Adam Idzkowski

Application of Double Current Bridge-Circuit for Simultaneous Measurements of Strain and Temperature

A four-terminal (4T) bridge-circuit unconventionally supplied by current sources connected in parallel to opposite arms, named double current bridge (2J) is presented. It has two different outputs from both diagonals. Their output voltages as the functions of arm resistance increments in absolute and in relative units are given. Example of its application is proposed. Signals conditioning formulas of the two-parameter (2D) measurement - of strain and temperature are discussed in details. Some results of experimentally design instrumentation of this bridge-circuit are shortly presented.

Monitoring and control system of charging batteries connected to a photovoltaic panel

In this paper the off-grid photovoltaic system consisting of a PV panel, MMPT charge controller and battery is described. The realization of a laboratory stand for charging or discharging batteries is presented. Original monitoring and control system, which is based on LabVIEW software and LabJack DAQ device, has been built. Data acquisition part, arithmetic part and front panel of program created in LabVIEW are described. Some problems with implementation of this system, providing the monitoring of electrical parameters, are mentioned.

Vehicle Speed and Length Estimation Using Data from Two Anisotropic Magneto-Resistive (AMR) Sensors

Methods for estimating a car’s length are presented in this paper, as well as the results achieved by using a self-designed system equipped with two anisotropic magneto-resistive (AMR) sensors, which were placed on a road lane. The purpose of the research was to compare the lengths of mid-size cars, i.e., family cars (hatchbacks), saloons (sedans), station wagons and SUVs. Four methods were used in the research: a simple threshold based method, a threshold method based on moving average and standard deviation, a two-extreme-peak detection method and a method based on the amplitude and time normalization using linear extrapolation (or interpolation). The results were achieved by analyzing changes in the magnitude and in the absolute z-component of the magnetic field as well. The tests, which were performed in four different Earth directions, show differences in the values of estimated lengths. The magnitude-based results in the case when cars drove from the South to the North direction were even up to 1.2 m higher than the other results achieved using the threshold methods. Smaller differences in lengths were observed when the distances were measured between two extreme peaks in the car magnetic signatures. The results were summarized in tables and the errors of estimated lengths were presented. The maximal errors, related to real lengths, were up to 22%.

Estimation of the object orientation and location with the use of MEMS sensors

The article presents the implementation of the estimation algorithms of orientation in 3D space and the displacement of an object in a 2D space. Moreover, a general orientation storage methods using Euler angles, quaternion and rotation matrix are presented. The experimental part presents the results of the complementary filter implementation. In the study experimental microprocessor module based on STM32f4 Discovery system and myRIO hardware platform equipped with FPGA were used. The attempt to track an object in two-dimensional space, which are showed in the final part of this article, were made with the use of the equipment mentioned above.

Errors and uncertainties of imbalanced bridge-circuits as primary converters for RTD sensors

The original way of evaluating accuracy of the resistance-to-voltage converter (imbalanced bridge-circuit) is presented. It is important because this converter is used as the input stage of industrial and laboratory temperature measurement systems. From circuit theory point of view it is the two-port circuit of type X with four variable resistances and it is supplied by a current (or voltage) source. Formulas of transfer coefficients are presented in general forms and in relative units. Moreover, two particular cases of this converter used in temperature measurements, i.e. with one or two RTD elements, are considered in detail. Error propagation functions are determined in two-component form, i.e. separately for both initial value and relative increment of a transfer coefficient (dependent on temperature). Values of limited errors and expanded uncertainties are calculated for a few variants of this converter with the Class A and B industrial Pt100 sensors. Formulas and example results allow to determine accuracy measures for the selected configuration of bridge-circuit and to compare with other configurations. Null adjustment, inside and outside the bridge, is also considered.

