Vibratory Gyroscope Scale Factor and Bias on-Run Self-calibration

Abstract

А new method for on-run periodic scale factor and bias self-calibration of vibratory gyroscopes in an inertial measurement unit with a redundant number of sensors is proposed. Self-calibration uses predefined virtual positive and negative angle rates to calibrate the SF, and the bias of the gyroscope that is in calibration mode, while the others, at least three gyroscopes of an inertial measurement unit, whose sensitivity axes do not lie in the same plane, operate in the measurement mode to measure the real angle rate of a vehicle. The projection of the current angle rate onto the sensitivity axis of the gyroscope being calibrated is computed from the results of measuring the full angle rate vector by the other three gyroscopes, creating conditions for the calibration procedure. In contrast to known methods, such as single-axis or multi-axis rotation of an inertial measurement unit and vibration modes reversal, the proposed method does not use mechanical rotation, which requires additional devices, and does not require a reorientation of the vibrating wave, which entails the need to align the parameters of the two measuring channels. The scale factor and bias calibration procedure using this method is the same for any gyroscope of an inertial measurement unit and can be applied to several gyroscopes at the same time. Therefore, the proposed method has great potential for an application not only for small-sized 4-gyro inertial measurement unit based on vibratory gyroscopes but also for multi-gyro inertial measurement unit based on micro-electro-mechanical gyroscopes. Experimentally shown that using the proposed method a gyro requirements mitigation coefficient can be substantially increased and can provide high accuracy for autonomous navigation systems based on low-cost, small-sized, and micro-electro-mechanical gyroscopes.