So I got bit by the "how the hell does this work" bug. An internet friend of mine has a prius steering column, which has a DC motor and a torque sensor in it. the ECU is AWOL. while he could find one in ajunkyard, it expects sensors his car he wants to put it in (early 70s bug) doesn't. WHat I would love to do is reverse engineer my own ECU for him that takes a reading from the built in torque sensor, and feeds a PWM motor controll to the assist motor. so I expected some sort of strain guage, but nope, thats only early models (looks like a strain guage in the pics atleast). the later model (his is 08) uses a flexing torque shaft with two inductive sensors on it ot see how hard he is flexing the steering column and controll the DC motor to assist that. THe attached image shows the sensor, there is no further information on the sensor in the PDF i took that shot from, but a google search for "prius power steering" will turn hte pdf up as the first result. For some reason I can't make a link to it, my computer is silly like that sometimes. the inductive sensor is not layed out in any way I am familiar with and need someone here smarter than me to help explain it to me. I am a ME by schooling, but have been playing with electronics as a hobby for about 8 years now (not as impressive as it sounds) and am trying to mix the two more and more. So tell me, what does that sensor rings output look like? I am used to a sensor "probe" with a toothed ring spinning near it, not an sensor "ring" around a toothed piece. I assume the phsycis are quite different between the two, so I have no idea where to start googling for info. IN SUMMARY, my question is: what do you call the type of inductive sensor shown in the attached file, and how does it work? Thanks a ton folks!