Bilylivska O. Method and Contactless Instrument for Control of Angular Position based on Self-oscillating Devices with Magnet-sensitive Transistors

Some features of angular position control of rotary supports have been considered taking into account the effect of the error of angular position adjustment on the radar accuracy. A new classification of instruments for angular position control has been proposed. Classification criteria are the output type, the type of contact with the measured medium, measurement range, and physical operating principles. The choice of magnetic type of the measurement methods and instruments was explained. An analysis of some scientific papers showed that self-oscillating devices for conversion of physical quantities based on reactive properties of semiconductor devices enable sensitivity increasing and measurement error reduction. A review of galvanomagnetic magnet-sensitive devices for controlling angular positions showed that magnet-sensitive transistors have much higher sensitivity than other galvanomagnetic transducers. Expressions describing the spatial distribution of the magnetic field of the diametrically magnetized permanent magnet and the dependence of axial component of magnetic field induction on the angular position of the object are derived. A new method for angular position control based on self-oscillating devices with magnet-sensitive transistors has been proposed. Its major difference from the existing methods is contactless conversion of angular position in the sine and cosine frequency signals using self-oscillating devices while magnet-sensitive transistors are sensitive transducers and active elements of the circuit at the same time. The proposed method provides in principle the possibility to increase probability of angular position control. The dependence of output frequency of the self-oscillating devices with magnet-sensitive transistors on angular position of the object (rotation shaft) was theoretically established and experimentally confirmed. Obtained equations differ from existing, because magnetic field induction associated with the angular position of the object is transforming into output frequencies of the self-oscillating devices with magnet-sensitive transistors. Angular position sensors based on self-oscillating devices with dual-drain and dual-collector magnet-sensitive transistors as well as their mathematical models have been developed, which enabled sensitivity increasing and angle measurement error reduction. A contactless instrument for control of angular position based on self-oscillating devices with magnet-sensitive transistors has been developed, which makes it possible to increase the probability of angular control. The mathematical model of the measuring transformation of the developed instrument has been proposed. This model differ from the known models in that it describe the transformation processes of physical quantities “angular position – magnetic field induction – frequency – digital value” and is a conversion function of the contactless instrument for control of angular position. The static metrological characteristics of measuring channel of instrument for angular position control based on self-oscillating devices with magnet-sensitive transistors were estimated. Basic errors of the control device have been detected. The conventional error of the developed device does not exceed 0.015%. The results of an experimental research of instrument for angular position control support theoretical expectations and confirm efficiency of the proposed method. By using a series criterion based on the sample median and a square successive difference criterion independence and stationarity of the statistical series of measuring values. It was confirmed, that the law of distributing of measurement error is normal. The dependence of Type I and Type II errors on the standard deviation of the measurement error of angular position have been estimated. It was calculated that the probability of controlling angular position by the developed device is 0.98, which is by 0,06 higher than that of the known instruments.