A safety device?

[anewguy]

I don't know how much such a thing would cost to make, but if someone has some plans somewhere I'd be game to try:

I'd like to see about building some sort of battery powered device sort of like a short range radar for lack of better terms. I'd like to put this on the bike I eventually build so that if it detects someone say within 15 feet of me or so (when turned on) I could trip a relay to power on some sort of lights to remind them I am there.

Any ideas?

Thanks!
Dave :)

[TheKid]

How about a motion sensor for security cameras?

[anewguy]

How about a motion sensor for security cameras?

That just might work! Thanks!

Dave :)

[Sparky]

motion sensors work off heat signatures. any difference in temperature from the overall norm trips it.

theoretically, if room temp was 98.6 degrees, a person wouldnt set it off. also, if you have 2 cars, a white and a black one side by side on a sunny day, the black one heating up faster will trip the sensor.

all this to say- good idea. but i suspect it would be going off ALL the time, unless you had a way to make the sensor near-sighted and only "see" 15feet or so.

there are such things as proximity sensors. but i dont know anything about them- they might not work for that.

[AtomicZombie]

Yes, motion sensors use a dual element pyro sensor that can detect the passage of heat from one element to the other. Even if it worked, it would be going off non stop.

There are many sonar solutions available that can easily connect to a microcontroller, but range will not be good enough for you...

http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/CategoryID/51/List/0/Level/a/ProductID/92/Default.aspx?SortField=ProductName%2cProductName

I think the solution toy your problem will be a complex one indeed. I did something close to this on a robot once, but it required an onboard P4, multi channel capture system and some massive machine vision coding. Even after all of that, it could only detect a face if the person was withing a few feet and very still.

If you do find a solution, I will be very interested.

Brad

[anewguy]

Yes, motion sensors use a dual element pyro sensor that can detect the passage of heat from one element to the other. Even if it worked, it would be going off non stop.

There are many sonar solutions available that can easily connect to a microcontroller, but range will not be good enough for you...

http://www.parallax.com/Store/Sensors/ObjectDetection/tabid/176/CategoryID/51/List/0/Level/a/ProductID/92/Default.aspx?SortField=ProductName%2cProductName

I think the solution toy your problem will be a complex one indeed. I did something close to this on a robot once, but it required an onboard P4, multi channel capture system and some massive machine vision coding. Even after all of that, it could only detect a face if the person was withing a few feet and very still.

If you do find a solution, I will be very interested.

Brad

Indeed, sensors such as you point to would work if you could get a trigger distance of 15 or 20 feet (I admit I didn't read the spec sheet yet to know the limits!], and in combination with a stamp module the basics aren't bad. The rub, as I'm sure you know, comes from the idea that unless at a dead stop on the bike, there would be no fixed area to judge the distance on. Exactly how to combine bike speed into the equation so as to accurately get the actual distance between objects isn't quite so easy. Perhaps a censor to detect speed of the rim in conjunction with the sonar and a little programming? Perhaps better added into the equation is if the object is getting progressively closer once detected at a threshold - that may not require a speed detection and consequent computations.

This would be all new to me, as my little electronics experience has never entailed this type of thing, but it might be fun.

The more I think of it, a "trip" at a certain proximity combined with the object getting closer may be all that is needed. I guess relative to bike speeds, the distances the sonar would travel would be relative and should be easier to set a threshold for - setting sensitivity for average speed first would probably result in a more accurate system. Trip a relay out one of the serial pins and on comes the lights.

Sounds TOO simplified, so PLEASE, point me to the bigger picture so I can increase my knowledge!

Thanks!

Dave:)

[anewguy]

Okay, here's a crazy idea. Can a depth finder as used on a boat somehow be adapted?

Dave :)

[AtomicZombie]

The magic questions would be...

- how much do you want to spend?
- how large of a device do you want to carry?

Brad

[anewguy]

The magic questions would be...

- how much do you want to spend?
- how large of a device do you want to carry?

