RU2811329C2 - Quasi-distribted rc sensor and method for measuring distribted physical fields - Google Patents

Abstract

FIELD: sensor devices.

SUBSTANCE: invention used measuring resistance and capacitance based on a quasi-distributed RC sensor. To measure resistance and capacitance, separate resistive R and capacitive C sensitive elements are used, connected in parallel to each other and forming separate sensitive RC elements, while the individual sensitive RC elements are connected in a tree structure and form a quasi-distributed RC sensor.

EFFECT: providing the ability to simultaneously measure several distributed physical quantities.

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Description

Field of technology to which the invention relates

The invention relates to the field of distributed measurements of physical quantities, namely to quasi-distributed sensors and methods for measuring parameters of distributed physical quantities based on such sensors.

Prior Art

There is a known method for implementing quasi-distributed resistive sensors (O. Oballe-Peinado et al ., “FPGA-Based Tactile Sensor Suite Electronics for Real-Time Embedded Processing,” in IEEE Transactions on Industrial Electronics , vol. 64, no. 12, pp. 9657 -9665, Dec. 2017, doi: 10.1109/TIE.2017.2714137), based on the use of resistive sensing elements and constant capacitors. The essence of this method is to use the transient process of capacitor discharge through the resistance of the resistive sensitive element under study. In this case, an analog-to-digital converter (ADC) is not used to analyze the transient process, and the discharge time of the capacitor is determined by the change in the logic level at the input of the programmable logic integrated circuit (FPGA) microcircuit. At the same time, to eliminate the influence of errors associated with the variability of the capacitance value of the capacitors and the unequal level of change in the logical level at different inputs of the FPGA, a high-precision resistor with a constant resistance is additionally introduced into each measuring circuit.

The disadvantage of this method is the use of only resistive sensitive elements and the measurement of only the field of one distributed physical quantity.

There is a known method for reading the readings of a capacitive sensor consisting of a plurality of capacitive sensing elements (US patent No. 7755683B2, IPC H04N 5/335 (2006.01), H04N 3/14 (2006.01), published 07.13.2010). Single capacitive sensing elements in this case are connected in a matrix structure, and at the intersection of one line of rows and one line of pillars there is only one capacitive sensing element. The measurement method includes: preliminary reset of the charge amplifier output voltage; connecting all lines of rows and columns of non-scanned capacitive sensing elements to the reference voltage; connecting the capacitive sensing element under study and the feedback capacitor to the inverting input of the amplifier; supplying a step voltage to the capacitive sensing element under study, connected to the inverting input of the amplifier; voltage reading in steady state.

The disadvantage of this method is the use of only capacitive sensing elements and the measurement of the field of only one distributed physical quantity. Also, the use of a matrix structure leads to the appearance of crosstalk during the measurement process and requires additional technical solutions to reduce the influence of crosstalk on the measurement results.

A distributed touch sensor and measurement method are known (US patent No. 9024909B2, IPC G06F 3/045 (2006.01), G06F 3/044 (2006.01), G06F 3/041 (2006.01), published 05.05.2015), which uses capacitive sensors elements together with resistive sensing elements to obtain greater measurement information compared to using only capacitive sensing elements. This distributed touch sensor consists of multiple sensing cells combined into a matrix structure consisting of a line of rows and columns. Moreover, at the intersection of one row line and one row line there is only one sensitive cell. The sensitive cell, in turn, consists of resistive and capacitive sensitive elements connected in parallel. The process of scanning sensitive elements is similar to how it is performed in resistive matrix structures, namely, the cell under study is selected and, using row and column line multiplexers, access to the matrix cell under study is provided. During the measurement process, the total electrical resistance of the sensitive cell under study is determined. In this case, the total electrical resistance can be determined at various frequencies. From the obtained value of total electrical resistance, the real and imaginary parts are separated and, using the previously obtained calibration characteristic, the resistance of the resistive sensitive element and the capacitance of the capacitive sensitive element of the corresponding cell are determined.

The disadvantage of this solution is associated with the disadvantage of matrix structures, namely the occurrence of crosstalk during the measurement process. This feature reduces the accuracy of measurements and requires technical solutions to reduce or eliminate the influence of crosstalk.

