53 replies to this topic

[gruntguru]

Ford's adaptive steering varies the steering ratio to suit road-speed. To do this it uses an "actuator" in the steering column. I assume the actuator adds angular displacement to the driver's input when required (at lower road-speeds).

 

This makes it a partial steer-by-wire. The steer computer does it's portion electrically. Of course it has a mechanical fail safe - defaulting to the "slow" rack ratio if the electrics fail.

 

Greg?

 

http://www.gizmag.co.../32413/pictures

[RogerGraham]

Hope you don't mind GG, I have an additional question for Greg.

 

Greg, about six months ago in another thread (I forget which), you mentioned the sensitivity of steering feel to the weight of the wheel, and even (if I recall correctly) the weight of such things as added switches on a steering column.  From the image GG linked, there's an entire shedload of added weight sitting within the wheel housing, which presumably can't help!  

 

Can you confirm that my sometimes-abysmal memory is correct regarding your earlier post, and comment on what effect all that additional weight inside the wheel might have?

[Greg Locock]

Roger - wasn't me, that I remember. Yes, you are somewhat sensitive to the polar moment of inertia of the steering wheel, but this extra mass is mostly at the wheel centre, therefore has a lesser effect. The big problem is the extra mass, and hence the effect on steering column bending modes.That's basically a dollar problem.

 

gruntguru-there is always a worm gear mechanical link between wheel and column, it's just that sometimes it rotates, We had a nice presentation on this system by the project lead a few months ago.It seems to do what it says on the box, and by the time we saw it they'd already decided on a set of targets for tuning it. I think the real why-buy is the ease of parking, perhaps we'll turn Americans into a nation of parallel parkers!

 

Rather like EPAS, I suspect in 10 years everyone will have it., 

 

Theoretically i prefer the BMW approach with the differential in the column, but that doesn't seem to be taking the world by storm.

[Dipster]

On the subject of EPAS am I alone in finding that it feels different to hydraulic systems? Fact or imagination?

[desmo]

How does one make valid comparison though? Steering feel is a largely subjective value to begin with, how many people have driven the exact same car, with all the other variables controlled, with and without EPAS?  The best you are likely to get is whatever consensus among people that have driven a lot of miles in many cars of both types emerges. I know some people claim EPAS categorically lacks feel but others inevitably disagree.  New technologies--even very good ones--in their initial uses are always disadvantageously underdeveloped compared to more mature technologies in place. Is there any inherent reason for electronic steering not to be capable of any behavior any other system can? 

[BRG]

The current generation of Porsche 911 changed over to EPAS and it was the one thing that most road testers seized upon as the only real flaw with the new car.  They all suggested that there was a loss of feel compared to the previous hydraulic system.

[Greg Locock]

Yes, but those reviewers didn't do a double blind test. Therefore they felt exactly what they were expecting to.

 

However, yes I agree there are some bad. and many average, EPAS systems out there (the same could be said of HPAS of course), and our benchmark for measured performance (you can measure it, just takes time and money) is still HPAS for many sub attributes. Neither journos nor enthusiasts buy new cars by and large, so in fact they are just venting in a meaningless fashion. The new car buyer likes low fuel consumption and very low parking efforts, both of which EPAS delivers. So suck it up.

 

Characterising the steering feel of a car is a tricky job. I don't use the exact same metrics as Lotus, but here is a paper showing an on centre handling test, other important ones are steering sweeps at constant speed, and frequency response.

 

http://www.proteanel...n-Services3.pdf

[RogerGraham]

The current generation of Porsche 911 changed over to EPAS and it was the one thing that most road testers seized upon as the only real flaw with the new car.  They all suggested that there was a loss of feel compared to the previous hydraulic system.

 

Yet in this month's CAR magazine, in a group test of M4 vs 911 vs F-type, the reviewer says of the 911:  

 

We've criticised the steering before, but I'm either acclimatising, it's getting better or these roads a little rough, because I love the consistency of the weighting, the ratio and the info that's coming up the rack.

 

 

Yes, but those reviewers didn't do a double blind test. Therefore they felt exactly what they were expecting to.

 

At the risk of going a little off-topic... that reminds me of something I read in an Aussie car magazine years ago. There was a test day for a new car, and at the end of the day a group of journos decided to test the new writer who was there.  They all talked about some imaginary negative aspect of the car in front of the new guy, who dutifully included that aspect in his article.  To a smaller or larger extent, you wonder how much that same effect spreads through the group of motoring writers.

