Full brake-by-wire close to mainstream ready

[whynot]

Looks like some in the industry are ready to have another go at brake-by-wire. Let's hope it is not another repeat of the 2005 Mercedes-Benz Sensotronic Brake Control (SBC) saga.

A brake calliper is a harsh environment for any electrical device. Lots of heat, vibration, and exposure to water, mud, dust, etc. It will be interesting to see what the as constructed components looks like.

https://www.goauto.com.au/news/gener...-24/95937.html

... Benefits of EMB are said to include improvements to anti-lock braking (ABS) function with the pedal “buzz” a driver feels when the system engages disappearing, faster brake application, better managed front-to-rear weight transfer under brakes, brake ‘feel’ options, potential manufacturing cost reductions, fuel consumption gains (due to less pad drag), and longer component life...


AN’s report says the incoming systems replace hydraulic callipers with electric ones that use motors to move the brake pads, rendering master cylinders, vacuum boosters and hydraulic lines redundant.

“The brake pedal is connected to an electric device that measures inputs such as the speed and force the driver uses when pressing the pedal.

“A pedal simulator observes driver intent though pedal travel and force and translates it into a signal that is processed through a central computer,” said ZF director of engineering Diego Cusi.

“That signal is now going to be issued out to the four corners.”

Tyre grip on the road creates another set of signals allowing the computer to apply different braking pressures to each wheel based on road conditions.

“The signal (from each wheel) is going to be interpreted, and then it is going to command the motor to deliver a certain force,” Mr Cusi explained.

[XR Martin]

Arnt brakes meant to have a redundancy?
If you lose hydraulics you can still brake (dual circuit), if you lose vacuum you can also still brake.

On an electric system if you lose electrics...?

[cs123]

Originally Posted by XR Martin

Arnt brakes meant to have a redundancy?
If you lose hydraulics you can still brake (dual circuit), if you lose vacuum you can also still brake.

On an electric system if you lose electrics...?

Car in front is the backup system...

[Citroënbender]

You can always pray!

The first thought in my head re weaknesses was not specifically electricity supply, but corrupt instruction of the system - whether by fault or hacking.

[whynot]

Originally Posted by XR Martin

Arnt brakes meant to have a redundancy?
If you lose hydraulics you can still brake (dual circuit), if you lose vacuum you can also still brake.

On an electric system if you lose electrics...?

There are techniques to provide redundancy in electrical systems.

For example, in large electrical substations the "protection" schemes (i.e protection relays, wiring, circuit breaker trip coils) are all duplicated. There are two sets of substation batteries, independent wiring following separate paths, two sets of protection relays, and two independent trip coils.

Just guessing here ... I imagine that in an electrical brake system for a car, it would possibly entail two sets of wiring out to the calliper, via two separate connectors. Considering the battery as one power source and the alternator as the other power source. Dual position sensors on the brake pedal. Maybe even having a primary and backup computer for the brake controller.

The bit that intrigues me is how the calliper is built and how the wiring loom goes out to it. I suppose that ABS speed wheel sensors have a good reliable history by now (and they operate in a similar environment).

It will be interesting engineering. Mass produce a cheap and reliable braking system.

[Citroënbender]

RR had a pretty comprehensive redundancy on their brakes for the Shadow and Spirit; two fully independent accumulator “powered” circuits fed each caliper and there might have been a regular (unboosted) master cylinder behind at least one of them as well. All they were missing was a RAT.

As the electric braking units are likely to be compact, I’d prefer to think there were equivalent allocations to a typical Brembo spec upgrade (4-6 motors per front caliper and 2-4 per rear), but on two parallel systems at least, and perhaps an hydraulic circuit with doseur valve plus accumulator for true emergencies. I’d feel pretty uncomfortable with it otherwise.

[smoo]

Another vague article that doesn’t really go into specifics.

So each caliper has its own motor or actuator and control module?
No power to individual brake actuator or thrown fault code = caliper locked on as failsafe.

Have been told something like that is in the pipeline in Europe for heavy vehicles, if they have an active EBS/ABS fault the park brake won’t release.What a great idea.

[petero1]

EMB brake system would be ideal to replace the horrible electric brakes used on caravans and trailers.

[123Cat]

And that would include, ( I hope ) a brakes on fail-safe when the backing plate hits the disk , to prevent people driving past that point

Oh no , thinking about it,,,, that is a bad idea,,,, to stop people on a highway,,,, ,too dangerous

Eg , the M7 , no stopping lane

[MITCHAY]

IMO another solution to a non existent problem much like drive by wire as far as I'm concerned