IMU Head Tracker Offset Calibration
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Solution Overview
Problem
Existing IMUs lack the capability to accurately measure and account for the offset between themselves and the object they are mounted on, especially in non-permanent installations, leading to inconsistent orientation measurements.
Innovation Solution
An IMU with built-in alignment capabilities, including an onboard processor and input device, that allows users to capture and apply offsets to calculate the orientation of the object of interest, offering three methods for alignment: using a pre-defined reference orientation, physical alignment, and remote device assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an IMU is mounted physically to an object with limited mounting ways, then the IMU can be installed on the object, but the front of the IMU cannot be accurately aligned with the front of the object
Solution Approach 1:
The system performs preliminary alignment by capturing a reference orientation image of the object before mounting the IMU. This reference image is stored and used later to calculate the offset between the IMU's coordinate system and the object's coordinate system, enabling accurate alignment without complex physical mounting procedures.
Solution Approach 2:
The patent replaces complex mechanical alignment procedures with an image-based computational approach. Instead of using precision mechanical fixtures or manual alignment tools, the system uses a camera to capture the object's orientation and computationally determines the IMU's offset from the object's reference frame, significantly simplifying the mounting process.
2Adaptability or versatility
If an IMU is mounted in a non-permanent position, then the IMU can be easily installed and removed, but the offset between the IMU and the object of interest is not readily knowable
Solution Approach 1:
The system performs self-calibration by automatically capturing images of the object, calculating the offset between the IMU and object coordinate systems, and storing this offset information for future use. This self-service approach eliminates the need for manual offset measurement or complex mounting procedures, allowing flexible repositioning while maintaining measurement accuracy.
Solution Approach 2:
The system performs preliminary offset calculation by capturing reference images and computing the transformation between coordinate systems before actual measurement begins. This pre-established offset information allows the IMU to be mounted in various positions while maintaining accurate object orientation tracking.
3Measurement precision
If an IMU measures only its own motion and orientation, then the IMU can accurately track itself, but it cannot directly measure the motion and orientation of the mounted object
Solution Approach 1:
The system introduces an image processing intermediary that captures visual information about the object's orientation and combines it with the IMU's motion data. The offset calculation acts as a mediator that transforms the IMU's self-referential measurements into accurate object-oriented measurements, preserving all necessary orientation information.
Solution Approach 2:
The patent merges the IMU's motion sensing capabilities with image-based orientation detection. By combining accelerometer/gyroscope data with visual reference frame information and applying the calculated offset, the system produces comprehensive object orientation measurements that leverage both self-measurement accuracy and object context.
Data Source
AI summary
A method of orienting an IMU to an object includes determining a physical offset between the IMU and the object. The user mounts the IMU on the object of interest in a position that is not necessarily physically aligned with the object of interest. The user places the object of interest into a known reference orientation and triggers the system via an input device to capture the IMU's momentary orientation. The assembly calculates the offset between the captured IMU orientation and the reference orientation of the object. The assembly continuously applies the calculated offset to the raw IMU orientation to calculate the orientation of the object of interest.