About Us

Dennis@home

On 29/07/2018 09:16, wrote:

I assumed ABS systems had always been microcontroller controlled, didn't
realise there were analogue versions. Interesting to know.

Ford had a mechanical system at one time.

Dave Plowman (News)

In article ,
dennis@home wrote:
On 29/07/2018 09:16, wrote:

I assumed ABS systems had always been microcontroller controlled, didn't
realise there were analogue versions. Interesting to know.

Ford had a mechanical system at one time.

Very first was the Dunlop Maxerette(sp?) fitted to the Jenson FF. Adapted
from aircraft technology. Think that only worked with permanent 4WD,
though, so perhaps just the one sensor?

--
*Snowmen fall from Heaven unassembled*

Dave Plowman London SW
To e-mail, change noise into sound.

TMS320

On 29/07/18 09:16, wrote:
On Thu, 26 Jul 2018 11:29:14 +0100 TMS320 wrote:
On 26/07/18 09:38, wrote:

It has to lock up or at least considerably slow down first, the
ABS isn't psychic. I imagine the algorithm simply takes the
average of the wheel speeds

and then operates on any wheel going much slower or much faster.
Of course
that
has a number of potential issues, eg on snow or ice the ABS has
no way of knowing if the car is skidding or parked, if 1 wheel is
going much faster than the other 3 is that wheel spinning or are
the others skidding etc. I'm sure car manufacturers have written
some clever algorithms that remember the speed up until now and
cross check against engine rpm and gear but
there's
only so much it can do.

This was discussed in control theory at university. Part of the
algorithm is double or triple differentiation of rotation speed. In
the days before cheap microprocessors easy to do with phase lock
loops.

I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by micros.

I guess they have put many more deductions in modern systems.
Clever people have been working on it for 40 years and no doubt
they have covered any eventuality people on news groups can
imagine.

No doubt, but the more complex ian algorithm becomes the more likely
it is that there's some nasty undisovered edge cases lurking in there
either due to the implementation or the algorithm itself which might
cause serious problems. In aviation they do formal proof checking,
multiple implementations of the same algorithm by different teams and
god knows what else to mitigate this, but I doubt the automotive
industry is quite so thorough simply due to cost.

Formal proof has limits. Test, test and test again on real product.

[email protected]

On Sun, 29 Jul 2018 16:39:18 +0100
TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by micros.

I suppose in theory there's little you can do in software that you couldn't
hardwire in TTL, but it would take a lot of hardware to do anything
sophisticated so would be hard to fit into a car module. I'm guessing the
earlier ABS systems were pretty simple affairs.

No doubt, but the more complex ian algorithm becomes the more likely
it is that there's some nasty undisovered edge cases lurking in there
either due to the implementation or the algorithm itself which might
cause serious problems. In aviation they do formal proof checking,
multiple implementations of the same algorithm by different teams and
god knows what else to mitigate this, but I doubt the automotive
industry is quite so thorough simply due to cost.

Formal proof has limits. Test, test and test again on real product.

Yes, formal proofs have been somewhat oversold in the past. All that happens
is you move a portion of the debugging from the code to the proof - its
irrelevant if the code passes the formal testing if the proof is bug ridden
itself and for any significant project the formal proofs can be gargantuan.

[email protected]

On Sun, 29 Jul 2018 13:09:22 +0100
"dennis@home" wrote:
On 29/07/2018 09:16, wrote:

I assumed ABS systems had always been microcontroller controlled, didn't
realise there were analogue versions. Interesting to know.

Ford had a mechanical system at one time.

How did that work , the difference in wheel speed caused some secondary
mechanical pump to work against the brake pump so lifting the shoe off
or something similar?

charles

In article ,
wrote:
On Sun, 29 Jul 2018 16:39:18 +0100
TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by micros.

I suppose in theory there's little you can do in software that you
couldn't hardwire in TTL,

The original Ceefax decoders were in 2 x 3U racks - all TTL. It all got
into one dedicated chip/

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

[email protected]

On Mon, 30 Jul 2018 10:13:44 +0100
charles wrote:
In article ,
wrote:
On Sun, 29 Jul 2018 16:39:18 +0100
TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by micros.

