A smart capacitive absolute angular-position sensor

Jong

et al. 1996

Abstract-A novel high-performance smart capacitive angularposition sensor with a full-circle measurement range is presented. The sensor is mainly composed of three parts: the capacitive sensing element, a signal processor and a microcontroller. Using an appropriate algorithm, the effects of the main undesired influences are eliminated or strongly reduced. The measurement range covers the full-circle range (360"). The structure of the sensing element is optimized to reduce the influence of the electric-fieldbending effect and the mechanical errors. The signal processor has a multicapacitance input and a single period-modulated output, and includes a nearly linear capacitance/period converter. The microcontroller acquires output data from the processor, calculates the positions and optionally communicates with the outside digital world. The resolution of the smart capacitive angular-position sensor is 1.5 arcsec, and the nonlinearity is less than f. 58 arcsec over the 0-360" range for a measurement time of 140 ms.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An accurate low-cost capacitive absolute angular-position sensor with a full-circle range

Jong

et al. 1996

“…In previous papers [1]- [5], it has been shown that, with capacitive sensors, a rather high accuracy and resolution can be obtained. The remaining inaccuracy is mainly caused by the electric-field-bending effect and mechanical errors.…”

Section: Introductionmentioning

confidence: 99%

“…The remaining inaccuracy is mainly caused by the electric-field-bending effect and mechanical errors. The use of guarding electrodes is very important as these reduce the influence of the electric-field-bending effect and also reduce the effect of external disturbing signals [1]- [5]. However, the guarding electrode cannot eliminate the influence of electric-field-bending effect completely.…”

Section: Introductionmentioning

confidence: 99%

The influence of electric-field bending on the nonlinearity of capacitive sensors

Jong

2000

Abstract-Three-layered electrode structures are often employed in multiple-electrode capacitive position sensors. Even when advanced algorithms and well-designed guarding electrodes are used, the electric-field-bending effect is still one of the major contributors to the nonlinearity of capacitive position sensors. In this paper, the effects of electric-field bending on linearities of five capacitive linear-position sensors have been studied based on a physical model of the capacitive sensor. It is shown that the effect of electric-field bending on linearities strongly depends on the sensor structures, and that it is significantly reduced when advanced sensor structures and algorithms are used. The results are very useful for optimizing the sensor structure according to its application.

“…Applications in accurate weighing equipment, angular encoders [5] and position sensors require a much higher accuracy over a 1 pF range.…”

Section: Introductionmentioning

confidence: 99%

A very accurate measurement system for multielectrode capacitive sensors

Toth

Kerkvliet

1996