Build a Better Sensor Characterization System | designnews.com

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| December 26, 2020

Sensor characterization is the process of establishing a basic understanding of sensor function in a controlled, known loading environment. Spending time testing sensors under various circuit load conditions and interface materials is critical to establishing performance benchmarks.

In the future, if you observe unexpected results, you can use the data in established performance benchmarks to determine possible causes, isolate variables, and systematically determine the root cause of the observed problems. Without such initial sensor characteristics, troubleshooting and debugging the device can become an expensive game of guessing, checking and then repeating the process.

Engineers hope to answer two core questions through sensor characterization

The basic performance of the sensors they plan to use. The second is how the sensor works with the interfaces, circuits and materials considered by the application.

When using force or load sensors, you may want to build your own load device and signal conditioning circuit from scratch. If the company involved has expertise in the field, this is not a bad choice. If not, it may be more cost-effective to purchase a sensor characterization kit off-the-shelf.

These kits can help engineers understand the performance of different force and pressure sensors in different circuits and controlled load environments. E.g,

Including desktop loading fixtures and on-board calibrated load cells. The load cell system is necessary to characterize the process because it allows the user to understand the function and performance of the sensor under a known load. This particular kit includes three interchangeable analog circuit module sensors and open source software for controlling lamps and recording sensor data, and a universal power supply.

After obtaining the baseline of the sensor characteristics, the next step is to start applying the load to the selected force-pressure sensor at the expected force frequency through the load cell kit or platform. The record of sensor performance should be kept in the relevant software program.

It is often noticed that the sensor responds differently to different circuit configurations. For example, compared with an inverting operational amplifier, the voltage divider has a much less linear output curve.

Once the most suitable circuit is selected for a given application, the design team will use the interface material for that application to test the sensor circuit system. Haidar explained that this kind of test helps to initially determine the value of the reference voltage, resistors and capacitors in the circuit. In addition, the test provides a baseline of linear hysteresis drift and repeatability based on specific circuit components and interface materials.

After the sensor characterization process is complete, the next step is to create a proof of concept, which will help determine whether the sensor can successfully capture its expected measurement results through the selected electrical and mechanical configuration. This will be the subject of subsequent articles.

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