Transverse sensitivity suppression using multi-axis surface encoder with parasitic error compensation

Transverse sensitivity that is mainly resulted from parasitic error motions can introduce undesired motion components and remarkably lower the manipulation qualities of most inertial sensors. This problem becomes even more apparent for multi-axial sensors as additional demands for multi-degree-of-freedom detection become higher. In this letter, a method to minify the transverse sensitivity of an inertial sensor by multi-degree-of-freedom optical sensing and measurement has been reported and tested. A multi-axis-surface-encoder-based biaxial optical accelerometer is fabricated for scheme validation. The surface encoder adopts multi-reading-unit arrangement, and it can not only detect small changes in displacement to calculate the applied acceleration along X- and Y-axes but also quantify the parasitic error motion caused by Z-twist. A suitable compensation strategy is also developed to reveal the concerned outputs without parasitic errors. Experimental results show that the configuration combined with the parasitic error compensation algorithm remarkably diminishes the sensor's transverse sensitivity and measurement error to 1.76% and 2.24%, respectively. Compared with the simple structure optimizations, the technique we proposed is more straightforward and effective. It is also applicable for transverse sensitivity suppression of other inertial sensors, allowing for a similar configuration, such as vibration sensors and inclinometers.