CALIBRATION PROCEDURE AND UNCERTAINTY ANALYSIS OF AN ELECTRONIC SCALE BASED ON TWO-CURRENT SOURCE SUPPLIED CIRCUIT
Original scientific paper The article presents the prototype version of an original weight scale in which a non-conventional supplying circuit of strain gauge load cells is applied. The paper discusses construction of an electrical circuit, the way of strain gauge transducer connection and the measuring procedure. As far as the authors know, this novel electrical circuit and its application in a weight scale system have never been mentioned in literature. The specifications for directreading weight scales typically include readability, repeatability, linearity and eccentricity. The values of these parameters were estimated and used for calculation of the weight measurement uncertainty in the tested measuring range of the designed device.
Unconventional Double-Current Circuit for Deflection and Temperature Simultaneous Measurement
In this paper some interesting and novel features of a four-terminal (4T) network are presented. A single DC current source (J) is switched over and connected in turns to opposite arms of the four-element bridge circuit. This two-output circuit with two voltage outputs is called a double current circuit (2x1J). The output voltages are differently dependent on the arm resistance increments and their values are given in absolute and relative units. An original application with two sensors acting as strain gauges and RTD’s is presented. Signal conditioning formulas of 2D measurement of deflection and temperature of a cantilever beam are discussed in detail. Some results achieved with the use of the circuit are presented, as well. DOI: http://dx.doi.org/10.5755/j01.eee.21.1.6834
BIOMETRIC RECOGNITION SYSTEM BASED ON THE MOTION OF THE HUMAN BODY GRAVITY CENTRE ANALYSIS
In this paper we present a novel approach that enab les the determination and measurement of important features associated with the human body movement. This information can be used in the construction of a biometr ic personal identification system. Biometrics is, essentially, a pattern recognition system based on measurements of unique physiological or behavioural features as acquired f rom an individual. The domain of biometric techniques is currently placed within recently developed disciplines of sci ence. Biometry or biometrics is simply defined as a utomatically recognizing a person using distinguishing traits an d is widely used in various security systems. Biome try can be defined as a method of personal identification based on ind ividuals' physical and behavioural features. Physio logical biometrics covers data coming directly from a measurement of part of a human body, for example a fingerprint, the shape of the face, or from the retina. Behavioural biometrics an alyses data obtained on the basis of an activity pe rformed by a given person, for example speech and the handwritten sign ature. The system of biometrics defined above can n ow be expanded, and a new biometrics system can be considered. In our approach, human foot pressure on a sur face is measured and the pressure data retrieved. The press ure parameters are collected without the necessity of any movements of the feet.