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'[EE] Car door sound detection (clapper?) [AVR] too'
2008\05\31@103920 by M. Adam Davis

face picon face
I need to detect a vehicle door closing from a device inside the
vehicle.  This will be used to trigger a telemtry device, and must be
installed by Your Grandma (TM) so it really can't be a switch and
wiring to the device.

Thus I'm trying to develop an algorithm that uses sound (via
microphone) to detect likely door closing events.

I haven't gone out with a recorder yet, but figuring out the
difference between a cough and a door closing in a car with windows
down does not seem trivial.

I'm using the AVR32 UC3 devices, so I've got a bit of processing power.

What sound detection algorithms have you seen, or what ideas do you
have (brainstorm on!) that I should look into?

I'm also using other methods to trigger the device (light from the
interior lighting, accelerometer, pressure, etc) but I'm primarily
interested in exploring the sound detection in this particular thread.

-Adam

--
Save Money * Save Oil * Save Lives * Save the Planet
http://www.driveslowly.org

2008\05\31@105944 by Xiaofan Chen

face picon face
On Sat, May 31, 2008 at 10:38 PM, M. Adam Davis <spam_OUTstienmanTakeThisOuTspamgmail.com> wrote:
> I'm using the AVR32 UC3 devices, so I've got a bit of processing power.
>
> What sound detection algorithms have you seen, or what ideas do you
> have (brainstorm on!) that I should look into?
>

I am not so sure if this can be an inspiration for you (using LPC-2148 ARM7).
http://wiki.sikken.nl/index.php?title=DigitalBatDetector

Xiaofan

2008\05\31@113114 by Herbert Graf

flavicon
face
On Sat, 2008-05-31 at 10:38 -0400, M. Adam Davis wrote:
> I'm also using other methods to trigger the device (light from the
> interior lighting, accelerometer, pressure, etc) but I'm primarily
> interested in exploring the sound detection in this particular thread.

FAR easier, if it works for you, is to detect the engine running.

The difference in noise on the 12V line between a stopped engine and
running engine in a car is profound and should be rather easy to detect.

TTYL

2008\05\31@114022 by Dr Skip

picon face
I once had a Ford with similar as part of its alarm. I would get random
triggers every so often which I attributed to the next car banging me with its
door. I was then at the airport on morning, parked in the deck, and got halfway
 to the building when I heard my alarm, so I went back. No one was by the car.
Rats! Didn't catch them.

Went to the building again and it went off again. Went out and still no one. A
few more times and I saw it correlated with the takeoff of each jet... ;)

The rumblings of the jets did it, and I suspect that it caused it in various
parking lots too along the way. Got to be very annoying once I knew these
outside sounds could trigger the inside sensor meant to detect a percussive wave.


M. Adam Davis wrote:
{Quote hidden}

2008\05\31@120228 by Sergey Dryga

face
flavicon
face
Dr Skip <drskip <at> gmail.com> writes:

<SNIP>
> The rumblings of the jets did it, and I suspect that it caused it in various
> parking lots too along the way. Got to be very annoying once I knew these
> outside sounds could trigger the inside sensor meant to detect a percussive
> wave.
>
> M. Adam Davis wrote:
> > I need to detect a vehicle door closing from a device inside the
> > vehicle.  This will be used to trigger a telemtry device, and must be
> > installed by Your Grandma (TM) so it really can't be a switch and
> > wiring to the device.
> >
> > Thus I'm trying to develop an algorithm that uses sound (via
> > microphone) to detect likely door closing events.
<SNIP>

Fireworks are great to set these alarms off too.  I remember at one fireworks
show about 10% of cars in the parking lot had their alarms set off by the
fireworks.  Majority of these alarm systems were probably commercial and not
used sound but body vibration.

For the "Your Grandma" installation, maybe something like a whoopy cushion can
be put on the seat and connected to a pressure sensor.  Or a piece of tubing
with a pressure sensor, the tubing can be jammed by the door to detect
opening/closing.  

Just using sound will be too noisy (no pun intended), too many false alarms
which will annoy grandma and the system will not be used.

