Reduction of time errors of the inertial measuring module by realization of its structural redundancy on the basis of three-axis micromechanical measuring instruments

Abstract

Redundant inertial measurement units (IMU) are used in security-critical operations since the advent of inertial technology. This approach allows you to create fault-tolerant systems that can detect and isolate defective sensors. Besides, experimental results have shown that redundant IMU is also an effective way to improve the performance of navigation systems. The question is only in the dependence of the accuracy of the unit on the number of sensors used and their mutual orientation.
 This paper analyses the influence of spatial orientation on the accuracy of an IMU with a redundant configuration in the case of using triaxial orthogonal micromechanical measuring modules as atomic structural units.
 The first part of this article concentrates on the geometry of the redundant IMU. Analysis of its metrological model of a redundant showed that, when dealing with orthogonal IMU triads, its resulting accuracy is independent of the relative orientation between them. This fact presents important practical implications since it demonstrates that using complex large-scale installation structures can be avoided. As a result, it is enough to place instead of an array of units, for example, only on one printed circuit board with any orientation. Also, it was found the relationship between the number of sensors employed and the accuracy improvement that enables us to ascertain the exact number of sensors needed to design a navigation system with a certain precision.
 The second part of this article shows the experimental approval of theoretical conclusions during the testing of a prototype block based on three low-cost units (MPU6050) built according to a symmetric tetrahedron scheme.
 The accuracy of the redundant block was experimentally evaluated based on the value of the errors in determining the modulus of gravity acceleration and a given angular velocity of a test rotary platform in a series of positions. The performance of the tested inertial measuring block was better on average in comparison with anyone module from this block that proved the possibility of using these approaches for MEMS sensors in high-accuracy application areas.