Brad

Well, given my situation, the answer would have to be not much to both! :) As you can tell, I've got no real clue about any of this, so I rely on the input of experts such as yourself for guidance. It would appear right now that perhaps this might be too big of a project for me?

I did find an interesting article that perhaps can be adapted to todays electronic components?

http://www.swtpc.com/mholley/PopularElectronics/Sep1964/PE_Sep1964.htm

These handheld units have a range of up to 200 feet.

Thanks much Brad - it's greatly appreciated! BTW - I feel awkward calling you Brad when it seems like you are more deserving of something other than a first name with everything you have done here for bikes, etc.. Would Mr. Brad be out of order? :)

[xPosTech]

Hi guys . . . long time no talk . . .

I think the answer to your question is available if you do a little research and are willing to scrounge around Goodwill and other second hand/resale outlets.

Years ago, before robots, Polaroid needed to measure distances to automatically set the focus on their increasingly user friendly instant cameras. Their answer was a small self contained sonar unit (actually audar - "audio detection and ranging"). Early robotics pioneers adapted the unit to proximity detection. Used Polaroid cameras became cheap with the advent of consumer digital cameras a few decades later.

Since the OP only needs either "too close" or "never mind" detection, I'm sure there is a solution using the guts from a Polaroid camera. The sonar unit was powered from the Polapulse battery in the film pack (wonderful technology BTW - Lots of current) of about 6 volts, so can be powered easily.

The unit sent out an ultrasonic pulse and then listened for the echo. If it got an echo, it measured the time it took for the pulse to get to the "bogey" and return. All this without a computer, although some digital circuitry was used. Ideal application for a cyclist's "too close" scenario.

My meds haven't kicked in yet this AM :cool: or I would try to find a circuit that would fill the bill. It's hard to sit and type for any length of time but I'll see what I can dig up later.

I'm back
(with my original user name)

Ted

[AtomicZombie]

http://www.acroname.com/robotics/info/articles/sonar/sonar.html

Brad

[savarin]

would this be any use?
http://www.metacafe.com/watch/814500/radar_gun_hacked/

[John Lewis]

How about the low tech solution. A helmet or standard rearview mirror and a manually operated switch. :)

John Lewis

[anewguy]

I like the helmet and rear view mirror idea - just a couple of pieces missing -> a manual switch and the lights it would turn on! :)

Actually, in my initial searches I had seen something on the Polaroid camera thing but didn't understand it. Seeing the kits available and their price is tempting. But, first things first. I'm going to be starting a temporary part-time work from home job for handicapped people, so I'll have a little money in a couple of months after I pay some of my local bills. therefore, I hope to be able to actually purchase the bike plan (the deltarunner trike) in November now! Will go from there on acquiring parts, etc., for the bike, then look into this sonar solution - it may be just what I'm looking for. Being only a self-taught (and not very well!) person on electronics, there is some of this stuff would take me a while to learn, so when the time comes I may cheat and ask for help here, as Brad and some of the rest of you seem to really know this stuff, and I have no clue!

Brad - can't remember if I asked before, but outside of double rim wheels and 40 spokes, will that plan require "extras", maybe like gussets or something, to be able to support a 350lb handicapped 6'3" guy like me? :)

Thanks again Brad and all the rest of you. I'm glad a friend referred me to AutomicZombie when I told him I was interested in building a recumbent bike!

Dave :)

[anewguy]

I went by our local Goodwill to see if they had any Polaroid cameras, but no luck. However, I remembered having some sort of instant camera at home on a closet shelf, a camera I haven't used in several years. Lo and behold it is a Polaroid - something called a OneStep Express.

Does anyone know if this camera has the board in it I would need? I noticed it seems to have a small censor of some sort, but I don't know if that has to do with the flash. I know it took Polaroid 600 film packs. If this is the correct camera, does anyone have any idea how to get it apart, as it seems to be all molded together?

Thanks again, everyone!

Dave :)