The closest to the claimed technical solution in terms of technical essence and achieved technical result is a quasi-distributed resistive sensor with a tree structure (Denisov E. S., Shafigullin I. D., Evdokimov Yu. K. Quasi-distributed resistive sensor with a tree structure // Autometry. - 2021 . – T. 57. – No. 2. – P. 117-121.). This quasi-distributed resistive sensor can be used in systems where only the external terminals of the sensor are available for connecting measurement equipment. A quasi-distributed resistive sensor consists of resistive sensing elements electrically connected in a tree-like structure. The use of a tree structure provides the ability to measure the resistance values of individual resistive sensitive elements using the “voltmeter-ammeter” method, providing different current flow paths for the probing and measuring signals. The tree structure allows the quasi-distributed sensor to be made into a single layer. The method for measuring distributed physical quantities is based on switching the source of the probing signal and the voltage meter. In this case, the paths of current flow for the probing and measuring signals are different.

The disadvantage of this method is the use of only resistive sensors, due to which it is possible to measure the field of only one distributed physical quantity. In the case of using heterogeneous resistive sensor elements that are sensitive to different physical quantities, the area resolution of a quasi-distributed resistive sensor for the corresponding field of the physical quantity decreases.

Disclosure of the Invention

There are known designs and methods that make it possible to measure the field of a distributed physical quantity based on quasi-distributed resistive or quasi-distributed capacitive sensors. However, they do not allow simultaneous measurement of fields of several distributed physical quantities.

Resistive-capacitive sensors are also known that allow simultaneous measurement of the field distribution of several physical quantities. However, such sensors are implemented on the basis of matrix structures, in which the main disadvantage is the occurrence of crosstalk that affects the accuracy of measurements.

The proposed invention eliminates these disadvantages.

The technical result achieved when using the claimed invention is to provide the possibility of simultaneous measurement of several distributed physical quantities.

The technical result is achieved by using separate resistive R and capacitive C sensitive elements, connected in parallel to each other and forming separate sensitive RC elements, while the individual sensitive RC elements are connected in a tree structure and form a quasi-distributed RC sensor.

A quasi-distributed RC sensor includes a set of electrically connected resistive and capacitive sensing elements that are sensitive to specific physical quantities. Separate resistive R and capacitive C sensitive elements are connected in parallel to each other and form a sensitive RC element, while the individual sensitive RC elements are connected in a tree structure that provides different paths for the flow of currents of the probing and measuring signals, with the ability to measure the resistance of a separate sensitive RC element according to the “voltmeter-ammeter” method in a steady state, after switching the source of the probing signal, and the value of the capacitance of a separate sensitive RC element according to the time constant of the discharge of the capacitive C sensitive element through a parallel connected resistive R sensitive element, which occurs after turning off the source of the probing signal.

At one internal point of a quasi-distributed RC sensor, n sensitive RC elements are connected, where n is an integer greater than 2. In this case, a separate sensitive RC element can be made in a single design.

A method for measuring physical quantities based on a quasi-distributed RC sensor includes the following steps:

step 1, in which the source of the probing signal is connected to the two terminals of the quasi-distributed RC sensor in such a way that the current of the probing signal generated by the source of the electrical probing signal flows through the measured sensing RC element;

step 2, in which the RC sensing element to be measured is connected to a voltage meter with a high input impedance through the other two terminals of the quasi-distributed RC sensor so that the measuring circuit current and the probing signal current flow through only one common RC sensing element to be measured;

stage 3, at which they wait for the period of time necessary to complete the transient processes associated with the charge of capacitive C sensitive elements along the path of the probing signal current;

stage 4, at which the value of the probing current is determined;

stage 5, at which the voltage drop across the sensitive RC element under study is determined using a voltage meter;

stage 6, at which the resistance value of the sensitive RC element under study is determined by dividing the readings of the voltage meter by the value of the probing current;

stage 7, at which the probing current is opened for the appearance of a transient discharge process of the capacitive C sensitive element in the sensitive RC element under study;

stage 8, at which the transient process is measured on the sensitive RC element under study using a voltage meter, while stages 7 and 8 are synchronized with each other and are performed simultaneously;

stage 9, at which the transient process obtained in stage 8 is approximated by the function: (Where – constant voltage component; – amplitude voltage value; – time constant of the RC element) and determine the time constant for this RC element;

stage 10, at which the capacitance value of the RC element under study is determined according to the formula: , based on the known time constant , determined at stage 9, and the resistance value calculated at stage 6 ;

stage 11, at which the resistance and capacitance of the measured sensitive RC element are recalculated into the corresponding physical quantities;

step 12, at which steps 1-11 are repeated to measure the resistance and capacitance of other sensitive RC elements in the structure of the quasi-distributed RC sensor and recalculate them into the corresponding physical quantities.