Sergey




2008\05\31@124133 by M. Adam Davis

face picon face
On Sat, May 31, 2008 at 11:31 AM, Herbert Graf <.....mailinglist4KILLspamspam@spam@farcite.net> wrote:
> On Sat, 2008-05-31 at 10:38 -0400, M. Adam Davis wrote:
>> I'm also using other methods to trigger the device (light from the
>> interior lighting, accelerometer, pressure, etc) but I'm primarily
>> interested in exploring the sound detection in this particular thread.
>
> FAR easier, if it works for you, is to detect the engine running.
>
> The difference in noise on the 12V line between a stopped engine and
> running engine in a car is profound and should be rather easy to detect.

I was actually planning on detecting the voltage difference (battery <
alternator) but I need to detect if the doors close even while the
engine is running.

More info about the application:

Every time a passenger enters or leaves the vehicle, or material is
loaded/unloaded I need to capture some small amount of data.  This can
happen while the engine is running, for instance dropping kids off at
school.

There will be a GPS - but detecting passenger/cargo loading/unloading
versus stopping at a stoplight leads to needing multiple triggers -
one of which is opening and closing the doors.

-Adam

--
EARTH DAY 2008
Tuesday April 22
Save Money * Save Oil * Save Lives * Save the Planet
http://www.driveslowly.org

2008\05\31@130343 by Carl Denk

flavicon
face
What about monitoring an interior light, could be the trunk (boot) light
also. They generally come on when a door is opened, though they also can
be manually activated, and usually remote lock unlocking turns on. Could
mount separate switches, they are inexpensive and fairly easy to
install. Switches could be reed with magnet, some wavelength light with
reflective surface. Is this for a particular model vehicle or generic to
be installed in almost any model? The service manual wiring diagrams and
troubleshooting may be a good source of info. Our 2002 Mercury Cougar
has a warning light for doors including rear hatch open. Would be simple
to add an optoisolator.

M. Adam Davis wrote:
{Quote hidden}

2008\05\31@130929 by Timothy J. Weber

face picon face
M. Adam Davis wrote:
> Every time a passenger enters or leaves the vehicle, or material is
> loaded/unloaded I need to capture some small amount of data.  This can
> happen while the engine is running, for instance dropping kids off at
> school.
>
> There will be a GPS - but detecting passenger/cargo loading/unloading
> versus stopping at a stoplight leads to needing multiple triggers -
> one of which is opening and closing the doors.

Sample continuously looking for amplitude peaks of the right duration,
then do FFT on that window of samples and compare spectrum fuzzily
against the average of many recorded samples??

Might be too much processing, and of course there's the "training"
effort, which might be specific to a given model of car.  OTOH, the
sounds seem like they'd be pretty consistent so it might not be too bad.
--
Timothy J. Weber
http://timothyweber.org

2008\05\31@131733 by Picbits Sales

flavicon
face
Pressure sensor.

The pressure wave caused by the door opening and closing is quite suprising.
I built a car alarm based around a simple pressure sensor.

Interior light is also worth considering as a backup ........
Dom
{Original Message removed}

2008\05\31@134548 by Info

flavicon
face
Could we see a pic of the waveform?

-----Ursprungligt meddelande-----
Pressure sensor.
The pressure wave caused by the door opening and closing is quite suprising.


2008\05\31@151102 by Dr Skip

picon face
You could offer a fuse replacement for the overhead light line that includes a
small resistor value and measure the drop, or just measure the voltage across
the fuse. There will be small drop in use.

If the car auto-locks, you could sample that line too. It will re-lock upon
reentry and drive, and will be unlocked to get cargo...


M. Adam Davis wrote:
{Quote hidden}

2008\05\31@154313 by Picbits Sales

flavicon
face
You could if the unit was still around.

I built this from a kit around 20 years ago.

Dom
----- Original Message -----
From: "Info" <EraseMEinfospam_OUTspamTakeThisOuTdatech.se>
To: "'Microcontroller discussion list - Public.'" <piclistspamspam_OUTmit.edu>
Sent: Saturday, May 31, 2008 6:47 PM
Subject: SV: [EE] Car door sound detection (clapper?) [AVR] too


> Could we see a pic of the waveform?
>
> -----Ursprungligt meddelande-----
> Pressure sensor.
> The pressure wave caused by the door opening and closing is quite
> suprising.
>
>
> --

2008\05\31@162840 by Nate Duehr

face
flavicon
face

On May 31, 2008, at 11:17 AM, Picbits Sales wrote:

> Pressure sensor.
>
> The pressure wave caused by the door opening and closing is quite  
> suprising.
> I built a car alarm based around a simple pressure sensor.


