Autonomous headlamp design

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Autonomous headlamp design

Postby Floyd » Aug 14, 2014 6:19 am

Hi all,

I am an electrical engineering student currently undertaking a third year design course. The project I am designing is an autonomous caving/mining headlight, detecting the environment’s ambient light to accordingly adjust the output light intensity and frequency. This will allow for hands-free operation, with the goals of saving power, increasing safety and convenience, as well as a more accurate colour reproduction of the dark environment. Some of the other features considered are the control characteristics of the light, type of light, weight distribution of the circuitry and a disable function to allow manual control of the light

I found a similar product ‘Petzl Nao’, unfortunately only after my design proposal was accepted. Their product measures the reflective light of its own beam which gives a small sensing angle and disregards light from the surroundings (e.g. from other cavers). Also there product comes with a $200 price tag (my market research on this product has everyone saying the price tag is its major flaw) for a max 355 Lumens. If the use of LDR's proves to be sensitive enough, I believe mine would be much more cost effective.

Also talking to a caving instructor in New Zealand, he said that he took a flame into a cave once and gave a realistic 3D feel to the environment. That's why I have a manual colour adjustment for the user.
Has anyone ever used a colour other than white light that gave a much more realistic visual of the environment?
At this stage I am trying to gather as much information as I can for the design. So far I am planning to use ~3 CREE XM-L/2 LEDs (possibly with multicolour LEDs), and simple optics with basic LDRs for light sensing. For the batteries, I will probably use 18650s or AAs, and a microcontroller to handle the logic of the dimming and colour variation. I am wondering if these are good choices; any feedback or ideas would be of great assistance.

Cheers,
Floyd
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Re: Autonomous headlamp design

Postby Caving Guru » Aug 14, 2014 6:53 am

Very cool idea. When I was first reading your post here I thought that your idea was original but I had forgotten about the Petzl NAO until you mentioned it but I am sure that you thought up the whole creation of such a light yourself on your own. The Petzl NAO only goes up to 355 lumens which is not very bright in my opinion for a caving headlight when you can encounter huge rooms and very tall passages in caves which I wish a headlight like mine (the Petzl Ultra which goes up to 400 lumens) could illuminate better. If you were to make a headlight that went up to 1,000 lumens and would adjust to the environment then I would be interested in buying a product like yours. I am sorry that I am not able to answer your questions though. I wish that I could though. If I had the skill set to make something like this and had thought of this idea myself, I would definitely be interested in taking the time and effort to make this a reality.

The El Speleo Headlight (originating from Croatia) seems to be the best caving headlight on the market right now. I do not own one personally but from all the caving headlights that I have seen other cavers use, it seems to be the best one being up to 1,000 lumens, having a very wide angle light projection, and being cost effective in my opinion at around $400 which is a lot cheaper than say the Scurion which goes up to 1,000 lumens and costs $1,000. I hope to save up enough money one day to buy an El Speleo Headlight but at the moment I have a limited amount of money that is not enough to buy an El Speleo Headlight.

If you were to base your design off of a headlight, I would suggest that you base it off of the El Speleo Headlight. As the El Speleo website says so themselves, "The best caving light on the planet. Used on expeditions in the deepest and longest caves in the world" (http://elspeleo.com/lights-cart/35/neutral2000-detail).
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Re: Autonomous headlamp design

Postby LukeM » Aug 14, 2014 9:48 am

Speaking to the subject of light color and seeing the most detail in the cave environment, there are two factors that will help with this - LED tint/color rendering index (CRI) and the placement of the light itself.

The light placement can't really be changed since the head is the most practical place for it, but as you can imagine moving it to the side, like when it's in your hand, will allow shadows to come to life and more clearly define the environment.

A flame is nice for illumination because it has a very warm tint which is pleasant to the eye, gives you full color rendition, and a nice wide area of illumunation. Cavers who use or have used carbide lamps are very familiar with this. A large flame will like a torch will also dance around giving some life to your surroundings. When it comes to LEDs the highest CRI you can find is around 92, and those suffer some from being less efficient/powerful and pricier. Many LEDs - often the brightest, most efficient versions - have a harsh, blueish tint and low CRI. Many mainstream headlamp manufacturers don't seem too concerned about that even though it makes colors appear dull and flat and provides poor depth perception. A good compromise between efficiency and color rendition is to use an LED with a neutral or warm tint that has slightly less efficiency than the top-tier bins.

You won't really gain anything from providing outlandish colors like red or green, although they can be a cool novelty and have some uses (amateur astronomers like to carry red lights when stargazing so their eyes don't lose their adjustment to the dark). I can imagine a low-power red light would be nice for camp trips where you don't want to disturb other people resting nearby.
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Re: Autonomous headlamp design

Postby Oddball » Aug 14, 2014 12:34 pm

LukeM wrote:
You won't really gain anything from providing outlandish colors like red or green, although they can be a cool novelty and have some uses (amateur astronomers like to carry red lights when stargazing so their eyes don't lose their adjustment to the dark). I can imagine a low-power red light would be nice for camp trips where you don't want to disturb other people resting nearby.


I have always pondered the prospect of making a headlight with 4 (or maybe six) lights that pointed at a 90 degree to you main light's orientation in maybe a red as not to affect others around you. The main priority was the one facing down at your feet, as I have, and sure plenty of you have, tripped over something small what was not illuminated enough because your main light was pointed to the front and not your feet. Or just the strain of negotiating some places and being tired of looking down at your feet the whole time.... Is my concept making sense or am I explaining it wrong?
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Re: Autonomous headlamp design

Postby caver.adam » Aug 14, 2014 12:40 pm

As for color, I've used cold white, warm white, and red in the past. A lot of which temperature of white you use is based on personal preference.

Red lights don't tend to ruin your night vision as much as white lights. When the number of lumens you could get in a cave was limited (before these nice CREE LEDs) you might use a red light in small passages or on breaks in order to preserve your night vision for when you got back into bigger passages. Not very useful these days.
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Re: Autonomous headlamp design

Postby Floyd » Aug 18, 2014 11:27 am

Hey guys, thanks for all your replies, they have all been extremely helpful in formulating a final design concept, which I have included in the following link.

If you can spare 3 minutes to fill out a quick survey about the product for the quantitative part of my market research that would be greatly appreciated and any additional feedback can be posted here or in the survey if you see any major flaws.

Thank you in advance.


https://www.surveymonkey.com/s/VX5CC6R
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