A problem of estimating the movement and orientation of a mobile robot is examined in this paper. The strapdown inertial navigation systems are often engaged to solve this common obstacle. The most important and critically sensitive component of such positioning approximation system is a gyroscope. Thus, we analyze here the random error components of the gyroscope, such as bias instability and random rate walk, as well as those that cause the presence of white and exponentially correlated (Markov) noise and perform an optimization of these parameters. The MEMS gyroscopes of InvenSense MPU-6050 type for each axis of the gyroscope with a sampling frequency of 70 Hz are investigated, as a result, Allan variance graphs and the values of bias instability coefficient and angle random walk for each axis are determined. It was found that in the output signals of the gyroscopes there is no Markov noise and random rate walk, and the X and Z axes are noisier than the Y axis. In the process of inertial measurement unit (IMU) calibration, the correction coefficients are calculated, which allow partial compensating the influence of destabilizing factors and determining the perpendicularity inaccuracy for sensitivity axes, and the conversion coefficients for each axis, which transform the sensor source codes into the measure unit and bias for each axis. The output signals of the calibrated gyroscope are noisy and offset from zero to all axes, so processing accelerometer and gyroscope data by the alpha-beta filter or Kalman filter is required to reduce noise influence.
Purpose. Investigation of a moisture frequency transducer based on a moisture-sensitive capacitive element of a cylindrical structure with mesh electrodes for a system for measuring the amount and parameters of crude oil. Methodology. When constructing a moisture-sensitive element, an oscillatory method for measuring humidity was applied to achieve high sensitivity and accuracy while maintaining a low cost of the device. A moisture sensitive capacitive sensor based on a cylindrical structure with mesh electrodes was introduced into the measuring generator system based on a transistor structure with a negative differential resistance. Findings. Analytical expressions are obtained to describe the dielectric constant of an inhomogeneous mixture of water and oil. Using these equations, the capacitance of a moisture-sensitive sensor with mesh electrodes is calculated as a dependence of the moisture content of crude oil. It was determined that the capacitance of the moisture sensitive sensor increased from 20 to 44 pF when the mass moisture of crude oil changed from 0 to 30%. The sensitivity of the developed capacitive sensor is 0.8 pF/% when using a measuring device in the form of a crude oil pipeline with a diameter of 50 millimeters. Originality. A mathematical model has been developed for the primary transducer of the moisture content of crude oil based on a cylindrical capacitor structure with net-like electrodes, which allows determining the value of the capacitance of the primary transducer of the moisture content of crude oil. A self-oscillator device for controlling the moisture content of crude oil has been developed on the basis of the structure of bipolar and field-effect transistors with a cylindrical capacitor structure with mesh electrodes. Practical value. Circuitry solutions for a moisture transducer for crude oil have been developed. The results of experimental studies showed that for the selected version of the moisture converter circuit, the output signal frequency decreased in the range from 1.617 to 1.27 MHz with a change in the mass moisture content of the Turkmen mixture from 0 to 30%, respectively, and is close to a linear dependence. The wide frequency range of the output signal of the secondary converter with the frequency output of the measured information increases the accuracy of moisture measurement in crude oil by an order of magnitude.
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