That is easy to accommodate as you can design the electronics such that when there is no power they cause maximum braking force and dump energy into the braking resistors. This can be done completely with power taken from the motor itself and if it’s not turning to generate power, then I would expect the parking brake system to engage, eg: a spring defaults it to “On” and power is used to keep it disengaged.
This can only be done with permanent magnetic motors which is not the norm for EVs for many reasons. In a non permanent magnetic motor on loss of power there is no energy to dump into braking resistors since the motor is not causing any resistance because the coils have been de-energized.
Most EVs have permanent magnet motors of some flavor right now (some have both a PM motor and a pure induction). I would assume that if you were having the motor be the primary braking system, and it was induction, there would be a tiny cheap magnet installed in it to generate bootstrap power to prevent exactly this scenario.
An even simpler design is to assume that the car can only start moving when there is power. If there is a loss of power while moving, then you can use the energy in the HV capacitors in the inverters to make a bootstrap field. That can be maintained till the car stops (and the user still has control of when/how much to brake). When the car comes to a halt, the parking brake is applied, and it won't move again till repaired.
All of that can be done with software-only - no hardware changes needed.
So rather than coasting to the shoulder when you run out of gas your tires immediately slam full on coming to a screeching, uncontrolled stop in the middle of the highway?
hah. I didn't see this before I wrote my comment. Really makes you wonder about this common SWE fantasy of mew ways to turn cars into big electronic touch screen devices, whether the people dreaming these ideas up have ever actually driven a car.
Nope. If your car lost power for whatever reason, the system would scavenge power from the inertia of the car and the brakes would still operate as they do when the car is operating nominally. The 1-10w needed to run the braking system is a rounding error in comparison to the 4-10kW of wind/rolling resistance at freeway speeds.
That would be the default of this system if the brakes are still able to communicate with and provide power for the brake pedal. Basically if the brake system lost external power, it would get the power needed to run via scavenging it from the motors. Once the vehicle came to a stop, it would then loose power and the parking brake would then engage.
The slam on brakes case would only trigger if there was gross damage to the braking system, where you might have bigger things to worry about.
I think you've lost sight of the initial concern that was raised. There's still a common-mode failure of loss of control power.
Control power is different from actuation power, the latter of which is what you're addressing. And it's not "gross damage" because it's a common-mode failure, so you can't just ignore it like that.
To lose local regen braking derived power requires a failure of the cars systems similar in nature to one that would cause loss of hydraulic fluid or air in a traditional braking system.
It is trivial to derive control power from actuation power - at least enough for a few can-busses that run from each wheel to up-to-12 independent sensors on the brake pedal.
It's trivial if you're doing an opportunistic design, but it's challenging to match the safety and reliability of a hydraulic system while beating the cost.
>That is easy to accommodate as you can design the electronics such that when there is no power they cause maximum braking force and dump energy into the braking resistors
This is still uncontrollable failure. What if the car is in the third lane doing enough speed and there's some cars behind? I assume no ABS, because ABS can't work with locked up brakes. This means no steering, just skidding whatever way.
Having no power would be hard as the brake system can easily generate power to operate itself if the vehicle is moving (and if its not moving that is what the parking brake is for). This is more of a scenario that occurs when there is a catastrophic failure in the braking system, such as the motor control electronics getting damaged.
So fallback in the case of power loss is you don't come coasting to a stop, your car just suddenly and unexpectedly slams on the brakes? What's it do for recovery, accelerate into the car in front of you?
This is entirely dependent on how your vehicle is designed. Pulling the electronic parking brake in my car (Audi S4) at a decent speed applies maximum braking effort to all 4 wheels simultaneously. It'll practically pop your eyeballs out.
Define "decent." I lost all hydraulic brakes on my 87 Toyota pickup due to a hole in a brake line and I had to drive it to the repair shop using only the cable-operated handbrake. Granted, I didn't go on the interstate, but at some point I was still doing 35-40mph.
I could not find anything that would prevent this in my brief skim of FVMSS 105 (US car brake regulations). The regulations are mainly about the performance of the braking system (eg: needs to stop car 10x from 60mph in under a specific distance) and only care a little about the specific technique.
You should see what you propose on cheap cars if motor pricing becomes less than the cost of regular hydraulic brakes.
> S5.1 Service brake systems. Each vehicle must be equipped with a service brake system acting on all wheels.
What is a "service brake"? Notice that the regulation you linked to includes requirements for EVs that have braking regeneration as a component of their "service brake".
It turns out that the top-level of FVMSS [1] says that "service brake means the primary mechanism designed to stop a motor vehicle."
