Angular Position Sensor Research Articles

The application of the capacitor's physics to optimize capacitive angular-position sensors

The distributions of the potential and charge density in a capacitive angular-position sensor with three electrode disks in an axis-symmetrical configuration have been found by creating a suitable physical model and solving Laplace's equation. The influences of geometrical parameters on the nonlinearity, which originates from the electric-field-bending effect, are discussed in detail for a capacitive angular-position sensor. The approximately analytical results are verified by a numerical analysis and are found to be very useful to predict the influences of geometrical nonidealities. The calculations are experimentally verified by using a novel, absolute angular-position sensor with a nonlinearity of less than /spl plusmn/17 and /spl plusmn/50 over measurement ranges of 15/spl deg/ and 90/spl deg/, respectively.

A microcontroller-based self-calibration technique for a smart capacitive angular-position sensor

A self-calibration technique for capacitive position sensors, based on the use of a microcontroller is presented. This technique offers a good trade-off between the memory size of the microcontroller and the algorithmic complexity. The application of this technique for self-calibration of the inaccuracy caused by the geometrical errors and pattern errors in a smart capacitive angular-position sensor is discussed. This self-calibration technique doesn't need any accurate reference. Experimental results show that the self-calibration is relatively effective in reducing the influences of the geometrical errors and pattern errors of the sensor. The reduction of the inaccuracy of the smart capacitive angular-position sensor amounts to more than a factor of two.

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

A novel high-performance smart capacitive angular-position 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/spl deg/). The structure of the sensing element is optimized to reduce the influence of the electric-field-bending 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 /spl plusmn/58 arcsec over the 0-360/spl deg/ range for a measurement time of 140 ms.

A novel smart resistive-capacitive position sensor

A novel smart resistive-capacitive angular position sensor is presented. The main advantages of this low-cost system are its simplicity, high stability and high reliability. A very linear oscillator is used in the processing circuit to convert the position quantity to a period-modulated signal which can be read out directly by a microcontroller. The system does not need an A/D converter. The nonlinearity of the smart angular position sensor system is less than /spl plusmn/0.3% (/spl plusmn/0.9/spl deg/) over the range of 270.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Control of a single‐link flexibe manipulator fabricated form composite laminates

AbstractAn experimental investigation on the control performances of a single‐link flexible manipulator fabricated from composite laminates is presented. The dynamic modeling of the flexible manipulator is accomplished by employing Hamilton's principle, prior to developing a finite element formulation. An output feedback controller associated with two collocated angular position and velocity sensors is designed and experimentally implemented. Comparative works are undertaken to demonstrate some of the advantages to be accrued from this proposed methodology. It is shown that the manipulator fabricated from composite laminates has superior performance characteristics, such as smaller tip deflections and a smaller input torque relative to the manipulator fabricated from aluminum. © 1995 John Wiley &amp; Sons, Inc.

A smart capacitive absolute angular-position sensor

Abstract This paper describes a novel low-cost smart accurate capacitive absolute 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 measurement, 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 compensate for mechanical errors in the sensor in order to obtain an accurate measurement and to reduce the mechanical demands on the sensor. This novel approach can also be applied directly to capacitive absolute linear-position sensors. A simple and cheap oscillator is used to measure the various sensor capacitances. The oscillator converts the analog capacitance information into the time domain and is directly digitized by a microcontroller, eliminating the need for an expensive AD converter.

Inductive absolute angular position sensor

Several novel structures of inductive absolute angular position sensors which are insensitive to mechanical plays are presented. It is shown how to design the sensor geometry, depending on the chosen signal shape and electronic treatment. A prototype built to give linear variations of the phase validates these principles.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Annular magnet position sensor

An absolute permanent magnet angular position sensor is presented. Its original geometry was optimized to obtain a perfectly linear variation law of the normal induction in the air gap. This sensor is characterized by a simple electronic treatment, a low realization cost, and a resolution on the order of a tenth of a degree. >

Modelling of a high resolution inductive transducer

An inductive angular position sensor is presented which, in contrast to a synchroresolver, is windingless. The geometry was optimized to generate a perfectly sinusoidal variation of the inductance over an electric pitch. The distortion rate between a sinusoidal curve is given as a function of the different geometrical parameters. By using the finite element program FLUX2D, a geometry was determined which produced a perfectly sinusoidal inductance variation. An optimized prototype is accurate to within 12 arc seconds. >