Unless a window is open.

--
Nate Duehr
@spam@nateKILLspamspamnatetech.com



2008\05\31@185956 by Brian B. Riley

picon face
But if the door window is open, what happens to pressure then?

On May 31, 2008, at 1:17 PM, Picbits Sales wrote:

> Pressure sensor.
>
> The pressure wave caused by the door opening and closing is quite  
> suprising.
> I built a car alarm based around a simple pressure sensor.
>
> Interior light is also worth considering as a backup ........
> Dom
> {Original Message removed}

2008\05\31@200312 by Jinx

face picon face
> The pressure wave caused by the door opening and closing is
> quite suprising

What if all the windows are open ?

2008\05\31@201335 by Jinx

face picon face
Honestly, I think sound detection is too problematic

How about ....

IR transmitters on the doors. Their outputs are picked up by
a centrally-located receiver. If a door opens, its transmitter
will no longer be received, as it's now pointing outside the car.
Could all be fixed in place with magnets


2008\05\31@221458 by David VanHorn

picon face
When the interior light turns on, there's an easily detectable glitch
in the 12V bus.
This has been used for car alarms since the 70's.
You can see it anywhere on the bus.

You can't easily tell it from other spikes, but then again, does it
really matter?
Engine on and off can be seen from the alternator whine and the
voltage of the 12V bus.

2008\05\31@221634 by Cedric Chang

flavicon
face
Lights that go on when car door is open are too problematic.
Monitoring sound or pressure is too problematic.
I recommend looking at some sort of active scanning.
1)  Look along outside of car for door openings.  Maybe mounted to  
top of front door windows.  Maybe infrared or ultra-sound or web cam.
2)  use webcam and rotating mirror to look at car doors from  
interior.   Perhaps glue mirrors or targets to doors so that you can  
see whether the door has opened.
3)  Easy mount wireless sensors at each door which detect door  
opening.  Wireless can be RF or ultra-sound or infrared.  Sensor  
consumes little battery power until door opens.  Sensor can be magnet  
and reed switch.   OR ????

cc


On May 31, 2008, at 1:10 PM, Dr Skip wrote:

You could offer a fuse replacement for the overhead light line that  
includes a
small resistor value and measure the drop, or just measure the  
voltage across
the fuse. There will be small drop in use.

If the car auto-locks, you could sample that line too. It will re-
lock upon
reentry and drive, and will be unlocked to get cargo...


M. Adam Davis wrote:
{Quote hidden}

2008\05\31@224918 by Dr Skip

picon face
The suggestion was to watch for the drop across a series resistor, different
than looking for blips in the supply voltage. Less problematic perhaps.

BETTER IDEA: Since a stop and open door (a safe one) usually involves putting
the car in Park, and doing so passes "Reverse", and passing Reverse on the gear
shift turns on the back-up lights, then tapping the backup light line will give
you a nice pulse at every stop. Speaking state-ly, the only time a parking
event will occur in error would be putting the car in park and everyone sitting
in the car without opening any door. A rare condition most likely.


Cedric Chang wrote:
{Quote hidden}


'[EE] Car door sound detection (clapper?) [AVR] too'
2008\06\01@005909 by Cedric Chang
flavicon
face

>
>> On May 31, 2008, at 8:49 PM, Dr Skip wrote:
>>
>> The suggestion was to watch for the drop across a series resistor,  
>> different
>> than looking for blips in the supply voltage. Less problematic  
>> perhaps.
>>
>> BETTER IDEA: Since a stop and open door (a safe one) usually  
>> involves putting
>> the car in Park, and doing so passes "Reverse", and passing  
>> Reverse on the gear
>> shift turns on the back-up lights, then tapping the backup light  
>> line will give
>> you a nice pulse at every stop. Speaking state-ly, the only time a  
>> parking
>> event will occur in error would be putting the car in park and  
>> everyone sitting
in the car without opening any door. A rare condition most likely.

Good idea, DS.  What is the easy install method for detecting "park" ?
cc

{Quote hidden}

> --

2008\06\01@022633 by Dr Skip

picon face
Hmmm. The line is usually easy to get to from behind the light. The bulb itself
is usually accessible for replacement, and in reverse would power up then down
(in case you wanted to share the housing).  There are probably various ways to
get at those.

