remember seeing people shake the gearstick before turning on the ignition? - this is part of the reason why they still do that!
[nostyle RIP 06 May 2025]
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @08:36PM (3 children)
Does reverse vs 1st actualy even matter if the engine isn't spinning? Not that squared away on the intricacies of the transmission
(Score: 0) by Anonymous Coward on Friday May 13 2022, @02:46AM (2 children)
If the hill is steep enough, just putting the manual transmission in gear will not hold it. Compression in one cylinder after another will leak down and the weight of the car will turn the engine. This happened to me on a hill that had no curbs to block the front wheels (I was still in the car, was able to apply brakes and stop it).
For this reason, I would put in 1st gear if the car was facing downhill (and reverse if facing uphill). That way the engine would be forced to turn in the correct direction if the car rolled. Many engines have internal features that can be damaged if the engine is turned "backwards".
(Score: 2) by janrinok on Friday May 13 2022, @09:33AM (1 child)
People could be killed if the vehicle runs away - the advice in the UK is to select the opposite gear as it is more difficult to turn the engine. Engines can be replaced - people cannot. I lost a niece about 40 years ago to just such an accident when she was crushed between a runaway car and a wall.
Leaving the wheels turned whether there is a kerb or not means that the vehicle will not roll too far. It might still pose a danger to others though.
[nostyle RIP 06 May 2025]
(Score: 0) by Anonymous Coward on Saturday May 14 2022, @04:19AM
> ...select the opposite gear as it is more difficult to turn the engine
Citation needed. First look I don't think there is much difference? For compression and expansion strokes the valves are closed. For intake and exhaust they are open (sequentially, with some overlap). Turning backwards still goes through the same valve timing events and the compression (as well as all the friction) is what makes the engine hard to turn?
The things that don't like to go backwards might be accessories, oil pump(s), the cam chain tensioner (so cam may skip a tooth and put the timing off) things like that.
(Score: 5, Interesting) by pTamok on Thursday May 12 2022, @08:00AM
Owners of Volkswagen e-Golfs know this to their cost. The car uses regenerative braking by default, only applying the mechanical brakes for the final stop, or when the ABS is determined to be required. As a result, the conventional disc-brakes are under used, and the discs rust like crazy - they are not kept clean by the very minimal amount of use they normally have. Rusty and or scored discs are a legally mandated inspection failure, so VW e-Golf users end up paying for (expensive) disc and pad replacements far more often than owners of VW Golfs with internal combustion engines.
The replacement design for the Golf platform, which is the fully electric ID.3 has drum brakes which don't have the same rusting & scoring problem. The regenerative braking works well enough that the drum brakes are needed only for the final stop.
With the right power controls, you would not even need the drum brakes: but whether you can produce a purely electrically powered braking system that meets the safetey/reliablity requirements is another question. Citroën have a history of innovative automotive engineering solutions, so if any company is likely to propose one, I would expect it to be them.
(Score: 2) by Opportunist on Thursday May 12 2022, @09:26AM
Please, the brakes on my first car were so crappy I needed a louder horn to get through traffic unscathed. Your future is my past!
(Score: 0) by Anonymous Coward on Thursday May 12 2022, @09:04PM
this is all my assumption:
with three phase wiring and AC it should be possible to "recycle the electrons".
for DC, the electrons run one way only.
for AC, it should be possible to "capture" the energy stored inside the situation of "flowing electrons". that is, if the source of the electron flow is physically and geometrically a circle, the moving electron flow should be able to be "frozen" thru time ... whatever. the triangle is the only one where you can "tease" one side of a better, "lower energy" possibility on the next side only to break the promise and instead tease the next one ... thus freezing the flow thru time (with resistance loss of wiring ofc) blaming it all on the circle shape, which is "greatest volume with least circumference". 3-phase w/ neutral thingy? it should turn forever but for extraction of torque ...
it should be possible to use mechanical brakes to entice a electrical setup to flow in reverse without rewiring if it is moving as a whole. "a change in ..." and all that. however, rewiring (power mosfets and digital logic and all that) is prolly more efficient.
i have never driven "one pedal". however, i used to shift to neutral in my ice-only car when approaching a distant red-light (*) ... i think i would prefer a pedal to "go" and a pedal to "stop -and/or regenerate" ... i assume with "one pedal" i have to personally judge what a coasting distance should be instead of just plain turning the car into a "motorless buggy" slowing thru friction alone.
i had to re-learn "coasting distance" with my e-bike but i love it. it seems to coast forever :D squeezing the right-brake level will activate "regeneration" however. which funnily doesn't work very good (stutters) if the battery is close to full ... good thing the left-one is mechanical.
if a battery performance is at 99% to go from 0m to 100m in x seconds and then you use the same motor to charge the battery and it takes less then x seconds and a distance of 100m to full stop you will have exceeded the battery performance. so maybe it's a good idea to keep mechanical brakes ... or a super capacitor?
(*) some people say this is bad for gearbox/torque converter? i never got problems from it. however motor then uses benzin as in idle mode (minimum cylinder fillings -aka- RPM) and internal motor friction is removed from overall vehicle movement. but i can see that this "saving" is bad for some :P