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Analog Angle Blog

Can a Car Be ‘Over-Sensored’?

I was reading the very favorable review of the seventh-generation Chevrolet Corvette in The Wall Street Journal (available here, although it may be behind a paywall) and all its impressive high-tech features. In addition to discussing the outstanding performance and ride, materials selection, construction subtleties, and more, I saw one paragraph that made me really stop, wonder, and then even worry a little. It read:

In order to better calibrate the behavior of the various adaptive driving modes (weather, eco, tour, sport and track) — modulating no less than 12 vehicle systems including the electric steering and magnetic adaptive dampers — the Stingray Z51's 19- and 20-inch wheels (front/rear) are fitted with tiny temperature sensors, because warm tires behave differently than cold tires. But because these sensing thermocouples heat up more slowly than the air inside the tires, their signals go through a special temperature-estimating algorithm before they are processed by the driving-mode head office.

(Source: GM)

(Source: GM)

Note: “Z51” is the Corvette's optional performance package.

Whoa… In addition to the now-mandatory tire-pressure-measuring subsystem, this car has an advanced temperature-measurement subsystem in the tires. It's more than just the thermocouples and basic data-reporting, too; it has additional data-processing algorithms, which take into account the different thermal time constants of air versus tire. No doubt this is made possible by the combination of low-cost, integrated sensor analog front ends (AFEs) in tandem with associated microcontrollers and non-volatile memory.

(Side note: I'd be interested in finding out why they chose thermocouples rather than solid-state sensors, as thermocouples don’t endure vibration well, and the modest temperature range here could have been handled by non-thermocouple sensors.)

It certainly is an impressive level of sophistication, and I am sure it provides an extra edge of performance near-perfection. But I wonder: Is all this really needed?

First, it does add some cost, and there's an unavoidable cascading chain of costs that usually crops up, beyond the parts themselves: design-in, qualification, BOM and sourcing, assembly, test, and more.

Secondly, there are post-sale issues. Sensors, as with any component, can fail or drift out of spec. While gross failures are usually detectable for sensors, it's often hard to tell when they are performing within spec or have drifted outside tolerance. So now you need additional algorithms to try to figure out if the reading is valid or not, and more complexity and code. Perhaps the vehicle will be recalled by the vendor because some non-critical, secondary or tertiary-level subsystem needs its code and algorithm adjusted? Will the dealer's test setup have to also be fairly advanced to accommodate testing all these new and unique functions? The list of questions can get pretty long, for sure.

Of course, there are places where more sensors, associated circuits, and firmware can improve safety (airbags and anti-rollover systems are two such cases). But you do have to wonder: Is too much of a good thing perhaps not such a good thing, after all? Just because you can sense everything and try to act on the data, should you? Or is that just setting the stage for an excessive number of headaches in the future?

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34 comments on “Can a Car Be ‘Over-Sensored’?

  1. Max the Magnificent
    August 27, 2013

    @Bill: Is too much of a good thing perhaps not such a good thing, after all? Just because you can sense everything and try to act on the data, should you? Or is that just setting the stage for an excessive number of headaches in the future?

    As always I am in two minds about this — on the one hand I like the idea of having a stripped down system with no sensors whatsoever (I don't have electric windows or central locking on my truck) because there's less to go wrong.

    On the other hand, if you have lots of sensor data (and you know how to use it) you can dramatically increase efficiency and safety and all sorts of other things.

    Last but not least, I don't think we have a choice — I think we're haeding for a world where there are sensors EVERYWHERE … cars are just an obvious target…

  2. Bill_Jaffa
    August 27, 2013

    There's also the issue of long-term maintainence–will you be able to get parts, calibration information, test processes, etc in 10+ years for all these sensors and their related circuity and firmware? That's going to be a challenge–and a car like the Corvette here may change owners over 10, 15 years, but it won't be scrapped, it will be sold, resold, inherited, etc.

  3. Max the Magnificent
    August 27, 2013

    @Bill: There's also the issue of long-term maintainence

    Good point — the building in which I have my office is about 15 years old — the lift (elevator) doesn't work because they can no longer get the parts … give me strength!!!

  4. RichQ
    August 27, 2013

    Whenever I read something like this I think of a line from one of the Star Trek movies where Scottie has disabled the ship that was going to pursue the Enterprise, showing Kirk a handful of modules and saying something like “The more complex the plumbing, the easier it is to stop it up.”

    The same is true in cars. I think that such things really are overkill in terms of adding function to the car.