HOWEVER, it may be easier, and grandma (maybe grandpa at least) friendlier to
provide a small rectangular magnet with a pair of clips and double sided tape
to attach to either column or floor shifter, and a reed switch or hall sensor
with double sided tape and the wires for the base around the shifter. Chances
are a thin, black twisted pair will be aesthetically OK and the run to your
electronics will be to somewhere in/on the dash or console so fairly short, and
routable and hidden along the way.

You could provide an 'install mode' on the electronics where they would
position the magnet near the bezel, and then position the magnet while in park,
reverse, or such (Park makes more sense this way). The 'box' would light an led
when it 'saw' the sensor and all was fine with the position. They then just
press and stick it in place. Installed!

If using the Park position, it's just a variation in the signal but same state
idea.



Cedric Chang wrote:
> in the car without opening any door. A rare condition most likely.
>
> Good idea, DS.  What is the easy install method for detecting "park" ?
> cc
>

2008\06\01@153218 by Cedric Chang

flavicon
face
I just thought of something.   What if the vehicle ( as many of mine  
are ) has a manual transmission ?
cc

{Quote hidden}

Cedric Chang wrote:
> in the car without opening any door. A rare condition most likely.
>
> Good idea, DS.  What is the easy install method for detecting "park" ?
> cc
>

2008\06\01@175338 by David VanHorn

picon face
Detecting gearbox position could be problematic.
Brake light on, and battery voltage drop (ignition turning off) might serve.
Brake light state can be tapped at the switch.

2008\06\01@180030 by Dr Skip

picon face
In my observation, very few grandmas use manual transmissions. Some hard core
ones may, but given arthritis, etc, and the availability of automatics, I'd bet
they all pretty much go for automatics.

BUT, since you ask, it's standard procedure to set the parking brake with a
manual trans, unless you want it to roll away when you get out. IF there are
younger consumers involved with manual transmissions, have a 'parking brake
option' programmed in.

Some alarms have multiple sensing methods, so you could have these 2 options
AND, perhaps one to tap into the dome light (many also have under-dash lights
that would make for a hidden tap, OR use a photo-trans/diode/whatever and a
tube shield to 'observe' the under dash or above dome light (non-contact
method). Combine the park sensor with the observation of the door light and
have more info to discern... There's even a brake switch on the brake pedal
lever below to turn the brake lights on. A foolproof 'stop' would be
brakes-then-park-then-light... Less inputs still work, but more might make one
feel better.

Then you can catch grandma tossing grandpa out of the car without stopping too! ;)


Cedric Chang wrote:
> I just thought of something.   What if the vehicle ( as many of mine  
> are ) has a manual transmission ?
> cc
>
>
>
>
>
> Cedric Chang wrote:

2008\06\02@010011 by Cedric Chang

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face
Brilliant !
cc
{Quote hidden}

2008\06\02@064922 by cdb

flavicon
face


:: IR transmitters on the doors. Their outputs are picked up by
:: a centrally-located receiver. If a door opens, its transmitter
:: will no longer be received, as it's now pointing outside the car.
:: Could all be fixed in place with magnets

Well on similar tack, what about flex sensors available form robotics
builders, glue them to the inside of the doors, they should give a
different strain reading between shut and open.

Colin
--
cdb, RemoveMEcolinTakeThisOuTspambtech-online.co.uk on 2/06/2008

Web presence: http://www.btech-online.co.uk  

Hosted by:  http://www.1and1.co.uk/?k_id=7988359





2008\06\02@071210 by YAP

picon face
On Sat, May 31, 2008 at 4:38 PM, M. Adam Davis <spamBeGonestienmanspamBeGonespamgmail.com> wrote:
{Quote hidden}

Use an atmospheric  pressure sensor.

Cheers
/Ake


--
---
Ake Hedman (YAP - Yet Another Programmer)
D of Scandinavia, Brattbergavagen 17, 820 50 LOS, Sweden
Phone: (46) 73 0533 146
Company home: http://www.dofscandinavia.com
Personal homepage: http://www.dofscandinavia.com/akhe
Automated home: http://www.vscp.org