The inventive method is illustrated in the figures

In fig. Figure 1 shows an implementation of a quasi-distributed RC sensor consisting of 7 sensitive RC elements.

In fig. Figure 2 shows an illustrative diagram of a quasi-distributed RC sensor, consisting of 7 sensitive RC elements, indicating the current flow paths of the probing signal driver and the measuring circuit when measuring the resistance and capacitance of the sensitive RC element RC2.

In fig. Figure 3 shows a block diagram of a device for measuring the resistance and capacitance of sensitive RC elements in the structure of a quasi-distributed RC sensor.

The essence of the invention

The quasi-distributed RC sensor consists of resistive R and capacitive C sensing elements. Separate resistive R and capacitive C sensing elements, connected in parallel to each other, form a RC sensing element. In this case, individual sensitive RC elements are connected in a tree-like structure, providing different paths for the flow of currents of the probing and measuring signals, with the ability to measure the resistance of an individual sensitive RC element using the “voltmeter-ammeter” method in a steady state, after switching the source of the probing signal, mode and value the capacity of an individual sensitive RC element according to the time constant of the discharge of the capacitive C sensitive element through a parallel connected resistive R sensitive element, which occurs after the source of the probing signal is turned off.

In fig. Figure 1 shows one of the possible ways to implement a quasi-distributed RC sensor consisting of 7 sensitive RC elements. At each internal point of the presented quasi-distributed RC sensor, 3 sensitive RC elements are connected, which in turn consist of resistive R and capacitive C sensors. In other implementations of a quasi-distributed RC sensor, the number of sensitive elements can increase or decrease depending on the characteristics of the process and the measurement object.

In fig. Figure 2 shows the distribution of the probing current and the current of the measuring circuit when measuring the resistance and capacitance of the sensitive RC element RC2 under study. In this case, the probe signal driver is connected between terminals T 1 and T 2 and ensures the flow of probe current through the sensitive RC elements RC1, RC2 and RC4. A voltage meter is connected between terminals T 5 and T 3 to provide the measuring circuit current through the RC sensing element RC2 under test. In this case, the current of the measuring circuit flows through the sensitive RC elements RC7, RC3, RC2 and RC5. With such switching of the probing signal former and the voltage meter, a measuring circuit similar to a four-wire measurement circuit is obtained, in which the influence of the measuring wires and other sensitive elements on the results of measuring the voltage drop across the sensitive RC element under study is minimized.

In fig. Figure 3 shows a block diagram of a device for measuring distributed physical fields based on a quasi-distributed RC sensor with a tree structure. This circuit includes: 1 – Probing signal generator; 2 – Probe current meter; 3 – Probing signal switch; 4 – Quasi-distributed RC sensor with tree structure; 5 – Voltage meter switch; 6 – Voltage meter; 7 – Control and data processing unit.

The illustrations in Fig. 1 - Fig. 3 are presented solely for the purpose of understanding the essence of the invention and do not in any way limit the scope of this invention.

The process of measuring distributed physical fields based on a quasi-distributed RC sensor with a tree structure consists of the following steps:

stage 1, at which the probe signal shaper 1 is connected to two terminals of the quasi-distributed RC sensor using the probe signal switch 3 so that the current of the probe signal generated by the probe signal shaper 1 flows through the measured sensitive RC element of the quasi-distributed RC sensor 4 with a tree structure . In this case, the configuration of the probe signal shaper 1 and the probe signal switch 3 is carried out using the control and data processing unit 7;

stage 2, at which the measured sensitive RC element of the quasi-distributed RC sensor 4 is connected to the voltage meter 6, with a high input resistance, due to the corresponding switching of the external terminals of the quasi-distributed RC sensor 4 and the inputs of the voltage meter 6 with each other using the voltage meter switch 5. Setup The switch of the voltage meter 5 is carried out using the control and data processing unit 7. In this case, the connection of the voltage meter 6 to the external terminals of the quasi-distributed RC sensor 4 occurs in such a way that the current of the measuring circuit and the current of the probing signal flow only through one common measured sensitive RC element;

