This paper describes a novel low-cost smart accurate capacitive absolu
te angular-position sensor with high accuracy and high resolution (18
bits r.m.s.). One of the novelties of this sensor is that, for each me
asurement, it uses all 24 segment electrodes along the circumference,
each of them ranging from 0 to 0.3 pF. The capacitance values between
these electrodes have a lot of redundancy with respect to the position
to be measured. The electronic processing uses this redundancy to com
pensate for mechanical errors in the sensor in order to obtain an accu
rate measurement and to reduce the mechanical demands on the sensor. T
his novel approach can also be applied directly to capacitive absolute
linear-position sensors. A simple and cheap oscillator is used to mea
sure the various sensor capacitances. The oscillator converts the anal
og capacitance information into the time domain and is directly digiti
zed by a microcontroller, eliminating the need for an expensive AD con
verter.