RU20578U1 - DEVICE FOR VERIFICATION OF POWER SENSORS WITH TENSOMETRIC BRIDGE DIAGRAMS - Google Patents

Abstract

A device for calibrating load sensors with strain gauge bridge circuits, comprising a load system for the sensor being calibrated, a voltage supply unit for the input diagonal of the bridge, an output voltage registration unit with an output diagonal in the form of an ADC and a data processing unit in the form of a computer, characterized in that the ADC is made of two-channel, with synchronous measurement of values at both inputs, between the voltage supply unit and the input diagonal of the bridge, a voltage divider is installed, the input of which is connected to the voltage supply unit, one the output is connected to one ADC channel, the second to the input diagonal of the bridge, and the output diagonal is connected to the second input of the ADC, both outputs of which are connected to a computer.

Description

Device for checking load cells with strain gauge bridge circuits

The utility model relates to testing equipment and can be used to verify, calibrate and monitor the status of load cells used in various sectors of the economy.

A device for calibrating or calibrating hopper scales, comprising a hoist with a gripper for an exemplary load, is mounted on the scale body (see the description of the invention to application No. 94038840, G 01 O 23/01, 1995/1 /). A disadvantage of the known device is its limited use, since it is fixed on the housing of the hopper scales, as well as the complexity of the verification procedure and its low accuracy, due to the presence of one exemplary load.

A device for calibrating load sensors, comprising a loading system of the calibrated sensor and a data recording and processing unit in the form of a computer (see the description of US patent No. 5092154, NKI 83 / 1B, 1992 III}. The disadvantage of this device is the low accuracy of the calibration of the sensors, due to using mechanical modeling of real load.

The closest to the claimed in its technical essence and the achieved result is a device for checking the force sensors used in installations for determining the heterogeneity of car tires (see the description of the application EPO No. 541354, G 01 L 25/00, 1993/3 /). The device contains a load control system MraCGOlG 23 | 01 GOIL 25 | 00

sensor, the voltage supply unit to the input diagonal of its tensometric bridge, the voltage registration unit from the output diagonal of the bridge, made in the form of an analog-to-digital converter (ADC), and the data processing unit, made in the form of a computer.

A disadvantage of the known device is the low accuracy of calibration of calibrated sensors. This is due to the instability of the output voltage of the voltage supply unit to the input diagonal of the bridge. Of course, for verification, you can choose a voltage source with highly stable output parameters, but this is not economically feasible, because such appliances are very expensive.

Declared as a useful model, a device for calibrating force sensors is aimed at improving the accuracy of their calibration using cheap voltage sources.

The specified result is achieved by the fact that the device for calibrating force sensors with strain gauge bridge circuits contains a system for loading the calibrated sensor, a voltage supply unit for the input diagonal of the bridge, a unit for recording output voltage from the output diagonal in the form of an ADC and a data processing unit in the form of a computer, while The ADC is made two-channel, with synchronous measurement of values at both inputs, between the voltage supply unit and the input diagonal of the bridge, a voltage divider is installed, the input of which is connected to the voltage supply, one output is connected to one ADC channel, the second to the input diagonal of the bridge, and the output diagonal is connected to the second ADC input, both outputs of which are connected to a computer ..

Distinctive features of the claimed device are:

- two-channel ADC performance, with synchronous measurement of values at both inputs;

-installation between the voltage supply unit and the input diagonal of the bridge of the voltage divider, the input of which is connected to the voltage supply unit, one output is connected to one ADC channel, the second to the input diagonal of the bridge, and the output diagonal is connected to the second input of the ADC;

-connection of both outputs of the ADC with a computer.

Due to the above distinguishing features, improved calibration accuracy is achieved. Indeed, since the voltage from the voltage supply unit is supplied to the divider, and from it to the input diagonal of the bridge and simultaneously to the ADC input, their ratio, despite the voltage drift from the output of the voltage supply unit, will be constant and, accordingly, the response of the strain gauge bridge to the supplied the voltage in the form of a signal from the output diagonal at each moment (subject to the load on the sensor) will be proportional to the input voltage. And since the ADC synchronously determines the magnitude of the voltage you get; its input to it from the divider and the output diagonal of the bridge, then no voltage fluctuations will affect the magnitude of the ratio of these two signals to each other, which means it will provide the highest accuracy in calibrating the sensors, since this is determined by the division ratio or the transfer coefficient of the divider, the accuracy of which is determined not by the accuracy of the resistances of the divider resistors themselves, but by the accuracy of maintaining their ratio, which under normal operating conditions almost invariably. In addition, the divider performs the function of a consonant of its device, providing a signal to the ADC within the nominal values for the inputs of the latter.

The essence of the claimed device is illustrated by an example of its implementation and the drawing, which presents its schematic block diagram.

The device contains a loading system of the verified sensor, which can be selected from among the known ones and is not shown in the drawing as not affecting the achievement of the claimed result, but being necessary for functioning as a whole. The device includes a voltage supply unit 1, which is selected from the known one, the output of which is connected to the input of the voltage divider 2. One output of the voltage divider is connected to the input diagonal of the strain gauge bridge 3 of the load cell (the sensor itself is not shown and its construction can be any) , and the second with the first input of the two-channel ADC 4. The second input of the ADC is connected to the output diagonal of the strain gauge bridge, its two outputs are connected to the input of the computer 5. The ADC can be made as an independent unit of and known or can be made in the form of a separate board, which is part of the computer, which can also be selected from among the known.

The device operates as follows. First, a voltage of, for example, 15 V (for example, any other depending on the type of strain gages in the sensors being calibrated) is applied to the input diagonal of the strain gauge bridge 3 of the unloaded verified sensor from the voltage supply unit 1, for example, and the output voltage from the output diagonal of the strain gauge bridge is measured via ADC 4 , the value of which is recorded in the memory of the computer 5, equipped with appropriate software.

Then the sensor is mounted on the base plate of the loading system, known from the description of the certificate for the utility model of the Russian Federation No. 15934 so that the force action elastically deforms the sensor sections on which the output diagonal strain gages are placed. After that, a fixed load is applied to the sensor, and the voltage from block 1 is fed through a divider 2 to the input diagonal

the strain gauge bridge and the first input of the ADC 4, the second input of which receives a signal from the output diagonal of the strain gauge bridge and both signals received through both channels on the ADC are simultaneously measured, and the results are transferred to the computer memory for subsequent processing.

Then the next fixed load is applied to the sensor and the measurement cycle is repeated. Having sequentially a series of measurements with a stepwise increasing load, carry out measurements with a stepwise decreasing load.

Depending on the programs used, on the basis of the measurements made, it is possible to construct for each sensor a graph of the error of the quasistatic calibration characteristic, including the loading and unloading curves and allowing to determine such components of the main error as the zero error, the linearity error, the hysteresis error, the reproducibility error, and others with very high accuracy due to the use of a voltage divider and two-channel ADC with synchronous measurement of the input signal ov.

Claims (1)

A device for calibrating load cells with strain gauge bridge circuits, comprising a load system for the sensor being calibrated, a voltage supply unit for the input diagonal of the bridge, an output voltage registration unit with an output diagonal in the form of an ADC and a data processing unit in the form of a computer, characterized in that the ADC is made of two-channel, with synchronous measurement of values at both inputs, between the voltage supply unit and the input diagonal of the bridge, a voltage divider is installed, the input of which is connected to the voltage supply unit, one the output is connected to one ADC channel, the second to the input diagonal of the bridge, and the output diagonal is connected to the second input of the ADC, both outputs of which are connected to a computer.