Satnav Yaw rate settings

[apemonkeyman]

Originally Posted by Bungle

Oh how wrong you are Pottsy!

Is that possible?

[steampig]

On most other cars the yaw rate sensor is part of the traction control system , When uncalibrated they can cause the vsc / traction control light to illuminate when cornering and send the whole system haywire. Normally fitted to the steering column they are also known as "Steering Angle Sensor"

[Pottsy]

Originally Posted by Bungle

Oh how wrong you are Pottsy!

Indeed, maybe I should have said:

Crackers - portable navs currently available don't have these DR (deduced reckoning) systems...

When this system arrives it will be interesting to see how well it works. It will need an accurate multiple accelerometer system, and still I suspect that if you go up hill at a constant speed it will confuse this with acceleration (just like my G Tech pro does).

[Bungle]

Originally Posted by Pottsy

...I suspect that if you go up hill at a constant speed it will confuse this with acceleration ...

I'm sure you are absolutely right.
It theoritically could be over come by clever calculating of vectors.
Accelerating on level ground will give you a 1G downwards force, and another force due to accelerating. If you are on a slope, the 1G downwards force is distributed through 2 axis, so the straight down force would be <1G. It could then work out if you are on an incline or accelerating (or both!).

It would be far too complicated (and expensive) to impliment in a sub £300 portable sat-nav, though.

[smiffy]

Didn't I read somewhere that VSA has a Yaw Sensor as well? I seem to remember seeing a photo of it somewhere on here. I guess it would use it to detect sudden swerves

[Kremmen]

I wonder why on the EX they didn't connect the speedo to the GPS and therefore have the true speed displayed at all times?

[Bog]

Originally Posted by Kremmen

I wonder why on the EX they didn't connect the speedo to the GPS and therefore have the true speed displayed at all times?

For ar*e covering reasons probably!

[Pottsy]

Originally Posted by Bungle

It theoritically could be over come by clever calculating of vectors.
Accelerating on level ground will give you a 1G downwards force, and another force due to accelerating. If you are on a slope, the 1G downwards force is distributed through 2 axis, so the straight down force would be <1G. It could then work out if you are on an incline or accelerating (or both!).

It doesn't work like that, sadly. When accelerating on the flat and going up a hill at a constant speed, the vector components all look the same. What is needed is another accelerometer to measure the pitch change - and these accelerometers need to be good, since any drift has a cumulative effect. If I just tip my G tech pro, it thinks we are accelerating.

I can think of 2 good systems that get it wrong. One is the human set of dual 3-way accelerometers, that can tell you you're accelerating when you're in fact going steady up a hill (somatographic illusion), and the other is laser gyros (£100,000's each) that drift by several miles over a few hours.

If you can get accurate speed and yaw (coupled with a map - this helps) then you can do good DR. I'm pretty sure that most aftermarket GPS systems that are designed to be permanently fitted to a car have systems like this built in.

[Pottsy]

Originally Posted by Bog

For ar*e covering reasons probably!

I think because the speed can be erroneous when the GPS cover is poor, and that sometimes there is no cover, and there is a lag. I'd like to have seen a system of gradual self calibration, using the GPS as a reference. The car does this anyway, but only uses the answer for the DR system, and not the speedo. What a waste!