SU808948A1

SU808948A1 - Device for measuring resistance increment

Info

Publication number: SU808948A1
Application number: SU792756492A
Authority: SU
Inventors: Олег Владимирович Галкин
Original assignee: Предприятие П/Я А-7701
Priority date: 1979-04-23
Filing date: 1979-04-23
Publication date: 1981-02-28

Description

1one

Изобретение ОТНОСИТСЯ к электроизмерительной технике и может быть использовано дл измерени приращений сопротивлени различных резистивных датчиков, например тензорезисторов .The invention relates to electrical measuring technology and can be used to measure the resistance increments of various resistive sensors, such as resistance strain gages.

Известно устройство дл измерени приращений сопротивлени , в котором примен етс мостова цепь, питаема импульсами напр жени 1.A device for measuring the increments of resistance is known, in which a bridge circuit is used, fed by voltage pulses 1.

Однако дл устройства характерно сильное вли ние емкостной составл ющей кабел на точность измерени и быстродействие. При изменении параметров кабел , например, за счет длины, измен етс длительность перехсф ного процесса. Это приводит к тому , что выходное напр жение мостовой установки, завис щее от измер емого приращени и напр жени переходного процесса, измен етс , создава погрешность измерени , дл уменьшени которой выходное напр жение усилител фиксируют на емкости синхродетектора через врем , значительно большее длительности переходного процесса , -что снижает быстродействие измерени 2 .However, the device is characterized by a strong influence of the capacitive component of the cable on the measurement accuracy and speed. When the cable parameters change, for example, due to the length, the duration of the transfer process changes. This leads to the output voltage of the bridge installation, depending on the measured increment and voltage of the transient process, creating a measurement error to decrease which the output voltage of the amplifier is fixed to the sync detector’s capacitance that reduces the measurement speed 2.

Наиболее близким по технической сущности к предлагаемому вл етс The closest in technical essence to the proposed is

устройство, состо щее из генератора импульсов, один выход которого св зан с мостовой цепью, в которую включен измер емый резистор. Усиленный сигнал разбаланса поступает на два синхродетектора, где фиксируетс в различные моменты времени под действием импульсов с выходов генератора импульсов 3.a device consisting of a pulse generator, one output of which is connected to a bridge circuit in which the measured resistor is connected. The amplified unbalance signal is fed to two sync detectors, where it is recorded at different points in time under the action of pulses from the outputs of the pulse generator 3.

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Однако из-за фиксации в синхродетекторах импульсов разной пол рности выходное напр жение в устройстве формируетс как разность выходных напр жений детекторов и поэтому также подвержено вли нию изменений емкости кабел . При увеличении его емкости напр жени , соответствующие моментам фиксации напр жений импульса и паузы, измен ютс , так как из0 мен ютс значени напр жений переходных процессов в эти моменты, что вызывает погрешность измерени . Дл уменьшени зтого вли ни фиксируют напр жени после окончани переход5 ных процессов, что резко снижает быстродействие измерени .However, due to the fixation in the sync detectors of pulses of different polarities, the output voltage in the device is formed as the difference between the output voltages of the detectors and, therefore, is also affected by changes in cable capacitance. With an increase in its capacitance, the voltages corresponding to the moments of the fixation of the impulse voltages and the pauses change, since the values of the transient voltages at these moments change, which causes a measurement error. To reduce this effect, stresses are recorded after the end of transition processes, which drastically reduces the measurement speed.

Цель изобретени - повышение точности и быстродействи измерени . Указанна цель достигаетс тем,The purpose of the invention is to improve the accuracy and speed of measurement. This goal is achieved by

Claims

0 that a device for measuring increments of resistance, containing a pulse generator, the first output of which is connected to the supply diagonal of a bridge measuring circuit, in one short arm of which there is a measuring resistor, unbalance amplifier included in the measuring diagonal of the bridge measuring circuit, two keys of sync detector, which capacitors of sync detectors are connected to the output of the unbalance amplifier, and the control input of the first switch of the first sync detector is connected to the second output of the impulse generator It is equipped with a comparison unit and a linearly varying voltage generator, the input of which is connected to the first output of the pulse generator, and the output is connected to one of the inputs of the comparison unit, the other input of the comparison unit is connected to the output of the first key of the first sync detector. dinene with control input of the second key of the second sync detector. FIG. 1 shows a functional diagram of the device; FIG. 2 is a time chart. The proposed device consists of a pulse generator 1, a bridge circuit 2 with a measured resistor 3, an unbalance amplifier 4, a linearly varying voltage generator 5, a first switch b and a second switch 7 of the sync detector, capacitors 8 and 9 of the sync detectors and a comparison unit Pulse generator 1 connected by the first output to the bridge circuit 2, consisting of active resistances one of which is measured by me and is connected to the bridge circuit of a cable, for example, a resistor 3, the unbalance amplifier 4 is connected to the diagonal of the bridge circuit 2 with its input, than its output through the keys 6 and 7 of the sync detectors is connected to the capacitors 8 and 9 of the sync detectors. The generator 5 linearly varies the voltage by its input connected to the first output of the generator 1, and its output to one of the inputs of the comparison unit 10 whose other input is connected to the output of the first key 6 of the sync detector, and the output is connected with the control input of the second key 7, the control key of the first key of the sync detector is connected with the second output of the pulse generator 1, the device works as follows. The pulse generator 1 generates square-wave pulses that feed the bridge circuit 2. The balance voltage, amplified by the amplifier 4, has the form (FIG. 2, curve 1). At time t, key b is briefly opened and the capacitor 8 is charged to voltage and., Corresponding to the voltage transient at time t. This voltage is compared with the voltage from the generator 5 of a linearly varying voltage and at the moment of their equality the comparison unit 10 is triggered. Under the action of a pulse from the output of this block, the switch 7 is momentarily opened and the capacitor 9 remembers the output voltage of the amplifier at a time t, the value of which determines the measured increment of the resistor 3, When the capacitance of the cable changes, for example, when it is increased, the transient process occurs with a large time constant (fig. 2, curve 2). At the same time, the capacitor 8 of the sync detector at the time C fixes the voltage and is greater than U, therefore the moment of equality of the voltages on this capacitor and from the generator 5 of the linearly varying voltage is shifted to a point which leads to the setting of the voltage on the capacitor 9, according to corresponding to the previous capacity, cable. Thus, tracing at time t, which follows immediately after the beginning of the supply pulse, the voltage values of the transient process -. Sa on its linear section and changing in accordance with it the moment of fixation of the output voltage of the unbalance pulse increases the measurement accuracy of the proposed device in comparison with the known ones, where the sync detector key opens at a constant time interval after the beginning of the power supply pulse of the bridge circuit. The device operates at those points in time when the voltage of the transient process is different from zero, which makes it possible to reduce the duration of the supply pulse and the period of their follow-up and, consequently, increase the measurement speed. The invention The device for measuring the increments of resistance, containing a pulse generator, the first output of which is connected to the supply diagonal of a bridge measuring circuit, one of the arms of which includes a measuring resistor, an unbalance amplifier included in the measuring diagonal of a bridge measuring circuit, two keys of a sync detector, through which the sync detectors capacitors are connected to the output of the imbalance amplifier, and the control input of the first switch of the first sync detector is co-connected with the second output pulse generator, characterized in that, in order to improve the accuracy and speed of measurement, the device