If the sensor failed because of dirt etc (through self checking) the ACC system shut itself down. You could choose to use standard CC.
Wet road etc? On poor roads I turned it off.
in the case of the news article if it was a fault with the car the signal was clearly in range.
The point i was making is by the time the vehicle goes into production there is very little redundancy and fail safe and certainly not a proper system
sorry i thought you meant minor roads rather than poor driving conditions
Yes.
Handle With Care !
If
You do not know that. Or if you do, please explain how?
See comments above.
Please show your workings for that.
I have already given one example of a 1990’s VW with a proper fail safe system that relies on real time self diagnosis.
Yes, I used to love that feature of PCC/ACC speeding up to the new speed limit.
It was only as part of adaptive CC so if there is someone in front of you it won’t breach the minimum following distance.
I think there was even a setting that you could choose whether it did it or not (agreed that’s not ideal for cab hoppers).
i haven’t said it was i haven’t said it wasn’t i am giving a plausible explanation as to what could of happened.
if the signal wasn’t in range then the limited fail safes would of kicked in and i don’t mean turning on a silly light on the dash.
the example you gave was of a single component that probably didn’t have any checking of its self. the system would of been linked to several other components maf map tps etc that would of had very rudimentary checking. the fail safe would of been either to turn on a silly light and carry on regardless or to go into limp mode. The two tracks were probably run in parallel and are there to avoid bad connection due to twisting.
how many times have you heard of a car going into the gararge to be plugged into the scan tool to be told oh its your lamba sensor? they clean it and the fault is still there so they replace it and the fault is still there. Simply because the fault is else where in the system but the brain has no control or clue about. All it knows is the reading isn’t 1. (14.7:1 is binary 1)
As i said when you gave the example of your vw proper systems have things in triplicate ie three of everything i don’t mean 1 sensor with three lots of gubbins i mean three sensors that have had proper quality control from three different batches. which will be connected with three separate harnesses whose connectors will be from three different batches to three different bits of electronics that compare the signals… etc etc. oh incidentally it will also be outside of the rose legislation as well which automotive doesn’t fall outside .
The sheer cost of this even if the engineers wanted to do it wouldn’t get past the budget committee and even if it did you certainly wouldn’t be able to pick up a car for 30k
i never gave it the chance to see if the distance control would stop it. i was straight on the brake turn the bloody thing off and leave it off. I was once told i was supposed to be using it which was soundly ignored. Had they insisted on it i would of asked for proper training. Telling me to rely on some other electronic system to save it is not good enough training in my book.
I am the driver not some electronic piece of kit. I have also heard companies getting rid of drivers because they relied on the systems rather than their ability and reporting them for due care and attention.
In fact several places i have worked get around all this by telling you to use the system when it is safe to do so, In other words we can bollock you for not using it and bollock you for using it.
The system looked at the two tracks in a single component. It saw a discrepancy in the two readings, so went into limp mode.
It is there to avoid a false “full steam ahead” or “stop” signal.
It would recognise (but not distinguish between) faults on the track, or in the loom.
What is a “proper system” varies on application.
In mechanical engineering all calculations are made then a Factor of Safety is added.
You might just double or triple everything! Or in weight sensitive areas, such as aviation the F of S might be much lower, but pilots are normally better trained than drivers and tend to obey VNE more than drivers do.
Triple sensors? Uncommon at least? Where is that seen? Power stations?
Too right.
They are driver aids not automated drivers.
Totally agree.
I agree it depends on the application of the product. in bridges and metal structure you have bending moments which have a government /official body leeway all this is calculated by the cad system. To be honest i did look into this when building my vehicle ramps for the rover and other cars but i lost 2 weeks trying to learn how to use the cad package and what half the numbers meant.
However we are talking about life critical stuff like planes… military equipment… guidance systems the list is endless all these systems are also exempt from rose and other h&s guidance cars for some stupid reason do not fall under this category.
I just see it as a different method of controlling the truck. You can instigate full throttle acceleration by either putting your foot on a pedal or pressing a button on the steering wheel. Both are equal examples of the driver being in full control. (I personally am happy to exclude the possibility of a medical incident rendering the driver incapable of switching off the button or reducing pressure on the pedal).
agreed the point i was making is where the truck decides to accelerate because it has seen a road sign or its decided when to slow down to a predetermined speed for a roundabout and decides when to accelerate out of the roundabout and at what rate.
I see that as still the driver being in full control having made the prior instructions to the truck that it will accelerate/decelerate to the new speed limit or road conditions.
Just up to the driver to know the capabilities of the truck and all it’s controls.
E.g. I still prefer Mercs that have both ACC and plain CC compared with Scanias that only have CC or Dafs that only have ACC
is that with or with out the crystal ball that allowed him to see the circumstances of the road and each roundabout he was going to encounter. or what about the mini roundabouts that the system didn’t know about
Bridges and buildings are also safety and life critical !
…The reaction of ‘The System’ shall, at the discretion of the Type Approval Authority, be checked under the
influence of a failure in any individual unit by applying corresponding output signals to electrical units or
mechanical elements in order to simulate the effects of internal faults within the unit.
The verification results shall correspond with the documented summary of the failure analysis…
https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:42023X0401
If a manufacturer wants to sell a car it must comply with all the relevant regs and bear the “E” mark.
They can’t just make stuff, sign off their own work, and sell it.
This isn’t the US Aerospace industry!
Agreed.
Don’t assume that the systems are better than they are. They are more clever than putting a brick on the throttle pedal.
But not as clever as the driver. (hopefully)
Just set the following distance to zero, and it tells you it is CC not ACC.
so joe bloggs comes along and plugs the component into a test rig. and the test rig has put it through its paces and checked all the bits its programed/ designed to check. so what its got a kite mark doesn’t mean that component wont fail at some point in its life. It also doesn’t guarantee that joe bloggs is competent and is doing his job 100% correctly 100% of the time.
as i mentioned earlier there is an “emissions scandal” still going on the ecu was kite marked in fact im betting all the components were didn’t stop the manufacturers from doing it.
Nobody has said that failures never happen.
Failure should be designed fail safe but even then fail non-safe is possible. This is true.
100% safe is not real.
Safety is about reducing risk to a minimum.
Zero risk is a good, but impossible target.
Someone bashing you over the head with a fire extinguisher, does not mean that fire extinguishers are a bad thing.
Such use of them is scandalous! 
some may disagree there
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years ago when diesels became more main stream i seem to remember a string of reports about diesel runway. 99% of people had the brains to deck the clutch and coast to the side of the road. These modern cars you cannot do that. I posted on a separate topic the other night where someone asked if you can buy a proper petrol merc turns out you cant even buy a manual anymore they are all auto’s. If you are going to eliminate the human element ie the driver then you have to have proper built in safe guards which are a darn sight more relevant than the stuff thought up in the 60’s with the odd bit tacked on.