    On the other hand, it may not be as bad as it seems. THe fact there are temperature sensors in the tires does not mean that they are measuring things in fractional degrees and computing the ideal handling characteristics. It could be something as simple as measuring a binary hot/cold condition and running a preconfigured adjustment to handling based on a simple decision tree. Sure, the marketing sounds like it is doing something fantastic, but the reality might be very, very simple. In that case, there is much less to go wrong, no need for calibration, and no big deal if the sensors fail altogether.

    I still think it's overkill, but perhaps the implementation is not as brittle as it first seems it would be.

  5. BillWM
    August 27, 2013

    My old truck was like Maxes truck — stick shift, crank windows and only a single transistor module in the ignition circuit — It ran beautifully for 160Kmiles and was still running in the old neighborhood for years after that —

    My newer truck although it is much larger, has many sensors and features and CAN and LIN buses everywhere, and does get a bit better mileage than the old truck.   However I have had more electronics malfunctions in that new truck — The stepper motors in the instruments went out – the engine caught fire once, the radio quit and the power mirrors and windows are held together with duct tape litterally due to not being able to get a matching door,and not having the computer to “Mate” the new door with the old truck myself.  The ABS brakes have failed once as well. The dealer always charges a fortune for repairs if I take that route — I really need to keep that truck, as I have torn ligaments in one leg and it is the only way to make the 8+ hr trip to see my children.

  6. Bill_Jaffa
    August 27, 2013

    Max, the non-repaired elevator is really being left that way to encourage employees to do what's good for them and take the stairs, and also save energy (elevators, especially older ones, are energy hogs). So please understand it is a benefit, not a problem (or bug)!

  7. Max the Magnificent
    August 27, 2013

    @William: …The stepper motors in the instruments went out – the engine caught fire once, the radio quit and the power mirrors and windows are held together with duct tape

    Don't tell me that your nickname for your new truck is “Lucky” 🙂

  8. Max the Magnificent
    August 27, 2013

    @Bill: Max, the non-repaired elevator is really being left that way to encourage employees to do what's good for them and take the stairs

    I have no problem taking the stairs (especially since — even when it was working — I could crawl up the stairs faster than the elevator woudl run) … but it's a mega pain when you have something heavy to carry … like the ASR-33 Teletype Terminal (with integrated paper tape reader and writer) that I picked up this past weekend.

    I was panting a bit when I got to the top of the stairs on the 32nd floor, let me tell you…

  9. BillWM
    August 27, 2013

    I know my new bigger truck will tow my books and equipment to a new job (I consult) and it also will haul a good load of large test equipment internally, and still have room for an assortment of tools and even a first aid kit.  The old truck was pretty much only good to tow about 1500lbs.   The other interesting thing is the truck even gets better mileage in town than the old mini-van with the crappy seats that killed my back and legs so baddly.

  10. Vishal Prajapati
    August 27, 2013

    I think more the sensors, more the headache. Untill something doesn't get standardised by international bodies, the more sensors is overkill. Like OBD-II standardisation will keep giving us the long term support as well as backward compatibility. This way we will not have to worry about future support.

  11. vbiancomano
    August 27, 2013

    Just give me a basic car, Detroit, one that runs flawlessly for at least the first 100k-miles without needing so much as new brakes. That'll be a greater challenge for you, automotive engineers, than adding ever complex electronics systems that might well need a backup if THEY fail.

  12. Davidled
    August 27, 2013

    ->I think that more the sensors, more the headache.

    That is true as system is more complex. But in the other view, more the sensor, vehicle is more intelligent with safety feature.  Vehicle diagnostic spec might be updated every OEM. Based on sensor input, engineer can manipulate all the features of vehicle to improve the vehicle functionality.

  13. samicksha
    August 27, 2013

    I was little surprised when i read the subject of blog “Can a Car Be'Over-Sensored'? which made me curious to read the entire blog, i still remember my first car in 1999 which was hatchback by Deawoo (Matiz), it did not had any parking alarm, reverse gear alarm, air bag or any heavy gadget, now i own Hyundai (i20) with updated features, GPS and many more and believe me sometimes it makes me feel irritated, although fact is there are N number of things added for your security..but we have built our brains to do easier jobs and i was doing easier job in my old car.

  14. Davidled
    August 27, 2013

    I agree how you feel for too many features. Also, some feature is a redundant for other clients.