[Greg Locock]

Sure, but to be honest that's not their fault. To get our assessments of handling to agree, for five different PD centres worldwide, involves a continual rotation and discussion and comparison of evaluators, jolly nice job if you can get it and don't mind travel.

 

No media agency would be able to afford that level of training, although I am quite impressed by the German mag AMS' approach, which does at least track ratings against past reviews and so on.

[Lee Nicolle]

Why are manufacturers trying to reinvent the wheel? An electric motor assisting a rack and pinion while not rocket science is just another drain on the electrical system. I am sure it can be made to work well though testers have not been very positive,, and often report it as electric steering. Hydraulic systems work well and you can cool the fluid as many have been for decades. To cool an electric motor will take more effort. It is surprising how much heat normal driving will heat the p/s oil. Yet alone spirited driving or motorsport.

Speedway and rallying for instance just fries the fluid so what would it do too an electric motor? Yet alone the huge alternator and battery to power it reliably.

[gruntguru]

Lee, I assume you are talking about EPAS and not the variable ratio steering in the OP. Greg covered two big pluses for EPAS - fuel economy and parking assist. Better fuel economy is also the reason the electric motors don't overheat.

1. They are very efficient - typically less than 10% of the power ends up as heat.

2. They only draw power when needed for steering assist, unlike HPAS which is always applying some drag to the crankshaft.

Edited by gruntguru, 07 June 2014 - 08:26.

[indigoid]

At the risk of going a little off-topic... that reminds me of something I read in an Aussie car magazine years ago. There was a test day for a new car, and at the end of the day a group of journos decided to test the new writer who was there.  They all talked about some imaginary negative aspect of the car in front of the new guy, who dutifully included that aspect in his article.  To a smaller or larger extent, you wonder how much that same effect spreads through the group of motoring writers.

 

 

Nothing else would explain their adoration of Holden Commodore IRS

[Greg Locock]

Lee, some recent reviews on electric steering

 

"Responsive steering and sharp handling"

"beautifully judged control weighs and responsive, accurate steering"

" everyone who spent time behind the wheel was impressed with the ... steering and handling"

" the steering is one of its highlights, offering progressive action, darty direction changes,"

 

Just because some companies don't know what they are doing with EPAS doesn't mean nobody does. Some companies didn't know what they were doing with HPAS either. Citreon pioneered the no feel steering, that was HPAS, it just had a spring to give weight to the feel (I'm not saying they didn't know what they were doing in particular, one of the few companies who were consistently interesting).

[Lee Nicolle]

Lee, I assume you are talking about EPAS and not the variable ratio steering in the OP. Greg covered two big pluses for EPAS - fuel economy and parking assist. Better fuel economy is also the reason the electric motors don't overheat.

1. They are very efficient - typically less than 10% of the power ends up as heat.

2. They only draw power when needed for steering assist, unlike HPAS which is always applying some drag to the crankshaft.

Lost me here somewhere. Better fuel economy? That I doubt. Less than 10% of the power ends up as heat? Electric motors produce plenty of heat and draw a fair amount of current that has to be replaced by the power dragging alternator. Ultimatly the total engine power loss may be better, but not by a lot.

As for only drawing powwr when being used well lets face it all drivers are correcting all the time.

 

Gregs comment below are more to the point, it now dawns on me. PARK ASSIST is all this is all about. I am sure it could be done hydraulically too but electric is easier.

I dont need park assist so do not need electric power steering. I can actually drive!

We have been in the era of 3 year throw away cars for quite a while. I expect the expense of repairs will be just another contributor too this.

More than a few of these modern front drive cars just about [and in some cases do] need the engine removed to replace the rack. Generally not very easy.

[gruntguru]

Better fuel economy? That I doubt.

Hard to argue.

[gruntguru]

Less than 10% of the power ends up as heat? Electric motors produce plenty of heat and draw a fair amount of current that has to be replaced by the power dragging alternator.

Yep - got me there too.

[gruntguru]

As for only drawing powwr when being used well lets face it all drivers are correcting all the time.

Of course - silly me!

[gruntguru]

Silly auto makers - seems they're all getting sucked into this EPAS nonsense.

[MatsNorway]

haha. But is the electric motor a brushless DC? brushed motors at 90% efficieny is not likely i think. It still is so little heat that its fine easily.

