Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Technology

Rear View LCD? 60

Posted by Cliff from the but-I-want-an-in-windshield-hud dept.
pctainto asks: "I'm doing some work designing a solar car for a certain unnamed university. We are contemplating installing a camera and LCD system to replace the rear view mirror, since it is hard to turn one's head in the car and it would make designing the cockpit much easier. Does anyone know of a camera/LCD system that would be relatively simple and would be able to survive for a few hours without needing a new battery? We need something with relatively high resolution, so, something like an x10 camera wouldn't work very well. (You have to be able to identify letters that are 20 cm high from a distance of 15 m)"
This discussion has been archived. No new comments can be posted.

Rear View LCD? More

Rear View LCD?

Comments Filter:

  • No answer, but... (Score:2, Insightful)

    by darsal ( 18194 )
    Do you really need to be able to identify letters in a regular rear view mirror? They look all wombly to me.

    Anyway, most of the signs around here have the letters on the front.

    • The issue is not so much being able to read writing, but that the clarity of vision you require to read lettering (should it be there) also implies that you are able to see other objects on the road around you sufficiently well to drive safely. Of course it may also be useful to be able to note down the license number of other road users who by their own dangerous driving involve you in an accident then speed off.

  • Are you talking about installing this "intead of" your rear view mirror?

    If you replace the mirror, how will you handle a malfunction on the interstate, in rush-hour traffic??? What happens if a connection goes out, or the screen just up and dies? (LCDs just "die" more often than CRTs) You'ld want to run it off of the car battery to insure constant power, and to do this you'ld probably need to use a B&W LCD...Color is just too power-hungry and the high resolution requirement puts a huge draw on the power as well.

    It sounds like a neat idea at first, but I don't think I want my safety riding on an LCD and a cheap camera...

    I think a blind-spot camera could be good, but not as a replacement for the rear view mirror...I doubt it would pass most state inspections anyhow.

    What about modifing a Marine Radar [marineradar.net] ...it's more information than you'ld usually have, and if it suddenly stops working, you won't DIE.
    • If you would read the post, you would notice that this if for a SOLAR car, hence no battery and it's not for cruising around picking up babes, but for some competition in all likelyhood. And yes, it would completely replace the rear view mirror.
      • SOLAR car, hence no battery

        I don't know of many "solar cars" that don't at least have a small battery attached...or you couldn't run the car on a cloudy day...can we say "Stop and go driving" :)
    • "I'm doing some work designing a solar car for a certain unnamed university. We are contemplating installing a camera and LCD system to replace the rear view mirror, since it is hard to turn one's head in the car and it would make designing the cockpit much easier."

      ...

      if it suddenly stops working, you won't DIE.

      If you're driving an experimental solar powered car, so cramped for space that you can't even turn your head, in rushhour traffic, as Princess Leia said: "You're braver than I thought!"

      When solar powered cars are run on the highway, they tend to be the only cars on the road.

      They require a lot of care, and a tremendous amount of maintenance. The lcd-rear-view does not sound very robust, but, from the article as posed, I suspect that its the least of their problems.

      Note to submitter: Until you grasp the difference between Comfort Systems (i.e. your mp3 player) and Safety Systems (i.e. rearview devices) please keep your car off my road. Thanks :)

    • Ugghh, almost finished this post, got distracted by other things, come back, and find someone else has already gotten to this:

      anyhow:

      First, you're not going to instantly DIE if your rear view mirrors suddenly vanished. Secondly, although the article does not absolutely say where this vehicle will run, I doubt it will be on a busy interstate. Deducing that this car is a university design project, and that he only needs it to run off of batteries for a couple of hours, I suspect this solar car will be used on a closed track.

      Also, LCD rear view cameras are already in use. My favorite motorcycle uses them.

      http://popularmechanics.com/automotive/sub_coll_ le no/2001/8/recycled_jet_setter/index2.phtml

      They are also used on some larger vehicles where a well placed camera is much more useful that any mirror.
      • First, you're going to instantly forget to close your bold tags. All joking and prodding aside, I really don't see a problem with using LCDs for an electric car (or any car for that matter, all things considered). LCDs have good enough longevity and MTBF to warrant their use, as well as market penetration and availibility. LCDs are permentantly mounted in some vehicles, as the parent pointed out, but their use is not limited to state of the art jet powered street bikes. Most police forces have an installed laptop (Toshiba ToughBook is a popular product), Garbage haulers often have a camera mounted in the back (whether they use an LCD is unknowenst to myself, but it's a possibility), and the applications aren't limited to just these vehicles.
        The major problems with LCD, as I see them: any modern LCD setup is going to cost a fair ammount of weight. This includes camera, cabling, power cables, the LCD unit, mountng hardware, and the battery that's going to power it. Having something modern like that stands out (good or bad way, folks), no doubt, and would be very cool indeed. However, since this is a competition, it would be best to choose the most efficient solution (if cutting drag from removing mirrors in their design has a net benefit--energy efficency wize, then it's the best solution). It also depends on what the particular goal of this test is; if the goal is win at all costs(monetary)that sure changes things, when compared to whether or not budget is a consideration. As an engineering principle, though, it's probably best to follow this rule of thumb: KISS (Keep It Simple, Stupid), many problems can occour from over-engineering something, especially in a project as sensitive as this.

