Tatsuo Shiozawa

Development of a dual-axis thermal convective gas gyroscope

This paper presents the development of a dual-axis gas gyroscope, whose working principle is based on the convective heat transfer and thermoresistive effect of lightly doped silicon. The working principle and the cross-sensitivity of the gas gyroscope are also analyzed. Experiments were performed to confirm the simulation results and good agreement has been achieved. The measured sensitivities for the X-axis and Y-axis were 0.107 mV deg−1 s−1 and 0.102 mV deg−1 s−1, respectively. Compared with a gyroscope of the same configuration but using tungsten as a sensing element, this gyroscope has 42 times greater sensitivity and one quarter the power consumption. These advantageous characteristics are inherited from the high TCR and high resistance of lightly doped p-type silicon. Nonlinearity and cross-sensitivity were measured to be smaller than 0.07% FS and 0.5% FS, respectively. The effect of acceleration on the sensitivity is 0.02 (deg s−1)/g and the measurement resolution based on sensitivity and noise analyses is 0.05 deg s−1. The relations between sensor performance, power consumption and ambient temperature were also realized.

Development of a Dual-Axis Convective Gyroscope With Low Thermal-Induced Stress Sensing Element

This paper describes the design, simulation, and fabrication of a dual-axis gyroscope, whose working principle is based on the thermal convective and thermoresistive effects in lightly doped p-type silicon. The sensor configuration consists of a piezoelectric pump and a microthermal sensing element that is packaged in an aluminum case with a diameter of 14 mm and a length of 25 mm. The novel structure of the sensing element reduces the thermal-induced stress up to 89% as compared with the previous design. The sensor has been fabricated by micro- electromechanical systems technology, and completely packaged and characterized. The measured sensitivities of the gyroscope for the X-axis and Y-axis were 0.082 and 0.078 mV/deg/s, respectively. The cross sensitivities between the two input axes were less than 0.26%, and the nonlinearity was smaller than 0.5% full scale in the range of plusmn200deg/s. The resolution was 0.2deg/s at a measurement frequency of 1 Hz. The noise equivalent rate was 0.18deg/s/radicHz, which is equivalent to an angle random walk of 10.8deg/radich in a 65-Hz bandwidth. The offset drift was 360deg/h in 12-h measurement.

Simulation and Fabrication of a Convective Gyroscope

In this paper, we present the simulation and fabrication of the gas gyroscope. The gas flow inside the hermetically packed sensor is simulated by utilizing 3-D transient compressible flow analysis. The pump working principle and the effect of the Coriolis acceleration on the laminar jet are validated by both analytical formulas and experiments. The sensor utilizes a new sensing element consisting of a thermistor heated by an interior heater, which is independently power-supplied. The sensor performance can be adjusted by the applied voltage on the heater. Both heater and thermistor are optimized in terms of thermal stress. The effect of thermal stress in a p-type silicon thermistor reduces the performance of sensor by 9.5%. The sensor has been calibrated and the role of the heater is verified.

A dual axis thermal convective silicon gyroscope

This paper presents the design, simulation and fabrication of a semiconductor gas gyroscope. The proposed sensor can detect dual axis of angular rate. The gyroscope configuration consists of two main parts, the piezoelectric pump and the micro sensing part, which consists of four thermistor wires with dimension of 400 /spl times/ 4 /spl times/ 2 /spl mu/m/sup 3/, (length /spl times/ width /spl times/ thickness). Good agreement between the sensitivity simulation results and the experimental data has been realized. This gas gyroscope is expected to be applied in ship anti-rolling and stabilization systems.

A dual axis gas gyroscope utilizing low-doped silicon thermistor

This paper presents the design, simulation and fabrication of a dual axis semiconductor gas gyroscope. The sensor configuration consists of a piezoelectric pump and a micro thermal sensing element, packaged in an aluminum case with diameter and length of 14mm and 25mm, respectively. Good agreement between the sensitivity simulation results and the experimental data has been realized. This sensor is to be applied in ship anti-rolling and stabilization systems.

Adual Axis Gas Gyroscope Based on Convective and Thermo-Resistive Effects in Silicon with Low Thermal-Induced Stress Sensing Element

This paper presents the design, simulation and fabrication of a dual axis semiconductor gas gyroscope. The sensor configuration consists of a piezoelectric pump and a micro thermal sensing element, packaged in an aluminum case with diameter and length of 14mm and 25mm, respectively. Novel structures of the sensing element and of the nozzle orifice are presented. The sensor has been fabricated and characterized. The measured sensitivities of the gyroscope for the X- and Y-axis were 0.082mV/deg/sec and 0.078mV/deg/sec, respectively. The cross-sensitivities between the two input axes were less than 0.26%. Non-linearity was measured to be smaller than 0.5% F.S. The resolution was measured to be 0.5deg/sec.

Convective Gas Gyroscope Based on Thermo-Resistive Effect in Si P-N Junction

Convective gas gyroscope based on thermo-resistive effect in Si p-n junction was presented. The p-n junction thermistor, which has very high temperature sensitivity and accuracy, has been utilized as the sensing element. The fabricated p-n junction has the temperature coefficient of resistance (TCR) of 10 times larger and resistance of 20 times lower than those of the silicon thermistor. The lower resistance reduces the thermal noise while the higher value of TCR increases the sensitivity. The measured sensitivities for the X-axis and Y-axis were 28 mV/deg/sec and 27.72 mV/deg/sec, respectively. The cross sensitivity and angular error between flow axis and input axis is measured to be 1%FS and 1.5%FS, respectively. Non-linearity was measured to be smaller than 0.07%F.S.

Fabrication and Characterization of 2-DOF Micro Convective Accelerometer

This paper presents the development of a dual axis convective microaccelerometer, whose working principle is based on the convective heat transfer and thermo-resistive effect of lightly-doped silicon. Different with developed convective accelerometer, the sensor utilizes novel structures of the sensing element which can reduce at least 93% of thermal-induced stress. By using numerical method, the chip dimensions and the package size are optimized. The sensitivity of the sensor was simulated; other characteristics such as frequency response, shock resistance, noise problem are also deeply investigated. The sensor has been fabricated by MEMS process and characterized by experiments.

Development of a Dual Axis Convective Gyroscope with Embedded Heater and Low Thermal-stress Thermistors

In this paper, we present a novel structure of the sensing element or thermistor for the gas gyroscope. The thermistor is heated by a heater core, which is power -supplied independently. This design allows low voltage on the thermistor so that the noise on output voltage is reduced. Both heater and thermistor are optimized in order to reduce the thermal induced stress which occurred in the old thermistors at its working temperatures. The effect of thermal stress appeared in a p-type silicon thermistors reducing the performance of sensor by 7.5%, which is calculated and confirmed by directly measuring relative change of the resistance of the thermistor. A circular flow inside the hermetic case is simulated in detail by utilizing 3D transient compressible flow with the interaction of fluid-solid phase. The working principle and the effect of the jet-pump integrated inside the sensor are explained and validated by experiments using anemometry technique.

Optimization and characterizations of the dual axis gas gyroscope

This paper presents the optimization of the sensing element and characterizations of the dual axis gas gyroscope. Six different design of the sensing element were simulated to obtain higher sensitivity with lower power consumption. The influence of the arms structure to the thermal distribution along the thermistor was clarified. The working principle and the cross-sensitivity of the gas gyroscope are also analyzed. Experiments were performed to confirm the simulation results and good agreement has been realized. The sensor is expected to be applied in ship anti-rolling and stabilization systems