2008\06\02@220356 by M. Adam Davis

face picon face
On Sat, May 31, 2008 at 1:02 PM, Timothy J. Weber <TakeThisOuTtwEraseMEspamspam_OUTtimothyweber.org> wrote:
> M. Adam Davis wrote:
>> Every time a passenger enters or leaves the vehicle, or material is
>> loaded/unloaded I need to capture some small amount of data.  This can
>> happen while the engine is running, for instance dropping kids off at
>> school.
>>
>> There will be a GPS - but detecting passenger/cargo loading/unloading
>> versus stopping at a stoplight leads to needing multiple triggers -
>> one of which is opening and closing the doors.
>
> Sample continuously looking for amplitude peaks of the right duration,
> then do FFT on that window of samples and compare spectrum fuzzily
> against the average of many recorded samples??
>
> Might be too much processing, and of course there's the "training"
> effort, which might be specific to a given model of car.  OTOH, the
> sounds seem like they'd be pretty consistent so it might not be too bad.

Thanks, this is a bit more interesting than what I've been noodling
over.  I'll have to consider this as I get more information...

-Adam

--
EARTH DAY 2008
Tuesday April 22
Save Money * Save Oil * Save Lives * Save the Planet
http://www.driveslowly.org

2008\06\02@222034 by M. Adam Davis

face picon face
On Sat, May 31, 2008 at 8:13 PM, Jinx <RemoveMEjoecolquittspamTakeThisOuTclear.net.nz> wrote:
> Honestly, I think sound detection is too problematic

I think that too, but it can be tried and if successful then it's very
cheap and dead easy to install.  A microphone based glass break sensor
that works in rooms of all sizes, with different types of windows, and
can tell the difference between a glass cup breaking and a window
break uses an 8 bit micro.

So I imagine there's a way...

> How about ....
>
> IR transmitters on the doors. Their outputs are picked up by
> a centrally-located receiver. If a door opens, its transmitter
> will no longer be received, as it's now pointing outside the car.
> Could all be fixed in place with magnets
>

The prototypes will have pressure, light, microphone, acceleration,
GPS, and switch inputs for testing various algorithms and
combinations.

If needed, the production part will have multiple methods, but going
from ideal to non-ideal:
1. Just a box that plugs into a 12V outlet
2. A box that plugs into a 12V outlet with a single device (light or
switch) that can be placed very non-critically and still sense the
desired status change (dome light going on, driver door opening, etc)
3. A box that plugs into a 12V outlet with several light or switch
sensors taped and wired to various locations
4. A box that plugs into a 12V outlet that also taps vehicle wiring
elsewhere, or requires removal of any part/trim/etc to place a sensor.

The IR transmitters sound interesting, and would lie somewhere between
1 and 2 above, but might be tricky to place so that they aren't also
blocked by the passengers or cargo.  Could have other drawbacks, but
I'll keep it in mind.

Given that we have a GPS on the final device, then some situations can
be filtered (during movement you don't need a trigger, so can ignore
wind gust on the freeway for a microphone or pressure sensor, for
instance).

-Adam

--
EARTH DAY 2008
Tuesday April 22
Save Money * Save Oil * Save Lives * Save the Planet
http://www.driveslowly.org

2008\06\02@222738 by M. Adam Davis

face picon face
I'll have to look at the power bus a bit more.  Would be interesting
to see if I can determine the difference from other power spikes.
There's a company near me that does whole house power device
detection.  Place a current and voltage sensor on the main line for
the house and look at the power signature as devices are turned on and
off.

Can detect when the refridgerator starts running, or furnace,
microwave, washer, dryer, various types of lights, etc, etc.  Very
interesting technology.

Would imagine the same can be done to some degree with just the
voltage at the 12V outlet, and used in combination with other cheap
techniques it might be enough.

-Adam

On Sat, May 31, 2008 at 10:14 PM, David VanHorn <microbrixEraseMEspam.....gmail.com> wrote:
> When the interior light turns on, there's an easily detectable glitch
> in the 12V bus.
> This has been used for car alarms since the 70's.
> You can see it anywhere on the bus.
>
> You can't easily tell it from other spikes, but then again, does it
> really matter?
> Engine on and off can be seen from the alternator whine and the
> voltage of the 12V bus.
> -

2008\06\02@223532 by M. Adam Davis

face picon face
I'll have to look at the power bus a bit more.  Would be interesting
to see if I can determine the difference from other power spikes.
There's a company near me that does whole house power device
detection.  Place a current and voltage sensor on the main line for
the house and look at the power signature as devices are turned on and
off.

Can detect when the refridgerator starts running, or furnace,
microwave, washer, dryer, various types of lights, etc, etc.  Very
interesting technology.

