Goran Miljković

U radu je predstavljeno jedno rešenje za linearizaciju i obradu analognog signala dobijenog uz pomoć NTC termistora. NTC termistor se široko primenjuje zbog svoje velike osetljivosti i niske cene, ali je glavni njegov nedostatak nelinearnost karakteristike. Upotrebljen je NTC termistor od 10 kΩ sa uskom tolerancijom od 1% rasipanja u odnosu na nominalne vrednosti. Pri realizaciji elektronskog bloka za linearizaciju i obradu analognog signala NTC termistora je korišćen dualni CMOS operacioni pojačavač MCP6022I/P. Ovaj operacioni pojačavač je pogodan za primenu jer spada u klasu RRIO operacionih pojačavača (Rail to Rail Input and Output). Primenom temperaturnog kalibratora Fluke 9103 urađeno je ispitivanje merenja temperature realizovanim elektronskim blokom i konkretnim termistorom. Eksperimentalni rezultati u temperaturnom opsegu 0-50C su predstavljeni i analizirani u radu.

Optical rotary pseudorandom encoders are an excellent solution for reliable and precise angular position measurement in various industrial motion systems. The paper describes an improved optical rotary pseudorandom encoder solution that has a reduced angular position measurement time. The presented encoder uses two heads to read the pseudorandom code and to form the main and control code words. The encoder algorithm has been improved so that code conversion is not performed after each new code word. In presented solution, after each new code word, a code reading error checking is performed, and the position is determined based on the previous measured value if no code reading error is detected. The functionality of the proposed encoder solution in the LabVIEW environment is tested.

Pseudorandom absolute position encoders represent an advanced version of the widely used absolute position encoders, particularly suitable for high-resolution angular position measurement. This paper presents a detailed performance analysis of the pseudorandom absolute position encoder with embedded serial pseudorandom/natural code converter, focusing on the maximum operating frequency and the absolute error in angular position measurement. The generalized analysis, applicable to various resolution values, represents a significant contribution of the paper. Determining the maximum operating frequency involves a detailed analysis of propagation delays in the serial code converter circuit. It is demonstrated that encoder resolution profoundly impacts performance, with a dual effect: higher resolution decreases the absolute error but also reduces the maximum operating frequency, necessitating the determination of the most suitable resolution value for each specific application. In addition to its theoretical importance, the generalized analysis aids practical application by facilitating performance calculations and the selection of the most suitable resolution for specific applications. The performance evaluation was conducted for code converters implemented using the widely used 74LVC logic circuits, considering a 6-bit converter as a representative example of converters with a single XOR logic gate in the feedback loop of the shift register, and an 8-bit converter as a representative example of serial converters with three XOR logic gates in the feedback loop. By applying the proposed analysis, the maximum clock frequency was determined to be 29.85 MHz for both resolution values (6 and 8 bits). Simulations in NI Multisim software validate the performed analysis, showing a strong correlation between simulation and theoretical results.

U radu je najpre opisan postupak izrade staklenog diska optičkog pseudoslučajnog enkodera. Potom je predstavljen postupak očitavanja koda sa realizovanog diska enkodera. Očitani signali, nakon njihove obrade, se vode na ulaze akvizicione kartice. U LabVIEW softveru je realizovan virtuelni instrument za određivanje ugaone pozicije na osnovu očitanih signala.

U radu su predstavljene performanse DPCM (Differential Pulse Code Modulation) sistema sa fiksnim Lloyd Max kvantizerom i prediktorom prvog reda. Sistem je primenjen za obradu snimljenog EKG (ElectroCardioGram) signala. Sagledane su mogućnosti korigovanja parametara sistema kao što su opseg kvantizera i vrednosti koeficijenta prediktora sa ciljem poboljšanja performansi sistema. Uočen je efekat propagacije greške nastale usled kvantizacije i predikcije.

Pseudorandom encoders represent a significant type of absolute position encoders that can be implemented using only a single code track on a code disk and a single reading head, making them especially suitable for high-resolution position measurements. Since pseudorandom code words used for encoding positions are not compatible with other electronics, pseudorandom encoders include a converter that translates the pseudorandom code into the natural binary code. This paper proposes an improved implementation of the serial Fibonacci pseudorandom/natural code converter used in pseudorandom position encoders. The improvement is based on modifying the way bits are written into the converter’s shift register, which reduces the propagation delay inside the code converter, thus enabling an increase in the clock frequency. Simulations of the proposed solution, performed in Multisim software, provide a realistic picture of its behaviour and performance. Based on the simulation results, the proposed solution enables a significant increase in the clock frequency of the code converter by 180.54% or 57.56%, depending on the encoder resolution. This significantly boosts the speed of code conversion and enhances the overall performance of the position encoder. The proposed solution is highly valuable for numerous position measurement applications, especially in the increasingly relevant high-resolution applications.

U radu je testiran rad optičkog modula TSL 1401-DB koji ima ugrađen čip sa linearnim nizom od 128 fotodetektora. Detaljno je analiziran princip rada optičkog modula i njegovo povezivanje sa matičnom pločom. Zatim je testiran rad ovog modula na primeru očitavanja inkrementalne trake sa diska inkrementalnog enkodera niske rezolucije. Predstavljeni su očitani signali sa inkrementalne trake prilikom rotacije diska enkodera.

Ovaj rad je posvećen određivanju maksimalne frekvencije takta serisjkog konvertora sekvence maksimalne dužine u prirodni binarni kod, kao jednog od najvažnijih faktora koji utiču na maksimalnu brzinu rada pseudoslučajnih apsolutnih enkodera pozicije. Maksimalna frekvencija takta je određena na osnovu detaljne analize propagacionih kašnjenja unutar serijskog konvertora koda. U radu se razmatra 5-bitni serijski konvertor, ali princip i prikazana analiza mogu da se primene i za druge vrednosti rezolucije. Na osnovu izvršene teorijske analize izračunate su konkretne numeričke vrednosti propagacionih kašnjenja i maksimalne frekvencije takta, za slučaj da je serijski konvertor koda realizovan pomoću 74LVC familije logičkih kola.

This paper presents a compact linearization circuit designed to compensate for the nonlinearity of an angular position encoder. The circuit comprises two main sections: a preprocessing circuit that generates a modified sine signal from the encoder output signals, and a two-stage piecewise linear analog-to-digital converter of a compact design that performs nonlinearity compensation and digital conversion of the modified sine signal. Compactness is achieved by utilizing a single flash analog-to-digital converter for both conversion stages, thereby reducing the number of power-consuming comparators and production costs. LabVIEW simulations demonstrate a major reduction in both the maximal absolute nonlinearity error and the relative nonlinearity error of the measurement system. Before linearization, these errors were 0.33067 rad and 21.05%, respectively, but decreased to 0.00654 rad and 0.10403% after linearization with the proposed circuit.