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The Disco uses deceleration sensors positioned in various positions in the vehicle to sense various impact scenarios. At the end of the day, if a roo bar reduces deceleration then that is taken into account by the sensors. When they sense the rate of deceleration that requires an airbag deployment, then they will launch. Simple
Thanks Wombathole and l00kin4 for the replies on winch mounting. It looks like a really neat solution.
The impact sensors don't just measure deceleration. Otherwise they wouldn't have gone off on my old one when i hit a smallish roo and didn't decelerate at all, the impact was too small to decelerate the vehicle.
You're right, they measure acceleration in a negative sort of way, and whether you like it or not, they're not magical. From the manual:Quote:
Originally Posted by Russrobe
Impact sensors are installed in the front and both sides of the vehicle. The use of multiple impact sensors provides shorter air bag trigger times, through faster detection of lateral and longitudinal acceleration, and improves detection accuracy.
There are two front impact sensors attached to brackets on the body front support frame, just above each front longitudinal.
Each impact sensor incorporates an accelerometer and a microcontroller powered by a feed from the RCM. The power feed also provides the interface connection through which the impact sensor communicates with the RCM using serial data messages. Acceleration is evaluated by the microcontroller and transmitted to the RCM, which then makes the decision on whether or not to activate the air bags and pretensioners.
To add
The driver and passenger air bags are only fired in a frontal impact that exceeds the stage 1 threshold. Both stages of the inflator in the driver and passenger air bags are fired. At impacts between the stage 1 and 2 thresholds, the delay between the firing of the two stages varies with the severity of the impact; the more severe the impact the shorter the delay. At stage 2 impact thresholds and above, the two stages of the inflator are fired almost simultaneously. The passenger air bag is disabled unless the front passenger seat is occupied by a large person (NAS only), or the passenger air bag deactivation switch is on (all except NAS). The time delay between firing the two stages of the inflator in the driver air bag is increased if the driver seat is forward of the seat position sensor switching point.
Interesting, I had to replace the RF impact sensor on my current D4 last year as it set off the airbag light. Will be pulling it apart to inspect this accelerometer! They're not cheap, It was about $180AUD from memory, very expensive for something that's included for free in every mobile phone currently on the market. I know, it's obviously got an important job and must be precise, but it's still the same tech.
More interesting that there has been a recent spate of airbags going off at as little as 10km/h in car parks with only minor panel damage.... Makes you wonder how the engineers decide on the acceleration (+/-) threshold.
So when I was involved in Motorsport, we’d use three axis solid state accelerometers to plot track and g-forces etc. You’d mount it centrally to get the best accuracy. For the bags it makes sense to place an accelerometer closest to the bag in question to capture the shock pulse as soon as possible, plus the intensity at the impact point (crumple zones and substrate of the vehicle will change the wave pattern). This explains the number of sensors on the vehicle and their placement. I cannot fathom why they’re going off in car parks other than they’re not small impacts and are triggering stage 1. Saying that, it should require it to be enough for bodily impact to a vehicle surface, and 10kph isn’t that.
I have been considering discreet winch mounts and came across an Australian made option currently only available for 200 series Toyota.
https://www.hiddenwinch4x4.com.au/about-us/
I spoke to the owner yesterday and I certainly like the idea of an Australian designed & compliant product.
https://www.hiddenwinch4x4.com.au/pr...fety-standards
What they need is a donor vehicle for a couple of days to take measurements and undertake test fitment.
They are NSW central coast based, so a logistical challenge for me coming from Brisbane.
Maybe someone else in the forum might be interested.
Cheers,
Scott
PS ...
I'm also aware of the new'ish UK option from Prospeed:
http://prospeed-group.co.uk/product/...-and-bull-bar/
Forum Thread: Prospeed hidden winch
I have the Devon unit which was put on a classic Discovery (1 milionth car??) This cost me $1400 from memory. It includes a bar that goes behind the bumper replacing the one that is discarded. You can get a cheaper unit without the bar and these were costing about $400-$500. These bars from prospeed are very expensive, and to me hardly look discreet. Other than a flip up front number plate and looking very closely at the gap in the front lower grill you would not know I had a winch in there. I cannot see these units coming anywhere near those costs, but i guess we would be supporting a Aussie product!.
Turtle60 - are you able to a reach the winch dog clutch lever?