Online Multi Camera-IMU Calibration

TL;DR

This paper introduces an extended Kalman Filter framework for online calibration of multi-camera IMU systems, improving real-time sensor calibration accuracy in visual-inertial navigation.

Contribution

It extends existing Kalman Filter methods to handle multiple cameras and reformulates measurement models for fiducial detection data, enabling online extrinsic calibration.

Findings

Validated stability and accuracy with non-overlapping cameras

Demonstrated improved real-time calibration performance

Open-sourced the generalized filter code

Abstract

Visual-inertial navigation systems are powerful in their ability to accurately estimate localization of mobile systems within complex environments that preclude the use of global navigation satellite systems. However, these navigation systems are reliant on accurate and up-to-date temporospatial calibrations of the sensors being used. As such, online estimators for these parameters are useful in resilient systems. This paper presents an extension to existing Kalman Filter based frameworks for estimating and calibrating the extrinsic parameters of multi-camera IMU systems. In addition to extending the filter framework to include multiple camera sensors, the measurement model was reformulated to make use of measurement data that is typically made available in fiducial detection software. A secondary filter layer was used to estimate time translation parameters without closed-loop feedback of sensor data. Experimental calibration results, including the use of cameras with non-overlapping fields of view, were used to validate the stability and accuracy of the filter formulation when compared to offline methods. Finally the generalized filter code has been open-sourced and is available online.