Why is acquisition speed critical for force measurement?

What is acquisition speed or frequency?

In any digital system, unlike an analog instrument, the force or torque sensor is never read continuously. Instead, the display regularly reads the sensor at a given frequency. The acquisition or sampling frequency is therefore the number of times the display reads the load cell per second. It is expressed in Hz (Hertz). If you acquire the curve, the number of points on your curve will be determined by this acquisition frequency. Be careful, however, as the acquisition frequency on the sensor and on the connection to the computer are generally different. This often explains why the result of the maximum calculation on the display, for example, is generally more accurate than that after acquisition on the computer.

For example, on our Centor Touch force gauges, the acquisition speed on the load cell is 5,000 Hz, but the transfer speed to the computer is now 1,000 Hz. You may therefore get slightly different results. In general, it's best to rely on the display.

Explanations :

In the case of fracture tests on rapidly breaking materials, we often see the type of curves shown opposite: the force drops very rapidly from its maximum to 0 in a few milliseconds.

Zoom 200Hz curve

Zoom 100 Hz curve

If we now zoom in on the peak of the curve at two different acquisition frequencies (100 Hz and 200 Hz), we can see that the curve is not in fact continuous, but a succession of points. We can quickly see that on the 100 Hz curve, the maximum will be lower than on the 200 Hz curve.