Nissan impact collision sensor - what method for read/detect ?

[Grossel]

Hi.

In bottom on both pillars, there are mounted a sensor, like this (link to similar on ebay). The thing I DO know about this component is limited to:

• Two wires. Don't know if it use chassis/ground also.
• In bottom, I can see a small pcb card, but it is encapsulated in some sort of epoxy so I can't access it nor have a look at the pcb without ruining it.

The question is - how does this component actually work? Or, is it a specific standard for electrical detection that a impact collision sensor have to follow? I.e. may it be

• Variable resistance ?
• Voltage spike (if there are magnetic coil or piezo element inside) ?
• Binary voltage goes high at impact ?

I assume it cannot be modbus since only 2 (possible 3 if chassis used as gnd) connectors.

 

[rjenkinsgb]

Most likely a simple mechanical inertia switch; a contact that closes or opens if it experiences acceleration beyond a certain threshold.

 

[Reloadron]

My limited read comes up with:
"In less complex devices, collision sensors use a simple pressure switch connected to a surface that is likely to encounter collisions. They may also use accelerometers that measure gravitational force changes, with rapid changes and high forces indicating an impact from an unexpected collision".

That is the result of Google using "how does a collision sensor work". Apparently there is no standard. The sensor deploys air bags if the collision is greater than 35 MPH head on. There is also forward collision warning which is another animal.

Ron

 

[Grossel]

Ok, thanks for answer. So if no standard is defined, I may need to resort to wood stick in order to test it under high g-forces. The second thing I wonder is if the inner mechanic is made in suc ha way that it is made for one time only.

 

[Reloadron]

Depending on what we read sensors detect a rapid deceleration in some cases which is fed to the onboard computer which can deploy air bags. I can't find a single definition of exactly how crash sensors work as it seems there are several types out there in use. The sensor you have could be any of the above. A Google of Nissan crash sensor brings up a bunch of images. I am also seeing front sensors and side sensors. I am seeing where some have an accelerometer and uC embedded in them. A Google of "crash sensor output" brings up more stuff including images.

Ron