- To make a sensor or instrument function as accurately or error-free as feasible, a sensor or collection of sensors must be calibrated.
- Electronic components are sensors. They are perceptive to alterations in their workplace. Unwanted and abrupt changes to the sensors’ operating surroundings result in undesirable output values.
- As a result, the observed output and the expected output are different. Sensor calibration is the process of comparing the measured output to the expected output.
- To improve the sensor’s performance, calibration is essential. It is employed to quantify structural flaws brought on by sensor.
- The structural error is defined as the discrepancy between the sensor’s measured value and its predicted value.
- Calibration ensures the accuracy and repeatability of measurement systems and instruments, including sensors. For accurate, dependable, and repeatable measurement results, calibrated sensors are a requirement.
- One of the essential requirements for efficient quality assurance is calibration.
Working Principle of Sensor Calibration
- Calibration of the sensors aids in enhancing their functionality and accuracy. Industries do sensor calibration using two well-known procedures.
- The first way involves businesses incorporating an internal calibration procedure within their production facility to undertake customized sensor calibration.
- In this case, the business incorporates the required hardware into its design for sensor output rectification. Through this procedure, the sensor calibration can be adjusted to meet the needs of a particular application. However, this procedure lengthens the time to market.
- As an alternative to this internal calibration process, several manufacturing firms offer sensor packages that include an excellent automotive-grade MEMS sensor in addition to full system-level calibration.
- Companies use onboard digital circuitry and software in this approach to assist designers in enhancing the performance and usability of the sensors. Digital circuitry, such as voltage regulation and analog signal filtering techniques, are used to shorten the product design cycle and reduce the number of components.
- Advanced sensor fusion methods are offered to the onboard processor to enhance overall performance and functionality. Some highly developed onboard signal processing algorithms also aid in shortening the production process, enabling quicker time to market.
- One-point calibration.
- Two-point calibration.
- Multi-Point Curve Fitting.
Characteristic of Sensor Calibration
Some of the terms used with the characteristic curve are
- Offset : The difference between the sensor output and the ideal linear response is indicated by this value.
- Sensitivity or Slope : This determines how quickly a sensor’s output changes. The sensor output varies more slowly than the optimal response, as indicated by a variation in slope.
- Linearity : Over the specified measurement range, not all sensors have a linear characteristic curve.
Characteristics of One point calibration
- When accurate measurement of a single level is required and the sensor is linear, one-point calibration is employed to rectify the sensor offset errors. Temperature sensors are typically calibrated at a single position.
Characteristics of Two-point calibration
- Errors in slope and offset are both corrected using two-point calibration. When a sensor’s output is known to be reasonably linear over a measurement range, this calibration is used. Here, reference High and reference Low are required as references.
Characteristics of Multi-Point Curve Fitting
- To obtain accurate measurements from sensors that are not linear over the measurement range, multi-point curve fitting is required.
- Thermocouples are typically fitted with multi-point curves when utilized in highly hot or extremely cold environments.
Application of Sensor Calibration
- The comparison of the desired output and the measured output is the simplest definition of sensor calibration. Numerous factors may contribute to these inaccuracies. Some of the mistakes in sensors include incorrect zero-reference errors, sensor range shift errors, mechanical damage errors, etc. Adjustment and calibration are not the same things.
- To ascertain the actual measurement errors, the calibration procedure involves putting the DUT- “Device Under Test” into configurations whose inertial input stimuli for the sensor are known.
- The calibration procedure enables us to arrive at the following conclusions
- The DUT was flawless.
- A mistake is discovered, yet nothing is changed.
- The inaccuracy is adjusted to the required amount once an adjustment is made to remove it.
- Sensor models are used for calibration. To track and modify the control processes, sensor calibration is used in control systems. To obtain accurate findings, automatic systems also calibrate their sensor.