        Perhaps they could even get a donation (and possible engineering help or consultation) from one of the major manufactures for their project, if they stuck a sticker on their car or something...
        • ---snip
          First, you're going to instantly forget to close your bold tags.
          ---snip

          Heh, I was so disgusted coming back to the machine to find that everyone else had now posted about LCD's being perfectly reliable that I didn't bother previewing. Doh!

          In any case, I do not think the weight of the LCD remote will be that significant in the overall scheme if this car will be carrying a 150lb driver, and especially if it will be carrying any batteries intended for the drivesystem. The camera/LCD/cabling/separate battery pack could easily be done under 10lbs. Get a 10lb lighter driver if you are concerned about the weight.

          It's already been stated that using a conventional mirror will not work; there goes the simplest solution. Something used on some limousines before closed circuit TV was practical was a periscope arrangement...it would probably still weigh as much as the LCD/camera combo, and then you would not have the absolute flexibility of placement that the LCD/camera route would give you.
      • Secondly, although the article does not absolutely say where this vehicle will run, I doubt it will be on a busy interstate.

        My thoughts exactly. Every time I've seen electric/solar college competition vehicles on a public road, they've always had lead and chase cars.

    • If you replace the mirror, how will you handle a malfunction on the interstate, in rush-hour traffic??? What happens if a connection goes out, or the screen just up and dies?

      You'd do the exact same thing that every trucker and RVer does -- do without. It's not that critical.

      • You'd do the exact same thing that every trucker and RVer does

        Only if you have wide mirrors like Truckers and RVers...I don't know of many vehicles that could be considered a "car" that are equiped with wide mirrors...
    • If you replace the mirror, how will you handle a malfunction on the interstate, in rush-hour traffic???
      Simple, they install a redundant system that includes a cranial rotation device. You may have heard of it, it's called a neck, turn it and look out the window.
      • If the car has bucket seats, it'ld be nearly impossible...and if they are using a 5-point harness instead of an over-the-shoulder seat belt (I think these should be in every vehicle's front seat), you CAN'T look out of the rear window.
        • People who have such a setup usualy also have somehow covered or shaded their rear window (because of the sun or just for coolness), so they couldn't use their internal rear view mirror anyways.
      • That's gut-busting! Should have been wrapped in the tags.

        Seriously, what do you do if your mirror falls off the windshield (glue goes)? Does the car explode? No. A proper car can rely on properly aimed side mirrors and the human neck to give a pretty good indication of what is going on on the road. If LCDs or HUDs were so problematic, they wouldn't be in use by the military now.

        And I for one would like to banish the darn rear view mirror from its location in my Mustang. I find it actually occasionally blocks my vision somewhat out of the FRONT window. If I could drop in a HUD system (see through) or an LCD in the center of the dash above the radio, that'd be even better without restricting front visibility!

        And I'll have to be sure to check my backup cranial-rotation system before I head out next time... want to make sure it is ready in case I need it! :)

    • ObJoke (Score:2)

      by Cadre ( 11051 )
      If you replace the mirror, how will you handle a malfunction on the interstate, in rush-hour traffic???

      ObJoke about the 'typical' rush-hour driver not caring the slightest about anyone behind them when they change lanes...

      To the poster: just swap out your driver right now with somebody from LA or DC and then you can just save yourself some money.

      • DC? (Score:2)

        by Andy Dodd ( 701 )
        I've driven in DC. Except for downtown (Which, like Arlington, doesn't seem to be contained entirely in Euclidean space), it's not that bad.

        Boston, on the other hand... YIKES.

  • It's heavier, consumes more power, etc... (Score:3, Interesting)

    by stienman ( 51024 ) <adavis@@@ubasics...com> on Thursday September 05, 2002 @08:37PM (#4203821) Homepage Journal
    Other solar car teams install these things (4-5" lcd, rearward facing camera) for a variety of reasons. It can provide a smaller cross section for wind resistance, and the camera and lcd can be placed more conveniently.