stage 3, at which they wait for the period of time necessary to complete the transient processes associated with the charge of capacitive C sensitive elements along the path of the probing signal current;

stage 4, at which, using the probing current value meter 2, the value of the probing current flowing through the investigated sensitive RC element of the quasi-distributed RC sensor 4 is determined. After which the value of the probing current is transmitted to the control and data processing unit 7;

stage 5, at which the voltage drop on the tested sensitive RC element is determined using a voltage meter 6. After which the value of the voltage drop on the tested sensitive RC element is transmitted to the control and data processing unit 7;

stage 6, at which, using the control and data processing unit 7, the resistance value of the sensitive RC element under study is calculated by dividing the reading of the voltage meter 6 by the reading of the probing current meter 2;

stage 7, at which, using the probing signal switch 3, the probing current is opened for the appearance of a transient discharge process of the capacitive C sensitive element in the sensitive RC element under study. In this case, the probing signal switch 3 is controlled using the control and data processing unit 7;

stage 8, at which the transient process is measured on the sensitive RC element under study using voltage meter 6. Next, the received data from the voltage meter is transferred to the control and data processing unit. In this case, stages 7 and 8 are synchronized with each other and are performed simultaneously;

stage 9, at which, using the control and data processing unit 7, the transient process obtained in stage 8 is approximated by the function: (Where – constant voltage component; – amplitude voltage value; – time constant of the RC element) and determine the time constant for this RC element;

stage 10, at which, using the control and data processing unit 7, the capacitance value of the RC element under study is determined according to the formula: , based on the known time constant , determined at stage 9, and the resistance value calculated at stage 6 ;

stage 11, at which, using the control and data processing unit 7, the value of the resistance and capacitance of the measured sensitive RC element is recalculated into the corresponding physical quantities;

step 12, at which steps 1-11 are repeated to measure the resistance and capacitance of other sensitive RC elements in the structure of the quasi-distributed RC sensor and recalculate them into the corresponding physical quantities.

Claims (2)

1. A quasi-distributed RC sensor includes a set of electrically connected resistive and capacitive sensing elements that are sensitive to certain physical quantities, separate resistive R and capacitive C sensing elements are connected in parallel to each other and form a sensing RC element, while the individual sensing RC elements are connected into a tree structure that provides different paths for the flow of currents of the probing and measuring signals, with the ability to measure the resistance of an individual sensitive RC element using the “voltmeter-ammeter” method in a steady state, after switching the source of the probing signal, and the capacitance value of an individual sensitive RC element according to a constant the discharge time of the capacitive C sensitive element through a resistive R sensitive element connected in parallel, which occurs after the source of the probing signal is turned off. 2. A method for measuring resistance and capacitance based on a quasi-distributed RC sensor is to connect the source of the probing signal to two terminals of the quasi-distributed RC sensor so that the current of the probing signal generated by the source of the electrical probing signal flows through the measured sensitive RC element, connecting the measured sensitive RC - an element to a voltage meter with a high input impedance through the other two terminals of the quasi-distributed RC sensor so that the current of the measuring circuit and the current of the probing signal flow only through one common measured sensitive RC element; determining the value of the probing current, determining the voltage drop on the test sensitive RC element using a voltage meter, determining the resistance value of the test sensitive RC element by dividing the readings of the voltage meter by the value of the probing current, ensuring the opening of the probing current for the occurrence of a transient discharge process of the capacitive C sensitive element in the sensitive RC element under test, measuring the transient process on the test sensitive RC element using a voltage meter, the stage at which the probing current is opened for the appearance of the transient discharge process of the capacitive C sensitive element in the test sensitive RC element and the stage at which the transient is measured The process on the sensitive RC element under study using a voltage meter is synchronized with each other and is carried out simultaneously, approximating the transient process with the function: (Where – constant voltage component; – amplitude voltage value; – time constant of the RC element) and determining the time constant for a given RC element, determining the capacitance value of the RC element under study according to the formula: , based on the known time constant and the calculated resistance value , recalculating the resistance and capacitance of the measured sensitive RC element into the corresponding physical quantities, repeating the previous steps to measure the resistance and capacitance of other sensitive RC elements in the structure of the quasi-distributed RC sensor and recalculating them into the corresponding physical quantities.

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