Would imagine the same can be done to some degree with just the
voltage at the 12V outlet, and used in combination with other cheap
techniques it might be enough.

-Adam

On Sat, May 31, 2008 at 10:14 PM, David VanHorn <EraseMEmicrobrixspamgmail.com> wrote:
> When the interior light turns on, there's an easily detectable glitch
> in the 12V bus.
> This has been used for car alarms since the 70's.
> You can see it anywhere on the bus.
>
> You can't easily tell it from other spikes, but then again, does it
> really matter?
> Engine on and off can be seen from the alternator whine and the
> voltage of the 12V bus.
> -

2008\06\02@223532 by M. Adam Davis

face picon face
I'll have to look at the power bus a bit more.  Would be interesting
to see if I can determine the difference from other power spikes.
There's a company near me that does whole house power device
detection.  Place a current and voltage sensor on the main line for
the house and look at the power signature as devices are turned on and
off.

Can detect when the refridgerator starts running, or furnace,
microwave, washer, dryer, various types of lights, etc, etc.  Very
interesting technology.

Would imagine the same can be done to some degree with just the
voltage at the 12V outlet, and used in combination with other cheap
techniques it might be enough.

-Adam

On Sat, May 31, 2008 at 10:14 PM, David VanHorn <RemoveMEmicrobrixEraseMEspamEraseMEgmail.com> wrote:
> When the interior light turns on, there's an easily detectable glitch
> in the 12V bus.
> This has been used for car alarms since the 70's.
> You can see it anywhere on the bus.
>
> You can't easily tell it from other spikes, but then again, does it
> really matter?
> Engine on and off can be seen from the alternator whine and the
> voltage of the 12V bus.
> -

2008\06\02@223550 by M. Adam Davis

face picon face
I'll have to look at the power bus a bit more.  Would be interesting
to see if I can determine the difference from other power spikes.
There's a company near me that does whole house power device
detection.  Place a current and voltage sensor on the main line for
the house and look at the power signature as devices are turned on and
off.

Can detect when the refridgerator starts running, or furnace,
microwave, washer, dryer, various types of lights, etc, etc.  Very
interesting technology.

Would imagine the same can be done to some degree with just the
voltage at the 12V outlet, and used in combination with other cheap
techniques it might be enough.

-Adam

On Sat, May 31, 2008 at 10:14 PM, David VanHorn <RemoveMEmicrobrixspam_OUTspamKILLspamgmail.com> wrote:
> When the interior light turns on, there's an easily detectable glitch
> in the 12V bus.
> This has been used for car alarms since the 70's.
> You can see it anywhere on the bus.
>
> You can't easily tell it from other spikes, but then again, does it
> really matter?
> Engine on and off can be seen from the alternator whine and the
> voltage of the 12V bus.
> -

2008\06\02@224010 by Jinx

face picon face
> The IR transmitters sound interesting, and would lie somewhere
> between 1 and 2 above, but might be tricky to place so that they
> aren't also blocked by the passengers or cargo

If an IR transmitter pings into the car space with enough power
it may not matter that something is in the way. And it's unlikely
that something would be in the way as you get closer to the hinge.
People would generally be sitting way back by the door latch,
perhaps a good 60cm from the hinge

We know how sensitive a VCR receiver is if the transmitter is in
the room, but point the transmittion out the door and it's lost
-----------------
Is there enough of a round-trip resistance difference in a car
body when a door is open ?
-----------------
I wonder if ultra-sound might work. If you flooded the car space
with it, would opening a door cause enough of a 'leak' to detect,
over and above the movement of people within ?
-----------------
Detecting an interior ceiling light would be simple, but getting the
wiring tidy might not be easy for the mechanically-challenged
-----------------
Most cars now would have a door indicator light on the dash ?
Perhaps tap into its supply or a photo-detector on the dash (not
very aesthetic)

2008\06\02@232633 by Jinx

face picon face
I wrote

> Is there enough of a round-trip resistance difference in a car
> body when a door is open ?

So, how many people went off to their car with a multimeter ?

Oh, just me then

There is a difference, but you're talking fractions of an ohm,
which might not be dependable in various weather conditions

2008\06\03@083300 by Hazelwood Lyle

flavicon
face
I have only been lightly reading this thread, please excuse me if I'm repeating a previous idea.
Don't most cars use CAN bus?
Could you connect in read only mode and monitor events?
It may not be "universal", but when it works, you'd get a great deal of data from all over the car.