    However, these same teams end up turning them off because they are practically useless (they put them in to meet requirements, but don't engineer them to actually work well), and they consume precious energy. In some cases more than would be wasted by placing a proper aerodynamic mirror externally.

    So they turn them off (against the rules) for the best of both worlds - lower wind resistance, lower power consumption - but at the risk of being disqualified.

    Furthermore, there is allready so little room in the cockpit, do you honestly think you can find a good place to put it? Outside the window is not only convenient, but frees up precious space inside the vehicle.

    That being said, you'll need to look for a nice high resolution camera (broadcast quality tv or better) and matching LCD. These will be very expensive, but solar cars aren't cheap and I'm sure you can find someone to donate one.

    Look particularily at what large motorhomes use. A local RV store ought to steer you in the right direction.

    -Adam
    • Comment removed based on user account deletion
    • So they turn them off (against the rules) for the best of both worlds - lower wind resistance, lower power consumption - but at the risk of being disqualified.

      I understand how turning off the camera/lcd systems saves power, but I'm curious how it reduces wind resistance. It seems like both for aerodynamics and for protection of the system, you would put the camera behind clear a clear plastic window shaped to match the contours of the body panel. Thus, nothing sticking up into the wind whether on or off. What am I missing here?
      • From the way I parsed it, you're missing the fact that they use a LCD+camera system instead of an external mirror, since the latter affects wind resistance. So by going with a power hungry but aerodynamically friendly LCD+camera system, and then just turning it off, they get the best of two worlds. Except for the added mass, of course. Does that make sense?
  • The S7 is street legal and has a live video rear view mirror. It shouldn't be too hard to see how they did it. It might be expensive though -- the car costs $375,000.

    http://www.saleen.com/auto/S7/S7con.htm [saleen.com]
    • American cars suck. period. You want hi tech and hi performance? Try a REAL car - Buy German. Audi has a concept coupe that has a rear view LCD.
      • Well, the staff car that we have parked downstairs (a Nissan Maxima) has one built into the dash. The display is normally used for things like the radio station and external temperature, but when the car is put into reverse it displays a colour image from a camera pointing backwards. It's a production car (not concept) and costs less than $300k too.

  • The obvious solution seems to be.. (Score:3, Interesting)

    by Mad Quacker ( 3327 ) on Thursday September 05, 2002 @08:43PM (#4203849) Homepage
    A small periscope type system?. You can get the rear view to a comfortable viewing angle without power or wind resistance, for the weight of a few mirrors. Adjust the mirrors' size/shape to get a good field of view.

  • It sounds nice, and I've heard of similar ideas before (placing cameras at the base of the A pillar looking backwards, and colour displays inside), but here's my question: how would you then reproduce depth perception? Even with the mirrors on my tiny hatchback, the mirrors allow me to easily determine the distance between myself and other cars behind me. I wouldn't be able to do that with a two-dimensional image.

    • Even with the mirrors on my tiny hatchback, the mirrors allow me to easily determine the distance between myself and other cars behind me. I wouldn't be able to do that with a two-dimensional image.


      Umm, looking into the mirror you are looking at a 2d image.

      • You're looking at a reflection of a 3d image. If you look into a mirror from 2 different points, you see 2 different things. Since depth perception comes from your brain's analysis of the view from 2 different points (your eyes), you do indeed have depth perception in a mirror.
        • You may have depth perception, but not necessarily stereoscopic depth perception. This actually came up yesterday in the article about the Geowall 3d projection system:

          "Stereoscopic vision works most effectively for distances up to 18 feet. Beyond this distance, your brain starts using relative size and motion to determine depth."

          http://www.scec.org/geowall/stereohow.html
          • Mod Bazzargh up. If you can perceive depth on a television broadcast you can perceive it on a LCD rearview mirror setup.
          • I don't know about your brain, but there still seems to be depth perception after 18 feet and the brain seems to care about it.

            It obviously varies from person to person and what they've been training their brains and eyes to do.
            • He wasn't saying there wasn't depth perception, but that beyond 18ft your brain starts using different methods to obtain the depth information
              • Yah but my point is there still seems to be a difference in depth perception when driving with two eyes vs driving with one eye. Tried it some time back to see how it would be like.

                So I get the impression that stereoscopic depth perception is still present beyond 18 feet.

                I dunno, try it yourself if you can. Maybe it's just my imagination.
  • If you don't, it might throw people off . . .
  • I can't read 20cm letters at that distance in the rearview on my car unless I hold the damn thing still.

    • I can't read 20cm letters at that distance in the rearview on my car unless I hold the damn thing still.

