Important criteria for a combined torque and steering angle sensor?

[Porsche356supersport]

Does anyone have any input on what are the key criteria in terms of developing a combined torque and steering angle sensor for EPAS applications. I'm particularly interested in understanding how the signals from such a sensor would be used and why the parameters are set as they are.

 

[GregLocock]

I don't know anything about the angle side of things. For torques you are basically looking at replacing the torsion bar in an HPAS. You may or may not be surprised to learn that the T bar is a significant part of a cars understeer budget, stiffer is nice but too stiff can be a problem, especially if you are just plugging a EPAS into a car that was designed for HPAS.

Typically a T bar in an HPAS locks out at around 8 Nm. that is above 8 Nm you get full assist from the HPAS. I'm not sure if that is necessarily a good idea with an EPAS, you might want to increase that limit.







Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Porsche356supersport]

Hi Greg, thanks for the input. We already use a sensor to read the torque via the torsion bar. Typically we are reading the differential torque over an angle of 7 degrees. A magnet is mounted on the torsion bar that allows us to measure relative change. Typically the torsion bars we see are rated anywhere from 4Nm to 7Nm. What I am after with my question is to find out what would be required if I combined the steering angle sensor (required for navigation/ESC/parking assistance) with the torque sensor used on the EPAS system.

 

[GregLocock]

I can't think of any particular gotchas there.

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.