    However, customer has always learning curve until system is comfortable for their usage. Once customer know the full features, they knew how system is beneficial their life and safety. For example, there are some features: emergency call, BT connection and GPS tracking to locate POI. These features are very helpful for customer.

  15. eafpres
    August 27, 2013

    Hi Bill–you surely have opened Pandora's ECM here (ECM = Engine Control Module)!  A random set of thoughts on this:

    1) All modern big-name automotive OEMs don't put anything into production without contracts to procure service parts for around 10 years.  Sometimes those are purchased at the end of the model year run–say a unique part runs for two years, at the end of year 2 they get a special quote from the supplier for an SPO build (SPO=service parts operations).  That is one reason parts cost so much–in many cases SPO is sitting on inventory for a decade or more.  So it may be expensive but you should be able to get parts.  I can still easily get all parts for my 1998 4Runner; in fact for popular models (the super Vette may not fall into this category) 3rd parties step in and make OEM eqivalent parts (generally mechanical/body parts) for even longer time frames.

    2) I own a certain prestige British brand car, whose marque was bought by a company in India, and who was in a partnership with Ford at the time my car was made.  Keeping up a long tradition of excellent cars with terrible electrics, mine had sensors for everyting, plus automation like retracting the steering wheel to make it easier to get in out, and nearly all of it has failed.  I had erroneous coolant warnings and brake fluid warnings, electric windows that stopped 20 mm short of full up (nice on rainy days), the ABS failed, I'm sure due to a senosr, and with it the electronic traction control, which causes faults to constantly fill the OBD memory and overwrite my digital dash with warnings, so I can never see the mileage, or see the fuel economy (oh, there were sensors for that…), and the battery is killed deader than dead every winter becuase the parked discharge rate is way too high due to feeding all those extra electronics whether I need them or not and regardless of whether the car is running or not.  So if you are going to over-sensor, don't do it in a British car, please!

    3) Something is very fishy in the story on the tire temperature.  Something as delicately tuned as described would need to know what kind of tires you were using, and many other things, to be useable.  So the likelihood it returns the right values seems near zero.  I agree with the comment it is probably marketing hype.   In fact, it would not surprise me if the “temperature” is not a thermocouple at all, but is a measurement that comes for FREE with the tire pressure sensors.  They have to compensate for temperature to read the right pressure, so they are probably just using that.  But some marketing hack let some engineering star tell him/her an exciting sounding feature story, and the rest is history.

  16. RedDerek
    August 28, 2013

    What is discussed in the new Corvette will “wow” the layman. I look at it from how everyone else seems to be looking.

    1. more complex = more potential problems

    2. Is it really looking at all the fine steps and if the temp goes up 1 degree, will you really notice the change if it was not working.

    3. With all the potential problems, the shops, especially the dealers, get more business.

    4. And in 10 to 20 years from now, I do not believe the cars will be on the road because the parts may not be available. And if so, one would have to buy the module and not be able to swap the IC. Can we say MONEY, MONEY, MOOONNEEYYY?

    I am pushing 400k miles on my '88 Bronco II right now. And it is over 25 years old. I have had to do some rewiring and it looks like some circuitry work soon.

    As for repairs, that will have to be another blog – analog sensors – get real.

  17. samicksha
    August 28, 2013

    Wow for sure @Red, they are consuming this complement since 1953, apart from this, the weight of the new Corvette was reported to be 1,562 kg meaning it would weigh more than the previous generation's C6 ZR1 model 1,508 kg. The ZR1 C6 weight, of course, included a supercharger and intercooler on its 6.2L engine, curious to see whats hidden in C7.

  18. Vishal Prajapati
    August 29, 2013

    @DaeJ, I agree the more the sensor, vehicle is more intelligent with safety feature.

     


    But untill they are verified in the field tests for long period of time to check its reliability, the safety feature can become troublesome.

  19. CarlWH
    August 30, 2013

    Hi Everyone,

     

    An interesting topic. Temperature and pressure are related, (see Boyles law), so TPMS systems, (direct ones), are aware of this fact.

     

    Are cars over sensored, I would argue no. I would say they can be badly made and designed, but that is not the sensors fault. We all hark bark to the days when we could fix them ourselves, get under the bonnet and tinker with the carbs for optimum perfomance. The days when if you hit something, the lack of inertial seat belts would cause internal injuries, or you would hit the steering wheel with your head, or the regular trips to the gas station to feed the tank with the leaded fuel.

