Analysis and Compensation of Cross-Axis Sensitivity in Low-Cost MEMS Inertial Sensors

Abstract

This paper is concerned with cross-axis sensitivity in low-cost MEMS triaxial accelerometers and gyroscopes. A highly-accurate rate table is used to perform simple six-point measurements on forty devices. The gathered cross-axis sensitivity matrices are subdivided into scale-factor, non-orthogonality and misalignment. Additionally, accel-to-gyro triad alignment is examined. By applying the inverted cross-axis sensitivity matrix to the sensor output and remeasuring all devices, nonorthogonality and accel-to-gyro triad alignment can be compensated to below 0.2 %. Analytical formulas allow the calculation of the achievable precision as a function of sensor noise, magnitude of stimulus and measurement time. Root-causes of non-orthogonality are discussed and a mechanism is proposed, where quadrature motion of one axis induces Coriolis force onto another axis. Lastly, good stability of the accel-to-gyro triad alignment across temperature is demonstrated, indicating that a once-measured compensation is valid across environmental changes and for an extended time.