[Greg Locock]

The problem with HPAS is the PAS pump, which ran all the time, chewing up power. Frankly that is a solvable problem, so to some extent it was laziness.

 

 

During the fuel economy tests the steering wheel doesn't move, so an EPAS uses zero power. Even in real world driving an EPAS uses far less power than an HPAS, the PAS pumps would at best have been no more efficient than the electric motor, and at worst, ie under no load, they are just heating the oil. As you know an HPAS pumps  oil at the maximum flow rate possible through the rack continuously, so it is inherently a lossy system. The assist is generated by closing off (choking) the return line.

Edited by Greg Locock, 09 June 2014 - 00:48.

[Lee Nicolle]

What draws more power? The alternator or the PS Pump? Probably 6 of one and half dozen of the other. HPAS draws very little power when not actually turning. Run and engine then turn left or right and you will hear the motor dragging, and many cars have a sensor to actually 'idle up' the engine on the rack. It seems that racks probably consume more power than a steering box. 

EPAS will have the alternator working harder most of the time to keep the battery up and when the battery dies the car is near undrivable. Batterys in modern cars have about TWICE the Cold Cranking amperage they had 30 years ago and often weigh nearly twice as much. And defenitly cost twice as much!

I feel the main reason for EPAS is park assist. Otherwise it is reinventing the wheel. Modern HPAS are very efficient and reliable. 

Fly by wire PS with no connection to the wheels will have a real struggle to be recognised by most government agencies worldwide I feel. And again as reliable as the electric system and battery. which makes me shudder!

[gruntguru]

What draws more power? The percentage of alternator power driving the EPAS or the PS Pump? 

Fixed that for you.

 

Answer. "The PS Pump".

[Wuzak]

Fly by wire PS with no connection to the wheels will have a real struggle to be recognised by most government agencies worldwide I feel. And again as reliable as the electric system and battery. which makes me shudder!

 

I guess you feel the same about fly by wire accelerators with no connection to the throttle?

[Lee Nicolle]

I guess you feel the same about fly by wire accelerators with no connection to the throttle?

Toyotas not withstanding [and has only cost toymota a $billion!] if the go pedal stops working it is usually not catastrophic. If the steering stops working the accidents get large quickly. 

[Lee Nicolle]

Fixed that for you.

 

Answer. "The PS Pump".

I feel you may be surprised actually. A normal [these days] 100 amp alternator drags a LOT of power when charging. Ask any dyno operator as more than a few have done power runs with and without the belt. Though most modern efi stuff really does require the alternator working for totally correct operation.

On my race cars the alternators are delete,, they caused more grief than anything else so when the rules changed making them optional they became obsolete. Broken brackets, belts coming off, slipping, turning upside down. Fans centrifuging out and jamming, plus a dead short burning  most of the wiring loom. That is an alternator!

Obviously for longer races and computer controlled engines they are needed. But they regularly cause dnfs with all of the above problems. This on club racing and big time too.

Smokey Yunicks wind powered generator was a good idea,, though a modern 75 amp 'race alternator' probably would struggle to turn.

[kikiturbo2]

Lee, some recent reviews on electric steering

 

"Responsive steering and sharp handling"

"beautifully judged control weighs and responsive, accurate steering"

" everyone who spent time behind the wheel was impressed with the ... steering and handling"

" the steering is one of its highlights, offering progressive action, darty direction changes,"

 

Just because some companies don't know what they are doing with EPAS doesn't mean nobody does. Some companies didn't know what they were doing with HPAS either. Citreon pioneered the no feel steering, that was HPAS, it just had a spring to give weight to the feel (I'm not saying they didn't know what they were doing in particular, one of the few companies who were consistently interesting).

 

having been in the automotive journalism for quite a while I am of the opinion that most journos have absolutly no idea about steering FEEL... and feel has nothing to do with precision, accuracy and steering weight.. Fact of the matter is, none of the electric systems currently on sale (and quite a lot of HPAS systems) give no feedback relating to front end grip whatsoever..  and I do realise that steering feel is not all about the rack but has to do with suspension design/geometry...

Edited by kikiturbo2, 10 June 2014 - 11:46.

[Greg Locock]

Yup, one of the important parameters for actual feel is the reverse efficiency of the rack pinion system, which is largely a function of the pinion angle, and the pressure plate loading. So you could have an unassisted steering system that was feelless if you really mucked up. That's probably a level of detail further in than most people go.

