Inter-Arm Registration via Image Velocity Feedback for Teleoperation
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Solution Overview
Problem
In computer-assisted devices with repositionable arms, determining accurate registration between imaging devices and other instruments is challenging, especially when the imaging device is not mounted to a repositionable arm, leading to difficulties in teleoperation and maintaining precise geometric relationships.
Innovation Solution
A control unit coupled to a repositionable arm that receives images from an imaging device, determines observed and expected velocities or orientations of instrument features, transforms them to a common coordinate system, calculates errors, and updates the registration transform to refine the geometric relationship.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the imaging device is not mounted to a repositionable arm, then the device complexity is reduced, but the registration accuracy between the imaging device and other instruments deteriorates
Solution Approach 1:
The system continuously captures images of the instrument from the imaging device, calculates observed velocities of instrument features, compares them with expected velocities based on repositionable arm kinematics, and updates the registration transform iteratively. This closed-loop feedback mechanism maintains accurate registration between the imaging device and instrument without requiring mechanical coupling, thus resolving the contradiction between reduced device complexity and maintained registration accuracy.
Solution Approach 2:
The patent replaces the traditional mechanical coupling between the imaging device and repositionable arm with a computational approach. Instead of physically mounting the imaging device to the arm, the system uses image processing, velocity calculation, and mathematical transformation to establish and maintain the geometric relationship. This substitution of mechanical connection with computational methods reduces device complexity while preserving registration accuracy.
2Measurement precision
If the registration transform is updated frequently, then the registration accuracy is improved, but the processing time increases
Solution Approach 1:
The system updates the registration transform iteratively using only the necessary image data and velocity calculations required for correction, rather than performing complete recalibrations. By applying partial updates based on observed velocity errors, the system achieves accurate registration while minimizing processing time and computational overhead.
3Measurement precision
If the observed velocity and expected velocity are transformed to a common coordinate system, then the error calculation accuracy is improved, but the computational complexity increases
Solution Approach 1:
The registration transform serves multiple functions simultaneously: it transforms coordinates between the imaging device and instrument reference frames, enables velocity comparison, and provides the basis for error calculation and update. This multi-functional use of a single transformation matrix reduces overall computational complexity while maintaining accurate error calculation.
Data Source
AI summary
Systems and methods for inter-arm registration include a computer-assisted system having a control unit coupled to a repositionable arm of a computer-assisted device. The control unit is configured to: receive, from an imaging device, successive images of an instrument mounted to the repositionable arm; determine an observed velocity of a feature of the instrument; determine an expected velocity of the feature of the instrument based on kinematics of the repositionable arm; transform the observed velocity and/or the expected velocity to a common coordinate system using a registration transform; determine an error between directions of the observed and expected velocities in the common coordinate system; and update the registration transform based on the determined error. In some embodiments, the instrument is a medical instrument and the imaging device is an endoscope. In some embodiments, the control unit is further configured to control the instrument using the registration transform.