Hysteresis
Sensor hysteresis, also known as sensor lag or deadband, refers to a phenomenon observed in sensors where the output value of the sensor does not change immediately as the input value crosses a particular threshold. Instead, there is a delay or a range of input values within which the sensor output remains unchanged, even though the input value is changing.
Hysteresis is often caused by mechanical, electrical, or physical characteristics of the sensor and its components. It can affect the accuracy and responsiveness of sensor measurements, particularly in situations where the input value is rapidly changing or fluctuating.
Key points about sensor hysteresis include:
Threshold Crossing: When an input value crosses a specific threshold on the increasing side (rising) or decreasing side (falling), the sensor output may not change until the input value exceeds a certain range.
Deadband: The range of input values within which the sensor output remains constant is referred to as the deadband. It is the difference between the upper and lower threshold values.
Response Time: The delay caused by hysteresis can result in a slower response time for the sensor to reflect changes in the input signal.
Repeatability: Hysteresis can impact the repeatability of sensor measurements, leading to variations in readings when the input signal is repeatedly cycled through the same range.
Calibration: Calibrating a sensor involves compensating for hysteresis to improve accuracy. Calibration factors can be applied to correct for the deadband effect.
Causes: Hysteresis can be caused by mechanical components, friction, backlash, elasticity, and other physical characteristics of the sensor’s materials and design.
Applications: Sensor hysteresis can impact various sensors, including temperature sensors, pressure sensors, position sensors, and more. It’s particularly relevant in control systems where accurate and timely measurements are essential.
Mitigation: To minimize the impact of hysteresis, sensors can be designed with tighter tolerances, improved materials, and advanced compensation techniques.
Understanding and accounting for sensor hysteresis is important when designing systems that rely on accurate and timely sensor measurements. It helps ensure that the sensor readings accurately reflect changes in the input signal and that control systems operate as intended.