     

    Ok a bit over the top, but the advancements are benefiical, or seen as a market differentiator. Unfortunately, car electronics has evolved and if you were starting from scratch you maybe would have done thing differently. Look at the amount of ECU's in a car, or the lines of code. A car has now more electronic cost than mechanical, and the push for realiability is on going. Yes there are bad examples, but this was true even before the electronics.

     

    Cars have to be more economical, and the way we use them will change, (Google's driverless car had one accident in 300k plus miles, and that was when it was parked and someone ran into it). By the way, have a think why Google would push for driverless cars.

     

    Motor industry demands at least 10 years support from its suppliers. Typically they have a developement time of several years for each model and new technologies will not be deployed until they have been thouroughly tested, (yes I know there have been problems). They work on their brand, and do not wish to damage it with recalls and bad publicity.

     

     

  20. SunitaT
    August 31, 2013

    It certainly is an impressive level of sophistication, and I am sure it provides an extra edge of performance near-perfection. But I wonder: Is all this really needed?

    @Bill, I dont think we need so much of sophistication but such features definitely helps the car manufacturers to improve their sales.

  21. SunitaT
    August 31, 2013

    now i own Hyundai (i20) with updated features, GPS and many more and believe me sometimes it makes me feel irritated,

    @samicksha, that is probably because you felt comfortable driving your old car which had very less sensors. I think many people who are first time car buyers prefer smartfeatures inside their cars because it improves the riding experience.

  22. SunitaT
    August 31, 2013

    However, customer has always learning curve until system is comfortable for their usage.

    @Daej, good point. I think people want smart features inside their car because it improves the riding experience and improves the security. I am sure once the customer is aware of all the features he will definitely use those features if he finds it useful.

  23. SunitaT
    August 31, 2013

    I think we're heading for a world where there are sensors EVERYWHERE

    @Max, I totally agree with your opinion. In future all the cars be fitted with multiple sensors. “Zero sensor” phrase might become the USP of car companies because by default all of them will have the sensors.

  24. SunitaT
    August 31, 2013

    Untill something doesn't get standardised by international bodies

    @Vishal, I agree with you. I think the standardising them will definitely help the end users because they can easily get the sensor parts incase they stop working. I am curious to know if such standards already exist.

  25. David Maciel Silva
    August 31, 2013

    In addition to the now-mandatory tire-pressure-measuring subsystem, this car has an advanced temperature-measurement …

    Long ago I started a project development for this purpose, was to apply off-road trucks in mining, were many tests but the tire pressure was too high and should not have as wires, communication failure was very much missing data ease.

    That was in mid 2004-2005, today I see many products with this purpose, low cost, do not know are effective, but are very presentable …

    http://www.amazon.com/Dorman-Solutions-974-001-Chrysler-Pacifica/dp/B001UC72UI/ref=lp_2201763011_1_2/186-4288022-4157569?ie=UTF8&qid=1377986966&sr=1-2

  26. Cookie Jar
    September 4, 2013

    I can't believe it.  Using thermocouples and a quirky a special temperature-estimating algorithm in this day and age.  I would have considered using an IR temperature sensor so it would read the temperature of the tread of the tire hitting the road.  Why use a simulation if you can read the real thing?  But then again the sensor window would be affected by dirt, rain, snow and mud.

     

  27. SunitaT
    September 6, 2013

    It is assessed that TPMS would reduce the amount of yearly vehicle crash accidents by about 120 and the yearly number of wounds due to vehicle smashes by around 8,500, when all vehicles are well-equipped with TPMS.

  28. Brad_Albing
    September 21, 2013

    @VP – Probably you won't see sensors being standardized to the extent you would like.

  29. Brad_Albing
    September 21, 2013

    @Will – just to clarify, Max is the crank, not the windows so much. HTH

  30. Brad_Albing
    September 21, 2013

    @Vince – can't wait to see what happens when we get drive- and steer-by-wire. That'll be a thrill….

  31. vbiancomano
    September 21, 2013

    A European (?) car maker announced a week ago it's going to develop a self-driving vehicle that does 90 percent of the work. “AUTO-mobile” indeed! I hope to be long gone by then…

  32. Brad_Albing
    September 21, 2013

    @Vince – well you don't have to drive one of those vehicles – by which I mean owning and driving a car is not mandatory – you can take the bus.

  33. vbiancomano
    September 21, 2013

    With high-technology taking all the pleasure and self-reliance out of doing even the smallest things, I'd rather be thrown under the bus….

  34. Brad_Albing
    September 22, 2013

    @VB – careful what you wish for….

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