I am sure there are others here with more info on this than I have.
It it feasible?

Lyle

2008\06\03@091947 by alan smith

picon face
Also look at the LMV1088

--- On Mon, 6/2/08, YAP &lt;RemoveMEx112358TakeThisOuTspamspamgmail.com&gt; wrote:

From: YAP &lt;EraseMEx112358spamspamspamBeGonegmail.com&gt;
Subject: Re: [EE] Car door sound detection (clapper?) [AVR] too
To: "Microcontroller discussion list - Public." &lt;RemoveMEpiclistKILLspamspammit.edu&gt;
Date: Monday, June 2, 2008, 4:11 AM

On Sat, May 31, 2008 at 4:38 PM, M. Adam Davis &lt;stienmanSTOPspamspamspam_OUTgmail.com&gt; wrote:
&gt; I need to detect a vehicle door closing from a device inside the
&gt; vehicle.  This will be used to trigger a telemtry device, and must be
&gt; installed by Your Grandma (TM) so it really can't be a switch and
&gt; wiring to the device.
&gt;
&gt; Thus I'm trying to develop an algorithm that uses sound (via
&gt; microphone) to detect likely door closing events.
&gt;
&gt; I haven't gone out with a recorder yet, but figuring out the
&gt; difference between a cough and a door closing in a car with windows
&gt; down does not seem trivial.
&gt;
&gt; I'm using the AVR32 UC3 devices, so I've got a bit of processing
power.
&gt;
&gt; What sound detection algorithms have you seen, or what ideas do you
&gt; have (brainstorm on!) that I should look into?
&gt;
&gt; I'm also using other methods to trigger the device (light from the
&gt; interior lighting, accelerometer, pressure, etc) but I'm primarily
&gt; interested in exploring the sound detection in this particular thread.
&gt;
&gt; -Adam


Use an atmospheric  pressure sensor.

Cheers
/Ake


--
---
Ake Hedman (YAP - Yet Another Programmer)
D of Scandinavia, Brattbergavagen 17, 820 50 LOS, Sweden
Phone: (46) 73 0533 146
Company home: http://www.dofscandinavia.com
Personal homepage: http://www.dofscandinavia.com/akhe
Automated home: http://www.vscp.org

2008\06\03@092518 by M. Adam Davis

face picon face
This is a good solution, except in this particular case there are two obstacles:
1. Liability - the more I attach to the car (especially critical
communication busses) the more risk I take and testing I have to do.
2. While diagnostics and engine data over OBDII (VPW, CAN, etc) are
fairly well defined, other messages (door open, etc) are
vehicle/supplier/manufacturer specific and may not even make it to the
OBDII connector.

Would be nice to have the extra data, though (MPG, etc)

-Adam

On 6/3/08, Hazelwood Lyle <spamBeGoneLHazelwoodSTOPspamspamEraseMEmfgnc.com> wrote:
> I have only been lightly reading this thread, please excuse me if I'm repeating a previous idea.
> Don't most cars use CAN bus?
> Could you connect in read only mode and monitor events?
> It may not be "universal", but when it works, you'd get a great deal of data from all over the car.
>
> I am sure there are others here with more info on this than I have.
> It it feasible?
>
> Lyle
>
> -

2008\06\03@140816 by Cedric Chang

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face

> On Jun 2, 2008, at 8:40 PM, Jinx wrote:
>
>> The IR transmitters sound interesting, and would lie somewhere
>> between 1 and 2 above, but might be tricky to place so that they
>> aren't also blocked by the passengers or cargo
>
> If an IR transmitter pings into the car space with enough power
> it may not matter that something is in the way. And it's unlikely
> that something would be in the way as you get closer to the hinge.
> People would generally be sitting way back by the door latch,
> perhaps a good 60cm from the hinge
>
> We know how sensitive a VCR receiver is if the transmitter is in
> the room, but point the transmittion out the door and it's lost
> -----------------
> Is there enough of a round-trip resistance difference in a car
> body when a door is open ?


