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Originally Posted by dayofpain
ok so aparently we are going to get really technical, i forogt how retarded online forums can be.
your description is just as fallable as mine.
there are two sensors in the car
1. measures the inertial force IE: g-force ( www.websters.com) of the car
2. measures the "direction the car is tipped" or the "degree" in relation to its horizontal axis.
the sensors correlate between each other and make the decision of which tires get torque and which do not.
lastly, i thought this thread was about how noone knew what they did, you posted the correct answer right off the bat.
i was just trying to help.
ALSO as point of reference. car makers tend to call shit anything they please whether its correct or not. IE: yaw sensor not measuring degrees in relation to vertical axiss but measuring degress against horizontal axiss. cause they think they are cool and innovative. they make up terms and use terms INCORRECTLY all the time. i took one such sensor apart and found it couldnt possibly measure the degree relation in which it was named for. due to its inner workings it could only measure based off of the horizon. UNLESS my sensor was mounted incorrectly (impossible due to bracket shape). |
Sorry, not trying to be retarded, just precise.
First, I just did a search for "inertial force". I've never heard the term before, but it turns out that it's a synonym to pseudoforce. Basically a perceived force that's a result of inertia (the tendancy of an object at rest to stay at rest). For example: centripital force isn't a real force it's a pseudoforce that you feel because you're moving in a straight line but the car is pushing on you as is goes around a turn, and that is indeed the force that's measured by a latteral G sensor.
However your 1st statement was:
"g's = measurement in "gravitys" of inertia in any direction."
The unit of measurement for inertia is actually the same unit as mass, which is either grams or pounds. Not's G's. G's are actually a measurement of acceleration (1G = 9.8m/ss), and in the case of "G-Force" we factor out the mass, and consider it a unit of Force, which is normally measured in Netwons or pounds-force. Your statment confused me, since you actually ment "inertial force" which was a term I hadn't heard before.
As far as yaw... yaw has
absolutely nothing to do with deviation from the horizon. Pitch and roll can be deviations from the horizon, but yaw is rotation about the verticle Z axis. Attemping to measure pitch or roll in conjunction with a system designed to keep you from spinning or pushing wouldn't work. Imagine your right side brakes coming on every time you drove down a hill, or hit a pot hole! Perhaps the reason the yaw sensor you took apart looked wrong is because you're thinking of roll and not yaw.
This is yaw:
Also, I don't know how old the sensor was that you took apart, but all the sensors used in cars these days would be solid state, and look simply like computer chips. Mechanical "yaw sensors" that you might be able to look at and figure out what they're measuring are called gyroscopes and can be found in older military aircraft, which due to their cost would never show up in a production vehicle.
The way a yaw sensor would be able to tell if your car is plowing of spinning is by comparing the wheel speed sensors (part of the ABS system) to the current yaw rate from the yaw sensor. In a stable turn there is a known speed difference between the inside and outside wheels. At a certain wheel speeds, if the yaw rate is too high for that turn the computer can deduce that the car is oversteering, and apply the brakes to the outside wheels, thus generating a yaw moment to counter the spin. If the yaw rate is too low, the car computer can deduce that the car is pushing and apply the brakes to the inside wheels and generate a yaw moment that will help the car turn.
At no point is there any torque split occuring. The EVO's AYC uses torque split left to right to control yaw instead of brakes, but in the STi it's all part of the ABS system... the DCCD and the latteral G sensor aren't used at all. That's a completely seperate system designed to balance the control aspects of a RWD car with the traction advantage of AWD.