 

Of course when we talk about feel I think it is a good idea to try and figure out what it is that we are trying to feel that is not related to the efforts. If I gave you a car that allowed you to estimate from the steering wheel torque how close the tires were to peak grip, and how hard they were working, and nothing else, would that be a good steering system or a bad one? Isn't everything else just noise (as in, not signal)? Oh OK, you also want the steering to pull on split mu surfaces when braking or accelerating.

 

And of course the tires are the dominant controller of feel, by definition EPAS is on modern cars with low rolling resistance tires (they ain't seen nothing yet) which may well have different targets for feel than the older ones.

Edited by Greg Locock, 10 June 2014 - 22:06.

[gruntguru]

I feel you may be surprised actually. A normal [these days] 100 amp alternator drags a LOT of power when charging. Ask any dyno operator as more than a few have done power runs with and without the belt. Though most modern efi stuff really does require the alternator working for totally correct operation.

On my race cars the alternators are delete,, they caused more grief than anything else so when the rules changed making them optional they became obsolete. Broken brackets, belts coming off, slipping, turning upside down. Fans centrifuging out and jamming, plus a dead short burning  most of the wiring loom. That is an alternator!

Obviously for longer races and computer controlled engines they are needed. But they regularly cause dnfs with all of the above problems. This on club racing and big time too.

Smokey Yunicks wind powered generator was a good idea,, though a modern 75 amp 'race alternator' probably would struggle to turn.

A 100A alternator draws about 2 kW when its flat out. EPAS (being slightly more efficient) puts less load on the engine than HPAS when loaded. When not loaded - and that is a lot of the time - EPAS puts zero load on the crankshaft.

 

It doesn't matter how unreliable alternators are - they are already there - can't do without them. If they can be used to run the PS as well, great! Are you seriously suggesting that adding a complete hydraulic system to the car is going to make it more reliable?

[Canuck]

Indeed. And I never had my old BB Chevy spin the p/s belt off. Nope. Never. Didn't happen.

[Lee Nicolle]

Indeed. And I never had my old BB Chevy spin the p/s belt off. Nope. Never. Didn't happen.

Alternator belts are the ones that cause all the problems. A well maintained car will never spit a waterpump or P steer belt unless it has failed through old age,,, or is also driving the alternator. Many engines share the waterpump and alternator on one belt. The alternator is what causes them to do silly things. Disconnect the charging system from the alternator and use it as a belt tensioner and most of the problems go away.

I have sold and serviced cars and commercials for a long time and the alternator belt and alternator is what cause the problems.As well as poor eaths which sometimes fool the alt to charge flat out, or not charge at all. On most brands of cars. They cause more problems than AC belts and drives. The humble PS belt and pulleys seldom cause any grief in comparison. On road cars not beyond annoying usually with squealing belts upon start up and sometimes belt noise too. Though broken brackets are not uncommon at all on many breeds of vehicle. Every belt failure I have experienced in 20 years has been alternator. Though sometimes they will take the others too. The modern serpentine systems which drive everything are a worry sometimes. I have watched them on dyno runs whipping and literally smoking around the alternator but not the other drives.

As for the EPAS not consuming power think again, all cars are constantly weaving driving down the road, worse roads do it more. Think about what you are doing when driving, constantly correcting against road camber, bumps, around other traffic. Try letting go the wheel for more than a few sec and see where you end up. HPAS is hydraulic power, EPAS is electric power which has to be replaced to the every increasing battery size by the alternator. Which will need to be larger [consuming more power] to run another accesorie. Some off roaders are already fitting two alternators of slightly smaller size to make life easier for drives and too have a back up charging system. Especially with two batteries.

Plus the increasing reliance on the electrical system is hardly ideal as a limp home out in the sticks.

Scarey moment for myself,, out in the Queensland channel country a 150 miles [and about 4 hours] from anywhere, do a creek crossing which are about every 4 km and the alternator stops charging,,,,,,oooh ****. Turn everything unnessential off and we are not stopping. Luckily about 1/2 hour later it started to charge again. So while it was a bit tense back to normal. IF the Landcruiser had EPAS that would have been another heavy current draw. The ignition actually draws very little. Even with 2 big batteries the ign, EPAS, brake lights, wipers, 4wd functions   would be making the batteries very sick. Two days later on that trip, a1000km on,  it actually spat the alternator belt off. And that was new the week before. Put the spare on and continued again with reservation though by then we were in civilisation,, no more than about 40 miles between homesteads. And regular traffic every hour or so.