I suppose in theory there's little you can do in software that you
couldn't hardwire in TTL,

The original Ceefax decoders were in 2 x 3U racks - all TTL. It all got
into one dedicated chip/

Was that chip stil hard wired or did it use software by then? The problem
with hardwiring is if you find a bug its a LOT harder and more expensive to
fix (if its even possible without a redesign) than just updating the ROM code
in subseqent batches.

charles

In article , wrote:
On Mon, 30 Jul 2018 10:13:44 +0100 charles
wrote:
In article , wrote:
On Sun, 29 Jul 2018 16:39:18 +0100 TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by
micros.

I suppose in theory there's little you can do in software that you
couldn't hardwire in TTL,

The original Ceefax decoders were in 2 x 3U racks - all TTL. It all got
into one dedicated chip/

Was that chip stil hard wired or did it use software by then? The problem
with hardwiring is if you find a bug its a LOT harder and more expensive
to fix (if its even possible without a redesign) than just updating the
ROM code in subseqent batches.

I think Mullard got it right.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

TMS320

On 30/07/18 09:42, wrote:
On Sun, 29 Jul 2018 16:39:18 +0100
TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by micros.

I suppose in theory there's little you can do in software that you couldn't
hardwire in TTL, but it would take a lot of hardware to do anything
sophisticated so would be hard to fit into a car module. I'm guessing the
earlier ABS systems were pretty simple affairs.

No doubt, but the more complex ian algorithm becomes the more likely
it is that there's some nasty undisovered edge cases lurking in there
either due to the implementation or the algorithm itself which might
cause serious problems. In aviation they do formal proof checking,
multiple implementations of the same algorithm by different teams and
god knows what else to mitigate this, but I doubt the automotive
industry is quite so thorough simply due to cost.

Formal proof has limits. Test, test and test again on real product.

Yes, formal proofs have been somewhat oversold in the past. All that happens
is you move a portion of the debugging from the code to the proof - its
irrelevant if the code passes the formal testing if the proof is bug ridden
itself and for any significant project the formal proofs can be gargantuan.

It's probably not so bad for software that processes data in a computer
system (with "unlimited" resources), which is [hoped to be] scalable and
the compiler and os handle the i/o. I don't have experience of this type
of project.

The problem is in attempts to rigidly impose these methods on a real
time system with complex hardware. High level stuff can be simulated and
when incorporated doesn't give problems but the bulk of development is
low level work and nothing can be proved except with physical live kit.
"Bugs" are not usually coding errors but an incomplete understanding of
the system.

[email protected]

On Mon, 30 Jul 2018 12:40:44 +0100
charles wrote:
In article , wrote:
On Mon, 30 Jul 2018 10:13:44 +0100 charles
wrote:
In article , wrote:
On Sun, 29 Jul 2018 16:39:18 +0100 TMS320 wrote:
On 29/07/18 09:16, wrote:
I assumed ABS systems had always been microcontroller controlled,
didn't realise there were analogue versions. Interesting to know.

The electronics industry didn't make a quantum leap from analogue to
microcontroller. There was an intervening period with boards full of
logic chips, plenty of which would have been part analogue, such as
monostables. Then, not all of it could instantly be mopped up by
micros.

I suppose in theory there's little you can do in software that you
couldn't hardwire in TTL,

The original Ceefax decoders were in 2 x 3U racks - all TTL. It all got
into one dedicated chip/

Was that chip stil hard wired or did it use software by then? The problem
with hardwiring is if you find a bug its a LOT harder and more expensive
to fix (if its even possible without a redesign) than just updating the
ROM code in subseqent batches.

I think Mullard got it right.

I've no idea what you're talking about.

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What mostly makes a small engine "wheeze" fast & slow, fast & slow, fast & slow?	ultred ragnusen	Home Repair	32	February 26th 18 07:29 PM
Loctite Cleaner Accelerator	Phil	Metalworking	7	October 15th 07 01:34 AM
Dial-Up Connection "Accelerator" Technique	Brad	Electronics Repair	10	March 28th 07 05:21 PM
FS Cyanoacrylate Thick, Thin, Accelerator & epoxy	Bill in Detroit	Woodturning	0	December 29th 06 11:53 PM
CA Accelerator	Kip	Woodturning	0	July 9th 05 08:56 PM

Menu

About Us