Method of upgrading the reliability of measurement inspection

Applying an auxiliary quantity, homogeneous with the measured one, is proposed in the quality control of an object made with the use of measuring channel and decision-making module. The result of processing this quantity in the measurement channel is applied for the additive and multiplicative correction of decision limits. This allows to reduce the impact of imperfect processing characteristics of measuring channel. The significant effectiveness of such correction, at different ratio of the components of processing error, is presented. The influence of errors of forming auxiliary quantity is also estimated.

Practical Methods for Vehicle Speed Estimation Using a Microprocessor-Embedded System with AMR Sensors

The proper operation of computing resources in a microprocessor-embedded system plays a key role in reducing computing time. Processing the variable amount of collected data in real-time improves the performance of a microprocessor-embedded system. In this regard, a vehicle’s speed measurement system is no exception. The computing time for evaluating any speed value is expected to be reduced as much as possible. Four computational methods, including cross-correlation, are discussed. An exemplary pair of recorded signals presenting the change in magnetic field magnitude is analyzed. The sample delay values are compared. The results of the evaluated speed and the execution time of the program code are presented for each method based on a dataset of 200 randomly driven vehicles. The results of the performed tests confirm that the cross-correlation-based methods are not always reliable in situations when the sample size is small, i.e., it is a segment of the impulse response caused by a driving vehicle.

The realization of temperature controller for small resistance measurement system

This paper concerns the issues of construction and experimental tests of a temperature stabilization system for small resistance increments measurement circuits. After switching the system on, a PCB board heats up and the long-term temperature drift altered the measurement result. The aim of this work is reducing the time of achieving constant nominal temperature by the measurement system, which would enable decreasing the time of measurements in the steady state. Moreover, the influence of temperatures higher than the nominal on the measurement results and the obtained heating curve were tested. During the working process, the circuit heats up to about 32 °C spontaneously, and it has the time to reach steady state of about 1200 s. Implementing a USART terminal on the PC and an NI USB-6341 data acquisition card makes recording the data (concerning temperature and resistance) in the digital form and its further processing easier. It also enables changing the quantity of the regulator settings. This paper presents sample results of measurements for several temperature values and the characteristics of the temperature and resistance changes in time as well as their comparison with the output values. The object identification is accomplished due to the Ziegler-Nichols method. The algorithm of determining the step characteristics parameters and examples of computations of the regulator settings are included together with example characteristics of the object regulation.

ALTERNATIVE METHOD OF UPPER EXTREMITY FUNCTION ASSESSMENT OF STROKE PATIENTS BY ANGULAR KINEMATIC PARAMETERS

This study focuses on the functional assessment of the upper extremity of stroke patients via analysis of angular kinematics features. Amplitudes and angular velocities of multi-joint movements more precisely describe functional state at different impairment levels. However, the arm movement as a whole could be analyzed by means of joint angle–angle diagrams, which illustrate the 2D trajectory of upper extremity during movement and show the visual ranges of upper extremity in different cycles of motion. The functional range of motion of each upper extremity segment in all patient groups for more accurate assessment of capability was calculated. Moreover, we calculated the area (S) between two curves in joint angle–angle diagrams as a novel index of the complete upper extremity movement range evaluation. Our findings correspond to clinical rates and upper extremity assessment based on joint angle–angle diagrams seems to be a promising method for accurate assessment and/or predicting the outcomes of rehabilitation programs.

Analysis and application of two-current-source circuit as a signal conditioner for resistive sensors

Abstract The article presents the analysis of metrological properties of a two-current-source supplied circuit. It includes such data as precise and simplified equations for two circuit output voltages in the function of relative resistance increments of sensors. Moreover, graphs showing nonlinearity coefficients of both output voltages for two resistance increments varying widely are presented. Graphs of transfer resistances, depending on relative increments of sensors resistance were also created. The article also contains a description of bridge-based circuit realization with the use of a computer and a data acquisition (DAQ) card. Laboratory measurement of the difference and sum of relative resistance increments of two resistance decade boxes were carried out indirectly with the use of the created measurement system. Measurement errors were calculated and included in the article, as well.