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2nd gen steering angle sensor for data acquistion

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2nd gen steering angle sensor for data acquistion

Old 03-21-09, 01:08 PM
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2nd gen steering angle sensor for data acquistion

Everywhere I read, steering, throttle, and brake inputs are some of the most important things to add to your logger. Well tps is pretty easy, and brakes you just need expensive pressure sensors (which I don't have yet. For now, I just tapped into the brake pedal switch.)

So here is a very easy way to get steering input into your data logger. I actually figured this out a few months ago but was not able to test it out on a racetrack to verify how good it would be. Most aftermarket datalogging steering sensors you'll have to make a bracket, and get a belt, etc. Well this is bolt on and you might even have this on your car still. If not, this sensor will probably be free since racers all have parts/parts cars lying around!

This is a stock steering angle sensor/turn cancel assembly from a car equipped with power steering and auto adjust suspension. My car is a manual steering car and only had the turn cancel assembly. You want to grab the one with an additional three wires on the front.

Heres a pic:



I checked an S5, but it did not have this type either. It may come only on S4s because of their different type of power steering.

This sensor is just a variable resistor. Unfortunately, it can only do one revolution. In other words, 180 degrees to the left and 180 degrees to the right. This should be ok for most racetracks but most likely wont work if your logging autox/drifting or for really tight courses.

Ok so you just wire this sensor up just like a 5v tps sensor. You need 5v supply, a ground, and the middle wire is the signal back to the logger. Then you are going to need to calibrate this sensor to your logger. Basically tell it straight ahead = 0 degrees, 180 degrees left, 180 degrees right. Every logger is different and I use a Racepak G2X but it is pretty easy to figure out. Just make sure you follow your lateral g trace curve. I think most loggers are setup for left turns are positive traces, and right turns are negative.

According to the FSM the resistor is 50k ohms, I measured mine and only got 45k ohms. So around 22.5kohms is the 0 degree reading. BTW the S4 FSM pages are 15-19 to 15-21.


Well I finally was able to take the car out to infineon and got some good logs.


Here is a snapshot of one lap with the steering sensor trace and lateral g trace:




Now turn 13 is a very tight turn. On this lap you can see I went over the 180 and the trace jumped back around. But I know the reason was I had understeer through this turn and had to add more steering.





So with this additional information, you should be able to spot oversteer and understeer situations a lot easier than just using a latg trace. I also added a calculated math channel called speed adjusted steering.


-Jack
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Old 03-23-09, 04:47 PM
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very cool!

we had to build the bracket and stuff for the POS honda...

we mostly use the data to compare drivers. to go any further, the books on the subject get really thick!

the brake pressure sensor is super easy to plumb in, that data is really easy to look at.
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Old 03-23-09, 10:41 PM
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Good find, I wish I hadn't pitched all that stuff when I modded my column for a removable steering wheel hub.
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Old 03-23-09, 11:44 PM
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Oh yeah, sorry about that, your going to have to use a stock style setup for this! I am using a momo hub & steering wheel. It has the holes that line up to the tangs on the sensor. I am also using a NRG quick release hub.


Originally Posted by j9fd3s View Post
very cool!

we had to build the bracket and stuff for the POS honda...

we mostly use the data to compare drivers. to go any further, the books on the subject get really thick!

the brake pressure sensor is super easy to plumb in, that data is really easy to look at.

I assume the brake pressure sensor is not metric. Did you get a metric tee adapter? Where'd you find it?


I also realized I spelled the title incorrectly. I should have double checked my typing.
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Old 03-24-09, 11:08 AM
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Originally Posted by jrx13 View Post
Oh yeah, sorry about that, your going to have to use a stock style setup for this! I am using a momo hub & steering wheel. It has the holes that line up to the tangs on the sensor. I am also using a NRG quick release hub.





I assume the brake pressure sensor is not metric. Did you get a metric tee adapter? Where'd you find it?


I also realized I spelled the title incorrectly. I should have double checked my typing.
Jack,

The metric T is the one from the FC rear brake circuit. Its the only 3x 10x1.00mm IF female T-block that I can find.

paul
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