 

So do we really need to put all our eggs in one basket just for park assist? I dont think so!

 

As a matter of interest too. Quite a few racers and hotrodders have gone to electric waterpumps. Most only pump at one speed, usually too fast so are another cause of overheating. A speedway sedan I was associated with fitted one and did not finish a feature race. And the fresh engine was decidedly lazy well before it should have been through being overheated too often. AND it kept flipping the alternator belt. On one occasion taking the PS belt with it. Standard Ford brackets [which have been known to break also] just with a bigger pulley on the alt to slow it down.. In the end after my harping he put the std waterpump back on, suitably slowed for racing and no more overheating! And when the alternator belt turned itself upside down three races on one night we put the simple belt back on between crank and pump and no more grief . For about the remaining 4 shows for the season. 

[Dmitriy_Guller]

As for only drawing powwr when being used well lets face it all drivers are correcting all the time.

Yikes, I just suddenly lost the urge to drive anywhere.

[Canuck]

I would have guessed that the epas is only powered when there's a need, not every time the operator twitches behind the wheel.

[Greg Locock]

The boost curve dies away to zero near 0 SWA to mprove on-centre feel. So the typical lane keeping inputs are virtually unassisted. that's for both HPAS and EPAS. The difference is the HPAS is pumping full flow even at straight ahead (albeit at low pressure).

 

http://liu.diva-port...3027/FULLTEXT01

[gruntguru]

I imagine that belt drive alternators may fade out as hybridisation becomes more common?

[Greg Locock]

https://en.wikipedia.../wiki/Dynastart

[desmo]

I've always wondered why that idea didn't catch on. Fewer components required seems like a Chapmanesque no-brainer. There must have been practical problems with implementing the concept.

[Greg Locock]

It is still used, kindasorta. I vaguely remember there's a GM light hybrid that uses an integrated flywheel/motor/generator/starter. They are trading off mass and cost for packaging efficiency I suspect, modern electric motors and alternators tend to be getting smaller and much faster for the same power, so restricting your electric motor to 6000 rpm may be a bad thing.

[Peter Morley]

Isn't EPAS popularity a result of the stop/start systems being fitted to cars these days (to fiddle the emissions figures) - e.g. it still works while the engine isn't running whereas HPAS doesn't.

 

As with 'electronic' hand brakes there could also be a weight advantage which has now become an issue after all the years of 'safety devices' adding weight.

[Greg Locock]

Dunno, I've rarely found much need to steer when stationary at traffic lights. Weightwise, no the advantage is almost certainly with HPAS

[Peter Morley]

Apparently some people need to reposition the wheels while stood at traffic lights and a lack of hydraulic power could cause them some difficulty.
Presumably they are the same people who use the City setting for power steering - our Fiat 500's normal EPAS setting is so light you can't imagine why anyone would ever need the City setting but presumably they are out there somewhere.

[Lee Nicolle]

I would have guessed that the epas is only powered when there's a need, not every time the operator twitches behind the wheel.

You need the power assistance whatever type at all times. Try driving without it. a whole lot different. Yes minor corrections do not require MUCH power. but it does require power.

 

IF the engine is running EPAS should work at stationary  the same as HPAS. Be damned dangerous if it did not.

 

As for variable speeds. The terrible drivers love very light steering, it goes with their inability to drive!

 

Though as the owner of a 71 Ford Galaxie with over assisted very slow steering light steering is nothing new. Many 50s 60s and 70s vehicles were similar. Though apart from replacing the hoses it is in A1 cond at 43 years old and 160000 miles. I doubt that EPAS systems will do that, especially in the age of 3 year throwaway cars!

[desmo]

Well, I remember cars from days past and in 1971 cars were in my experience generally a lot more "3 year throwaway" then than newer ones today are. It used to be considered something of a marvel for a car to make 100,000 miles and 20 years later the most popular Japanese cars were practically just getting broken in at 100K.

[Greg Locock]

A couple of thoughts 

 

a) building a car that would last 200000 miles is a fair overspend by the manufacturer. As our knowledge of reliability improves do you think we'll move towards a Chapmanesque design philosophy where the whole thing falls apart at the finish line? (what would be an acceptable life?)