      That's probably the fault of the mirror, not the concept. Most rear view mirrors are mounted on stems which have a tendency to amplify vibrations in the car.

      So lets go over the needs for a moment... .2m @ 15m at about 6 pixels of resolution (the minimum I'd need to make out a letter). That's .033333m per pixel @ 15m, which is .1273 degrees (or about 7.6 arc-minutes). Looking at some pinhole spycams, I see 400, 420, and 430 line resolutions commonly. At those resolutions, you'd need at most a 50, 54, and 55 degree lens, respectively, to make out the letters at that distance. Absent from the requirements is an indication of what angle the lens needs to view.

      Thus, from a basic spycam with good resolution hooked up to a standard lcd pocket tv you should be able to get what you need. A digital webcam is probably far more than you need, in this case.

  • why not just use seethrough solar panels? (see www.sta.com.au) - DSC dye-sublimation solar collectors are cool!
  • You're probabbly out of luck for an electronic solution, for two simple reasons:

    1) Depth Perception. Obviously, a single camera is not going to give you any sense of depth perception, so it could be very difficult to judge distances.

    2) Focus. A camera is going to need to focus on a particular distance away, which will not be particularly helpful when attempting to drive any sort of vehicle: Anything particularly far from that focused distance will be fuzzy, unidentifiable, and difficult to nail down an exact position for.

    • I agree. The other thing that crossed my mind at first is the focus change your eye has to do as well as the camera. I heard it mentioned that LCD headsets (for VR) give the user a headache after a while as the eye is focused at one depth for such a long time.


      With the usual rearview mirror, the eye is focused at a relatively long range on cars etc. from looking through the windscreen, and as the mirror is reflecting light from behind the car, your eye is still at the same focal depth when you look in the mirror... if you had an lcd it would be focused on something a meter away (at most) as opposed to many meters away


      I wear reasonably low powered glasses to drive, but sometimes notice this change when I look down at the speedo


      can anyone with neccessary physics background confirm this?


      - James

    • 1) Depth Perception.
      Only good to about 18 feet.
      2) Focus.
      Ever hear of a fixed focus camera? Should be able to stay in focus unless you get really really close (at which point a camera wont matter now will it?)
  • A friend of mine wanted to do this with his car, but with three cameras. Rear view, left rear, and right rear. (The selection was controlled by the use of the directional signal.) The only problem was that drivers wanted to watch the LCD rather than driver the car. :-(

    A quick search with YFSE returns places like Marshall Electronics that produce plug and play solutions. A 4" active LCD will set you back about $225, but, will draw 400mA at 12 volts.

    That does not include the camera, but those will use only 100-200mA at 9V. The unfortunate part is the camera and a lens to get the ability to read the letters you want to read are going to cost about $400-500.

    Try www.mars-cam.com for more info.
  • I worked on a project for the Future Truck competition. (see futuretruck.org for more info)

    We installed a prototype system developed by the Donnelly Corporation that had a system of cameras (4 in all) and a computerized system that stitched them into a seamless rear-view image.

    The proposed advantages were
    -Wider field of view (less blind spots)
    -A fisheye mode that would automatically switch on when the vehicle was put in reverse.
    -Reduction of drag by removing outside rear-view mirrors

    I believe that the total vehicle weight stayed about the same after we installed the system (The outside rear-view mirrors that we removed were the large stock ones found on GMC Suburbans.
  • You could rig a rear facing parascope. (No, not the kind you see in submarine movies with lenses so that you have to press your face against it. Just use simple mirrors and tubes.) You won't have to worry so much about malfunctions. It also costs less. Plus the image will be usable even on a bright sunny day.
  • Try a camera obscura, it's perfectly suited for
    a solar vehicle. It's light, it requires no electric power source,
    it's solar-powered and you can control the image size.

    You'd have to use a few mirrors to get the image
    the way you want and where you want it and you'd
    have to create a small viewing box. No big deal
    and should be the cheapest way to go.

    In case you're wondering a camera obscura (latin
    for dark room) is more well known as a pin hole
    camera. Anyway it may not be easy to devise one for your
    apllication but it would be worth looking into.
    (no pun intended)

    • other than the fact a camera obscura operates around f128, which is 14 stops less light, which works out to make it impossible to contrast to with normal viewing conditions. unless u add a photo multiplier tubes....
      • f128 is function of the size of the pinhole. It could be made worse or better.
        The physics could be played with, I didn't say it was easy
        and it may not be cheap. But it's solar-powered. They might need
        to use some fiber optic technology as well as lenses and/or mirrors.

Slashdot Top Deals

I have hardly ever known a mathematician who was capable of reasoning. -- Plato

Close