INTEGRATED PHOTONICS OPTICAL GYROSCOPES OPTIMIZED FOR AUTONOMOUS VEHICLES

Abstract

Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05°/√Hr or below (e.g. as low as 0.02°/√Hr), which makes them comparable to fiber optic gyroscopes (FOGs) in terms of performance, at a much lower cost. The low bias stability value in the integrated photonics optical gyroscope corresponds to a low bias estimation error (in the range of 1.5°/Hr or even lower) that is crucial for safety-critical applications, such as calculating heading for autonomous vehicles, drones, aircrafts etc. The integrated photonics optical gyroscopes may be co-packaged with mechanical gyroscopes into a hybrid inertial measurement unit (IMU) to provide high-precision angular measurement for one or more axes.

Description

Claims

1. An inertial measurement unit (IMU) comprising: a packaging substrate disposed within a housing;a mechanical motion-sensing device in the form of an integrated circuit (IC) mounted on the packaging substrate, wherein the mechanical motion-sensing device provides low-precision motion data for a plurality of axes of motion;a modularized integrated photonics optical gyroscope mounted on the packaging substrate, wherein the modularized integrated photonics optical gyroscope provides high-precision rotational measurement data for an axis of motion among the plurality of axes of motion that is perpendicular to the packaging substrate; anda processing device mounted on the packaging substrate, wherein the processing device uses the low-precision motion data and the high-precision rotational measurement data to monitor performance integrity of the IMU to satisfy a predetermined safety standard for an autonomous vehicle.

2. The IMU of claim 1, wherein the housing has a floor, a roof parallel to the floor, and four sidewalls connected perpendicularly between the floor and the roof to form an enclosed box structure, wherein a first sidewall and a third sidewall are parallel to each other and a second sidewall and a fourth sidewall are parallel to each other, and the first and the second sidewalls are perpendicular to each other, and wherein the packaging substrate on mounted on the floor.

3. The IMU of claim 2, wherein the modularized integrated photonics optical gyroscope is mounted parallel to the floor.

4. The IMU of claim 3, wherein a second modularized integrated photonics optical gyroscope is mounted on the first sidewall that is perpendicular to the floor.

5. The IMU of claim 4, wherein a third modularized integrated photonics optical gyroscope is mounted on the second sidewall that is perpendicular to the floor as well as perpendicular to the first sidewall.

6. The IMU of claim 5, wherein the processing device receives high-precision rotational measurement data for three mutually perpendicular axes of motion from the three modularized integrated photonics optical gyroscopes.

7. The IMU of claim 1, wherein the mechanical motion-sensing device comprises micro-electro-mechanical systems (MEMS)-based gyroscopes and accelerometers.

8. The IMU of claim 1, wherein the modularized integrated optical gyroscope comprises a front-end chip that launches light into a rotation-sensing element and receives light back from the rotation sensing element, thereby generating the high-precision rotational measurement data.

9. The IMU of claim 8, wherein the rotation-sensing element of the optical gyroscope comprises silicon nitride (SiN) based low-loss waveguides.

10. The IMU of claim 9, wherein the SiN-based low-loss waveguides comprise one of: a micro-resonator ring, or a waveguide coil with a plurality of turns.

11. The IMU of claim 9, wherein the SiN-based low-loss waveguides are distributed among two or more vertical layers, wherein light is evanescently coupled between the two or more vertical layers.

12. The IMU of claim 8, wherein the rotation-sensing element comprises a fiber loop.

13. The IMU of claim 1, wherein the IMU is part of an inertial navigation system (INS).

14. The IMU of claim 13, wherein the INS is aided by satellite-based navigation data.

15. The IMU of claim 14, wherein when satellite-based navigation data is absent or unreliable, the processing device uses a dead-reckoning (DR) algorithm to predict upcoming position of the autonomous vehicle at least partially based on the high-precision rotational measurement data provided by the modularized integrated photonics optical gyroscope and the low-precision motion data provided by the mechanical motion-sensing device.

16. The IMU of claim 15, wherein the DR algorithm uses additional motion data from one or more sensors in addition to the data provided by the modularized integrated photonics optical gyroscope and the mechanical motion-sensing device.

17. The IMU of claim 1, wherein the processing device executes a sensor fusion algorithm.

18. The IMU of claim 17, wherein the sensor fusion algorithm uses the high-precision rotational measurement data provided by the modularized integrated photonics optical gyroscope, the low-precision motion data provided by the mechanical motion-sensing device, and additional motion data provided by external sensors.

19. The IMU of claim 18, wherein the additional motion data is communicated to the processing device by a vehicle control area network (CAN) bus.

20. The IMU of claim 18, wherein the high-precision rotational measurement data provided by the modularized integrated photonics optical gyroscope is used to calibrate the low-precision motion data provided by the mechanical motion-sensing device and the additional motion data provided by the external sensors.