There might be a difference in how sound is transmitted through the  
body.
cc
{Quote hidden}

2008\06\03@140958 by Cedric Chang

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What you need is a trained monkey to jot down notes.  Could help  
grandmother unload as well.
cc
{Quote hidden}

> --

2008\06\09@080948 by Alan B. Pearce

face picon face
>> The difference in noise on the 12V line between a stopped engine and
>> running engine in a car is profound and should be rather easy to detect.
>
>I was actually planning on detecting the voltage difference (battery <
>alternator) but I need to detect if the doors close even while the
>engine is running.

One car alarm system I saw described as a project (in Electronics Australia
IIRC) was to detect the voltage drop on the 12V line when the interior light
came on. Now this may not be viable if the engine may be running.

I seem to recall the project could detect something like 10-50mV drop in
voltage due to the draw from the lamp, and used a 555 timer as the detector,
but I may well be wrong on the latter bit.

2008\06\09@171333 by Herbert Graf

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face
On Mon, 2008-06-09 at 13:09 +0100, Alan B. Pearce wrote:
> I seem to recall the project could detect something like 10-50mV drop in
> voltage due to the draw from the lamp, and used a 555 timer as the detector,
> but I may well be wrong on the latter bit.

A wrinkle with this idea is these days the door switches no longer go to
the lights. Instead stuff like this is handled by the "body control
module".

Why this is important is due to various features, a "light on" doesn't
necessarily mean door open, and a "light off" doesn't mean doors closed.

For example, my Toyota Matrix turns it's interior lights on when the
"unlock" button is pressed on the keyfob. If you don't physically open
the door within 30 seconds the doors lock and the light turns off.

On the other side, if you open and door the light turns on, but if you
leave the door open longer then a certain amount of time the light turns
off. Opening any other door does not turn the light back on (I think),
yet closing the door does!?? Until you put your key in the ignition,
then the light turns off, or you hit the lock button.

TTYL

2008\06\10@080601 by Alan B. Pearce

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{Quote hidden}

My Focus Ghia does something like this, shut the door and the light stays on
for around 10 seconds, then fades down - except when you put the key in the
ignition then it fades down faster. And if you close the door and lock it,
the light turns off almost immediately.

But the electric windows don't go through the "body control module", they
control the windows directly, with a small amount of electronics to detect
the limits. Seems to be a separate add-on module that can be used in less
well equipped vehicles.

2008\06\10@144553 by Herbert Graf

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face
On Tue, 2008-06-10 at 13:05 +0100, Alan B. Pearce wrote:
> But the electric windows don't go through the "body control module", they
> control the windows directly, with a small amount of electronics to detect
> the limits. Seems to be a separate add-on module that can be used in less
> well equipped vehicles.

Possibly interesting but mostly pointless tidbit of info:

I recently purchased a microwave oven. Turns out the door closed switch
no longer controls the light directly, the MCU turns the light
on/off! :) You can tell because the light stays on for a fraction of a
second after the door is closed.

TTYL

2008\06\10@203940 by Sean Breheny

face picon face
As long as it doesn't control the magnetron!!!

Where I work someone brought in an old "workhorse" microwave (mid
1980s vintage) to supplement the two we have in the cafeteria. I
discovered one day that if you pulled the door open slightly (but not
all the way), the light inside would come on AND you would hear a fan
noise as if the microwave were running. Mind you, this is with the
microwave in an idle state (not presently cooking)!!! Using a general
coverage receiver which covers 2.4GHz, I verified that it is not
producing radiation when in this state. It seems as though there must
be more than one "door open" switch and by opening it just the right
amount you can cause the two switches to be in different states which
confuses it somehow.

Sean



On Tue, Jun 10, 2008 at 2:45 PM, Herbert Graf <KILLspammailinglist4spamBeGonespamfarcite.net> wrote:
> I recently purchased a microwave oven. Turns out the door closed switch
> no longer controls the light directly, the MCU turns the light
> on/off! :) You can tell because the light stays on for a fraction of a
> second after the door is closed.
>

2008\06\10@222557 by Robert Ammerman

picon face
> It seems as though there must
> be more than one "door open" switch and by opening it just the right
> amount you can cause the two switches to be in different states which
> confuses it somehow.
>
> Sean

I believe multiple switches are required to provide redundant safety.

-- Bob Ammerman
RAm Systems


2008\06\11@035612 by Alan B. Pearce

face picon face
>> It seems as though there must be more than one "door open" switch
>
>I believe multiple switches are required to provide redundant safety.

The microwaves I have had have definitely had two switches, one on each door
latch, and they have all had two door latches.

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