So I think you are exactly right. There is nothing in the law that says you can't use a 100% brake regen system in an EV. It just has to work and meet the performance standards (and perform regen on all wheels). But I'd guess that you aren't going to see the traditional brake system disappear unless it starts getting in the way. They don't cost a lot (relative to the price of the car), don't weigh a lot, are really reliable, and work really well.
Also the challenge of old receivers was which Doppler shift frequency to listen on depending on if the target satellite is going towards or away. By knowing the rough ___location (from cell towers, known wifi AP’s etc), they can get an instant lock.
They have also been the cause of fire[0] on the Mir space station. They make for a reasonable emergency oxygen supply (no working infrastructure required), but you don't want to use them regularly due to the fire risk they represent.
I am starting to see resolution doesn't matter. According to the specs, Valve Index has a very low average pixel density of about 13-15ppi. Criminal. Compare that to the high end iPhone display's pixel density of 128ppi. So if we could have ocular displays around 100ppi @720p, that would look a lot better than that of Valve Index displays at its seemingly impressive 1440x1600.
It's hard to discuss a monitor being 100ppi@720p because those 2 variables are related via a third variable size. A 720p screen would be 100dpi at about 14" and indeed that is a common size for crappy laptops. A tiny screen with that PPI strapped to your face would look like shit. For instance a 2" square screen would be 200px x 200px.
A 20/20 or 1.0 visual acuity equals 1MOA(1/60deg).
A 20/20 equivalent 360 degrees panorama image is has a size of 21600x10800px minimum. For a VR headset with 120x120 degrees H/VFOV(178deg diagonally), you need a 7200x7200px panel. 2 x 7200px x 7200px x 24bpp x 144Hz = 360Gbps, or worth 4x 100GE LAG’d, or one PCIe 4.0 x23 link, or one DDR5 channel.
Our retina only needs ~8 megapixels - the same number of pixels as 4K/UHD (3840x2160 is 8,294,400 pixels).
High pixel density is only required at the middle of where our gaze is - the surrounding can be highly compressed because our eyes are not very sensitive. No pixels are required where our blind spot is, and our colour and light level sensitivities varies from fovea outwards, so there are other compression possibilities too.
If the display can "move" with your eyes (high pixel density only for fovea e.g. contact lens) then the display also only needs a limited number of pixels.
Valve index has a PPI of 598. What I assume you are talking about is PPD, or Pixel per Degree. Iphone doesn't have a fixed PPD since the distance to your eyes is not fixed.
An ocular 720p display at 100ppd would be be about an inch diagonally at 10cm from you eye balls. That's basically unuseable
It’s easier to use weight instead of volume if you want measurements more precise than a 1/4 cup.
Most home ovens struggle to hit the set point to within 25F for most of their internal volume. They also have large swings in temperature as cheap heating elements do not respond quickly.
I think the idea is to reduce (its reduce, reuse, recycle in order of preference) as a bag of toner needs less resources than a cartridge.
The internet indicates a 5k page cartridge costs ~5kg of CO2 to make, and each trip to the recycling center costs ~1kg of CO2 (rough average cost of shipping a package).
A 5k page pouch in a box weighs 0.2kg, assuming a 4x weight->CO2 cost (high end of plastic production), it comes out to 0.8kg of CO2 per pouch. This is less than the CO2 cost of shipping back the cartridge for recycling.
If you assume the cost of return shipping and recycling is free, the cartridge will need to last >6 times to be worth it from a initial cost perspective. The figures I can find on cartridge lifetimes is 3-4 recycles before they are too worn to recycle again.
Even though its single use, its still a net win from a lifecycle perspective.
If you’re the kind of party that prints so much a 5000 page toner bag is worth the effort, you’re not going to be returning single toners to HP. You get a big box and send 50 at once.
Also you should be aware a lot of those toners include some other roll that has a limited life, which means you can’t recycle (or refill) them forever. But if you get toner from a bag you’d have to replace the roll separately anyway. This might be skewing your figures.
On a desktop in Chrome, with a fairly powerful processor, its taking ~4 seconds to show the calculator after it makes the call to Uno_UI_Windows_UI_Xaml_Application_Start_Windows_UI_Xaml_ApplicationInitializationCallback.
In general the slow part is getting the data out of the ADCs, so by interleaving multiple you can increase the speed. To reduce costs, if you have a repetitive signal, you can trigger the ADCs at different points in the waveform to build up a better idea of what is going on.
For scopes that can do these high sample rates they frequently use two lasers and have the scope capture the beat between them as a demo of how fast they are.
