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The effects of the tube wall on the fluid flow, permeability and streaming potential are reported for a porous transducer for use in a liquid circular angular accelerometer. Fluid flow and pressure near the surface of the transducer are modeled and validated numerically. We show that the differential pressure across the transducer is not affected by the tube wall. A capillary bundle model is employed to represent the transducer to obtain the radial porosity, permeability and streaming potential distributions due to wall effects. A simulated spherical packing is generated from measured particle parameters to specify the model by calculating the radial porosity distribution. The theoretical permeability and streaming potential coupling coefficient are located within one standard deviation from the mean of measurements. Due to the radial distribution of streaming potential, the electrode can be configured into a large streaming potential region to measure the signal more efficiently. Three electrode configurations are described based on these results, which can be applied to increase the signal of the sensor. [ABSTRACT FROM AUTHOR]

This paper is concerned with the permeability modeling for a kind of porous transducer, which is sintered by glass microspheres. This kind of transducer is used to measure the streaming potential in the liquid-circular angular accelerometer. Kozeny-Carman (KC) equation is improved by taking into account the shape of fluid channel, the porosity of porous transducer, and the particle size distribution (PSD) of glass microspheres in the transducer. Under the assumption of star-like fluid channels, the shape factor is analyzed numerically and further evaluated. The notion of equivalent diameter of microspheres is applied to avoid the error of permeability calculation resulting from the usage of the average diameter. By implementing the experiments of transducers with 9 different PSDs, a relationship among the equivalent diameter, the tortuosity, the average diameter, the porosity and the skewness of the PSD is obtained. The comparison results illustrate that the proposed permeability model considerably reduces the large prediction errors of the previous models when dealing with the mixture of different microspheres and the large skewness of PSD. [ABSTRACT FROM AUTHOR]

In order to compensate errors of inertial measurement unit which is the core of rotational inertial navigation system, self-calibration is utilized as an effective way to reduce navigation error. Error model of navigation solution and initial alignment is used to establish the relationship between navigation errors and inertial measurement unit (IMU) errors. A second order damper is added to the vertical velocity channel to suppress the divergence and then the vertical velocity error can be regarded as an effective observation to estimate the error parameters. Since the accuracy of the self-calibration method is susceptible to the positioning error of gimbals, total least squares (TLS) method is utilized in identification of the error parameters. Experimental results show that all of the twenty-one error parameters can be estimated with the proposed rotation scheme. Compared to least squares (LS) method, TLS method can improve the position accuracy of 8 h by 46.2%. [ABSTRACT FROM AUTHOR]