IMU Body-to-Vehicle Re-Alignment After Device Movement
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Solution Overview
Problem
Inertial navigation systems (INS) using mobile devices experience reduced accuracy due to misalignment between the body and vehicle frames, leading to increased drift and error when non-holonomic constraints are discontinued after movement of the mobile device relative to the vehicle.
Innovation Solution
A method and apparatus for timely re-estimating the misalignment between the body and vehicle frames by identifying key points in time before and after movement, allowing for the resumption of non-holonomic constraints to improve navigation solution accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the mobile device is moved relative to the vehicle, then the device can be repositioned for different usage scenarios, but the frame alignment between body and vehicle frames is lost causing increased navigation drift and reduced accuracy
Solution Approach 1:
The system performs preliminary actions by detecting the movement event and immediately initiating the re-alignment process before navigation accuracy deteriorates significantly. The movement detection triggers a sequence of operations including identifying time points, determining frame orientation, and re-estimating misalignment parameters in advance to restore accurate navigation.
Solution Approach 2:
The system implements feedback by continuously monitoring the relationship between body and vehicle frames and using this information to adjust the navigation solution. When misalignment is detected, the system uses feedback from the IMU data and detected movement to re-estimate the alignment parameters and correct the navigation drift.
2Adaptability or versatility
If non-holonomic constraints are discontinued after mobile device movement, then the system can accommodate frame misalignment, but position errors increase due to drift and navigation accuracy decreases
Solution Approach 1:
The system applies dynamics by making the constraint application adaptive rather than static. The non-holonomic constraints are dynamically adjusted based on the detected frame orientation and misalignment parameters. When the mobile device is repositioned, the system updates the alignment transformation and re-applies constraints with corrected parameters, maintaining reliability while accommodating movement.
Solution Approach 2:
The system changes parameters by re-estimating the misalignment parameters (rotation angles and translation vectors) between body and vehicle frames after mobile device movement. These updated parameters are then used to transform the IMU measurements into the vehicle frame correctly, allowing non-holonomic constraints to be re-applied with accurate parameters that maintain position determination reliability.
3Measurement precision
If the misalignment between body and vehicle frames is re-estimated after movement, then navigation accuracy can be restored, but the process is time-consuming during which navigation solution drifts
Solution Approach 1:
The system applies the skipping principle by rapidly processing the re-alignment through efficient algorithms that skip unnecessary computational steps. The system uses the detected movement information and current IMU data to directly compute the updated alignment parameters without performing exhaustive calculations, thereby rushing through the time-consuming re-estimation process and minimizing navigation drift during the transition.
Solution Approach 2:
The system performs preliminary actions by pre-processing IMU data and movement detection before the actual re-alignment computation. By identifying the movement event and preparing the necessary transformation parameters in advance, the system reduces the computational time required for the full re-alignment process, thereby minimizing the time during which navigation accuracy is compromised.
Data Source
AI summary
A method, apparatus and computer program product are configured to re-estimate misalignment between the body frame of an inertial measurement unit (IMU) and the vehicle frame following movement of a mobile device embodying the sensor(s) of the IMU relative to the vehicle. In a method, movement of the mobile device relative to the vehicle is detected. In response to detecting movement of the mobile device relative to the vehicle, the method identifies (i) a point in time prior to or corresponding to commencement of movement of the mobile device relative to the vehicle and (ii) a subsequent point in time at which the mobile device is stable relative to the vehicle. The method then determines the frame orientation between body and vehicle frames. Based upon the determined frame orientation between body and vehicle frames, the method also includes determining a navigation solution for the vehicle in reliance upon non-holonomic constraints.