Originally used in space applications (Attitude and Orbit Control Systems for spacecraft), HRG is now used in advanced inertial navigation systems, in attitude and heading reference systems, and HRG gyrocompasses. Therefore, the gyros can operate in either a "whole angle mode" that sense the standing waves' position or a "force rebalance mode" that holds the standing wave in a fixed orientation with respect to the gyro. The electronics which sense the standing waves are also able to drive them. The device is then able to sense rotation. Therefore, when subject to rotation around the shell symmetry axis, the standing wave does not rotate exactly with the shell, but the difference between both rotations is nevertheless perfectly proportional to the input rotation. This is the wave inertia effect, discovered in 1890 by British scientist George Hartley Bryan (1864–1928). It causes a slow precession of a standing wave around this axis, with an angular rate that differs from input one. In application to the HRG shell, Coriolis forces cause a precession of vibration patterns around the axis of rotation. When coated, tuned, and assembled within the housing, the Q factor remains over 10 million. Such resonators have to be fine-tuned by ion-beam micro-erosion of the glass or by laser ablation in order to be perfectly dynamically balanced. The Q factor is limited by the coating (extremely thin film of gold or platinum) and by fixture losses. This shell is driven to a flexural resonance by dedicated electrostatic forces generated by electrodes which are deposited directly onto separate fused quartz structures that surround the shell.įor a single-piece design (i.e., the hemispherical shell and stem form a monolithic part ) made from high-purity fused quartz, it is possible to reach a Q factor of over 30-50 million in vacuum, thus the corresponding random walks are extremely low. Navigation system in early 1980’s.The HRG makes use of a small thin solid-state hemispherical shell, anchored by a thick stem. Honda succeeded in developing low-cost & high performance Hydrodynamic Gyroscope and used them for car Honda, a Japanese automaker, paid anĪttention on Hydrodynamic Gyroscope (Gas Rate Sensor) which was initially developed for Japanese Defense Since then, Hydrodynamic Gyroscope or Vibrating Gyroscope were used for mass-produced automobile orĬamera and changed its image of expensiveness or short operating device. Therefore, a lot of Japanese manufacturers were interested in and focused on these
The accuracy of these Gyroscopes is not very high, but they are superior in operating life, environmental In 1970’s, Hydrodynamic Gyroscope such as Gas Rate Gyro and Vibrating Gyroscope was actively developed in US. Gyroscope was in practical use in 1980’s, and Fiber Optic Gyroscope followed in 1990’s. In thoseĭays, Strapdown Gyroscope was gradually increased while Platform Gyroscope was decreasing.įrom 1980’s to 2000, mechanical Gyroscope was replaced by non-mechanical Gyroscope. In 1980’s, Inertial Navigation System by Strapdown Ring Laser Gyro was adopted by Boeing and Airbus. Therefore, high accuracy gyroscope is needed for dead reckoning. Depending on the accuracy of gyroscope, errors of heading is accumulated. In dead reckoning, position data is estimated by integral of gyroscope, odometer and accelerometer. However, the accuracy of localization is worsened in Tunnel or Multipath propagation. Through the use of GNSS with centimeter-level positioning accuracy, fully autonomous driving will come closer to realization. Position Accuracy by Gyro Error & Vehicle Speed Detection error can be decreased by introducing external signal of GNSS, vehicle speed etc.Communication method supports RS232C and CAN.Real-time output of behavior and attitude realized by means of advanced inertial arithmetic algorism.Small size, high accuracy and low cost (Small but having accuracy of attitude angle 0.1 degrees).Our MEMS IMU not only detects and outputs 3-axis angular velocity and 3-axis acceleration but also calculatesĪnd outputs attitude angle (roll and pitch) and azimuth angle (yaw).