msckf-based visual-inertial odometry with online time calibration

A time calibration and odometer technology, applied in the field of positioning and navigation, can solve problems such as time out of synchronization, VIO algorithm performance degradation, failure, etc.

Active Publication Date: 2021-03-16
TSINGHUA UNIV
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Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the performance of the entire VIO algorithm is degraded or even invalid due to the time asynchrony between the image data and the IMU data sequence in the visual inertial sensor system. visual-inertial odometry

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  • msckf-based visual-inertial odometry with online time calibration

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[0052] The present invention proposes an MSCKF-based visual-inertial odometer with online time calibration, which will be further described in detail in conjunction with specific embodiments below.

[0053] The present invention proposes a visual-inertial odometer based on MSCKF with online time calibration, and the visual-inertial odometer performs the following steps:

[0054] 1) Define the state vector x of the visual-inertial odometer VIO, and define the error state vector of the VIO Specific steps are as follows:

[0055] 1-1) Define the augmented IMU state vector as where the superscript T represents the vector transpose, x I is the IMU state vector, namely where the unit quaternion Indicates the relative rotation from the IMU coordinate system to the global coordinate system, G p I and G v I represent the position and velocity of the camera coordinate system in the global coordinate system, respectively, b g and b a Represents the random walk of the accele...

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Abstract

The invention provides an MSCKF-based visual inertiaodometerwithan online time calibration function, and belongs to the technical field of positioning and navigation. A method comprises steps as follows: time offset variables are added to a state vector; a camera and an inertial measurement unit collect visual images and measure accelerated velocityand angular velocity respectively; the visual images are subjected to feature extraction and feature matching, and two-dimensional observation of feature points in an image plane is obtained; when primaryaccelerated velocityand angular velocity dataare collected by an accelerometer and a gyroscope of the inertial measurement unit respectively, the state vector and a covariance matrix of the visual inertiaodometer are propagated; when the cameracollects new visual images once, the state vector and the covariance matrix are augmented; when the state updating condition is met, a feature point projection model with time offset is established,and the state vector and the covariance matrix are updated; finally, the state vector is subjected to marginalization treatment according to marginalization conditions. The performance of a VIO (virtual input / output) algorithm is not affected by the time offset, so that the MSCKF-based visual inertiaodometer has quite high practicability.

Description

technical field [0001] The invention relates to the technical field of positioning and navigation, in particular to an MSCKF-based visual-inertial odometer with online time calibration. Background technique [0002] In recent years, state estimation has become a hot topic in the field of computer vision and robotics, and it has important manifestations in applications such as autonomous driving, mobile robots, augmented reality, and virtual reality. Among different sensor combinations, the visual-inertial sensor system (composed of a camera and an inertial measurement unit IMU, referred to as a visual-inertial system) has received extensive attention due to its small size, low cost, and good complementarity. In the visual-inertial odometer VIO algorithm, in order to obtain accurate pose estimation, the IMU data in the visual-inertial system is often required to be strictly time-synchronized with the image data of the camera. There is a certain time offset between the IMU da...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01C22/00
CPCG01C22/00
Inventor 孟子阳刘宇真
Owner TSINGHUA UNIV
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