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Object Inertial Extrinsics Error

Created by: IMU

Overview

These metrics refer to the error between a sequence of measured and optimized extrinsics involving the IMU. Put in mathematical terms:

ΓOEΓIMUEΓCIMUΓOC\Gamma^{E}_{O} \approx \Gamma^{E}_{\text{IMU}} \cdot \Gamma^{\text{IMU}}_{C} \cdot \Gamma^{C}_{O}
  • EE is the inertial frame, a gravity-aligned frame with its origin coincident with the first IMU navigation state
  • OO is the object space
  • IMU\text{IMU} is the current IMU navigation state
  • CC is any component that can observe the object space directly, e.g. a camera

The transform ΓOE\Gamma^{\text{E}}_{O} is the object inertial extrinsic. This calculation is performed for every navigation state of the IMU, since a navigation state directly corresponds to a synced component's observations to the object space in question.

Note that only one of these metrics is created per object space. This metric is closely related to Composed Relative Extrinsics; the strategy is basically the same. However, since IMU cannot directly observe objects, we use the navigation states to infer the relative extrinsics.

Object Inertial Extrinsics

Definition

Object inertial extrinsics error metrics contain the following fields:

Field
TypeDescription
nav_component_idUUIDThe UUID of the IMU component this metric was generated from.
navigation_statesAn array of extrinsics-velocity objectsThe inferred navigation states of the object inertial extrinsic cost.
world_extrinsicsAn array of world extrinsics objectsThe inferred world pose (component from world) of the object inertial extrinsic, ΓOC\Gamma^{\text{C}}_{O}
component_relative_extrinsicsAn array of extrinsics objectsThe inferred component relative extrinsics, ΓCIMU\Gamma^{\text{IMU}}_{C}
object_inertial_extrinsicsAn array of extrinsics objectsThe inferred object inertial extrinsics, ΓOIMU\Gamma^{\text{IMU}}_{O}
misalignmentsAn array of extrinsics objectsThe residual error of each object inertial extrisnic.