A Self-Check Method for Enhancing the Measurement Accuracy of Analog Sensors Under Electromagnetic Interference

Inaccurate measurements of analog sensors caused by electromagnetic interference (EMI) signals threaten the security and reliability of sensor-based systems. This article proposes a self-check method for recognizing and correcting disturbed measurements of analog sensors under EMI signals. The core basis of this method involves the use of a dummy sensing element to make the sensor sensitive only to EMI signals, rather than the measurand. This configuration enables the sensor to switch between normal mode and self-check mode through switching devices. Then the sensor response to EMI signals in normal mode is characterized by that in self-check mode, which is computable. A detailed implementation framework is derived to ensure that the sensor responses to EMI signals in both modes are highly similar, involving the properties of the dummy sensing element, the input voltage of the operational amplifier (opamp), and the power supply rails. Owing to its low demand for additional components and computing resources, the proposed self-check method is cost-effective and convenient to implement. Its effectiveness and robustness are validated on a temperature sensor, an ambient light sensor, a linear variable differential transformer (LVDT) and a wireless temperature sensor node with EMI experiments using different signals parameters, temperatures and light intensities. The experimental results show that this method can enhance the measurement accuracy of analog sensors to help maintain the functioning of sensor-based systems under EMI signals.