Mobile Device INS Initialization via Frame Alignment
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Solution Overview
Problem
Mobile devices experience accuracy issues when used as navigation aids inside vehicles due to misalignment of their reference frames with the vehicle and Earth frames, leading to inaccurate inertial navigation system outputs.
Innovation Solution
A mobile device equipped with a GNSS receiver, accelerometers, gyroscopes, and a motion-bias-orientation circuit that determines accelerometer and gyroscope biases, as well as spatial relationships between the device's frame of reference and the vehicle and Earth frames, to initialize and re-initialize the inertial navigation system accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mobile device is used as a navigation aid inside a vehicle, then portability and map accuracy are improved, but reference frame misalignment causes navigation accuracy to deteriorate
Solution Approach 1:
The patent replaces mechanical alignment methods (physical orientation of the device) with an automated computational system. The motion-bias-orientation circuit automatically determines spatial relationships between the mobile device frame, vehicle frame, and Earth frame using sensor data from accelerometers, gyroscopes, and GNSS receivers, eliminating the need for manual mechanical alignment while maintaining navigation accuracy
Solution Approach 2:
The patent introduces a motion-bias-orientation circuit as an intermediary component that processes sensor data and computes transformation parameters between different reference frames. This intermediary system acts as a mediator that translates measurements from the mobile device's coordinate system into the vehicle's and Earth's coordinate systems, resolving the reference frame misalignment issue
2Measurement precision
If frame of reference alignment is manually adjusted, then navigation accuracy may be improved, but system complexity and user burden increase
Solution Approach 1:
The motion-bias-orientation circuit performs self-service by automatically determining spatial relationships and computing transformation parameters without user intervention. The system uses its own onboard sensors (accelerometers, gyroscopes, GNSS receiver) to autonomously calculate the orientation between the mobile device, vehicle, and Earth reference frames, eliminating the need for manual alignment procedures
Solution Approach 2:
The patent dynamically changes the parameters used for navigation calculations by computing transformation parameters (rotation matrices, orientation angles) that adapt to the varying spatial relationship between the mobile device and vehicle. These parameters are continuously updated based on sensor measurements, allowing the system to maintain accuracy despite changes in device orientation or vehicle motion
3Measurement precision
If multiple sensors are used to determine spatial relationships, then navigation accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the functionality of multiple sensors (accelerometers, gyroscopes, and GNSS receiver) into a unified motion-bias-orientation circuit that processes data from all sensors simultaneously. By combining these sensor inputs, the system achieves accurate determination of spatial relationships while avoiding the need for separate processing chains, thereby reducing overall power consumption and simplifying the system architecture
Data Source
AI summary
Aspects of the disclosure relate to initializing an inertial navigation system (INS) of a mobile device. Accelerometer bias of a plurality of accelerometers of the mobile device, and gyroscope bias of a plurality of gyroscopes of the mobile device, are determined. A first spatial relationship between a first frame of reference of the mobile device and a second frame of reference of a vehicle transporting the mobile device is determined. A second spatial relationship between the first frame of reference and a third frame of reference of a surface beneath the vehicle is determined. Each of the frames of reference are determined based on output of at least two of the GNSS receiver, the plurality of accelerometers, or the plurality of gyroscopes. The INS is provided with the accelerometer bias, the gyroscope bias, the first spatial relationship, and the second spatial relationship to initialize the INS.