Bias instability refers to the variation or drift in the output of a sensor or measurement system over time, particularly in inertial measurement units (IMUs) or gyroscopes. It represents the instability or fluctuations in the bias (the offset or error from the true zero value) of the sensor. Essentially, bias instability indicates how much the sensor’s measurement drift fluctuates without any external influences, such as changes in temperature or environmental conditions.
In the gyroscopes or accelerometers (key components in GNSS/INS systems), bias instability is considered one of the most critical parameters in the majority of inertial navigation (INS) applications, as it determines how accurately the system can maintain position or orientation over time. If the bias instability is high, the sensor will show more significant drift in its measurements over time, leading to larger errors in navigation, positioning, or orientation estimates.
Bias instability is typically expressed in degrees per hour (°/hr) or radians per hour (rad/hr) for gyroscopes, and meters per second squared (m/s²) for accelerometers. These units quantify the amount of drift or instability in the sensor’s measurements over a given time period, which is crucial for evaluating and compensating for long-term errors in high-precision applications.
In many high-precision applications, such as navigation or guidance systems, minimizing bias instability is critical for achieving long-term accuracy. Engineers often design systems with compensation techniques to reduce or correct the effects of bias instability, thereby improving the overall system performance.
