Torque Sensor Calibration Is Important, How To Do It?

Torque sensor calibration is important, how to do it?

Basic principle of torque sensor:

Torque measurement: Using the strain gauge electric measurement technology, a strain bridge is formed on the elastic shaft, and the electric signal of the elastic shaft torsion can be measured by supplying power to the strain bridge. After the strain signal is amplified, it becomes a frequency signal proportional to the torsional strain through voltage/frequency conversion. as the picture shows:

Rotational speed measurement: The rotational speed measurement is carried out using the principle of magnetoelectricity. Each disk has 60 teeth, and the shaft drives the disk to generate 60 pulses per revolution. When sampling at high or medium speed, you can use the method of frequency measurement, and sampling at low speed The accurate speed can be measured by the method of measuring cycle. The accuracy of this sensor can reach ±0.1%～±0.5% (F·S). Since the output of the sensor is a frequency signal, it can be directly sent to the computer for data processing without AD conversion. The speed measurement method of this sensor adopts the built-in speed measurement, and the user needs to indicate whether to monitor the speed signal when ordering!

Torque sensor product features:

1. The signal output waveform square wave amplitude can be 5V/12V.

2. It can enter the working state after turning on the machine, no preheating process is required.

3. High detection accuracy, good stability and strong anti-interference.

4. It can continuously measure positive and negative torque without repeated zero adjustment.

5. Small size, light weight, easy to install.

6. The sensor can be used independently from the secondary instrument. As long as the power supply of ±15V (200mA) is provided according to the pin number of the socket, the equal square wave or pulse wave frequency signal whose impedance is proportional to the torque can be output.

Purpose of torque sensor calibration:

Calibration is the determination of the relationship between an output measurement and an input measurement (here torque) under predetermined conditions. Compare with a reference of the same instrument unit. Torque calibration is only allowed with a recoverable reference torque. The traceability of the force on the measured object alone proves to be insufficient, because how the force is transformed into torque under leverage is not put into words. Predetermined conditions include environmental conditions such as temperature, relative air humidity and the consequences of sensor installation and load. The torque as an input quantity must be formed mechanically and otherwise must be a known quantity. Therefore, as a calibration object, we strive for high precision from the beginning to the end. Calibration makes a classification between the input quantity (true torque within the scope of the calibration method) and the output quantity. The calibration object is either a torque sensor or a measuring chain which, in addition to the torque sensor, also includes a measuring amplifier and a display unit.

Dynamic Calibration:

Torque transducers currently used in field test bench technology are calibrated purely statically in a broad sense, although practical applications are all dynamic, as revealed in Chapter 4. The measuring principle of strain gauges is known and its validity is the same for both static and dynamic loads, so these behaviors must be proven to a good approximation. However, with the increasing accuracy and the corresponding requirements for the traceability of the measured quantities, the practical dynamic calibration problem is also becoming more and more important.

As a dynamic calibration in the narrower sense, it must be recognized that the torque obtained during the calibration changes rapidly over time, which in its dynamics corresponds to the possible operating time changes.

Accuracy adjustment and measurement method:

This requires both determining the reference torque and measuring the output of the torque sensor sensor to be calibrated while the torque is continuously changing. This requires special attention to the simultaneity of the measurements. Furthermore, if the amplifier type is not exactly the same for the reference and calibration objects, the signal travel time of the amplifier has an effect on the rapidly changing torque. Different signal travel times may also be the result of different adjustments and different characteristics of the filters.