Automatic dimming bicycle light help! – University Major Project.

Discussion in 'The Projects Forum' started by AdamMortlock, Nov 21, 2013.

  1. AdamMortlock

    Thread Starter New Member

    Nov 21, 2013
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    Hi guys,

    Warning! I am no Electrical wiz!

    I am a (BA) Product Design student studying at the University of Derby. I am currently going through my major project research module, I have evaluated the market and found a need for an automatic light switching device between two different LED’s (mimicking a car full beam/ dipped beam light setup) I want this product to automatically do this through the sensing of its surroundings.

    I have done research into Photodiodes, Accelerometers and Reverse-Biased LED’s, I want to be able to make this product change through either the monitoring of the light using a reversed biased LED (to know when a car’s lights are coming towards it, or going into street lit areas) or the use of an Accelerometer to monitor movement in the surrounding area for objects moving faster or slower than the cyclist, but not stood still. I will be running this product from a set of rechargeable batteries (early on in the project so not sure specifically on types Li-on most likely, something giving around 2300mAH)

    As I say I really have little experience in this (If any), I hope someone could give me help/ advice in what is realistic in a solution for this project, I understand I have not given much to go off. Obviously the smaller and lighter the solution the better.

    I will check back on here very regularly (every couple of hours) and look forward to see what you all know! Please if I am going completely up the wrong street with the technology I have already looked into or this is an unrealistic project please tell me!

    For a bit of inspiration: http://www.kickstarter.com/projects/1670187625/seesense-the-intelligent-bike-light-with-road-sens this is a light that is a more complex version of what I am trying to do (I think)

    Thanks for your time,

    Adam.
     
  2. poopscoop

    Member

    Dec 12, 2012
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    Light detection is the easiest solution. Do you intend to use a micro controller? How many sensors would you like? One on the front/back/top etc?

    This can be done in hardware using a handful of IC for cheap, but depending on the flexibility you desire a uC may be a better option.

    Once you make that decision you can start deciding whether to use a LDR, a phototransistor, photodiode, etc.
     
  3. AdamMortlock

    Thread Starter New Member

    Nov 21, 2013
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    Thanks for the help! I think a sensor for the front is all I need, as long as it covers the width of the beam (no more than 100 degrees) I think some kind of duel sensor? to stop it dimming for temporary light sources (false alarms)

    Thanks,

    Adam.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Light sensing will be a big challenge in my opinion, because of the difficulty of discriminating between different sources. Is the incoming light a point source from a cyclist's dim headlight, or is it reflected from a sign or from a car far down the road, or a streetlight? Maybe moonlight?

    My wife's Camry has the auto-dimming feature. It works but is just barely acceptable. It's fair to assume that Toyota engineers used a state-of-the-art approach, so getting this same level of performance from a DIY solution seems unlikely to me. It's worse when you consider that the range of things to discriminate is wider for a bicycle rider than for an automobile on a highway.

    I would think an ultrasonic rangefinder might be able to "see" objects that are not stationary. But you'd need a computer to recognize such a pattern.

    I wonder if an easy way for the rider to dim the light isn't the better solution. Humans are REALLY good at pattern recognition, and are usually bored while riding the bike anyway.
     
  5. MrChips

    Moderator

    Oct 2, 2009
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    I think you need three photosensors, one to measure light intensity from a narrow viewing angle coming towards the rider, a second to detect cars coming from behind and the third to measure ambient lighting.

    LDRs would do.
     
  6. wayneh

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    FWIW, I believe some systems use modulation of the headlight to allow eliminating triggering on reflected signals, which carry the original modulation.
     
  7. mcgyvr

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    Oct 15, 2009
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    So if I've read this properly you simply want to have a 2 function (high/low) bicycle light and a light sensor.. When the sensor is "seeing" light lower than "X" it will turn on the bright light and when detected light is higher than "X" it will turn off the bright light..

    Just a simple comparator circuit switching on the high beams when needed and done..
    Not sure why it needs to be any fancier than that.
     
  8. gerty

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  9. wayneh

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    Ambient light sources completely confuse such a device. Street lights, neon signs, reflectors, and on and on. Just drive around and turn off your brain so you can see the lights the way a sensor would - they're everywhere. An oncoming bicycle headlight is not very bright and is rarely pointing directly at you, it "flashes" as it moves around. If you were alone on a dark, country road, maybe it would work.

    Heck, look how many drivers can't seem to figure out how to control their brights.
     
  10. mcgyvr

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    I assumed this was for a bicycle to dim when approached by an oncoming car?
    As such I would think that it should be fairly easy to pick a set tipping point where its very clear there is an oncoming light directly into the sensor.. Ambient light will cause the sensor to see "more" light but not enough if the point is chosen properly to dim the brights..

