Ren-Young Liu

Fiber optic gyros for space, marine, and aviation applications

Fiber-optic gyroscopes (FOGs) are under development at Honeywell as the primary next generation inertial sensor. The open-loop FOG technology has been successfully transitioned to production for attitude heading reference systems and the results of this effort are reported. New developments in closed-loop FOG technology aimed at high performance space applications and at navigation grade aviation applications, are underway. In the former case, results on a high precision FOG are reported. In the latter case, special emphasis is placed on improvements of depolarized FOG technology, which promises to produce a low cost navigation grade sensor.

Fiber-optic gyro development for a broad range of applications

Progress in fiber-optic gyroscope development at Honeywell is reported here. The results illustrate the versatility of the technology, showing its potential to meet both the low-cost, small-sized needs of tactical guidance, as well as the very high perfomance needs of inertial navigation and precision applications. In the case of inertial navigation, data is presented that illustrates the possibility of employing a low-cost depolarized design for this use.

Test results of Honeywell's first-generation high-performance interferometric fiber optic gyroscope

Honeywells first-generation, high-performance interferometric fiber-optic gyroscope (IFOG) was tested along with sensor electronics over a limited static and dynamic temperature environment. This serrodyne closed-loop IFOG consisting of polarization-maintaining fiber components and a LiNbO3 phase modulator has simultaneously achieved inertial-grade requirements for bias stability, bias repeatability, bias temperature sensitivity, bias temperature-rate sensitivity, random noise, and scale-factor error over the tested temperature range.

Miniaturized, low-cost IFOG IMU for tactical weapon applications

Honeywell, under contract to the US Air Force, has developed a 25 cubic-inch IFOG IMU brassboard which demonstrated performance of < deg/hr bias stability, < 0.05 deg/(root) hr random noise and < 250 ppm scale factor accuracy over the full military temperature range. To overcome the size constraint of 25 cubic-inch, the three-axis IFOG optical cluster was configured with the minimum IMU configuration having only eight optical components. Special loop-closure signal processing was developed to accommodate all three- axis sensor electronics within a single 3.4-inch electronic board. To achieve the IMU cost target of < 6000 dollars, the design utilizes a very lowest cost optical components such as an 830nm light source along with a 1300 nm single- mode fiber sensing coil. Further cost reduction was realized through the robust design which provides very relaxed gyro assembly tolerances. The 25 cubic-inch IFOG IMU will have sufficient performance, small size, ruggedness for high-g launch, and low unit production cost to be suitable for use in a wide variety of tactical weapon systems.

Test results from a tactical grade IMU using fiber optic gyros and quartz accelerometers

Honeywell has been under contract with the US Air Force to develop a very small tactical grade fiber optic gyro (FOG) IMU. This paper covers program requirements, the FOG IMU description and test results. The unit is 25 cu. inches in volume and has a gyro performance specification of 1-10 deg/hr over the full military temperature range. The unit has been designed with cost the most important parameter in a tradeoff with performance in the specified range. The design approach to the FOGs includes the use of non-polarization maintaining fiber and a unique signal processing approach to minimize the number of components. The use of allied signal quartz vibrating beam accelerometers provides for small size and low cost with tactical performance. Test results over environment evaluate the stability of the gyro and accelerometer parameters through repeated calibrations.

Test Results Of A Prototype Serrodyne Closed-Loop Interferometric Fiber Optic Gyroscope

The test results of a prototype serrodyne closed-loop interferometric fiber optic gyroscope are reported. The rotation sensor used a low-coherence superradiant diode at 0.85 microns wavelength with a polarization-maintaining sensing coil, polarizer and loop coupler. A wide bandwidth Ti:LiNb03 phase modulator was used to provide bias modulation and serrodyne frequency shifting. Performance of the sensor before and after loop closure is discussed. No degradation of the random walk or bias stability was noted with loop closure. The scale factor and dynamic range were improved. Various contributors to scale factor error are discussed.