 

b) With the plethora of electronic stuff in a modern car is it not likely they'll be scrapped sooner than more mechanical cars? Witness the number of 8 year old BMW 7 series in scrapyards

[Peter Morley]

Electronics will definitely be a major problem with keeping recent cars running in the future.
A long time ago a friend was quoted 1200 euros for a new electronics box for a Toyota that was worth less than that.

I don't know what the current figures are but it used to be that around 50% of a car's total energy usage was in its manufacture, hence keeping a car for a long time is more environmentally friendly and persuading people to trade in a young car for a new 'energy efficient' one was a fallacy.

Edited by Peter Morley, 19 June 2014 - 08:03.

[Dipster]

A couple of thoughts 

 

a) building a car that would last 200000 miles is a fair overspend by the manufacturer. As our knowledge of reliability improves do you think we'll move towards a Chapmanesque design philosophy where the whole thing falls apart at the finish line? (what would be an acceptable life?)

 

b) With the plethora of electronic stuff in a modern car is it not likely they'll be scrapped sooner than more mechanical cars? Witness the number of 8 year old BMW 7 series in scrapyards

On both points 'a' and 'b' Land Rover have been doing it for years. My '98 Defender continues to serve me as it has since new. Still using little diesel (about 35+ mpg - really). No electronics to fail - other than lights all it has is a heater motor and wiper/washers.

 

Edit: And a starter of course! I wouldn't want to swing it over with a handle.....

Edited by Dipster, 19 June 2014 - 08:58.

[Tenmantaylor]

Lot's of racing sims have had similar options for years. For racing I don't like it as you can theoretically hold the wheel at a given position and vary the steering with the accelerator as you change speed through a corner. This introduces an element that requires compensating for. In practice on the road in day to day driving this could well be useful and make driving easier/more comfortable but not good for precision driving in my experience.

[Lee Nicolle]

A couple of thoughts 

 

a) building a car that would last 200000 miles is a fair overspend by the manufacturer. As our knowledge of reliability improves do you think we'll move towards a Chapmanesque design philosophy where the whole thing falls apart at the finish line? (what would be an acceptable life?)

 

b) With the plethora of electronic stuff in a modern car is it not likely they'll be scrapped sooner than more mechanical cars? Witness the number of 8 year old BMW 7 series in scrapyards

Yesterday fitting some new tyres on a late Statesman I managed to break the 'sensor'  attached to the inside of the valve. A several hundred dollar item.

A. I did not even know it was there. I suspect it was broken while breaking the bead. And really the valve 'tits' should be replaced every few years as the heat and dirt causes them to fail.

B. it is so vulnerable making a fairly simple task a lot harder.

C the actual part is WAY over priced. Yes this is just 'bling' [ luckily the spare had one]  but another example of electronic components pricing the car to the scrappers.

[indigoid]

Yesterday fitting some new tyres on a late Statesman I managed to break the 'sensor'  attached to the inside of the valve. A several hundred dollar item.

A. I did not even know it was there. I suspect it was broken while breaking the bead. And really the valve 'tits' should be replaced every few years as the heat and dirt causes them to fail.

B. it is so vulnerable making a fairly simple task a lot harder.

C the actual part is WAY over priced. Yes this is just 'bling' [ luckily the spare had one]  but another example of electronic components pricing the car to the scrappers.

 

This failure (based on your description) has nothing to do with newfangled electronics and everything to do with spectacularly awful design on Holden's part.

 

Presumably the part is there for a reason. With that in mind, it and the wheel should have been designed such that it was safe from the evils of tyre-changing machinery.

 

One of my bikes has tyre pressure sensors in the wheels. Has worked flawlessly for over 5 years now. The transmitters haven't even needed new batteries.

Edited by indigoid, 20 June 2014 - 08:47.

[Canuck]

If that sensor array is anything like mine, now that the spare is missing it's sensor (or rather, there are only 4 active and not 5), there will be a trouble code thrown and a light on the dash. 

[gruntguru]

Got to agree with Indigoid. The redundancy issues are usually deliberate decisions by the manufacturer rather than some inherent issue with the technology or with technology in general. The PC industry makes an interesting comparison. Redundancy is ensured by the pace of development so makers don't need to protect their parts and repair business. Standardisation has lead to competition and low cost and easy repair and upgrade.