    I understand exactly about ambient light,etc.. but wouldn't think it would be a problem if the tipping point is chosen properly..

    Maybe its for bicycle to bicycle intervening only..
    Or course I've never heard of any "bicycle rage" problems because of "that a-hole blinded my with his pee wee herman light so I ran him off a cliff" either.
     
  11. wayneh

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    Good point, I was thinking this was for everything else BUT an oncoming car, which as you know is a more "defined" source to trigger on. I could be wrong, but I can't imagine any bicycle headlight - typically 6W or less - being bright enough to bother a car driver in the oncoming lane.

    As usual, it comes down to speculating on the design specs.
     
  12. mcgyvr

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    as with any project... The devil is in the details..
     
  13. bwack

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    Nov 15, 2011
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    This topic on "oncoming blinding lights" comes up on a bicycle forum quite often. Not exactly rage, but it is mostly annoying and when the light is pointing forward I'd say I'm actually blinded by them in some cases.

    The problem is that all the amount of efforts put into shaping the car beam is not put into the beam shaping of the bicycle light. .. and then there is the more affordable high power lights from china that cyclist are buying these days.

    Car lights have strict regulation for the beam and amount of stray light allowed in certain zones around the beam. In England you must use lights for left side driving.. On a cars headlight bulb you can see that the top of the glass is coated to stop light from the bright source escaping onto oncoming. Some of those projection lamps in modern cars use a blinding plate set in the focus plane between the source and aspheric lense to shape the beam... The blinding plate (if it is a plate) is what gives that sharp cut-off in the beam.

    None of this concerns are implemented in the high powered and so ever affordable bicycle LED lights, unless you are in Germany where also bicycle lights are regulated.

    Many cyclists push the light down. It's better and i must say I'd rather have an annoying light oncomming on me than not see the rider at all.

    Better optics will solve the problem and as a bonus you will get more lumens hitting the road rather than spoiled.. You get away with a smaller light (less heat to sink) and a smaller battery. Check out the Philips lights. The output is pretty impressive for the power usage. On offroad cycling, stray light is welcomed.. This guy explains the Philips Safelight better than me :) http://www.youtube.com/watch?v=7fXA1wdm-bQ .. There are other similar lights too that are road legal in Germany.

    It's better to have better optics. Then you get most of the light down on the path in front of the bike, then you will get away with less power and a smaller battery. Anyway I like the project and it sounds fun. You could have a sensor in a tube with a lense (perhaps cylindrical) to only let lights in the height of head lights enter the sensor........... I looked at the kickstarter project with rear light automatical dimming when cars come up to it.. This is not a problem. Cars when they come up to the bicyclist the driver will not be sitting behind the cyclist for long. The other thing is, why is this a problem for cyclists and not cars? Are you sure cyclists will buy such a product when they use whatever shines the road for the cheapest money?
     
    Last edited: Nov 21, 2013
  14. wayneh

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    I see the point but I would counter that a bicycle headlight needs different features than a car headlight. The orientation of a car's light, relative to the road, is far more predictable than that of a bicycle which must use subtle steering changes to maintain balance. This tends to swing the beam horizontally a few degrees at least. I wonder if you could employ gyroscopic steering of the beam to keep it steady on the path. Sort of the opposite of the steered headlights that some luxury cares have. I wonder if I just uttered a patentable idea.

    Vertically, the only excuse for dispersion I can think of is to compensate for sloppy alignment of the light onto the bike.

    Finally, the bicycle light is as much a "be seen" light as it is meant to illuminate the path. I think they throw more light around so as to be seen from more angles than a car driver needs. A car driver is mostly concerned with lighting the path ahead.
     
  15. mcgyvr

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    And as with anything in the world.. "most" people will just buy the cheap light or whatever product it is..

    Its marketing and conveying the "benefits" of a product that makes a consumer buy the "better" product.
    Or just slap an "apple" on it and all the suckers will come running to buy it.
     
  16. wayneh

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    A lot of work and delivering on expectations repeatedly over decades went into making that icon synonymous with a desirable product. Try using your own pear icon and see how it goes for you. ;)
     
  17. mcgyvr

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    I knew that comment would get at least one of the "fanboys" panties in a bunch... :p :D
     
  18. wayneh

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    Yup, it's too easy! :p

    I agree that "cheap" is the easy sell. Anything more requires a story and/or an educated consumer. It's a tough hurdle.
     
  19. mcgyvr

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    The best "sales" information I ever got was
    "No one cares about features...Sell them on the benefits"
     
  20. Metalmann

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    Dec 8, 2012
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    "I've never heard of any "bicycle rage" problems because of "that a-hole blinded my with his pee wee herman light so I ran him off a cliff" either."




    Yeah, but idiotic human nature; never lets me down.

    You know, first time for everything.;)
     
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